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Abstract
Experiments were conducted to evaluate the effects of relative humidity (r.h.; 75%, 80%, 85%, 97%) and temperature (10, 13, 15, 25, 30 °C) on aflatoxin production in previously dried (3.5% moisture content; m.c.) Brazil nuts. Initially Aspergillus spp. were isolated from the surfaces of whole in-shell (WIS) Brazil nuts imported from Peru using A. flavus and A. parasiticus agar (AFPA). Isolates were subsequently screened for aflatoxin production using yeast extract sucrose medium. Total aflatoxin (B1+B2+G1+G2+M1) was analyzed using an immunoassay technique while the presence of aflatoxin was confirmed using thin-layer chromatography. The surface of shelled half-nuts (simulating damaged or trimmed nuts), shelled whole (SW) nuts, and WIS nuts following a chlorine wash and water rinse, served as sites for inoculation (10 μl; 105/ml) using an aflatoxigenic isolate. Maximum concentrations of total aflatoxin and B1 were detected in nuts stored at 97% r.h. and at temperatures of 25–30 °C. Shelled half-nuts contained the highest total (6817 ng/g) and B1 (4483 ng/g) aflatoxin. WIS nuts contained the least total and B1 toxin with maximum concentrations of 93 and 49 ng/g, respectively. Aflatoxin was not detected (detection limit of 1.75 ng/g) in nuts maintained at either 10 °C (97% r.h.) or at 30 °C (75% r.h.) for up to 60 d. Maximal moisture contents (%) and water activity values (aW) for nuts stored at these conditions were 4.50 and 0.78, and 9.14 and 0.92, respectively. Results of this study indicate that the limiting moisture content and aW values required to control aflatoxin production () in SW and WIS stored at 30 °C for up to 60 d are 4.5, 0.68, 5.0, and 0.75, respectively. Overall, increasing the relative humidity and temperature during storage resulted in an increase in aflatoxin and these were shown to be the most significant variables influencing toxin production in Brazil nuts.
... It is well-known that several biotic and abiotic factors exert direct effects on mycotoxin production, including humidity, temperature, substrate composition (Ciegler 1978;Arrus et al. 2005;FIB 2009), water activity, aeration, microbial population and competition, stress factors, insects, and substrate (Ciegler 1978;Bhatnagar et al. 2002). Among them, temperature is considered one of the most critical determinants (Arrus et al. 2005;Freitas-Silva et al. 2013). ...
... It is well-known that several biotic and abiotic factors exert direct effects on mycotoxin production, including humidity, temperature, substrate composition (Ciegler 1978;Arrus et al. 2005;FIB 2009), water activity, aeration, microbial population and competition, stress factors, insects, and substrate (Ciegler 1978;Bhatnagar et al. 2002). Among them, temperature is considered one of the most critical determinants (Arrus et al. 2005;Freitas-Silva et al. 2013). ...
... Contamination with mycotoxins is a recurrent problem in Brazil nuts and is caused mainly by post-harvest infection with Aspergillus section Flavi species. In general, the temperature remains between 25 and 30°C throughout the Amazonia region (Arrus et al. 2005;Freitas-Silva et al. 2013) and is higher than 30°C post-extractivism (Silva et al. 2016). Temperature is a key environmental factor that may favor the growth of these fungi and aflatoxin production (Arrus et al. 2005). ...
Aspergillus nomius is a potent producer of aflatoxins B and G and is one of the most common species of fungi found in Brazil nuts. Temperature is considered a major abiotic factor that influences fungal colonization and aflatoxin production in nuts during pre- and post-harvest. Therefore, assessment of the response of aflatoxigenic species to different temperatures is important to add information about the understanding of aflatoxin production by Aspergillus nomius and may help in the development of new strategies to prevent aflatoxin contamination. The aim of this study was to evaluate the effect of temperature (25, 30, and 35 °C) on the radial growth, aflatoxin production (B and G), and aflatoxin gene expression of seven A. nomius strains isolated from Brazil nuts. The optimal temperature for growth was 30 °C and was also the best condition for the expression of the aflR, aflD, and aflQ genes. However, maximum production of aflatoxins B and G occurred at 25 °C. Interestingly, high expression of the structural gene aflQ was observed in the maximum aflatoxin production condition (25 °C). The present study demonstrates that temperature may influence aflatoxin production by A. nomius. The combination of molecular and physiological data aids the understanding of the aflatoxigenic species response to different temperatures and can assist in predicting the driving environmental factors that influence aflatoxin contamination of Brazil nuts.
... The relationship between the moisture content of the nuts and fungal growth indicated that the reduction in moisture content was efficient in reducing pre-existing fungal contamination in the product (Table 1). However, the fungi already contaminate the nuts in the forest (STDF, 2008), since they are present in the soil (CALDERARI et al., 2013;BAQUIÃO et al., 2012) and in the air near the production area as well as in the Brazil nut pods in the forest ARRUS et al., 2005). ...
... The water activity remained at a high value even after pre-drying, which was close to the optimum value for the growth of Aspergillus flavus (0.80-0.95) (PEREIRA et al., 2002), and aflatoxin production (0.68-0.87) (ARRUS et al., 2005). Baquião et al. (2012) demonstrated that water activity plays an important role in fungal growth during this period, with a consequent potential risk for aflatoxin production. ...
... Whereas aflatoxins are thermostable (NUNES et al., 2003), it is possible that some of the potential AFPA detected were from non-aflatoxigenic strains, or that some field conditions may or may not have enabled the production of these toxins. According to Arrus et al. (2005) and Leite et al. (2014), although the fungi of the genus Aspergillus are toxin producers, they are not always related to the presence of aflatoxins. Nunes et al. (2003) added that the fungus can be inactivated or eliminated during processing, and may not be present in the manufactured product, although any mycotoxins produced will remain. ...
The natural drying of in-shell Brazil nuts carried out by the extractivists is not effective in reducing contamination by aflatoxin-producing fungi. Thus the use of an artificial heater could prove to be a favourable method to bring about a rapid reduction in the moisture content of the nuts and thereby prevent fungal growth. Hence the objective of this study was to evaluate the efficiency of a natural convection-type drier with respect to the physical, physicochemical and microbiological quality of nuts after drying for 6 hours at 45 °C. A random block experimental design with two treatments (nuts before and after drying) was used, using 10 replications of 3 kg. The nuts were analysed for their moisture, ash, protein, dietary fibre, total carbohydrates and lipid contents, water activity, total count of filamentous, potentially aflatoxin-producing fungi, and also the quantification of aflatoxins B1, B2, G1, G2 and the total aflatoxins. There was no effect of drying on the Aspergillus flavus and Aspergillus parasiticus counts or on the physicochemical composition of the nuts, except for the ash content. However the moisture content of the nuts was reduced by 39.7% and there was a decrease in the contamination by pre-existing total filamentous fungi. The dryer was effective in reducing the average time taken for drying as compared to the traditional method used by extractivists.
... During the harvest, the Brazil nut has approximately 26% of water content on wet basis (% w.b.) (NOGUEIRA et al., 2014). During processing in industry, this value ranges from 3.50 to 11.25% w. b. (ARRUS et al., 2005), reaching 2.00% w.b. which is an appropriated water content for the market (ALVARES et al., 2012). Regardless of which stage the product is in, a suitable methodology for analyzing the water content, safely, is required. ...
... Water contents in the studied samples indicate typical waters for Brazil nuts during processing and marketing steps. Álvares et al. (2012) studying the quality of processed Brazil nuts marketed in Rio Branco city, Acre State, Brazil, found water contents varying from 2.00 to 3.12% w.b., being this interval compatible with value for shelled nuts from industry, that showed a water content of 2.30% w.b. Arrus et al. (2005) analyzing in-shell nuts from industry and storing the samples for 60 days at 30°C and 97% of relative humidity, found water contents from 3.50% to 11.26 % w.b. These values comprise those three remained contents for the studied samples, which are 4.50; 7.25 and 9.10% w.b. ...
... This is especially important to processing industry, because the product with high water content is more susceptible to become rotten, to mould growth and to mycotoxins synthesis. This information is corroborated by several authors as Freire et al. (2000); Arrus et al. (2005); Baquião et al. (2012) and Reis et al. (2012). ...
ABSTRACT: The Brazil nut plant (Bertholletia excelsa Bonpl.) is native from Amazonia region. The nuts are extensively used as food and in cosmetic industries. During its processing, one of the most important parameters to be determined is its water content, which is critical to drying and storage steps. Thus, the objective on this study was to verify the accuracy of the method of oven at 105 °C to 24 h on water content measurement for Brazil nuts, in comparison to water content levels determined by Karl Fisher titration. It was verified that applying oven at 105 °C to 24 h to determine water content of Brazil nuts is not adequate, once the results were higher than those obtained from Karl Fisher titration. The samples submitted to oven showed high peroxide value, indicating its oxidation and consequent formation of volatile secondary compounds, which could be the reason to overestimation of water content determined.
Keywords: Karl Fischer, oil, peroxide, quality.
RESUMO: A castanheira-do-brasil (Bertholletia excelsa Bonpl.) é uma planta nativa da região da Amazônia. As nozes são amplamente utilizadas como alimento e nas indústrias de cosméticos. Durante o seu processamento, um dos parâmetros mais importantes para ser determinado é o teor de umidade, o qual é crítico para as etapas de secagem e armazenagem. Assim, o objetivo deste estudo foi verificar a exatidão do método de estufa a 105 °C por 24 h sobre a determinação de umidade para a castanha do Brasil, em comparação com os níveis de umidade determinados por titulação de Karl Fisher. Verificou-se que a aplicação da estufa a 105 °C por 24 h para determinar o teor de umidade da castanha não é eficiente, uma vez que os resultados foram mais elevados do que os obtidos a partir de titulação de Karl Fisher. As amostras submetidas à estufa apresentou alto índice de peróxidos, indicando a sua oxidação e consequente formação de compostos voláteis, que poderia ser a razão para a superestimação do teor de umidade determinado.
Palavras-chave: Karl Fischer, óleo, peróxido, qualidade.
... During the harvest, the Brazil nut has approximately 26% of water content on wet basis (% w.b.) (NOGUEIRA et al., 2014). During processing in industry, this value ranges from 3.50 to 11.25% w. b. (ARRUS et al., 2005), reaching 2.00% w.b. which is an appropriated water content for the market (ALVARES et al., 2012). Regardless of which stage the product is in, a suitable methodology for analyzing the water content, safely, is required. ...
... Water contents in the studied samples indicate typical waters for Brazil nuts during processing and marketing steps. Álvares et al. (2012) studying the quality of processed Brazil nuts marketed in Rio Branco city, Acre State, Brazil, found water contents varying from 2.00 to 3.12% w.b., being this interval compatible with value for shelled nuts from industry, that showed a water content of 2.30% w.b. Arrus et al. (2005) analyzing in-shell nuts from industry and storing the samples for 60 days at 30°C and 97% of relative humidity, found water contents from 3.50% to 11.26 % w.b. These values comprise those three remained contents for the studied samples, which are 4.50; 7.25 and 9.10% w.b. ...
... This is especially important to processing industry, because the product with high water content is more susceptible to become rotten, to mould growth and to mycotoxins synthesis. This information is corroborated by several authors as Freire et al. (2000); Arrus et al. (2005); Baquião et al. (2012) and Reis et al. (2012). ...
ABSTRACT: The Brazil nut plant (Bertholletia excelsa Bonpl.) is native from Amazonia region. The nuts are extensively used as food and in cosmetic industries. During its processing, one of the most important parameters to be determined is its water content, which is critical to drying and storage steps. Thus, the objective on this study was to verify the accuracy of the method of oven at 105 °C to 24 h on water content measurement for Brazil nuts, in comparison to water content levels determined by Karl Fisher titration. It was verified that applying oven at 105 °C to 24 h to determine water content of Brazil nuts is not adequate, once the results were higher than those obtained from Karl Fisher titration. The samples submitted to oven showed high peroxide value, indicating its oxidation and consequent formation of volatile secondary compounds, which could be the reason to overestimation of water content determined.
Keywords: Karl Fischer, oil, peroxide, quality.
RESUMO: A castanheira-do-brasil (Bertholletia excelsa Bonpl.) é uma planta nativa da região da Amazônia. As nozes são amplamente utilizadas como alimento e nas indústrias de cosméticos. Durante o seu processamento, um dos parâmetros mais importantes para ser determinado é o teor de umidade, o qual é crítico para as etapas de secagem e armazenagem. Assim, o objetivo deste estudo foi verificar a exatidão do método de estufa a 105 °C por 24 h sobre a determinação de umidade para a castanha do Brasil, em comparação com os níveis de umidade determinados por titulação de Karl Fisher. Verificou-se que a aplicação da estufa a 105 °C por 24 h para determinar o teor de umidade da castanha não é eficiente, uma vez que os resultados foram mais elevados do que os obtidos a partir de titulação de Karl Fisher. As amostras submetidas à estufa apresentou alto índice de peróxidos, indicando a sua oxidação e consequente formação de compostos voláteis, que poderia ser a razão para a superestimação do teor de umidade determinado.
Palavras-chave: Karl Fischer, óleo, peróxido, qualidade.
... During the harvest, the Brazil nut has approximately 26% of water content on wet basis (% w.b.) (NOGUEIRA et al., 2014). During processing in industry, this value ranges from 3.50 to 11.25% w. b. (ARRUS et al., 2005), reaching 2.00% w.b. which is an appropriated water content for the market (ALVARES et al., 2012). Regardless of which stage the product is in, a suitable methodology for analyzing the water content, safely, is required. ...
... Water contents in the studied samples indicate typical waters for Brazil nuts during processing and marketing steps. Álvares et al. (2012) studying the quality of processed Brazil nuts marketed in Rio Branco city, Acre State, Brazil, found water contents varying from 2.00 to 3.12% w.b., being this interval compatible with value for shelled nuts from industry, that showed a water content of 2.30% w.b. Arrus et al. (2005) analyzing in-shell nuts from industry and storing the samples for 60 days at 30°C and 97% of relative humidity, found water contents from 3.50% to 11.26 % w.b. These values comprise those three remained contents for the studied samples, which are 4.50; 7.25 and 9.10% w.b. ...
... This is especially important to processing industry, because the product with high water content is more susceptible to become rotten, to mould growth and to mycotoxins synthesis. This information is corroborated by several authors as Freire et al. (2000); Arrus et al. (2005); Baquião et al. (2012) and Reis et al. (2012). ...
The Brazil nut plant (Bertholletia excelsa Bonpl.) is native from Amazonia region. The nuts are extensively used as food and in cosmetic industries. During its processing, one of the most important parameters to be determined is its water content, which is critical to drying and storage steps. Thus, the objective on this study was to verify the accuracy of the method of oven at 105 °C to 24 h on water content measurement for Brazil nuts, in comparison to water content levels determined by Karl Fisher titration. It was verified that applying oven at 105 °C to 24 h to determine water content of Brazil nuts is not adequate, once the results were higher than those obtained from Karl Fisher titration. The samples submitted to oven showed high peroxide value, indicating its oxidation and consequent formation of volatile secondary compounds, which could be the reason to overestimation of water content determined. Restrições ao uso da estufa para determinação de umidade de castanha do Brasil RESUMO: A castanheira-do-brasil (Bertholletia excelsa Bonpl.) é uma planta nativa da região da Amazônia. As nozes são amplamente utilizadas como alimento e nas indústrias de cosméticos. Durante o seu processamento, um dos parâmetros mais importantes para ser determinado é o teor de umidade, o qual é crítico para as etapas de secagem e armazenagem. Assim, o objetivo deste estudo foi verificar a exatidão do método de estufa a 105 °C por 24 h sobre a determinação de umidade para a castanha do Brasil, em comparação com os níveis de umidade determinados por titulação de Karl Fisher. Verificou-se que a aplicação da estufa a 105 °C por 24 h para determinar o teor de umidade da castanha não é eficiente, uma vez que os resultados foram mais elevados do que os obtidos a partir de titulação de Karl Fisher. As amostras submetidas à estufa apresentou alto índice de peróxidos, indicando a sua oxidação e consequente formação de compostos voláteis, que poderia ser a razão para a superestimação do teor de umidade determinado. Palavras-chave: Karl Fischer, óleo, peróxido, qualidade. Recebido em agosto/2016; Aceito em outubro/2016.
... These authors also state that the Brazil nut, after the traditional pre-drying at this site, reaches 15% b.u., reducing by 50% its initial content, however, this moisture is still not low enough to avoid growth of micro-organisms. Leite (2008), when studying the behavior of the product stored in the predrying conditions mentioned above, found that after 90 days of storage, the nut reaches water activity of 0.74, exceeding the limit of 0.70 recommended by Arrus et al. (2005a) to prevent production of aflatoxin. The storage conditions of nuts seem to have an important influence on the population of fungi Aspergillus section Flavi (Reis et al., 2014). ...
... After the increase period, verified until the first 30 days of period of storage (Figure 3), fungal contamination remained relatively stable with a reduction in moisture content of the environment and almond during storage. Arrus et al. (2005a), when performing storage studies with nuts in shell also observed that the humidity of 5% avoided the growth of toxigenic fungi. However, in this study, the moisture content of almonds was obtained only after 60 days of storage, indicating that a more efficient pre-drying before storage or in a system with hot air injection in the warehouse are required in order to maintain the quality of the nuts during storage. ...
... Therefore, the reduction in moisture and water activity of the seeds by drying is extremely important to reduce the critical levels of contamination (Arrus et al., 2005b), a situation observed in this study using the warehouse with forced ventilation. Leite (2008) and Arrus et al. (2005a) also observed an increase in the contamination of total and potentially aflatoxigenic fungi in the Brazil nut on the first 30 days of storage. Thus, considering the conditions in the Amazon region, even the 30-day storage can be worrisome, because of the high temperatures and relative humidity of the environment that the nuts are submitted, which are favorable to fungal contamination. ...
ABSTRACT The traditional system of collection and storage of Brazil nut compromises seriously the quality of these almonds as it contributes to the high incidence of contaminants, like fungi of the genus Aspergillus, which can produce aflatoxins. In this study, the objective was to evaluate the influence of the storage period in studied conditions, on the physicochemical characteristics and on the microbiological contamination of Brazil nuts. The experimental was designed as completely randomized, considering as treatments the storage period (0 - control, 30, 60, 90, 120 and 150 days) with four replicates of 3 kg of Brazil nuts each. The samples were submitted to physicochemical and microbiological analysis. It was observed that almonds submitted to the storage had their moisture content reduced by 78.2% at 150 days of storage, however, this reduction was not fast enough to avoid surface contamination by filamentous and potentially aflatoxins producing fungi. The critical period of contamination occurred on the first 30 days of storage when there was an increase of the studied fungi, as well as B1 and total aflatoxin. The studied storage conditions were four times more effective in reducing the product moisture content than the traditional methods, however, pre-drying is necessary to avoid contamination of the product.
... Fungal contamination of this food product is a common public health problem in many countries and fungal invasion in Brazil nut causes a major economic impact on the marketing of this product, leading to losses in the production chain. Brazil nut contamination is mainly associated with aflatoxins, which belong to a group of fungal toxins known as mycotoxins, which have strong carcinogenic and hepatotoxic activity (Arrus, Blank, Abramson, Clear, & Holley, 2005;de Mello & Scussel, 2009;Freitas-Silva & Venâncio, 2011;Martins, Klusczcovski, & Scussel, 2014;Pacheco & Scussel, 2007). The contamination of Brazil nuts seeds with aflatoxins produced by strains of Aspergillus section Flavi has been reported (Arrus et al., 2005;Baquião, 2012;Pacheco & Scussel, 2007). ...
... Brazil nut contamination is mainly associated with aflatoxins, which belong to a group of fungal toxins known as mycotoxins, which have strong carcinogenic and hepatotoxic activity (Arrus, Blank, Abramson, Clear, & Holley, 2005;de Mello & Scussel, 2009;Freitas-Silva & Venâncio, 2011;Martins, Klusczcovski, & Scussel, 2014;Pacheco & Scussel, 2007). The contamination of Brazil nuts seeds with aflatoxins produced by strains of Aspergillus section Flavi has been reported (Arrus et al., 2005;Baquião, 2012;Pacheco & Scussel, 2007). According to the report of the Codex Alimentarius Commission, the limit of aflatoxins in Brazil nuts for consumption is 10 mg kg À1 , and 15 mg kg À1 for shelled nuts destined for further processing. ...
... During the harvesting of Brazil nut pods, the nuts are processed under the environmental conditions of the Amazon region, with temperatures generally greater than 30 C and relative humidity greater than 70%. These conditions affect the moisture content (mc) and water activity (Aw) of the Brazil nut and provide conditions for aflatoxigenic fungi to produce aflatoxins (Arrus et al., 2005;de Mello & Scussel, 2009;Martins et al., 2014;Pacheco & Scussel, 2007). Therefore, an efficient drying process that maintains the organoleptic features of the nuts must be applied in order to avoid fungal infestation. ...
Fungal contamination of Brazil nuts can cause health problems, which limits their worldwide consumption and leads to economic restrictions for the producing regions. In this study the contamination of Brazil nut seeds by aflatoxin-producing fungal strains was investigated. It was observed that of the 31 strains isolated from the inside of the seed coat, 39% showed aflatoxigenic potential, indicating a high level of contamination by microorganisms which produce aflatoxins, which have strong carcinogenic and hepatotoxic activity. The moisture content and water activity are determining factors for fungal growth. Measurements of the dielectric properties at microwave frequencies of the Brazil nut shell and the kernel reveals that the shell has a higher loss tangent (0.12) at 30 °C relative to the kernel (0.06) and high values for the penetration depth of both shell (20 cm) and kernel (35 cm) that are related to their chemical composition. Microwave heating was employed leading to reductions in the moisture content (46.4%) and water activity (20%). Furthermore, the effectiveness of microwave dielectric heating as a disinfestation process for contaminated nuts was investigated, showing that colonization inside the shell decreased by 61.67% and on the kernel by 81.75%, without damaging the organoleptic properties of the Brazil nut seeds.
... Moisture content is correlated with the water activity of tree nuts, and high levels of both of these factors favour the development of moulds and other microorganisms during storage (Arrus et al., 2005;Venkatachalam and Sathe, 2006). Water activity is the amount of free water available in materials, including food samples, that is able to take part in enzymatic, physical and chemical reactions (Maltini et al., 2003;Maneffa et al., 2017). ...
... Water activity also influences the development of aflatoxins in Brazil nuts. High temperature (25-30°C v. 13-15°C) and high relative humidity (97% v. 80-85%) are the main contributors to the development of aflatoxins in Brazil nut kernels, but aflatoxin development at 30°C can be curtailed by storage treatments that maintain water activity ≤0.68 (Arrus et al., 2005). The optimum water activity for storage of almond, Brazil nut, cashew nut, hazelnut, macadamia nut, pecan nut, pine nut, pistachio and walnut is A w < 0.53 and a temperature of 25°C (Venkatachalam and Sathe, 2006). ...
The global market for tree nuts is growing rapidly with trade in excess of $US32 billion annually. Tree nuts have a high oil content and fatty acid composition that can render them susceptible to oxidative rancidity and rapid deterioration. In spite of their global importance, there is limited information on optimal storage conditions and shelf lives of many species of tree nut. This review explores current knowledge of the major factors that influence the shelf life of tree nuts. Storage conditions greatly influence the quality and shelf life of tree nuts. Tree nut species differ in their storage requirements because of their varying oil and fatty acid compositions. In general, nuts with high levels of monounsaturated fatty acids are more stable and less susceptible to oxidative rancidity than nuts containing high levels of polyunsaturated fatty acids. Temperatures ranging from 4 to 15°C, kernel moisture content around 2.5%, relative humidity of about 40-60%, oxygen concentration less than 2.5%, and dark conditions are ideal storage conditions for most tree nuts. Harvesting time, cultivar and storage of nuts either as nut-in shell or as kernel also affect the quality and shelf life of nuts. There is a need for tree-nut industries to derive universal rancidity indicators for quality control. Optimised storage conditions will provide the best nutritional quality and health benefits of tree nuts for consumers.
... The concentration of aflatoxin varied in different region worldwide due to temperature and relative humidity variation. The most appropriate condition for aflatoxin formation is at 18-20% moisture content with more than 82% relative humidity and optimum temperature of 25-30 • C (Ahmed and Asghar, 2021). The observed results in this study are supported by Nath et al. (2019) who studied red chilli powder and reported that storage temperature and packaging material significantly affect the quality characteristics of red chilli powder. ...
... another study, significant increase in aflatoxins in Brazil nuts stored at 25 • C with the increase in relative humidity (75-97%) was observed (Arrus et al., 2005) while Nakai et al. (2008) stored peanuts (hulls and 69 in-shells) at different temperatures and relative humidity levels and noted high aflatoxin contamination in peanuts at 24-26 • C at 83-84% relative humidity. In the present study differences in total aflatoxins in spices was observed. ...
The current research aims to examine the effect of storage conditions on aflatoxin production in different spices. For this purpose, different samples of spices (Red chilies, Black peppers, and Cumin) were packaged in different packing materials, high-density polyethylene bags, and jute bags and stored in a controlled environment at 25 • C temperature with varying relative humidity conditions (RH: 65%, 75%, 85%) and evaluated for moisture content , total phenolics, Aspergillus count, total fungal count, and aflatoxins. Packaging materials and storage conditions showed a gradual increase in the tested parameters with increased humidity. The mean Aspergillus count for red chillies, cumin, and black pepper was lowest in HDPE (2.20 × 10 2 , 3.00 × 10 1 and 4.50 × 10 1 , respectively) with 65% moisture content. Aflatoxins were also detected highest (3.33 ppb) in the jute package with 85% moisture content as compared to HDPE (0.9 ppb) for red chilies. Evaluated results proved that spices packed and stored in polyethylene bags retained better quality at 65% relative humidity, where aflatoxin levels were not detected even at 90 days storage period. However, the aflatoxin level was observed lowest (0.13 ppb in cumin) after 120 days of storage. Thus, the utilization of polyethylene packages as compared to jute bags has a better effect on the safety and quality of spices by controlling aflatoxin production during storage.
... There are some studies in literature about secondary metabolite formation of microorganisms induced by water activity in nut fruits (Arrus et al., 2005;Venkatachalam and Sathe, 2006;Gallo et al., 2016) or about the effects of different treatments on water activity of the products (Akçin and Bostan, 2019;Marzocchi et al., 2017). Lopez et al., (1995) investigated hygroscopic behavior of Negret, Pauetet and Tonda Romana hazelnut cultivars. ...
... aw conditions. Arrus et al. (2005) indicated that aflatoxin development initiated in Brazilian nuts at ≤0.68 water activity and 30°C storage temperature. On the other hand, Venkatachalam and Sathe (2006) indicated optimum storage temperature for almond, Brazil nut, cashew nut, hazelnut, macadamia, pecans, pine nuts, pistachios and walnuts as 5°C and aw value as ˂ 0.53. ...
Objective Observation of the changes in water activity values of some Turkish hazelnut cultivars at different moisture levels (ML) at varying ambient temperatures. Thus, especially in hazelnut storage and transfer processes, regulations regarding the protection of the quality of the product under changing humidity and temperature conditions are foreseen. Material and Methods In this study, water activity (aw) of Tombul, Palaz, Çakıldak and Kalınkara hazelnuts were determined at different ML (2, 4, 6, 8, 9 and 12%) and different temperatures (20, 21, 22, 23, 24, 25, 26, 27, 28, 29 and 30°C). Regression equations were generated to estimate aw values of hazelnuts with a known moisture at different ambient temperatures. Results Considering the entire temperatures, it was observed that a unit (1%) increase in moisture yielded 0.055 - 0.062 unit increases in Çakıldak hazelnut cultivar, 0.052 - 0.055 unit increases in Palaz cultivar, 0.047 - 0.050 unit increases in Tombul cultivar and 0.047 - 0.048 unit increases in Kalınkara cultivar. Different aw values were observed at the same ML of the cultivars and generally the aw values were tended to increase with increasing temperatures. Conclusion It was concluded that water activity influenced several quality parameters (color, lipid oxidation and etc.). Present findings revealed that hazelnut cultivars with the same moisture levels might have different water activity values. The fact that the varieties at the same ML have different water activity values indicates that it will be more objective to use the water activity value in storage or shelf life studies. In the calculations made using the obtained formula, it was seen that Palaz and Kalınkara (at the same ML) had higher aw values than the other two cultivars. For this reason, it is thought that storing Palaz and Kalınkara separately from Tombul and Çakıldak cultivars may reduce the possible risks.
... Moisture content is correlated with the water activity of tree nuts, and high levels of both of these factors favour the development of moulds and other microorganisms during storage (Arrus et al., 2005;Venkatachalam and Sathe, 2006). Water activity is the amount of free water available in materials, including food samples, that is able to take part in enzymatic, physical and chemical reactions (Maltini et al., 2003;Maneffa et al., 2017). ...
... Water activity also influences the development of aflatoxins in Brazil nuts. High temperature (25-30°C v. 13-15°C) and high relative humidity (97% v. 80-85%) are the main contributors to the development of aflatoxins in Brazil nut kernels, but aflatoxin development at 30°C can be curtailed by storage treatments that maintain water activity ≤0.68 (Arrus et al., 2005). The optimum water activity for storage of almond, Brazil nut, cashew nut, hazelnut, macadamia nut, pecan nut, pine nut, pistachio and walnut is A w < 0.53 and a temperature of 25°C (Venkatachalam and Sathe, 2006). ...
The global market for tree nuts is growing rapidly with trade in excess of $US32 billion annually. Tree nuts have
a high oil content and fatty acid composition that can render them susceptible to oxidative rancidity and rapid
deterioration. In spite of their global importance, there is limited information on optimal storage conditions and
shelf lives of many species of tree nut. This review explores current knowledge of the major factors that influence
the shelf life of tree nuts. Storage conditions greatly influence the quality and shelf life of tree nuts. Tree nut
species differ in their storage requirements because of their varying oil and fatty acid compositions. In general,
nuts with high levels of monounsaturated fatty acids are more stable and less susceptible to oxidative rancidity
than nuts containing high levels of polyunsaturated fatty acids. Temperatures ranging from 4 to 15 °C, kernel
moisture content around 2.5%, relative humidity of about 40–60%, oxygen concentration less than 2.5%, and
dark conditions are ideal storage conditions for most tree nuts. Harvesting time, cultivar and storage of nuts
either as nut-in shell or as kernel also affect the quality and shelf life of nuts. There is a need for tree-nut
industries to derive universal rancidity indicators for quality control. Optimised storage conditions will provide
the best nutritional quality and health benefits of tree nuts for consumers.
... Whitaker et al. (2010) conducted a study in which 12,000 g of nut samples were divided in five grades (high quality, insect damaged, mold damaged, mechanical damaged, and other defects), and found that almonds from the insect damaged grade accounted for 76.3% of the total almonds containing aflatoxin. Among the many insect pests of almond, Amyelois transitella, the navel orangeworm (NOW), has the greatest contribution to the invasion of aflatoxin-producing fungi and subsequent aflatoxin accumulation in almond kernels (Arrus et al. 2005;Campbell et al. 2003;Schatzki and Ong 2001). NOW larvae serve a dual role in the infection of almond kernels, by creating wounds that facilitate infection and also by carrying and bringing the spores and propagules of aflatoxin-producing fungi to the almond kernel (Palumbo et al. 2008(Palumbo et al. , 2014. ...
... Aflatoxin production is influenced by environmental factors such as climatic conditions, the level of insectfeeding damage (Palumbo et al. 2014), as well as water activity (a w ), pH and nutrient conditions. Overall, aflatoxin production is greater from 20°C to 35°C, with an optimum at 28-30°C while the minimal a w requirements usually range between 0.83 and 0.87 a w (Arrus et al. 2005;Astoreca et al. 2014;Klich 2007;Gallo et al. 2016;Giorni et al. 2011;Molina and Giannuzzi 2002;Sanchis and Magan 2004). Alkaline pH conditions inhibit aflatoxin production while optimal initial conditions range from pH 4 to 6 (Keller et al. 1997). ...
Almonds can be contaminated with aflatoxins, produced mainly by Aspergillus flavus and A. parasiticus. Infection can be facilitated by insect injuries during hull split, which begins four to six weeks before harvest. Within this period, it is unknown which kernel stages are most susceptible to aflatoxin contamination. Developing almonds of the Nonpareil cultivar were inoculated weekly with a spore suspension of A. flavus or A. parasiticus for five weeks after hull split in 2013. The almonds were infested with eggs of the lepidopteron navel orangeworm (NOW) (Amyelois transitella) before each spore inoculation. Aflatoxin levels were quantified at harvest using HPLC. Aflatoxin contamination was consistently higher in NOW-damaged kernels, although aflatoxins were also detected in undamaged kernels at each inoculation date. Insect injury is not required for kernel infection but it is a key risk factor for high aflatoxin contamination. Laboratory inoculations were also performed on Nonpareil almond kernels collected during the summers of 2013 and 2015. Aflatoxin levels were significantly lower on dried almonds but the ability to produce aflatoxins was restored when almonds were incubated with high humidity or when the Aspergillus species were inoculated on almond meal agar amended with ground kernels. Therefore, aflatoxins can accumulate in kernels with low aw, should sufficient moisture favors aflatoxin production. In our field experiment, the orchard micro-climate had sufficient humidity to enable aflatoxin production in both damaged and undamaged dried kernels.
... The increase in the incidence of Aspergillus sp. in the kernels of both hybrids from the beginning of storage to the sixth month when stored in bags and in silos during summer storage (Figures 3 c and d) might be attributed to the high relative humidity, with monthly averages that ranged from 73.4 to 88.4%, as shown in Figure 2 (b). According to Arrus, Blank, Abramson, Clear and Holley (2005), the incidence of Aspergillus sp. increases with increases in relative humidity and temperature. ...
... According to Thompson and Henke (2000), A. flavus and A. parasiticus can grow and produce aflatoxins in temperatures above 21°C. Additionally, Arrus et al. (2005) verified an increase of Aspergillus sp. with a relative humidity of 70%. ...
The aim of this study was to assess alternatives for viable corn storage for small rural properties in two annual storage experiments. A 4×5 factorial design was used with four types of storage (conventional bags, hermetic bags, metal silos and corncobs) and five periods of storage (0, 3, 6, 9 and 12 months). We used corn hybrids 2B688RR and 30K73Hx cultivated in winter 2012 and summer 2012/2013 in the city of Dois Vizinhos, Paraná, Brazil. The moisture contents, counts of Aspergillus sp. and Fusarium sp., and the occurrence of aflatoxins (B1, B2, G1 and G2) were assessed. The kernels stored in hermetic bags had lower moisture contents. Aspergillus sp. and Fusarium sp. were observed in 20.37 and 86.11% of winter storage samples, respectively, and in 83.3 and 91.6% of summer storage samples, respectively. The storage system and time of storage had no influence on the occurrence of Aspergillus sp. and aflatoxins in the winter crop samples. The corncobs from the summer crop samples had the lowest counts of Aspergillus sp. and did not have aflatoxins. We detected aflatoxins at concentrations of 2.8-14.5 and 3-197.5 µg kg-1 in the winter and summer crop samples, respectively.
... During storage, dried pistachios act as hygroscopic materials and that their moisture content increase depending on the type of packaging films. It is noticeable that the presence of moisture increases the possibility of the fungi growing and consequently aflatoxin formation (115). It was also observed that cellophane films was unsuitable for packaging of pistachios due to their high moisture permeability, low strength, low sealing ability, and high cost of production (116). ...
Pistachios are good sources of some functional compounds that are essential for human health. In addition to consuming dried pistachios (salted/roasted) or used as ingredients in a variety of confectionery and cookery products, consuming fresh pistachios is also gaining a foothold in the market. This review presents pre-and postharvest operations to prevent microbial contamination and to preserve physicochemical properties of fresh and processed pistachios for extending their shelf life. There is a potential in pistachios to be contaminated with some undesirable microbes, especially aflatoxin-producing fungi, during pre-and postharvest operations. In this regard, strategies to the prevention of aflatoxin production and the decontamination of produced aflatoxin in pistachios have been of interest to researchers. Different practices including sorting, thermal processing, biological control, ozone treatment, gamma irradiation, ultraviolet irradiation, and cold plasma have been proposed for aflatoxin decontamination. Sorting out damaged pistachios is one of the most important postharvest strategies to reduce aflatoxin levels (up to 98%) that can be done manually or electronically. The majority of pistachios (~85%) are consumed as roasted form that combining roasting with lemon juice improves the elimination of aflatoxin (up to 93%). Drying and packaging are the most important methods to maintain quality and improve the shelf life of pistachios. Laminated and metallized films with vacuum or modified atmosphere are the proper packaging for pistachios.
... The literature suggested that the moisture content above 17% and warmer temperatures (above 24 • C) are effective in inducing the formation of AFs in corn and feed (121,122). Indeed, the review of literature manifested that due to the higher moisture content of nuts, these products are the main susceptible foodstuffs for AFs contaminations (123). Therefore, in addition to local climatological factors, standard storage of nuts and decreasing the moisture content of these products before entering storage sites and local/global markets can dominantly affect the prevalence of AFB1 in such foodstuffs. ...
The future GCC-connected environmental risk factors expedited the progression of nCDs. Indeed, the emergence of AFs is becoming a global food security concern. AFs are lethal carcinogenic mycotoxins, causing damage to the liver, kidney, and gastrointestinal organs. Long-term exposure to AFs leads to liver cancer. Almost a variety of food commodities, crops, spices, herbaceous materials, nuts, and processed foods can be contaminated with AFs. In this regard, the primary sections of this review aim to cover influencing factors in the occurrence of AFs, the role of AFs in progression of nCDs, links between GCC/nCDs and exposure to AFs, frequency of AFs-based academic investigations, and world distribution of AFs. Next, the current trends in the application of PPs to alleviate AFs toxicity are discussed. Nearly, more than 20,000 published records indexed in scientific databases have been screened to find recent trends on AFs and application of PPs in AFs therapy. Accordingly, shifts in world climate, improper infrastructures for production/storage of food commodities, inconsistency of global polices on AFs permissible concentration in food/feed, and lack of the public awareness are accounting for a considerable proportion of AFs damages. AFs exhibited their toxic effects by triggering the progression of inflammation and oxidative/nitrosative stress, in turn, leading to the onset of nCDs. PPs could decrease AFs-associated oxidative stress, genotoxic, mutagenic, and carcinogenic effects by improving cellular antioxidant balance, regulation of signaling pathways, alleviating inflammatory responses, and modification of gene expression profile in a dose/time-reliant fashion. The administration of PPs alone displayed lower biological properties compared to co-treatment of these metabolites with AFs. This issue might highlight the therapeutic application of PPs than their preventative content. Flavonoids such as quercetin and oxidized tea phenolics, curcumin and resveratrol were the most studied anti-AFs PPs. Our literature review clearly disclosed that considering PPs in antioxidant therapies to alleviate complications of AFs requires improvement in their bioavailability, pharmacokinetics, tissue clearance, and off-target mode of action. Due to the emergencies in the elimination of AFs in food/feedstuffs, further large-scale clinical assessment of PPs to decrease the consequences of AFs is highly required.
... Mycotoxins are a group of toxic compounds naturally produced by several species of fungi, mainly by Aspergillus flavus and Aspergillus parasitiscus. Aflatoxins are the most significant mycotoxins because of their toxic cancer-causing nature, among which, the aflatoxins B1, B2, G1 and G2 are known as the most important types (Arrus et al., 2005); due to their high risks of contaminating agricultural products, they are considered as potential threat to human health and livelihoods. Aspergillus favours pollution and products containing fat and high carbohydrates like oil seeds and nuts (Martins et al., 2008). ...
... The indigenous communities of LAC are especially exposed to mycotoxins since the processes of storage, harvesting and processing of food are not regulated, so as they are contaminated by mycotoxin-producing fungi, these toxins can persist and consequently generate the adverse effects associated with this exposure. Regarding this, several studies have been conducted to evaluate the presence of mycotoxins, especially AFB 1 in foods consumed by these communities, such as maize, milk, eggs, nuts, peanuts, rice, dried fruits and their derived products, as well as biomonitoring in population, where the exposure of indigenous people to these compounds from the consumption of mycotoxin-contaminated foods has been demonstrated (Lorena Díaz de León-Martínez et al., 2020;Diaz et al., 2015;Zuki-Orozco et al., 2018); in the same way, effects on the health of the indigenous populations of the region that have been attributed to the consumption of mycotoxins have been demonstrated, such as early kidney damage, malnutrition, liver damage, growth impairment in children, among others (Arrus et al., 2005;de León-Martínez et al., 2019;Díaz de León-Martínez et al., 2019;Khlangwiset et al., 2011;Resnik et al., 1995;Smith et al., 2017;Torres et al., 2015). ...
Latin America and the Caribbean (LAC) was declared a new epicenter of the coronavirus pandemic by the World Health Organization (WHO) on May 22nd, 2020. As of January 13th 2021, the numbers of deaths and cases caused by COVID-19 in LAC reported are 552,000 and 17’485,000 respectively. LAC concentrates the largest percentage of indigenous populations throughout the world. In this region, poverty is persistent and particularly rural indigenous peoples hold the steepest barriers to health services and experience profound discrimination based on ethnicity, poverty, and language, compared to their non-indigenous counterparts. The information regarding the health of indigenous populations, in general, is scarce, and this problem is aggravated in the face of the COVID-19 pandemic. Therefore, the main objective of this work is to address the overall scenario of indigenous peoples in the Latin American and Caribbean region from March 2020 to January 2021, in this manner gathering information regarding health problems, economic, social, cultural and environmental factors that make indigenous populations in LAC particularly vulnerable to serious health effects from the COVID-19 pandemic, as well as compiling the mitigation strategies implemented in indigenous communities.
... , as well as A. parasiticus, which can also produce the G-aflatoxins G 1 and G 2 [2-4] . The former occurs mainly in cereals such as corn and wheat [5], the latter in cotton, Brazil nuts, peanuts and soil [6]. Both species are found particularly in regions with a warm climate such as Sub-Saharan Africa, Iran, Iraq, India and Southeast-Asia [7], but in more recent times they have also been found in Southern Europe due to global warming [8]. ...
Aspergillus flavus and A. parasiticus are the main causes of aflatoxin contamination in various foods, particularly grains, as they can thrive in environments with lower water activity and higher temperatures. The growth of Aspergillus and the formation of the mycotoxins aflatoxin and cyclopiazonic acid are strongly influenced by environmental stimuli and can be reduced by modulating parameters such as water activity, pH, temperature and light during the storage. This study has two objectives—on the one hand, to assess how global warming and an increase in exposure to sunlight affect growth and mycotoxin formation, and on the other hand, how the findings from these experiments can be used to reduce fungal growth and mycotoxin formation in stored foods. Using growth substrates with two different water activities (aw 0.95, aw 0.98), together with a light incubation device consisting of different chambers equipped with diodes emitting visible light of five different wavelengths (455 nm, 470 nm, 530 nm, 590 nm, 627 nm) plus white light, we analyzed the growth and mycotoxin formation of selected Aspergillus flavus and A. parasiticus isolates. It was shown that light with a wavelength of 455/470 nm alone, but especially in combination with a lower water activity of aw 0.95, leads to a significant reduction in growth and mycotoxin formation, which was accompanied by reduced transcriptional activity of the responsible mycotoxin biosynthetic genes. Therefore, these results can be used to significantly reduce the growth and the mycotoxin formation of the analyzed fungi during storage and to estimate the trend of fungal infestation by Aspergillus flavus and A. parasiticus in water activity- and light exposure-equivalent climate change scenarios. Mycotoxin-producing aspergilli can be effective and sustainably inhibited using a combination of short-wave light and lowered water activity in the substrate. A higher annual mean temperature accompanying climate change may lead to an increased spread of aflatoxin-producing fungi in areas that were previously too cold for them. On the other hand, there will be regions in the world where contamination with aflatoxin-producing fungi will be reduced due to increased drought and sun exposure.
... [25]. For Arrus et al., peeled nuts must be kept with MC around 4.5% to avoid the growth of A. flavus and AFL production [26]. The environmental a Results are expressed in average ± standard deviation (range); the limit of quantification were: AFB1=0.410, ...
Objective: Evaluate exposure to aflatoxins in processed Brazil nut (chopped and sliced) products marketed in Amazonas State. Methods: The samples were purchased during the 2017 harvest at the local retail in the city of Manaus/AM/Brazil in the form of sliced and chopped. Moisture content (MC) and water activity (aw) were verified, aflatoxins (AFB1, AFB2, AFG1, AFG2) were quantified by liquid chromatography. To characterize the risk of exposure to genotoxic use the population margin of exposure (MOE). Results: Chopped and sliced Brazil nut samples analyzed here presented an MC average of 1.62% and water activity of 0.26. These values indicate that samples are safe, according to physical-chemical baselines. Regarding aflatoxins presence, 8% of the samples presented aflatoxins total levels >10 μg/kg. A risk evaluation was performed in which exposure of the population to these substances is observed and, once found; the MOE was 1036 ± 793 (<10 000). Conclusion: Regarding the risk assessment, it was possible to observe that there is a possibility exposure of the population to these substances since the average of MOE found was 1036±793, or <10 000, characterizing this possible risk.
... The fungi responsible for the rot disease in infected groundnut seeds yielded three different fungi, A. niger, A. versicolor and A. fresen (Ihejirika et al., 2005). Similarly, the seed mycoflora of Brazil nut pods (Bertholletia excelsa) dominated by Penicillia and A. flavus Arrus et al. (2005)The surface disinfected seeds of cowpea, lupin and bean showed lesser incidence of seed-borne storage mycoflora compared to non-disinfected seeds (Embaby and Abdel-Galil, 2006 and lead to teratogenic effect on ducklings, hamsters, rats, trout, rabbits and a number of other vertebrates. In India, aflatoxin contaminated groundnut cake and maize meal contributed to the death of more than 2,00,000 broiler chickens and 2000 baby chickens in Andhra Pradesh and Karnataka respectively (Jelinek et al., 1989;Vasanthi and Bhat, 1998). ...
... Effect of a w and temperature on A. flavus growth and AFs production on tree nuts Tree nuts are commodities with moderate to high risk of AFs contamination because they are produced at environmental conditions favouring fungal growth and AFs production by aflatoxigenic fungi especially A. flavus (Arrus et al., 2005;Gallo et al., 2016). The incidence of AFs contamination in nuts is low; however, their levels vary widely and can produce high levels in a small number of nuts (Campbell et al., 2003). ...
The contamination of Aspergillus flavus and subsequent aflatoxins (AFs) has been considered as one of the most serious food safety problems due to their acute and chronic adverse effects on humans and animals. This review collects the available information from recent years on the effect of the major environmental factors such as water activity (aw), temperature, CO2, and pH on the fungal growth, the expression of AFs-related genes, and AFs production by A. flavus on foods. In particular, the relationship between the relative expression of key regulatory (aflR and aflS) and structural genes (aflD, aflO, aflQ, etc.) and AFs production under different environmental conditions are collected and discussed. The information collected in this review can be used to design control strategies of A. flavus and AFs contamination in practical applications, primarily during storage and processing. These data suggest that integrating various post-harvest methods with synergistic functions may be more efficient for the control of A. flavus growth and AFs production, although the individual environmental factors alone have an impact.
... Silva et al. [5] reported that during the harvesting of Brazil nut pods, the nuts are processed under the environmental conditions of the Amazon region, with temperatures generally greater than 30 C and relative humidity greater than 70%. These conditions affect the moisture and water content of the Brazil nut and create an atmosphere conducive to the production of aflatoxin by aflatoxigenic fungi [28][29][30][31][32]. The drying process is one of the critical processing stages of the Brazil nut which is considerably challenging, and hence, it is necessary to perform efficiently to avoid the fungal growth favored by moisture and water content. ...
... Although A. flavus normally contaminates maize, cereals, spices, and dried fruit (Arrus et al., 2005;Molyneux et al., 2007;Zinedine et al., 2007;Hernández-Hierro et al., 2009;Astoreca et al., 2012), its presence in cheese has been reported by several authors (Barrios et al., 1997;De Santi et al., 2010;Baranyi et al., 2015). As such, mycotoxins AFB 1 , AFB 2 , AFG 1 , and AFG 2 have all been detected in cheeses (Taniwaki et al., 2001). ...
The expression of genes associated with aflatoxin biosynthesis by different Aspergillus flavus strains growing on a cheese model system has not been studied. To control aflatoxin biosynthesis, it would be useful to understand the changes in gene expression during cheesemaking and relate those changes to toxin production. The objective of this study was to evaluate the effects of pH, water activity, and temperature on the expression of 2 regulatory genes (aflR and aflS) and 1 structural gene (aflP) involved in aflatoxin biosynthesis, using 3 aflatoxigenic A. flavus strains growing on a cheese-based medium and reverse-transcription real-time PCR. The gene expression patterns were influenced by A. flavus strain and environmental conditions. The structural gene aflP and the regulatory genes aflR and aflS showed similar expression patterns in each A. flavus strain, but we also observed inter-strain differences. We observed the highest expression levels at 6 and 9 d of incubation by A. flavus strains CQ8 and CQ103, and saw a decrease in the days following. Strain CQ7 showed the lowest expression of these genes. We observed the highest expression levels of these genes at pH 5.5, water activity 0.95, and 20 to 25°C; strain CQ103 showed a different pattern for the aflS gene, with maximum expression at pH 6.0 on d 6 of incubation. For the 3 strains, we found a strong correlation between the relative expression of the aflR and aflS genes and the concentration of aflatoxins under conditions that simulated cheese ripening. Control strategies to avoid aflatoxin contamination during cheesemaking could use the detection of regulatory gene expression.
... Various studies have been carried out to investigate the effects of fungicides and the onset of drug resistance in fungal species [18][19][20][21]. In this regard, Snelders (2009) examined the effect of azole pesticides on drug resistance in Aspergillus species. ...
Background and purpose:
Aspergillus flavus is an important pathogen in immunodeficient patients. Due to the abundance of this fungus in nature, fungicides are commonly used to preserve and maintain agricultural products. Long-term exposure to these pesticides can lead to the induction of drug resistance in this fungus.
Materials and methods:
For the purpose of the study, 10 strains of A. flavus ATCC 204304 were cultured in benomyl and diazinon pesticides at the concentrations of 62.5, 125, 250.500, 750, 1000, 1500, 2000, and 2500 mg/L in nine steps. Morphological changes and resistance to voriconazole, itraconazole, and amphotericin B were evaluated at the end of each step. Subsequently, changes in the expression of mdr1 and cyp51C genes were studied in the strains showing drug resistance.
Results:
The results showed that during the nine stages of the adjacency of strains with benomyl and diazinon at different concentrations, resistance to voriconazole, itraconazole, and amphotericin B in these toxins increased by 30% and 10%, respectively. In addition, the microscopic examination of resistant strains revealed the absence of sporulation, and only mycelium was found. Macroscopically, the color of the colonies changed from green to white. Furthermore, the investigation of the expression of mdr1 and cyp51c genes in these strains showed a decrease and increase in adjacency with diazinon and benomyl, respectively.
Conclusion:
As the findings indicated, exposure to agricultural pesticides can lead to the incidence of morphological changes and resistance to amphotericin B, itraconazole, and voriconazole in the sensitive species of A. flavus by altering the expression of genes involved in drug resistance.
... Mycotoxins are a group of toxic compounds naturally produced by several species of fungi, mainly by Aspergillus flavus and Aspergillus parasitiscus. Aflatoxins are the most significant mycotoxins because of their toxic cancer-causing nature, among which, the aflatoxins B1, B2, G1 and G2 are known as the most important types (Arrus et al., 2005); due to their high risks of contaminating agricultural products, they are considered as potential threat to human health and livelihoods. Aspergillus favours pollution and products containing fat and high carbohydrates like oil seeds and nuts (Martins et al., 2008). ...
Aspergillus flavus toxin contamination of pistachio nuts is a serious problem in terms of health and food security. In this paper, in order to increase the nut shelf life by eliminating or reducing the amount of toxin-producing fungus Aspergillus flavus, pistachios were irradiated with cold plasma, using Atmospheric Pressure Capacitive Coupled Plasma (AP-CCP) generating device using Argon gas. The advantages of this device are both its mobility, adjoining a nuts carrying container for thorough irradiation of the nuts and that the device can be designed in the form of an array of torches for treatment of large quantities of nuts in open air as against in a vaccum chamber. In this way, the sample of nuts are firstly soaked with fungus and then irradiated in different conditions in terms of power, pressure and time. The analysis of experimental results indicates 4 log (66.6%) fungus reductions. This pathogen reduction was observed in 100 Watts, at atmospheric pressure and irradiation duration of 10 minutes. © 2018 Journal of Microbiology, Biotechnology and Food Sciences.
... During the harvest, the Brazil nut has approximately 26% of water content on wet basis (% w.b.) (NOGUEIRA, 2011). During processing in industry, this value ranges from 3.50 to 11.25% w. b. (ARRUS et al., 2005), reaching 2.00% w.b. which is an appropriated water content for the market (ALVARES et al., 2012). Regardless of which stage the product is in, a suitable methodology for analyzing the water content is required. ...
The official methods adopted by different worldwide agencies for determination of water content of Brazil nut is the dissication in drying oven at 105 ºC during 3 or 24 hours and dissication until constant height of samples. However, applying these methods for Brazil nut, may result in inconsistent values, possibly due to lipid oxidation. Thus, the objective of this study was to evaluate the accuracy of the oven-drying methods, recommended by the official agencies, and to determine the oven-drying correct parameters, such as temperature and exposure time. For this purpose, samples were placed in drying ovens set at 85, 90, 95 and 105 °C and weighed hourly, between 3 and 12 hours and after 24 hours of exposure, and the results were compared to Karl Fisher titration, considered as a reference method in this study. The temperature of 105 °C, for any exposure time, resulted in overestimated water content compared to reference method. However, there was no difference between the water content values obtained by oven-drying assay at 90 °C for 6 hours and by the reference method, allowing to conclude that the determination of water content in Brazil nut samples, in drying oven under these conditions, can be performed with the same accuracy and precision of the Karl Fischer method. © 2018, Universidade Federal de Uberlandia. All rights reserved.
... During the harvest, the Brazil nut has approximately 26% of water content on wet basis (% w.b.) (NOGUEIRA, 2011). During processing in industry, this value ranges from 3.50 to 11.25% w. b. (ARRUS et al., 2005), reaching 2.00% w.b. which is an appropriated water content for the market (ALVARES et al., 2012). Regardless of which stage the product is in, a suitable methodology for analyzing the water content is required. ...
The official methods adopted by different worldwide agencies for determination of water content of Brazil nut is the dissication in drying oven at 105 ºC during 3 or 24 hours and dissication until constant height of samples. However, applying these methods for Brazil nut, may result in inconsistent values, possibly due to lipid oxidation. Thus, the objective of this study was to evaluate the accuracy of the oven-drying methods, recommended by the official agencies, and to determine the oven-drying correct parameters, such as temperature and exposure time. For this purpose, samples were placed in drying ovens set at 85, 90, 95 and 105 °C and weighed hourly, between 3 and 12 hours and after 24 hours of exposure, and the results were compared to Karl Fisher titration, considered as a reference method in this study. The temperature of 105 °C, for any exposure time, resulted in overestimated water content compared to reference method. However, there was no difference between the water content values obtained by oven-drying assay at 90 °C for 6 hours and by the reference method, allowing to conclude that the determination of water content in Brazil nut samples, in drying oven under these conditions, can be performed with the same accuracy and precision of the Karl Fischer method.
... Water activity (aw) and temperature are limiting factors for fungal growth and AF production during storage. The effects of temperature and aw on AF production by A. flavus grown on various agricultural crops and food has been widely studied (Molina and Giannuzzi, 2002;Arrus et al., 2005;Ribeiro et al., 2006;Giorni et al., 2008). For the growth of A. flavus in shelled peanuts for example, 0.98 was optimal aw, and 37 °C was the optimum temperature. ...
Filamentous fungi belonging to Aspergilli genera produce many compounds through various biosynthetic pathways. These compounds include a spectrum of products with beneficial medical properties (lovastatin) as well as those that are toxic and/or carcinogenic which are called mycotoxins. Aspergillus flavus, one of the most abundant soil-borne fungi, is a saprobe that is able growing on many organic nutrient sources, such as peanuts, corn and cotton seed. In many countries, food contamination by A. flavus is a huge problem, mainly due to the production of the most toxic and carcinogenic compounds known as aflatoxins. In this paper, we briefly cover current progress in aflatoxin biosynthesis and regulation, pre- and postharvest preventive measures, and decontamination procedures.
... But to avoid hypothermia, the ambient temperature in the OR should be between 24 and 26°C (Nastase et al. 2016). Moreover, the optimum temperature for sporulation is 25-30°C (Cabral 2010) and the highest density of this mycotoxin is produced in these ranges (Arrus et al. 2005). Therefore, indoor temperature in majority of departments of this hospital was suitable for sporulation and the risk of airborne fungi was higher than outdoor because human sensitivity to spore formulation is higher . ...
Fungi are one of the bioaerosols in indoor air of hospitals. They have adverse effects on staff and patients. The aim of this study was to investigate the effects of three incubation temperature on the density and composition of airborne fungi in an indoor and outdoor space of hospital. Sabouraud dextrose agar was used for culture the fungi. For improvement of aseptic properties, chloramphenicol was added to this medium. The density of airborne fungi was less than 282 CFU/m³. The highest density was detected in emergency room and the lowest of them was in neonatal intensive care unit (NICU) and operation room (OR). Results showed that fungi levels at 25 °C were higher than 37 and 15 °C (p = 0.006). In addition, ten different genera of fungi were identified in all departments. The predominant fungi were Fusarium spp., Penicillium spp., Paecilomyces spp., and Aspergillus niger. Moreover, the density and trend of distribution of Fusaruim spp. in the indoor space was directivity to outdoor space by ventilation system. The present study has provided that incubation temperature had effect on airborne fungi remarkably. We are suggested that more studies would be conducted on incubation temperature and other ambient factors on airborne fungi.
... Studies in relation to nuts are generally related to socioeconomics ( Camargo, 2010;Shepard Jr. & Ramirez, 2010). Among these studies, the benefits of Brazil nuts on health ( Yang, 2009), as well as the harmful effects caused by mycotoxin-producing fungi contamination due to incorrect storage, should be highlighted ( Arrus et al., 2005;Kwiatkowski & Alves, 2007;Freitas-Silva & Venâncio, 2011). In addition, studies on the aspects of the ecology of B. excelsa, such as phenology, distribution, pollinators and main dispersants ( Peres & Baider, 1997;Zudeima, 2003;Maués, 2002;Tonini, 2011), as well as their increasing use in the recovery of degraded areas, crop consortia and incentive for the valuation of rural areas ( Fernandes & Alencar, 1993;Costa et al., 2009;Ferreira & Tonini, 2009) should be encouraged. ...
The Brazil nut (Bertholletia excelsa) is a species of tree native to the Amazon region. The exploitation of its wood and fruit provides significant economic value. Due to this important economic value, different studies related to the Brazil nut tree provide relevant information about the beneficial and harmful relationships between the tree and other organisms. However, such information is scattered and difficult to access. The objective of this study was to compile the available information on the different relationships between the Brazil nut tree and other organisms to support future studies and strategies to better manage the resources and benefits of this tree. We found 194 species that interact with the Brazil nut tree. These species consisted of predators, dispersers, competitors, pollinators, floral visitors, pathogens and microorganisms. Although exploitation of the Brazil nut has occurred for many decades in native forests, the production of seedlings and cultivation of the species are relatively recent events, with few occurrences of pests and diseases recorded for B.excelsa in native forests and plantations. In contrast, pollinators, floral visitors and dispersers were recorded in abundance, as well as contaminating fungi that deteriorate the nut. Considering the volume and diversity of records it is possible to infer that there is a need for constant monitoring of the Brazil nut in plantations and natural areas, as well as to encourage research related to the specific biotic interactions of Brazil nuts.
... A. flavus may produce only AFB 1 and AFB 2 whereas A. parasiticus is able to produce AFB 1 , AFB 2 , AFG 1 , and AFG 2 (Giorni et al., 2007;Vaamonde, et al., 2003). Although these species normally grow on maize (Astoreca et al., 2014;Giorni et al., 2007), cereals and their derivatives (Zinedine et al., 2007), spices (Hern andez-Hierro et al., 2009), cocoa (Copetti et al., 2011), dried fruit and nuts (Arrus et al., 2005;Molyneux et al., 2007), their presence has been reported in some dry-cured meat products. Thus, Ismail and Zaky (1999) analysed 50 luncheon meat samples being 14% of them positive for AFB 1 . ...
Aspergillus flavus and Aspergillus parasiticus are mould species producers of aflatoxins (AFs) and may grow on dry-cured ham during the ripening process. In this study, the influence of different water activity (aw) and temperatures on the temporal relative expression of three genes involved in AFs biosynthesis and their relationship with AFs production on dry-cured ham-based medium were evaluated. In general, the regulatory aflR and aflS genes showed similar expression patterns, and the expression of the structural aflP gene was much higher than that obtained for aflR and aflS genes. Regarding A. flavus, a decrease of aw regardless of temperature caused an increase of the expression of the regulatory aflR and aflS genes. Concerning A. parasiticus, the highest and lowest expression values of the regulatory aflR and aflS genes were found at 0.95 aw and 0.85 aw, respectively. The expression of the structural aflP gene of both species was stimulated at low temperature and aw. The PCA analysis indicated that both toxigenic species showed a strong correlation between the relative expression of the aflR and aflS genes and the concentration of AFs under conditions which simulate dry-cured ham ripening. This suggests that an early detection of the expression of regulatory genes can be a good indicator of possible AFs contamination of dry-cured ham through ripening.
... Natural occurrence and inadequate long-term storage are the main routes leading to the presence of Aspergillus in foodstuff. The mold finds especially good conditions for its proliferation in the Amazon rainforest, with temperatures more than 25°C and relative humidity above 80% (Arrus et al., 2005;Atayde et al., 2012;Johnsson et al., 2008). Specifically, the Brazil nut has been recently reported as a preferred substrate for Aspergillus fungi (Calderari et al., 2013;Reis et al., 2012). ...
... 2006;Berno et al., 2010;Colpo et al., 2013). There are even efforts to understand the relationship of these nuts with the aflatoxigenic fungi (Arrus et al., 2005;Pacheco et al., 2010;Martins et al., 2012). Studies conducted to comprehend the behavior of the Bertholletia excelsa seeds during the pre-processing and industrialization steps are still incipient (Ribeiro et al., 1993;Nogueira et al., 2014;Kluczovski et al., 2015), however, such types of research have emerged due to the current demand for export of a product that fits the laws of importing countries (Álvares et al., 2012). ...
Tribolium castaneum is an insect that occurs worldwide and it is a pest that attacks stored products, in particular, grains and seeds. The adult and immature forms are categorized as secondary pests which feed on grains or seeds previously damage in storage conditions. The objective of this study was to describe the type of damage caused by adults and immature of T. castaneum in Brazil nuts and identify the type of damage caused by Coleoptera. It was also verified whether the shell can protect the almond from the attack of this pest. The lesions inflicted by this insect starts as a scratched surface, which evolves into galleries and even injuries capable of modifying the original shape of the almond. Due to its capacity to promote considerable damage with consequent losses in the value of the nuts, T. castaneum may be listed among pests of Brazil nut categorized as primary pest by its ability to initiate injuries in the intact almond.
... Contamination with aflatoxins and aflatoxigenic fungi in Brazil nuts have been the focus of studies in Brazil and in several other countries (Arrus et al. 2005;Pacheco and Scussel 2007;Olsen et al. 2008;Baquião et al. 2012;Calderari et al. 2013). This is due to the requirement established primarily by the European Union (EU 2010). ...
Bertholletia excelsa is the tree that produces Brazil nuts which have vast economic importance in the Amazon region and as an export commodity. The aim of this study was to assess the presence of Aspergillus section Nigri in Brazil nut samples at different stages of its production chain and to verify the toxigenic potential for fumonisin B2 (FB2) production of these isolates along with the presence of this mycotoxin in Brazil nut samples. The fungal infection ranged from 0 to 80% at the different stages of the harvest and processing chain and the water activity of the nuts from 0.273 to 0.994. A total of 1052 A. section Nigri strains were isolated from Brazil nuts and 200 strains were tested for their ability to produce FB2: 41 strains (20.5%) were FB2 producers with concentrations ranging from 0.09 to 37.25 mg/kg; 2 strains (1%) showed traces of FB2, less than the detection limit (0.08 mg/kg); and 157 (78.5%) were not FB2 producers. Although several samples showed high contamination by A. section Nigri, no sample was contaminated by FB2.
... To the best of our knowledge, there has been no available study focusing on the atmospheric pressure plasma decontamination of aflatoxigenic fungal infection on grain-like food products due to their high pathogenicity. Hazelnut was chosen as model food sample owing to the facts that they are susceptible to toxigenic fungal infection during postharvest operations, transport and storage, and that fungal contamination may result in mycotoxin production (Arrus et al., 2005;Williams et al., 2004), cause health problems and financial burden especially during exportation. Mycotoxins are produced at the end of the exponential phase or at the beginning of the stationary phase of the mold growth, which corresponds to the fifth day for Aspergillus, at optimal conditions of temperature (27e30 C) and relative humidity (85%) to produce aflatoxins (Carjaval and Castillo, 2002). ...
... and Bonpl) that grow in the Amazon forest may get contaminated by fungi and aflatoxins (AFLs) (Steiner et al., 1992, Pacheco andScussel, 2009), as do other tree nuts. The aflatoxigenic Aspergillus species that have been isolated from Brazil nuts are A. flavus, A. parasiticus and A. nomius (Cartaxo et al., 2003;Castrillon et al., 2003;Arrus et al., 2005;Scussel, 2004;Olsen et al., 2008). Their growth is directly related to the climate conditions of that region and to the conditions during their storage, transport and commercialization, if there is no control of moisture content (m.c.) and temperature. ...
High moisture content, relative humidity, temperature and environment rich in oxygen (O₂) are the main factors for tree nuts to get infected by fungi and so aflatoxins (AFLs) contaminated. During storage and commercialization dry Brazil nuts packs need to maintain their safety and quality. Modified atmospheres in storage (macro-environment) and packaging (micro-environment) have been used to prolong food shelf life by reducing O₂ concentration with inhibitory gases or, more recently, by adding O₂ absorber pads. This work reports the application of O₂ atmosphere reducing methods on stored shelled Brazil nut packs aiming fungi and AFL degradation as well as hygienic conditions improvements. The methods applied were: (a) ozone - O₃, (b) carbon dioxide - CO₂ and (c) O₂ absorber pads with and without vacuum. Nuts were submitted to microbiological tests (fungi, aflatoxigenic strains, yeast and bacteria), moisture content and AFLs analysis. From all O₂ reducing atmosphere evaluated, the best performance was obtained with O₃. A reduction on fungi growth (1.8 x 104 cfu.g-1 to 2.6 x 10 cfu.g-1) and yeast destruction after the first month of storage were registered. Also O₃ was the only nut treatment that was able to degrade AFLs. None of the spiked (AFLs: 15 ppb) nut samples O₃ treated had AFLs detected up to the LOQ of the method (0.36 μg.kg-1 for AFB1+AFB2+AFG1+AFG2) i.e., much lower than the allowed by the European Union regulation (MRL: 4 and 2 ppb for total and AFB1, respectively), thus producing safer nuts. All other treatments stabilized and/or inhibited microorganisms growth. Add CO₂ and O₂ pads played an important role on nut quality. Further study will be carried out in order to adjust O₃ concentration and application conditions for longer period of storage.
... A. flavus can also produce aflatoxins which are highly toxic to mammals e both human beings and farm livestock. Aflatoxins are hepatotoxic, teratogenic, mutagenic and immunosuppressive (Arrus, Blank, Abramson, Clear, & Holley, 2005). Hence, inhibition of mold growth on food and feed crops is necessary, not only to reduce commercial loss but also to mitigate risk to human and animal health. ...
Background
Pecan is an excellent source of monounsaturated and polyunsaturated fatty acids and bioactive compounds, which are attributed benefits to the health. Several studies relate that both pre-harvest and post-harvest factors can depreciate the nuts quality and reduce their lifetime.
Scope and approach
This review covers the current knowledge about the critical and determinants factors for maintaining pecan nut quality in terms of chemical composition and sensorial aspects, as well as enlists positive and negative effects of each process and steps from planting to the final consumer.
Key findings and conclusions
At pre-harvest, the cultivar choice, growing place, and handling can be defined to achieve a specific composition and maximum nut quality. During storage the negatively impact factors are moisture over 4%, high oxygen pressure, temperatures higher than 10 °C, and roasting at high temperatures for long periods. Greater preservation of quality can be achieved with the cultivar 'Mahan' (which has a lower content of compounds related to lipid oxidation), with humidity below 4%, under a temperature below 10 °C in packaging with an oxygen pressure lower than 3 kPa. However, storage conditions are not optimized, and new preservation methods and technologies, should be investigated for fungal control and mycotoxin development; and to reduce nutritional, sensorial and bioactive compound losses in pecan processing and storage. In this review, we also list the factors that affect quality, the oxidation and degradation markers identified in pecans, which can be adopted as biomarkers in storage management.
Abstract
Poverty and unemployment in families may produce child labour. These and other factors, such as uneven development, may deprive parts of society from social privileges. Indeed, uneven development is the main cause of poverty and unemployment, especially in a country’s marginal, ethnic and religious areas. Following the Revolution, Iranian society was confronted with a rising population – it has doubled over the four decades. Unlike the population, the country’s economy has not experienced a boom; instead, there has been a downward turn in the economic-development rate under sanctions and macro-level policies, leading to higher levels of unemployment and poverty. Under these circumstances, families use their children’s labour to make up part of their expenses. Families without caretakers or with irresponsible caretakers also cause child labour. Some heads of families are unable to work and support their families for reasons such as addiction, illness and disability, while others have already died. Thus, families are faced with rising poverty, and this prompts children to enter the work cycle. Poverty in families without caretakers or with irresponsible caretakers proves the ineffectiveness of the country’s protection policies. This article is an excerpt from the book Traces of Exploitation in Childhood (A Comprehensive Research on Forms, Causes and Consequences of Child Labour in Iran).2
Keywords: Child labour, harms, community, culture, childhood study
Abstract
The identity/ethnic diversity in Contemporary Iran has co-occurred with the development of globalization processes and brought about interethnic conflict, oriented toward identity- and justice- seeking in order to eradicate discrimination and inequality in line with achievement of social development. This is the issue that the present research has sought to investigate among the Persian, Azeri, Kurd, Arab, and Baloch in Iran. The Iranian social identities are dissatisfied with the dominance of the Persian identity elements over their fundamentals, and do not find the reduced status of Iranian historical identity in accordance with justice and development of the collective identities.
The present article is an extract from author’s recently published book2 which has adopted a hybrid qualitative approach (GT), in-depth interview surveys and tools, library documentation, and an open questionnaire in thirteen provinces to extract and classify data in the following areas: religious identity and national identity (interaction or opposition), interethnic cultural borders, ethnic and national movement dead-end, elimination of cultures, and a peace-oriented approach to resolving the crisis. Thus, a conceptual model has been obtained, shaping basic factors (economic and ideological), intervening factors (media and lifestyle), grounded factors (legal and cultural parameters and resource mismanagement), and phenomenal orientation (claim for justice and socio-political gap) and presenting strategic action (peaceful action, acceptance of the present conditions, and state-nation interaction) and its outcomes (stability and decline of social capital).
Keywords: Iran, Ethnic Identity, Iranian National Identity, Persian, Azeri, Kurd, Arab, Baloch, Development, Justice.
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Abstract
In the contemporary era, Iran has undergone a continuous experience of identity/ethnic multiplicity, which has caused serious interethnic conflicts revolving around discrimination and inequality in the urge for identity and justice and with a peace-oriented trace as the process of globalization has developed.
In this research, the influence on Iranian civilization in terms of land, language, and religion have been investigated in five ethnic groups, including Persian, Azeri, Kurd, Arab, and Baloch, given different aspects of Islamic and Western governments. The consideration of the Persian ethnic identity as the exclusive component of Iranian national identity has reduced ancient Iranian identity and brought about claims for identity in other ethnic groups.
The present article is an extract from author’s recently published book2 which has adopted a hybrid qualitative approach (GT), in-depth interview surveys and tools, library documentation, and an open questionnaire in thirteen provinces to extract and classify data in the following areas: religious identity and national identity (interaction or opposition), interethnic cultural borders, ethnic and national movement dead-end, elimination of cultures, and a peace-oriented approach to resolving the crisis. Thus, a conceptual model has been obtained, shaping basic factors (economic and ideological), intervening factors (media and lifestyle), grounded factors (legal and cultural parameters and resource mismanagement), and phenomenal orientation (claim for justice and socio-political gap) and presenting strategic action (peaceful action, acceptance of the present conditions, and state-nation interaction) and its outcomes (stability and decline of social capital).
Keywords: Iran, Ethnic Identity, Iranian National Identity, Persian, Azeri, Kurd, Arab, Baloch, Peace.
1 www.kameelahmady.com
2 Ahmady, Kameel. From border to Border ( A comprehensive reach on Identity and Ethnicity in Iran), 2021, Mehri Publishing, London, UK
To read a related articles and to download click here: https://kameelahmady.com/identify-and-ethnicity/
In recent years, global nut, spice, and herb productions have developed rapidly, and consumption has also increased. During the same period, a massive outbreak of food pathogens was linked to nuts, spices, herbs, and their products, leading to a major change in the way those products are processed. Cold plasma is a new technology used in food processing, which can improve the safety and extend shelf-life of product. A variety of active substances generated by cold plasma can act on microorganisms at ambient temperature and even on complex geometric shapes and heat-sensitive materials without leaving any chemical residues. The chapter introduces the application of various plasma discharge modes (plasma jets, dielectric barrier discharges, and microwave-driven discharges) on surface decontamination of nuts, spices, and herbs. In addition, a brief overview of the effect on their surface color, antioxidation activities, and other qualities with cold plasma treatment. We believe that cold plasma has a wide application prospect in extending the shelf-life and maintaining the quality of these dried foods.
Aflatoxins are group of secondary fungal metabolites produced by Aspergillus species, such as Aspergillus flavus and Aspergillus parasiticus. The aflatoxin producing moulds can grow on cereals and legumes in the field, poorly dried harvested crops in storage, processed food, and feed products. The study was carried out with the aim to determine the level of aflatoxin contamination of cereals grain and legumes in Zaria metropolis, Kaduna State, Nigeria. Ninety (90) samples were collected, which comprises of 18 samples each of millet, sorghum, maize, beans, and groundnuts respectively. The samples were subjected to proximate analysis. The grains were further subjected to cultural isolation and microscopic identification. The isolates were then screened for aflatoxin production ability with neutral red desiccated coconut agar and viewed under UV light (365nm). The remaining portions of the samples was grounded and extracted with 80% (v/v) methanol. The enzyme-linked Immunosorbent Assay (ELISA) technique was used in quantifying the total aflatoxin content of the samples. The results revealed that all the cereals and legumes analysed contain organic and inorganic nutrients that can support the growth of aflatoxigenic moulds and production of aflatoxins. Some major parameters such as carbohydrate content, crude protein, crude lipid, and ash contents were statistically significant (p < 0.05). Thirty-one (31) isolates from the 90 samples were confirmed to be A. flavus and seventeen (17) were A. Parasiticus, with percentage occurrence of 34.4% and 18.9% respectively. All the isolates were screened and demonstrated ability for aflatoxin production under UltraViolent light (390nm). The results also revealed a high concentration of aflatoxin (11.04 µg/kg) in millet and a low concentration in sorghum (1.07 µg/kg). The contamination levels within the grains were found to be statistically significant (p < 0.05). Aflatoxin contaminations also occurred in 48 samples out of the 90 samples analysed. The grains samples analysed were found to be contaminated with varying amounts of aflatoxins, which is harmful to humans and animals. Therefore, steps should be taken to ensure that grains are properly dried prior to storage. Keywords: aflatoxin, A. flavus, A. parasiticus, cereals, Enzyme-linked Immunosorbent Assay, legumes
Penicillium spp. are emerging as producers of mycotoxins and other toxic metabolites in nuts. A HPLC-MS/MS method was developed to detect 19 metabolites produced by Penicillium spp. on chestnuts, hazelnuts, walnuts and almonds. Two extraction methods were developed, one for chestnuts and one for the other three nuts. The recovery, LOD, LOQ and matrix effect were determined for each analyte and matrix. Correlation coefficients were always >99.99%. In walnuts, a strong signal suppression was observed for most analytes and patulin could not be detected. Six strains: Penicillium bialowiezense, P. brevicompactum, P. crustosum, P. expansum, P. glabrum and P. solitum, isolated from chestnuts, were inoculated on four nuts. Chestnuts favored the production of the largest number of Penicillium toxic metabolites. The method was used for the analysis of 41 commercial samples: 71% showed to be contaminated by Penicillium-toxins. Cyclopenin and cyclopenol were the most frequently detected metabolites, with an incidence of 32% and 68%, respectively. Due to the risk of contamination of nuts with Penicillium-toxins, future studies and legislation should consider a larger number of mycotoxins.
Coffee bean-contaminating fungi were determined in random samples collected in Riyadh, Kingdom of Saudi Arabia, using the direct plating technique. Forty-five samples were examined and 12 fungal species belonging to 5 genera were isolated. Aspergillus niger was the most widely distributed and most frequently isolated fungus (86.67%). The ability of the predominant fungus, A. niger, to produce oxalic acid was evaluated using high-performance liquid chromatography. About 50% of the tested A. niger isolates produced oxalic acid; the amount produced was in the range of 90–550 ppm of oxalic acid. Because A. niger was the predominant and most widely distributed toxigenic fungus in the examined samples, more efforts should be directed to minimize the risk of oxalic acid contamination of commoditized coffee beans in the Kingdom of Saudi Arabia.
Sorghum, which is consumed in Tunisia as human food, suffers from severe colonization by several toxigenic fungi and contamination by mycotoxins. The Tunisian climate is characterized by high temperature and humidity that stimulates mold proliferation and mycotoxin accumulation in foodstuffs. This study investigated the effects of temperature (15, 25 and 37°C), water activity (aw, between 0.85 and 0.99) and incubation time (7, 14, 21 and 28d) on fungal growth and aflatoxin B1 (AFB1) production by three Aspergillus flavus isolates (8, 10 and 14) inoculated on sorghum grains. The Baranyi model was applied to identify the limits of growth and mycotoxin production. Maximum diameter growth rates were observed at 0.99aw at 37°C for two of the isolates. The minimum aw needed for mycelial growth was 0.91 at 25 and 37°C. At 15°C, only isolate 8 grew at 0.99aw. Aflatoxin B1 accumulation could be avoided by storing sorghum at low water activity levels (≤0.91aw). Aflatoxin production was not observed at 15°C. This is the first work on the effects of water activity and temperature on A. flavus growth and AFB1 production by A. flavus isolates on sorghum grains.
Sound inshell runner-type peanuts, manually damaged inshell peanuts, shells, sound kernels, deskinned kernels and skins were stored in separate flasks under an atmospheric relative humidity of 100% at 28°C. After 5 d, water was adsorbed at levels of 1.2, 1.7, 3.9, 0.9, 1.0 and 9.5 g/100 g dry material, respectively. Surface disinfected components were inoculated with conidiospores of Aspergillus parasiticus NRRL 2999 and incubated under the same conditions. The time required for visible growth of the fungus was 8, 6, 4, 12, 10 and 3 d, respectively. The time for appearance of the conidiospores was 14, 10, 6, 16, 13 and 6 d. After a 3-wk incubation period, aflatoxin levels in peanut components were 111.4, 159.1, 4.4, 58.7, 99.0 and 1.5 μg/g, respectively.
The occurrence of aflatoxins was investigated in one hundred samples of Brazil nuts (Bertholletia excelsa Humb. & Bonpl.) from producers and from several seed marketing posts, in the region of Manaus, State of Amazonas and São Paulo, state of São Paulo. The samples were classified according to four types of product presentation: naturally within the shell; dehydrated within the shell; dehydrated without shell and within the chestnut bur. Three samples were found contaminated with aflatoxins types B1 and G1. The toxicity levels for B1 were regarded as: medium (0,1 ppm) and very high (2.25 ppm); those ofaGI were regarded low (0.075) and very high (1.5 ppm).
One hundred samples of Brazil nuts from the States of Amazonas and São Paulo, were analysed mycologically and toxicologically for aflatoxins B1 and G1. Three hundred and twelve fungi were isolated of which 91 were of the genus Aspergillus, 83 of the genus Penicillium and the remainder included 23 different genera. Amongst the Aspergillus samples, 26 were producers of aflatoxin, distributed into three species: Aspergillus flavus Link (18); Aspergillus parasiticus Speare (7) and Aspergillus fresenii Subram (1). Of the 100 extracts of analysed nuts, three were afiatoxin-positive.
The water relations of three isolates representative of each of the closely related species Aspergillus fiavus, A. nomius, A. oryzae and A. parasiticus were examined at three temperatures, 25°C, 30°C and 37°C. Media were prepared over a wide range of water activity (aw) from 0.996 to 0.75, controlled by a mixture of glucose and fructose. Water relations of A. fiavus, A. oryzae and A. parasiticus were very similar. The minimum aw for germination and growth of each of these three species was 0.82 at 25°C, 0.81 at 30°C and 0.80 at 37°C. A. nomius was slightly less xerophilic, with minimum aw values for germination and growth of 0.83 at 25 and 30°C, and 0.81 at 37°C. Reported differences in water relations between A. fiavus and A. parasiticus were not substantiated. The "domestication" of A. oryzae has not affected its water relations.
During peanut processing, further removal of aflatoxin-contaminated kernels from electronically sorted and unblanched commercial lots was achieved by color sorting of the kernels after light roasting and deskinning. A modified procedure for efficient recovery of aflatoxin from an individual kernel in a small-scale system was applied for analysis of discolored kernels sampled over 3 consecutive years in Taiwan. The highest and average aflatoxin contents in 60 kernels sampled each year were 1,930 and 150 ppb in 1994, 4,040 and 160 ppb in 1995, and 410 and 32 ppb in 1996, respectively. In 1994, 1995, and 1996, 66.7, 85.0 and 61.7%, respectively, of the kernels tested contained aflatoxins; 16.7, 13.3, and 6.7% contained 50 to 100 ppb and 16.7, 15.0, and 10.0% contained more than 100 ppb. Enhanced aflatoxigenic mold infection and aflatoxin production were monitored in peanut kernels artificially inoculated with Aspergillus parasiticus at various inoculum concentrations and incubated under 100% relative humidity at 28°C or at ambient temperature for various periods. In all cases, aflatoxin content deviated tremendously from kernel to kernel. The highest aflatoxin content observed in a single kernel was 945,000 ppb. In uninoculated kernels incubated in the same conditions, the growth of naturally occurring mycoflora was observed; the highest aflatoxin content was 5,190 ppb.
OBJETIVOS: A presença de micotoxinas em alimentos tem sido correlacionada a várias patologias humanas, e as autoridades de saúde no mundo todo têm implementado ações para diminuir a ingestão desses compostos pela dieta. Realizou-se pesquisa para analisar os níveis de aflatoxinas e ocratoxina A de alimentos para consumo e avaliar o potencial de risco da exposição humana a essas micotoxinas. MÉTODOS: Foram analisadas 366 amostras de alimentos consumidos no Distrito Federal, no período de julho de 1998 a dezembro de 2001, como amendoim e derivados, castanhas, milho, produtos de trigo e/ou aveia, arroz e feijão. As amostras foram processadas, e as micotoxinas extraídas, detectadas e quantificadas por fluorescência após separação em cromatografia camada delgada. RESULTADOS: Foram detectadas aflatoxinas em 19,6% das amostras, em amendoim cru e derivados, milho de pipoca, milho em grão e castanha-do-pará (>2 mig/kg). Amendoim e derivados apresentaram maior incidência de contaminação por aflatoxinas (34,7%) com amostras contendo até 1.280 mig/kg de AFB1+AFG1 e 1.706 mig/kg de aflatoxinas totais. Das amostras positivas, AFB1 estava presente em 98,5%, AFB2 em 93%, AFG1 em 66,7% e AFG2 em 65,4%. A ocratoxina A não foi detectada (<25 mig/kg) em nenhuma amostra analisada. CONCLUSÃO: Os níveis de contaminação encontrados em amendoim e derivados ultrapassaram os níveis máximos permitidos pela legislação brasileira, podendo significar fator de risco para a população que os consome regularmente. A conscientização dos produtores de alimentos e as ações de vigilância sanitária permanentes são essenciais para diminuir a exposição humana a esses compostos e prevenir doenças crônicas advindas dessa exposição.
In this research, 30 hazelnut samples were used to determine their internal mould populations and their aflatoxin contents. The results showed that Aspergillus was the most common genus in the experimental samples (96.6% of all samples). Thirty-one% of isolates were classified as Aspergillus flavus and none of the samples contained aflatoxins. In the second part of the experiment, the kernels were inoculated with conidia of Aspergillus parasiticus and incubated at three different humidified conditions and two different temperatures for 45 days. Aflatoxin contents of the samples kept in 98% relative humidity and at 28 degrees C were higher (904.6 micrograms/kg) than that of the other samples. On the other hand, no aflatoxin was detected in the control samples that were not inoculated but kept at the same conditions.
California exports tree nuts to countries where they face stringent standards for aflatoxin contamination. Trade concerns have stimulated efforts to eliminate aflatoxins and Aspergillus flavus from almonds, pistachios and walnuts. Incidence of fungi on tree nuts and associations among fungi on tree nuts were studied. Eleven hundred pistachios, almonds, walnuts and brazil nuts without visible insect damage were plated on salt agar and observed for growth of fungi. Samples came both from California nut orchards and from supermarkets. To distinguish internal fungal colonization of nuts from superficial colonization, half the nuts were surface-sterilized before plating. The most common genera found were Aspergillus, Rhizopus and Penicillium. Each species of nut had a distinct mycoflora. Populations of most fungi were reduced by surface sterilization in all except brazil nuts, suggesting that they were present as superficial inoculum on (rather than in) the nuts. In general, strongly positive associations were observed among species of Aspergillus; nuts infected by one species were likely to be colonized by other species as well. Presence of Penicillium was negatively associated with A. niger and Rhizopus in some cases. Results suggest that harvest or postharvest handling has a major influence on nut mycoflora, and that nuts with fungi are usually colonized by several fungi rather than by single species.
The desirability, indeed the necessity, for standardization of methods for the examination of foods for contaminant and spoilage mycoflora has been apparent for some time. The concept of a specialist workshop to address this problem was borne during conversations at the Gordon Research Conference on "Hicrobiological Safety of Foods" in Plymouth, New Hampshire, in July 1982. Discussions at that time resulted in an Organizing Committee of four, who became the Editors, and a unique format: all attendees would be expected to contribute and, in most cases, more than once; and papers in nearly all sessions would be presented as a set of data on a single topic, not as a complete research paper. Each session would be followed by general discussion, and then a panel would formulate recommendations for approval by a final plenary session. The idea for this format was derived from the famous "Kananaskis I" workshop on Hyphomycete taxonomy and terminology organized by Bryce Kendrick of the University of Waterloo, Ontario in 1969. Attendance would necessarily be limited to a small group of specialists in food mycology. The scope of the workshop developed from answers to questionnaires circulated to prospective participants. To generate new data which would allow valid comparisons to be drawn, intending participants were given a variety of topics as assignments and asked to bring information obtained to the workshop.
The effect of water activity (aw) on growth and aflatoxin production by Aspergillus parasiticus NRRL 2999 was determined using submerged cultures in which the aw was adjusted by addition of glycerine, glucose, or a mixture of salts. At a sub-optimal aw aflatoxin production was low in the glycerol and glucose media while no strong inhibition of mycelial growth occurred. A similar effect was obtained in surface cultures on agar media in which the aw was adjusted by addition of glycerine or sucrose. The effect of a sub-optimal temperature was the reverse; compared to inhibition of mycelial growth in surface cultures, the effect on aflatoxin production was slight. No detectable quantities of aflatoxin B1 were formed at 0.83 aw and at 10 C nor at four combinations of higher aw and temperature. The aw was measured by a recently developed device using the dewpoint principle.
In order to investigate the relation between growth and aflatoxins production of Aspergillus parasiticus on solid foods or plant materials, powdered plant materials were used as media for cultivating this aflatoxinogenic strain. Cultivation was carried out under 100% humidity, resulting in active fungal growth and aflatoxins production. Experiments were carried out on 13 types of plant materials, and it was found that the fungus grew actively on powdered plant materials containing large amounts of glucides or lipids. The production of aflatoxins was especially active in the latter media containing lipids. However, in Castor seeds, in spite of rapid fungal growth (as in the other samples rich in lipids), aflatoxins production was remarkably low. Some chemical constituents in Castor seeds may inhibit aflatoxins production.
The relationship between injury by the lesser cornstalk borer (LCB), Elasmopalpus lignosellus (Zeller), and invasion of peanut, Arachis hypogaea L., pods and seeds by species of the Aspergillus flavus group (A. flavus Link and A. parasiticus Speare) were studied under laboratory and field conditions. In the laboratory, LCB larvae were an excellent vector of an A. parasiticus color mutant (ATCC 24690) to all developmental stages of peanut pods. Fungal invasion and aflatoxin concentration in seeds were higher in immature pods (stage 2–3) than in more mature pods (stage 4–6). Contamination of seeds with ATCC 24690 was directly related to the extent of pod injury by larvae of the LCB. In field studies, over 50% of the LCB larvae collected from peanut were naturally contaminated with species of the A. flavus group. The planting date and harvest date of peanut had little influence on the incidence of fungal contamination of pods and seeds, or on aflatoxin content in seeds. However, increased pod injury by the LCB significantly increased the percentage of seeds infected with species of the A. flavus group. Seeds in pods with only external scarification from larval feeding had a significantly higher percentage of A. flavus group infection than seeds from uninjured pods. Therefore, infection and contamination of visibly uninjured seeds with aflatoxigenic fungi were enhanced by external injury to peanut pods by the LCB.
Brazil nut and pistachio nut samples from lots known to be contaminated with aflatoxins were visually inspected in detail. Kernels were split lengthwise in halves, and internally highly discolored kernels were analyzed individually. Highly contaminated Brazil nut kernels showed yellow fluorescence if illuminated with light at 360 nm. However, not all fluorescent kernels were contaminated with aflatoxins, and brown spotted kernels also contained these toxins. While contaminated Brazil nut kernels showed different appearance, only brown or brown spotted pistachio kernels were highly contaminated with aflatoxins. In yellowish fluorescent pistachio kernels no aflatoxins, citrinin, kojic acid, patulin, or ochratoxin A could be detected (detection limits: 10-100 mug/kg, 0.5-1, 40-50, 0.2-0.5, and 0.1-0.3 mg/kg, respectively). Slightly discolored kernels and sound kernels were analyzed in different batches. In this way it was shown that contaminated kernels were internally discolored. Ratios of 4700 uncontaminated kernels to 1 kernel containing aflatoxin B1 and 4300 to 1, respectively, were calculated for two pistachio nut samples from different lots. A similar ratio for Brazil nuts could not be calculated since not all highly contaminated kernels were analyzed individually. The highest aflatoxin B1 concentration in a pistachio kernel was 1400 mg/kg; in a Brazil nut 4 mg/kg aflatoxin B1 and 1.2 mg/kg aflatoxin G1 were detected. The high aflatoxin concentrations in a few kernels indicate that the usual sampling sizes of 20 and 50 lb (Brazil nuts and pistachio nuts, lots < 200 bags and 75 000 lb, respectively) may not be sufficient.
Current practice in the collection, handling and storage of Brazil nuts is described. Laboratory and field methods of determining moisture contents, the relationship between moisture content and relative humidity, and the effect of moisture content on respiration rate have been investigated. In storage experiments, deterioration was slow both at very low and very high moisture contents whereas rather rapid spoilage occurred at intermediate levels. These findings are discussed with reference to current commercial practice and work on other seeds.
The combined effects of water activity (a(w)) and temperature on mycotoxin production by Penicilium commune (cyclopiazonic acid - CPA) and Aspergillus flavus (CPA and aflatoxins - AF) were studied on maize over a 14-day period using a statistical experimental design. Analysis of variance showed a highly significant interaction (P ≤ 0.001) between these factors and mycotoxin production. The minimum a(w)/temperature for CPA production (2264 ng g(-1) P. commune, 709 ng g(-1) A. flavus) was 0.90 a(w)/30 °C while greatest production (7678 ng g(-1) P. commune, 1876 ng g(-1) A. flavus) was produced at 0.98 a(w)/20 °C. Least AF (411 ng g(-1)) was produced at 0.90 a(w)/20 °C and most (3096 ng g(-1)) at 0.98 a(w)/30 °C.
Available methods to quantitate fungal growth in infected grains are far from satisfactory. A chemical method to estimate fungal growth in infected plant tissue has been successfully used to estimate accurately the somatic amount of Aspergillus parasiticus on infected grains. Varieties of maize and of groundnuts were studied with respect to their capacity to promote fungal growth and aflatoxin production. No direct correlation was observed between fungal growth and aflatoxin production by the fungus among varieties of maize and groundnut, suggesting that genotypes support different amounts of fungal growth and also different amounts of aflatoxin production per unit growth of the fungus.
Out of 7 isolates of Aspergillus flavus obtained from rotting orange (Citrus reticulata) fruits, 3 isolates were found to be toxigenic, producing variable amounts of aflatoxin B1 on a semisynthetic liquid medium.
The most toxigenic isolates were further evaluated in plain juice and juice supplemented either with 0.05% yeast extract or 0.5% sucrose or both, at three different incubation periods.
The maximum yield of aflatoxin B1 (162.5 μg/25 ml) was obtained from the juice supplemented with both sucrose and yeast extract within an incubation period of 10 days, whereas a sharp decline in aflatoxin B1 (30 μg/25 ml) was observed when incubation was extended beyond 10 days. The addition of yeast extract has a promoting effect on the yield of aflatoxin in comparison to the sucrose.
Isolates of Aspergillus flavus produced 0.2 to 63 mg of aflatoxins B(1) and G(1) per 100 ml in a nutrient solution consisting of 20% sucrose and 2% yeast extract. Various factors influencing the fermentation were studied. The maximal amount of toxin was produced by ATCC culture 15548 in 1-liter flasks containing 100 ml of medium incubated as stationary cultures for 6 days at 25 C.
Sound mature kernels, broken mature kernels, immature kernels, and unshelled Early Runner peanuts were heat-treated in controlled
environment cabinets and inoculated with spores ofAspergillus flavus. Treatments were incubated at 97–99% relative humidity at different temperatures ranging from 5 to 55C and also at 30C with
relative humidities ranging from 55 to 99%. Samples were removed after 7 and 21 days and assayed for aflatoxin, free fatty
acids, and peanut kernel moisture. The limiting relative humidity for aflatoxin production byA. flavus was 85±1% relative humidity for 21 days at 30C. The limiting low temperature for visible growth and aflatoxin production
by the fungus was 13±1C for 21 days at 97–99% relative humidity. Damaged kernels, however, developed some afllatoxin in 21
days at 12C. The maximum temperature for aflatoxin production was 41.5±1.5C for 21 days at 97–99% relative humidity. Fungus
growth and sporulation at 43C were equal to that at 40C, but no aflatoxin was produced. Moisture content of immature kernels
was higher at equilibrium with the same relative humidity than the moisture content of sound mature kernels, damaged kernels,
or kernels from unshelled peanuts. There appeared to be no proportional quantitative correlation between synthesis of aflatoxin
and production of free fatty acids in nonliving peanuts, but no aflatoxin was produced without a simultaneous increase in
free fatty acids.
An effective selective medium for the enumeration of Aspergillus flavus and Aspergillus parasiticus has been developed by modification of Bothast and Fennell's Aspergillus Differential Medium. Results can be obtained with the new medium, Aspergillus flavus and parasiticus Agar (AFPA), after 42 h incubation at 30 degrees C. The medium is thus suitable for use in quality control as a guide to the presence of A. flavus and, potentially, of aflatoxins. AFPA has been extensively tested on peanuts and soils. Results were reproducible and comparable with those on standard fungal enumeration media incubated for much longer periods. A very low percentage of false positive or negatives was found.
An effective technique for assessing fungal infections of particulate foods such as cereals, nuts, fruits and vegetables is surface disinfection with a sodium hypochlorite solution before plating directly onto agar media. The surface disinfection procedure is used to inactivate the surface mycoflora then permitting assessment of the percentage of particles invaded by specific fungi. A previously recommended procedure treating samples with 0.4% chlorine for 2 min has been shown to be ineffective for barley highly contaminated with conidia of either A. flavus or A. parasiticus. An international collaborative study has demonstrated that modifying the procedure by increasing the chlorine concentration to 0.8%, or increasing the contact time to 8 min, or increasing the volume of chlorine solution is not the answer, especially with surface contamination loads of approximately 10(6) conidia/g. The inclusion of a 70% ethanol pre-rinse prior to a 0.8% chlorine treatment for 2 min made a significant improvement to the inactivation of surface conidia of A. flavus on barley. However, pretreatment with ethanol inactivated some of the internal Alternaria infections especially when the ethanol was not rinsed off. Further studies including an ethanol pre-rinse are recommended to optimise the surface disinfection procedure for seeds and nuts which have a high concentration of fungal surface contaminants.
A wide range of field and storage fungi were isolated from black pepper, white pepper and Brazil nut kernels from Amazonia. A total of 42 species were isolated from both peppers. Aspergillus flavus and A. niger were isolated more frequently from black than from white pepper. Other potential mycotoxigenic species isolated included: A. ochraceus, A. tamarii, A. versicolor, Emericella nidulans and Chaetomium globosum, Penicillium brevicompactum, P. citrinum, P. islandicum and P. glabrum. Species isolated from pepper for the first time were Acrogenospora sphaerocephala, Cylindrocarpon lichenicola, Lacellinopsis sacchari, Microascus cinereus, Petriella setifera and Sporormiella minima. Seventeen species were isolated from Brazil nut kernels. A. flavus was the dominant species followed by A. niger.
P. citrinum and P. glabrum were the only penicillia isolated. Species isolated for the first time included Acremonium curvulum, Cunninghamella elegans, Exophiala sp., Fusarium oxysporum, Pseudoallescheria boydii, Rhizopusoryzae, Scopulariopsis sp., Thielavia terricola and Trichoderma citrinoviride. Considerably more metabolites were detected from black than white pepper in qualitative analyses. Chaetocin, penitrem A, and xanthocillin were identified only from black pepper, and tenuazonic acid was identified from both black and white pepper. Aflatoxin G2, chaetoglobosin C, and spinulosin were identified from poor quality brazil nuts. Aflatoxin B1 and B2 were also only detected in poor quality brazil nuts at concentrations of 27.1 μg kg−1 and 2.1 μg kg−1 respectively (total 29.2 μg kg−1).
The aflatoxin distribution of single insect damaged Nonpareil almonds (1999 crop) has been measured. Separate distributions were obtained for pinhole, insect (feeding), and gross damage. Only a low level of aflatoxin contamination ( = 0.0003 ng/g) was found for pinhole-only damaged nuts. The distributions for insect and gross damage did not differ, but did differ significantly from the distribution previously obtained for gross damaged Ne Plus almonds from a different producer (Schatzki, T. F.; Ong, M. S. J. Agric. Food Chem. 2000, 48, 489-492; also 1999 crop). The Nonpareil almond distribution could be explained on the basis of a preharvest hull splitting, similar to previous results in pistachios (0-4 weeks versus 2-6 weeks preharvest). The Ne Plus distribution differs in detail from pistachio results and from the Nonpareil results found here. This may indicate additional cultural damage of Ne Plus almonds around harvest time and/or use of different sorting parameters. Aflatoxin lot averages of 31.7 and 3.47 ng/g were obtained for 100% insect damaged Ne Plus and Nonpareil almonds, respectively. (The previous Ne Plus work contained a calculation error, which is corrected here.) The distribution functions were used to compute the seller's risk of nonacceptance of lots in the European Union. To obtain a 95% acceptance rate, aflatoxin B(1) levels of 0.12 and 0.22 ng/g would be required, which would correspond to 3.8 and 1.2% (feeding and gross) insect damage in Nonpareil and Ne Plus almond lots, respectively.
Four different Aspergilli (Aspergillus oryzae, A. parasiticus, A. terreus and A. versicolor) were grown on wheat grains underdifferent degrees of relative humidity 14, 50, 74, 80 and 90%. Samples of wheat grains were taken monthly for a period of six months and examined for mycotoxin production. A. oryzae was found to produce aflatoxins B1, B2, zearalenone, DON and T-2 toxins under elevated degrees of humidity and prolonged periods of storage. A. parasiticus produced aflatoxins B1, G1, NIV, DON and T-2 toxins in high concentrations during a period of not more than three months storage at 14% relative humidity; at an increased level of relative humidity of 74% ochratoxin A, zearalenone and sterigmatocystin were also produced at high levels. The isolate was drastic in toxin production. A. terrus produced toxins at 14% relative humidity (aflatoxin G2 and DON) at levels much higher than any other prevalent degrees of humidity. A. versicolor is highly sensitive to relative humidity and grain moisture content It produced aflatoxins B1, G1, NIV and DON at a relative humidity of 50% and another toxins (aflatoxin G2, ochratoxins A, B and zearalenone) at 74%. The microorganism can be considered a trichothecene producer under suitable relative humidity.
Two aflatoxin-producing isolates of Aspergillus flavus were grown for 5 days on Wort media at 2, 7, 13, 18, 24, 29, 35, 41, 46, and 52 C. Maximal production of aflatoxins occurred at 24 C. Maximal growth of A. flavus isolates occurred at 29 and 35 C. The ratio of the production of aflatoxin B(1) to aflatoxin G(1) varied with temperature. Aflatoxin production was not related to growth rate of A. flavus; one isolate at 41 C, at almost maximal growth of A. flavus, produced no aflatoxins. At 5 days, no aflatoxins were produced at temperatures lower than 18 C or higher than 35 C. Color of CHCl(3) extracts appeared to be directly correlated with aflatoxin concentrations. A. flavus isolates grown at 2, 7, and 41 C for 12 weeks produced no aflatoxins. At 13 C, both isolates produced aflatoxins in 3 weeks, and one isolate produced increasing amounts with time. The second isolate produced increasing amounts through 6 weeks, but at 12 weeks smaller amounts of aflatoxins were recovered than at 6 weeks.
Die Paranuss. II. Verderb und Bildungsbedingungen fuer Aflatoxin (The Brazil nut. II. Spoilage and conditions for aflatoxin formation)
- H K Frank
- L Betancourt
- M Uboldi
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Escherichia coli on pecans
- Beuchat
Edible nuts. Non-wood forest products
- Fao
The internal rots of Brazil nuts
- Holubova-Jechova
Aspergillus on tree nuts
- Bayman
Die Paranuss. II. Verderb und Bildungsbedingungen fuer Aflatoxin (The Brazil nut. II. Spoilage and conditions for aflatoxin formation)
- Frank
Aflatoxigenic fungi and their detection
- Hocking
Deterioracado de castanha do Par.1. Armazenamento das amendoas (Deterioration of Brazil nuts. I. Storage of nuts)
- Yokoya