Warapa Mahakarnchanakul

Kasetsart University, Krung Thep, Bangkok, Thailand

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Publications (11)25.29 Total impact

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    ABSTRACT: Fusarium spp. are plant pathogens producing fumonisins and trichothecenes that both affect human and animal health. In the present study, 40 fungal strains were isolated and species identified from 35 shrimp feed samples and from 61 agricultural raw materials. F. verticillioides was the predominant species (85 %) mostly found in corn and soybean meal, while no Fusarium contamination was detected in shrimp feed. Levels of 10 % of F. oxysporum were isolated from peanut and 5 % of F. equiseti contamination in corn and peanut. To determine the ability of toxin production, enzyme-linked immunosorbent assay, polymerase chain reaction, and ultra-pressure liquid chromatography-tandem mass spectrometry were performed. All but four of the fumonisin-producing strains contained the FUM1 gene. No Fusarium synthesized T-2 toxin nor contained the Tri5 gene. This survey brings more data on mycotoxin contamination in the food chain of animal feed production, and leads to the awareness of the use of contaminated raw materials in shrimp farming.
    Mycotoxin Research 11/2013; DOI:10.1007/s12550-013-0182-y
  • Nampeung Anukul, Kanithaporn Vangnai, Warapa Mahakarnchanakul
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    ABSTRACT: Mycotoxins are the secondary metabolites produced from toxigenic fungi recognized as major food and feed contaminants. They are a source of grave concern in food contamination, resulting in mycotoxicosis in humans and animals. To date, many regulations on the allowable levels of each mycotoxin have been established in several countries. Consumers and food producers expect that toxin contamination in food and feed, based on government regulations and guideline levels, should have no adverse consequences on human and animal health. This review is an extension of the discussions during the international seminar entitled Risk Assessment and Risk Management of Mycotoxins for Food Safety in Asia, which was jointly organized by Kasetsart University (Thailand) and the Food and Fertilizer Technology Center for the Asian and Pacific Region (Taiwan) and held in Chonburi, Thailand, in September 2011. In this review, we discuss the recent findings on mycotoxins in food and feed, with emphasis on aflatoxins, fumonisins, ochratoxins, and zearalenone, as well as the national management programs that will supply a wider knowledge base for establishing appropriate control measures for mycotoxins in Asian countries. However, we believe that continuing support from national governments and regional communities is essential to encourage and fund activities that contribute to a reliable exposure risk assessment and risk management of mycotoxins in the region, and also to improve our understanding and practices in order to protect consumers from the health threat posed by mycotoxin contamination. Copyright
    Journal of Food and Drug Analysis 09/2013; 21(3):227-241. DOI:10.1016/j.jfda.2013.07.009 · 0.40 Impact Factor
  • SUPRANEE MANURAKCHINAKORN, UMAPORN CHAMNAN, WARAPA MAHAKARNCHANAKUL
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    ABSTRACT: Retarding browning and softening of fresh‐cut mangosteen during storage under modified atmosphere packaging (MAP) by pretreatment with preservative dips was investigated. Mangosteens at stage 1 of maturity were peeled and immersed for 30 min in different mixed solutions including 2% sodium erythorbate + 0.2% calcium chloride (CaCl2), 1% aluminium sulfate + 1% sodium chloride (NaCl), 1% ascorbic acid (AA) + 1% NaCl + 1% CaCl2 and 1% citric acid + 1% NaCl + 1% CaCl2 prior to active MAP (5% O2 + 9% CO2) using low‐density polyethylene bag. Quality changes of the fresh‐cut mangosteens were monitored during storage at 4C for up to 12 days. The fruit treated with 1% AA + 1% NaCl + 1% CaCl2 exhibited the best quality of appearance and texture in terms of lightness, firmness, weight loss, exudation and sensory score during the storage. However, in‐package atmospheric compositions of all treatments were similarly developed throughout the storage. PRACTICAL APPLICATIONSConsumption of fresh‐cut mangosteen has been increasing rapidly due to its unique lusciousness. However, discoloration and firmness loss of the product are crucial limiting factors to acceptability by consumers. Chemical treatment with the mixed solution of 1% ascorbic acid + 1% sodium chloride + 1% calcium chloride has high potential for practical applications due to its effectiveness in maintaining appearance and texture of the product. Furthermore, the use of inexpensive preservative results in reducing production cost.
    Journal of Food Processing and Preservation 12/2012; 36(6). DOI:10.1111/j.1745-4549.2011.00617.x · 0.94 Impact Factor
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    ABSTRACT: Pathogenic Vibrio parahaemolyticus in prawn has been a major cause of saefood-borne infection outbreaks. An understanding of its behavior in prawn helps ensure safety of the seafood consumption. The objective of this investigation was to understand the pathogenic V. parahaemolyticus behavior in non-sterile prawn in a laboratory and frozen food factory as responding to temperature. The behavior was observed in a laboratory. It was found that in the laboratory this pathogen grew in a temperature range of 15–44 °C but died in −20 to 10 °C. The primary Baranyi and modified Gompertz models excellently explained the pathogenic growth and death characteristics, respectively. The effects of temperature on the primary-model parameters were well described by the Kohler, Ratkowsky, asymptotic and non-linear Arrhenius models. The behavior of the pathogen was also observed in a freezing process line. The pathogen responded to temperature in a similar manner to that in the laboratory results although the actual line process involved more influencing factors. Therefore, the laboratory results of temperature effect on the pathogen behavior can provide a good guideline of safety for process design and control of the seafood. The response similarity was beneficial in the information usage of pathogen behavior in prawn which was satisfactorily interchangeable between these two environments.
    Food Control 08/2012; 26(2):479–485. DOI:10.1016/j.foodcont.2012.02.009 · 2.82 Impact Factor
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    P Noonim, W Mahakarnchanakul, K F Nielsen, J C Frisvad, RA Samson
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    ABSTRACT: During 2006 and 2007, a total of 64 Thai dried coffee bean samples (Coffea arabica) from two growing sites in Chiangmai Province and 32 Thai dried coffee bean samples (Coffea canephora) from two growing sites in Chumporn Province, Thailand, were collected and assessed for fumonisin contamination by black Aspergilli. No Fusarium species known to produce fumonisin were detected, but black Aspergilli had high incidences on both Arabica and Robusta Thai coffee beans. Liquid chromatography (LC) with high-resolution mass spectrometric (HRMS) detection showed that 67% of Aspergillus niger isolates from coffee beans were capable of producing fumonisins B(2) (FB(2)) and B(4) when grown on Czapek Yeast Agar with 5% NaCl. Small amounts (1-9.7 ng g(-1)) of FB(2) were detected in seven of 12 selected coffee samples after ion-exchange purification and LC-MS/MS detection. Two samples also contained FB(4). This is the first record of freshly isolated A. niger strains producing fumonisins and the first report on the natural occurrence of FB(2) and FB(4) in coffee.
    Food Additives and Contaminants - Part A Chemistry, Analysis, Control, Exposure and Risk Assessment 02/2009; 26(1):94-100. DOI:10.1080/02652030802366090 · 2.34 Impact Factor
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    ABSTRACT: In 2006 and 2007, 32 Thai dried coffee bean samples (Coffea arabica) from two growing sites of Chiang Mai Province, and 32 Thai dried coffee bean samples (Coffea canephora var. robusta) from two growing sites of Chumphon Province, Thailand, were collected and assessed for the distribution of fungi with the potential to produce ochratoxin A (OTA). The overall percentage of fungal contamination in coffee was 98% and reduced to 60% after surface disinfection. There were remarkable ecological differences in the composition of ochratoxigenic species present in these two regions. Arabica coffee bean samples from the North had an average of 78% incidence of colonization with Aspergillus of section Circumdati with Aspergillus westerdijkiae and A. melleus as the predominant species. Aspergillus spp. of section Nigri were found in 75% of the samples whereas A. ochraceus was not detected. Robusta coffee beans from the South were 98-100% contaminated with predominantly A. carbonarius and A. niger. A. westerdijkiae was only found in one sample. The diversity of the fungal population was probably correlated with the geographical origin of the coffee, coffee cultivar, and processing method. Representative isolates of section Circumdati (52) and Nigri (82) were examined for their OTA production using HPLC with fluorescence detection. Aspergillus westerdijkiae (42 isolates out of 42), A. steynii (13/13), and A. carbonarius (35/35) in general produced large amounts of OTA, while one isolate of A. sclerotiorum produced intermediate amounts of OTA. 13% of the A. niger isolates produced OTA in intermediate amounts. OTA levels in coffee bean samples were analyzed using the Ridascreen OTA ELISA kits. Of the 64 coffee bean samples analyzed, 98% were contaminated with OTA in levels of <0.6-5.5 microg/kg (Arabica) and 1-27 microg/kg (Robusta). Presence of OTA in representative coffee samples was also confirmed by LC-MS/MS after ion-exchange purification.
    International Journal of Food Microbiology 09/2008; 128(2):197-202. DOI:10.1016/j.ijfoodmicro.2008.08.005 · 3.16 Impact Factor
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    ABSTRACT: Two novel species of Aspergillus section Nigri from Thai coffee beans are described as Aspergillus aculeatinus sp. nov. and Aspergillus sclerotiicarbonarius sp. nov. Their taxonomic status was determined using a polyphasic taxonomic approach with phenotypic (morphology and extrolite profiles) and molecular (beta-tubulin, internal transcribed spacer and calmodulin gene sequences) characteristics. A. aculeatinus sp. nov. is a uniseriate species with a similar morphology to Aspergillus aculeatus and Aspergillus japonicus, but producing smaller conidia (2-5 microm). A. aculeatinus sp. nov. produced neoxaline, secalonic acid D and F, and aculeacins. A. sclerotiicarbonarius sp. nov. is a biseriate species similar to Aspergillus carbonarius and Aspergillus ibericus, but produces abundant sclerotia and some unique indol-alkaloids. The type strain of Aspergillus sclerotiicarbonarius sp. nov. is CBS 121057(T) (=IBT 28362(T)) and the type strain of Aspergillus aculeatinus sp. nov. is CBS 121060(T) (=IBT 29077(T)).
    International Journal of Systematic and Evolutionary Microbiology 08/2008; 58(Pt 7):1727-34. DOI:10.1099/ijs.0.65694-0 · 2.80 Impact Factor
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    ABSTRACT: The genus Aspergillus is one of the most important filamentous fungal genera. Aspergillus species are used in the fermentation industry, but they are also responsible of various plant and food secondary rot, with the consequence of possible accumulation of mycotoxins. The aflatoxin producing A. flavus and A. parasiticus, and ochratoxinogenic A. niger, A. ochraceus and A. carbonarius species are frequently encountered in agricultural products. Studies on the biodiversity of toxigenic Aspergillus species is useful to clarify molecular, ecological and biochemical characteristics of the different species in relation to their different adaptation to environmental and geographical conditions, and to their potential toxigenicity. Here we analyzed the biodiversity of ochratoxin producing species occurring on two important crops: grapes and coffee, and the genetic diversity of A. flavus populations occurring in agricultural fields. Altogether nine different black Aspergillus species can be found on grapes which are often difficult to identify with classical methods. The polyphasic approach used in our studies led to the identification of three new species occurring on grapes: A. brasiliensis, A. ibericus, and A. uvarum. Similar studies on the Aspergillus species occurring on coffee beans have evidenced in the last five years that A. carbonarius is an important source of ochratoxin A in coffee. Four new species within the black aspergilli were also identified in coffee beans: A. sclerotioniger, A. lacticoffeatus, A. sclerotiicarbonarius, and A. aculeatinus. The genetic diversity within A. flavus populations has been widely studied in relation to their potential aflatoxigenicity and morphological variants L- and S-strains. Within A. flavus and other Aspergillus species capable of aflatoxin production, considerable diversity is found. We summarise the main recent achievements in the diversity of the aflatoxin gene cluster in A. flavus populations, A. parasiticus and the non-toxigenic A. oryzae. Studies are needed in order to characterise the aflatoxin biosynthetic genes in the new related taxa A. minisclerotigenes and A. arachidicola.
    Studies in Mycology 02/2007; 59:53-66. DOI:10.3114/sim.2007.59.07 · 9.30 Impact Factor
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    ABSTRACT: The objective of this study was to determine the potential antimicrobial activity of extracts and essential oils of spices from Thailand against foodborne pathogenic bacteria. The antimicrobial efficacy of ginger (Zingiber officinale), fingerroot (Boesenbergia pandurata), and turmeric (Curcuma longa) was evaluated against five strains of Listeria monocytogenes and four strains of Salmonella enterica ssp. enterica serovar Typhimurium DT104. Antimicrobial activity was investigated in microbiological media by using an agar dilution assay and enumeration over time and a model food system, apple juice, by monitoring growth over time. In the agar dilution assay, water extracts of the three spices had no effect on L. monocytogenes. Similarly, 50% ethanol extracts of ginger or turmeric had no effect. In contrast, ethanolic fingerroot extracts at 5 to 10% (vol/ vol) inhibited most L. monocytogenes strains for 24 h in the agar dilution assay. Commercial essential oils (EO) of ginger or turmeric inhibited all L. monocytogenes at < or = 0.6 or < or = 10%, respectively. Fingerroot EO inhibited all strains at < or = 0.4%. In the enumeration-over-time assay, a 5% fingerroot ethanol extract reduced ca. 4 log CFU/ml Listeria by around 2 log in 24 h while 10% inactivated the microorganism in 9 h. Fingerroot EO at 0.2% inactivated 4 log CFU/ml L. monocytogenes in 6 to 9 h. Neither extracts nor commercial EO had any effect on Salmonella Typhimurium DT 104 with the exception of fingerroot EO, which inhibited all strains at < or = 0.7%. Addition of 0.2% fingerroot EO to apple juice reduced 4 log of L. monocytogenes Scott A and both strains of Salmonella Typhimurium to an undetectable level within 1 to 2 days. It was concluded that fingerroot EO and extract have potential for inhibiting pathogens in food systems.
    Journal of food protection 11/2005; 68(10):2054-8. · 1.80 Impact Factor
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    C. Thongson, P.M. Davidson, W. Mahakarnchanakul, J. Weiss
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    ABSTRACT: Aims:  The objective of this research was to determine the antimicrobial activity of conventional and high-intensity ultrasound-assisted (HI-US) solvent-extracted Thai spices, including ginger (Zingiber officinale Rose), fingerroot (Bosenbergia pandurata Holtt) and turmeric (Curouma longa Linn).Methods and Results:  Extracts were obtained using hexane, isopropanol and a 7 : 3 isopropanol : hexane mixture as solvents with and without HI-US. The antimicrobial activity of the extracts was assayed against four strains each of Listeria monocytogenes and Salmonella Typhimurium DT 104 using an agar dilution assay. Application of HI-US did not alter antibacterial activity against S. Typhimurium, but antilisterial activity of some HI-US spice extracts decreased. Solvent type affected antimicrobial efficacy of extracts with hexane producing the least antimicrobial activity. Fingerroot extracted with isopropanol–hexane and without HI-US had the best antilisterial effect while HI-US–isopropanol fingerroot extract had the greatest antimicrobial efficacy against S. Typhimurium.Conclusions:  Application of HI-US reduced time of extraction to 5 min, compared with the 24 h required for conventional extraction and maintained antimicrobial activity against Salmonella but slightly reduced activity against Listeria.Significance and Impact of the Study:  HI-US in combination with proper solvent selection may offer a new tool to optimize extraction of spice essential oil for use as antimicrobial agents, and reduce processing time and costs.
    Letters in Applied Microbiology 09/2004; 39(5):401 - 406. DOI:10.1111/j.1472-765X.2004.01605.x · 1.75 Impact Factor
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    ABSTRACT: The ginger, galangal, turmeric, and fingerroot extracts were determined for their antimicrobial activities against foodborne pathogenic bacteria, spoilage bacteria and fungi by using agar dilution assay. Salmonella enterica serotype Typhimurium and Eschericia coli O157:H7 were resistant to ginger, galangal, turmeric, and fingerroot extracts. Minimal inhibitory concentrations (MICs) of ginger, galangal, turmeric and fingerroot extracts against those gram-negative bacteria were 8–10% (v/v). Fingerroot extract showed stronger inhibitory activity against Listeria monocytogenes, Bacillus cereus, and Staphylococcus aureus than ginger, turmeric, and galangal extracts. MICs of fingerroot extract was 0.2–0.4% (v/v). For the spoilage bacteria Lactobacillus plantarum and L. cellobiosus, galangal extract gave the most efficiency of with MIC at 4% (v/v). The results showed that fingerroot and ginger extracts had antifungal activity ranging from 8 to 10 and 10% (v/v) against Aspergillus flavus, A. niger, A. parasiticus and Fusarium oxysporum, respectively. Moreover, inhibition over time of E. coli O157:H7 was studied in TSB added with spice extracts at concentrations ranging from 8 to 10% (v/v). The 8% galangal and 10% fingerroot extracts showed bactericidal effect at 36 hours and 9 hours, respectively. While 8% turmeric extract showed bacteriostatic effect. In conclusion, rhizomatous spice extracts had antimicrobial effect against some spoilage and pathogenic microorganisms, thus it has potential to be used as natural preservative agents.