Article

Pectolytic Enzymes in Sweet Bell Peppers (Capsicum annuum L.)

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Abstract

Low levels of polygalacturonase (PG) and pectinesterase (PE) activities were quantitated in sweet bell peppers at four stages of maturity based on surface ground color (dark green, light green, turning, and red). The PG activity increased during pepper ripening and was maximal at the turning stage while the PE activity declined during ripening and was maximal at the light green stage. Pepper texture measurements were found to decline concomitantly with the increase in PG activity. Pepper PG showed pH optimum between 4.8 to 5.0 and increased temperature stability with advanced ripening. Compared to tomatoes, pepper PG activity was 116- to 164-fold lower and pepper PE activity was 429- to 1900-fold lower than the corresponding tomato enzymes.

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... Pectin methylesterase (PME): The crude enzyme extract was prepared according to the methodology described by Pressey and Avants (1982) and Jen and Robinson (1984). Approximately 4 g of plum pulp was weighed out, and 8 mL of 0.2 N sodium chloride (NaCl) was added. ...
... The extract was placed in the freezer (-18 °C) until quantification. The activity of the PME enzyme was measured using a modification of the method of Rouse and Atkins (1955), cited by Jen and Robinson (1984), in which a unit of PME activity is defined as the amount capable of catalyzing the demethylation of pectin corresponding to the consumption of one nmol of 0.001 N NaOH in 10 minutes. For the quantification, 30 g of the reaction solution (1 g mL -1 of citric pectin added to 100 mL of 0.2 N NaCl) was added to 4 mL of the enzyme extract, and the solution was calibrated to pH 7.0 with solutions of NaOH 1 N and acetic acid to increase and decrease the pH, respectively. ...
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The use of extracts of algae in agriculture has been growing because of their benefits to plant development and production. The objective of this study was to evaluate the effects of Ascophyllum nodosum extract on the postharvest quality of ‘Irati’ and ‘Reubennel’ plums and on the incidence of brown rot. The treatments consisted of concentrations of 0, 0.1, 0.2, 0.3 and 0.4 mL L-1 of a commercial product containing algae extract (Algamare®) that were applied to the fruits by immersion. The fruits were then stored for 15 (cv. Irati) or 30 days (cv. Reubennel) at 2.5 °C and 90% RH and for two additional days at ambient conditions for further physicochemical analysis. A batch of ‘Reubennel’ plums was inoculated with Monilinia fructicola and kept for seven days in a cold room and an additional nine days at room temperature to evaluate the occurrence of brown rot. The postharvest application of the extract at a concentration of 0.4 mL L-1 altered some of the physicochemical characteristics of the fruit after storage; an increase in the total phenolic compound content and PG activity were observed in ‘Irati’ plums. Reubennel fruits had higher titratable acidity, a lower TSS/TA ratio, lower pulp firmness and higher PME activity. The most significant effect was observed with the application of A. nodosum extract at 0.4 mL L-1, which significantly reduced the incidence and severity of brown rot in the inoculated fruits and had a similar control effect as the application of the fungicide iprodione.
... This work studied the PME (pectin methylesterase) and PG (polygalactorunase) properties of Granada, Esmeralda, Jade, Diamante, Granito, Maciel, Eldorado and Jubileu clingstone peaches, defining the stablest enzyme of it. The PG activity used PRESSEY (1986) methodology and the PME determination used JEN & ROBINSON (1984) methodology. For the physical and chemical properties were used AOAC (2000) methodology. ...
... Essas enzimas atuam diretamente sobre o amolecimento dos frutos durante sua deterioração, reduzindo sua vida útil e, ainda, têm importância sobre o processamento tecnológico dos frutos, pois estão diretamente relacionadas com a viscosidade do produto, influindo em operações como a clarificação e a concentração. O efeito residual de enzimas como as pectinametilesterases (PME) e poligalacturonases (PG) também podem interferir sobre a turbidez e coloração de sucos clarificados ao catalisar reações de escurecimento não enzimático, via Reação de Maillard, comprometendo sobremaneira os aspectos sensoriais do produto final e sua vida-de-prateleira (LUH, 1980;ANTHON, 2002;LIMA, 2002 a, b ROBINSON, 1984;VILAS BOAS et al., 2000). ...
Article
O presente trabalho objetivou estudar as propriedades das enzimas pecticas em cultivares brasileiras de pessegos. As enzimas pecticas influem na qualidade dos frutos, especialmente de frutos climatericos como o pessego, pois atuam diretamente no amolecimento dos frutos durante sua deterioracao, reduzindo sua vida util. Tambem tem importância no processamento dos frutos, pois estao diretamente relacionadas com a viscosidade do produto em operacoes como a clarificacao e a concentracao. Neste trabalho estudou-se o comportamento e atividade in vitro das enzimas pectinametilesterase (PME) e poligalacturonase (PG) em pessegos das cultivares Granada, Esmeralda, Jade, Diamante, Granito, Maciel, Eldorado e Jubileu, definindo a enzima mais termoestavel da cultivar de menor atividade de PG e PME. A Atividade da PG foi determinada utilizando a metodologia descrita por PRESSEY (1986) e a atividade da PME segundo JEN e ROBISON (1984). As propriedades fisicas e quimicas foram determinadas segundo AOAC (2000), enquanto a estabilidade termica das enzimas seguiu o procedimento descrito por LOWRY (1955). A PG da cv. Eldorado mostrou maxima atividade no entorno do pH 5,0 enquanto que, para a PME, a maxima atividade foi observada no pH 7,0. Para PG e PME a temperatura otima foi a de 25oC. A estabilidade termica da PME foi significativamente maior que a da PG, decorrente de uma menor constante de velocidade de inativacao e maior tempo de meia-vida para qualquer condicao de temperatura, podendo ser utilizada como indicador de termoinativacao para controle durante o processamento tecnologico de sucos e polpas de pessegos. Palavras-chave: Pessegos; PME; PG; Estabilidade termica.
... The activity of the enzyme pectin methyl esterase (PME) was determined using a method described by Jen and Robinson (1984), and the results were expressed in micromole of NaOH per g min −1 . The activity of the enzyme polygalacturonase (PG) was measured according to Pressey and Avants (1973), and the results were expressed as enzymatic activity unit (UAE) per g min −1 . ...
... it was determined according to Jen and Robinson (1984), where it was examined the ability of the enzyme to catalyze the demethylation of pectin corresponding to 1 mol of NaOH per minute under the test conditions. The results were expressed as UAE g min −1 . ...
... for sweet bell peppers (Capsicum annuum L., Solanaceae)[17] [41]. The enzyme extracts were prepared from 100 g of cubiu pulps of each studied ripening stage. ...
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Cubiu fruits (Solanum sessiliflorum Dunal, Solanaceae) are known for their high nutritional value and low caloric content. This work aimed at evaluating biochemical indices of cubiu fruits according to different tissues (peel, pulp and placenta) and ripening stages (green, turning, ripe and fully ripe). The fruits were randomly harvested to investigate sensory aspects (colorimetry, blanching effect, pigments) and biochemical indices (moisture and dry matter, Total Soluble Solids (TSS), pH, Titratable Acidity (TA), TSS/TA ratio, ascorbic acid, Alcohol-Insoluble Solids (AIS), pectinesterase activity and pectin content). The analyses were performed at the laboratory of Instituto Nacional de Pesquisas da Amazônia (INPA), Manaus, Brazil. The blanching process preserved pulp colors at all ripening stages. Chlorophylls were higher in green peels; flavonoids and carotenoids, in fully ripe peels. Anthocyanins were entirely absent. Pulp (turning fruits) showed the highest moisture content (91.05), followed by ripe pulp (90.70) and fully ripe pulp (90.62). Pulp TSS changed little whereas placenta TSS declined and were associated with increased TA and pH reduction (fully ripe fruits). Pulp pH and TA varied little whereas placenta pH was notably low and TA was remarkably high (fully ripe fruits). Pulp TSS/TA ratio showed predominance of TSS while in placenta, there was predominance of organic acids. AIS, precursors of pectin, were stable during ripening. The statistical analysis of dietary fiber content showed one modal value in the AIS. In pulp, pectinesterase activity correlated inversely with pectin content. Cubiu fruits were significant sources of bioactive compounds, e.g. chlorophylls, flavonoids and carotenoids, predominantly in the peel and the pulp; soluble functional fibers, e.g. pectin (g/100 g fresh weight), particularly in the green peel (1.00) and the fully ripe pulp (1.12), and other versatile molecules, e.g. ascorbic acid (mg/100 g fresh weight), especially in the fully ripe peel (32.45) and placenta (24.84) and the turning placenta (21.27). Cubiu fruits are rich in ascorbic acid and should be included in the human diet.
... Cell wall hydrolases and all enzymatic assay procedures were performed at 4 • C, and the results were calculated as specific enzyme activity in reference to the total protein (P) content of each sample, as proposed by Bradford (1976). Cell wall hydrolases were assayed according to Jen and Robinson (1984) and Pressey and Avants (1982), pectin methylesterase (PME, EC 3.1.1.11) activity was based on the unit of specific enzyme activity (U), defined as the amount of enzyme capable of removing a methyl group from pectin, and results are expressed as U min − 1 mg − 1 of protein (P). ...
Article
This study investigated how pulsed light (PL) postharvest treatment influences acerola ripening physiology and quality, thus physiologically mature acerola 'Okinawa' were treated with PL (0.6 J.cm − 2) and stored for 16 days at 10 • C. Compared to untreated, PL-treated acerola showed a 5% reduction in climacteric respiration with 78.65 mol CO 2 kg − 1 h − 1 and a one-day delay in ethylene peak of 2.65 µL C 2 H 4 kg − 1 h − 1. PL-treated acerola also showed 13% lower weight loss and was 12% firmer probably due to the enhanced antioxidant enzymes that reduced hydrogen peroxide content with lower membrane lipid peroxidation, in addition to inhibition of cell wall hydrolysis. The higher polyamine levels induced by PL may be explained by the greater synthesis, inhibition of degradation, and enhancement of back-conversion reactions. PL treatment would have increased the total vitamin C by 33% as a result of lower degradation and more efficient recycling reactions, while polyphenols would have increased 10% by reducing oxidation and enhancing synthesis. Although the storage period exerted the main influence on 'Okinawa' acerola, results indicate that PL delayed ripening and promoted quality as an elicitor of antioxidant metabolism thus representing a hormetic phenomenon.
... Atividade da enzima pectinametilesterase (PME; EC: 3.1. 1.11) Foi determinada de acordo com a metodologia de Jen e Robinson (1984) [12] e expressa em unidade de atividade enzimática por min (UAE min -1 ). ...
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A utilização de biofilmes comestíveis são uma das alternativas tecnológicas eficientes na manutenção da vida útil de frutos e hortaliças. A fina camada de material comestível atua como excelente propriedade de barreira artificial, e associada à refrigeração age mantendo a qualidade pós-colheita dos frutos. Este trabalho teve como objetivo avaliar a aplicação do biofilme a base de alginato de sódio sobre a manutenção da qualidade pós-colheita de pimentões verdes (Capsicum annuum L.). Os frutos foram selecionados, lavados, sanitizados, revestidos com 1% e 3% de alginato. Frutos sem revestimento foram utilizados como controle Após aplicação do revestimento os frutos foram armazenados em expositor vertical a 7°C e 87±1% UR por até 15 dias. A cada três dias Foram realizadas analises de perda de massa fresca, firmeza do fruto, teores de acidez titulável e de ácido ascórbico, pH, parâmetros de cor, e atividade da enzima pectinametilesterase (PME). O uso do revestimento foi eficiente em retardar o metabolismo dos frutos de pimentão. O revestimento também foi capaz de manter por mais tempo a firmeza dos frutos quando comparados com o controle. Frutos revestidos apresentaram maiores valores de SS e AT, menor atividade da enzima pectinametilesterase, menor perda de massa fresca, e melhor aspecto visual durante os 15 dias de armazenamento.
... The HT delayed polyuronide solubilization in both green and red sticks (Fig. 3E and F). Although cell-wall degradation is limited in pepper compared to other fruit species softening to a melting texture (Jen and Robinson, 1984;Ogasawara et al., 2007;Cheng et al., 2008), firmness loss proceeds during postharvest storage even without substantial dehydration. The lower softening rate of HT sticks could result in part from the inhibition of the activity of cell-wall degrading enzymes. ...
Article
Given the proscription of using chemicals from synthesis, the alternatives for postharvest management of organic produce are limited. Consequently, great interest is being devoted to develop and optimize alternative postharvest approaches. In this work we tested mild heat treatments for green and red fresh-cut peppers and evaluated their effect on quality maintenance under normal distribution and retail temperatures (4 °C). Pepper sticks (1 × 5 cm) at red and green ripening stages were heat-treated (HT) by immersion in water at 45, 50 or 55 °C (1, 3 or 5 min) and quality maintenance during storage was evaluated. Green peppers were more tolerant to HT than red fruit. Both green and ripe peppers subjected to hot water dips at 45 °C for 3 min showed lower spoilage than the control. The treatments markedly reduced soft rots (2 and 4 fold for red and green fruit respectively). Hot water dips also prevented shriveling, weight loss, color changes and contributed to maintain lower fruit respiration during storage. The treatments did not alter sugar content, acidity or antioxidant capacity. Despite of the effective control of soft rots only a slight reduction of microbial counts (<1 log CFU g−1) was found. This suggests that other responses besides biocide effects or microbial wash-off are involved. The treatments delayed pectin solubilization and softening and prevented membrane leakage. Short mild heat treatments (45 °C, 3 min) may be a simple and appealing non-chemical approach to supplement the benefits of low temperature management, extending the shelf life of organic fresh-cut green and red peppers.
... The extraction procedure for pectinmethylesterase (PME, EC 3.1.1.11) assay used pulp (5 g) and freeze-dried peel (0.5 g) homogenized with 20 mL of cold NaCl (0.2 M) which were filtered through Whatman n.1 filter paper, filtrate was used as enzyme extract (Jen & Robinson, 1984 ). Enzyme activity was measured as 5 mL of extract plus 30 mL of citrus pectin substrate (1%) in NaCl (0.2 M, pH 7.0) were titrated with NaOH (0.01 N). ...
... 40%) bending resistance than air-stored fruit (Table 2). Texture loss of peppers has been mainly related to dehydration since wall metabolism is more restricted than in other commodities (Jen & Robinson, 1984;Toivonen & Brummell, 2008). Bending resistance correlated better with mass loss than with softening. ...
... The extraction procedure for pectinmethylesterase (PME, EC 3.1.1.11) assay used pulp (5 g) and freeze-dried peel (0.5 g) homogenized with 20 mL of cold NaCl (0.2 M) which were filtered through Whatman n.1 filter paper, filtrate was used as enzyme extract (Jen & Robinson, 1984 ). Enzyme activity was measured as 5 mL of extract plus 30 mL of citrus pectin substrate (1%) in NaCl (0.2 M, pH 7.0) were titrated with NaOH (0.01 N). ...
... The polygalacturonase enzyme (PG) level was determined according to Pressey and Avants (1973), and the results are expressed in EAU g −1 min −1 . The pectin methyl esterase (PE) level was determined according to Jen and Robinson (1984), and the results are expressed in mol of NaOH g −1 min −1 . ...
... The extraction procedure for pectinmethylesterase (PME, EC 3.1.1.11) assay used pulp (5 g) and freeze-dried peel (0.5 g) homogenized with 20 mL of cold NaCl (0.2 M) which were filtered through Whatman n.1 filter paper, filtrate was used as enzyme extract ( Jen & Robinson, 1984). Enzyme activity was measured as 5 mL of extract plus 30 mL of citrus pectin substrate (1%) in NaCl (0.2 M, pH 7.0) were titrated with NaOH (0.01 N). ...
... The degree of damage was expressed according to a subjective arbitrary scale of values (1=high, 2=moderate, 3=low and 4=null). Results were expressed through means from each repetition; Pectinmethylesterase Enzyme (PE), determined according to Jen and Robinson (1984). Results expressed in UE.min -1 .g of tissue -1 ; and Polygalacturonase Enzyme (PG), determined according to Pressey and Avants (1973). ...
Article
The purpose of this research was to study the control of physiological damages in late peach cultivars during cold storage. The research was carried out over the course of two years (2003 and 2004), using yellow pulp peaches ('Flordagrande', 'Maciel' and 'Peach') and white pulp peaches ('Chimarrita', 'Marli' and 'Chiripá'). All the fruits were exposed to temperatures of 20°C and 75±3% of U.R., in a B.O.D., for 0, 24 and 48h. The fruits were then kept in a cold chamber at 0±0.5°C and 92±3% of R.H., for 28 d. The analyses, done from 4 to 6h after the removal of the fruits from the cold chamber, were conducted at harvest time (day 1 - initial stage), after one day of delayed storage, and at 7, 14, 21 and 28 d as well as two days after each one of these days (7+2, 14+2, 21+2 and 28+2 d). The yellow pulp cultivars, regardless of delayed storage, did not present any wooliness or leatheriness. The white pulp fruits, not submitted to delayed storage, developed either one or the other physiologic disturbances. Due to their low level of pulp firmness, control 'Chimarrita' and 'Marli' peaches, were classified as wooly. Control 'Chiripá' peaches, with firmness over 30 N, presented leathery skin. High pectinmethylesterase enzymatic activity was verified in those fruits with woolliness. polygalacturonase activity was similar in both wooly and normal maturing fruits. Regarding the fruits which were found to be leathery, they had a high pectinmethylesterase enzyme activity and a low polygalacturonase enzyme activity as compared to wooly and/or normal fruits. Delayed storage for 48h, in all cultivars provided advanced ripening. Delayed storage for 24h was effective in the control of woolliness and firmness retention (leatheriness) of white pulp cultivars.
... At 28 days, PME of the latter samples decreased significantly. No correlation was found between PME activity and days of ripening, however the PME activity in the different prickly pear varieties was similar to that reported in other fruits like mango, tomato, strawberry, and bell pepper, where the highest enzyme activity is shown at green stage and then it declines during ripening [20][21][22]. ...
Article
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Biochemical and nutritional changes were studied during the ripening process of three prickly pear (Opuntia spp.) cultivars with different ripening behavior. Fresh weight loss was the main physicochemical change among cultivars. No significant postharvest differences were found in total soluble solids, titratable acidity and pH. Blanca cristalina and Esmeralda showed an increase in carotenoids, while these diminished in Naranjona. The evaluated cell wall enzymes showed particular behaviors during the ripening of each cultivar, suggesting a fine biochemical control and not a clear relationship between cultivars. Besides, nopalitos analysis showed differences in the β-carotene and lutein levels, the content of these pigments was higher than in other vegetables.
... Pectinmethylesterase (PME, E.C. 3.1.1.11) was extracted, and its activity determined according to Jen and Robinson (1984). Pulp tissue (5 g) was homogenized with 25 mL of ice-cold 0.2 mol L À1 NaCl in a Kinematica Polytron 1 (Switzerland) The homogenate was filtered through Whatman No. 1 paper, and the filtrate was collected as the enzyme crude extract. ...
... The following characteristics were evaluated: fruit mass, determined by the average value of individual weighting with the results expressed in grams (g); length and diameter with the aid of a caliper rule and results expressed in centimeters (cm), relation length/diameter (fruit shape) obtained by calculating the ratio between the two, and the classification made according to scale adapted from Lopes (1982), in which fruit have compressed (RF <0.9), spherical (RF ≤ 0.9 ≤ 1.1), caplet (1.1 <RF ≤ 1 , 7) and cylindrical (RF> 1.7) format; internal cavity and pulp thickness using a digital caliper in millimeters (mm); pulp coloration using a 1-5 color scale (1 -yellow, 2 -intense yellow, 3 -salmon, 4 -orange, 5intense orange); fruit firmness, determined with the fruit pressure tester penetrometer, obtaining readings in lbf, lately converted into (N) vitamin C determined by titration with Tilman solution (DFI -2,6dichloro-phenol-indophenol 0.02%) according to the methodology proposed by Strohecker and Henning (1967) and the results expressed in ascorbic acid 100 g -1 mg; soluble solids (SS) directly in the homogenized juice of the edible fraction through reading in digital refractometer (PR model -. 100, Palette, Atago Co, LTD, Japan), results expressed in percentage (%) (AOAC, 2005); titratable acidity (TA) according to the method of the Association of Official Analytical Chemistry (2005), the results expressed as citric acid percentage, and the ratio soluble solids/titratable acidity was obtained by the ratio between soluble solids and titratable acidity of the fruit pulp; pH, with the aid of a potentiometer (AOAC, 2005), the soluble sugar by Antrona method according to Yemn and Willis (1954); total and soluble pectin were extracted by the methodology described by McCready and MacComb (1952) and determined according to Blumenkrantz and Asboe-Hansen (1973), the results expressed in mg of galacturonic acid per 100 g fresh pulp mass, using a standard curve for galacturonic acid; pectinmethylesterases enzyme activity (PMEs), determined by the method of Jen and Robinson (1984), result expressed in EU/min/g of tissue; and the activity of the polygalacturonase enzyme (PG), for extracting the enzyme source (Pressey and Avants, 1973), the determination was performed by the DNS method (Miller, 1959) and the results expressed as UAE/g fresh weight. ...
Article
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This work aimed to evaluate the new postharvest quality of papaya tree hybrids grown in a region of semi-arid climate, aiming to find the most suitable for marketing as new cultivars. It was conducted in a commercial farm in the municipality of Mossoró-RN, an experiment in a randomized block design with 14 treatments (12 hybrids in testing, plus two more cultivars already marketed, Tainung No. 1 and Sunrise Solo), with 4 replications. The fruits were harvested during the second maturation stage (fruit with up to 25% yellow skin) and taken to the Postharvest Laboratory of UFERSA, where they were accommodated at room temperature (22 ± 1°C and 60 ± 5% RH) until they reaches the fifth maturation stage (fully ripe fruit, with 76-100% of yellow skin), and analyzed for their physical, physical-chemical and biochemical traits. There was great variability among hybrids for the evaluated quality characteristics. However, the hybrids showed characteristics such as mass and dimensions of fruits, vitamin C, soluble solids, pulp thickness that fall under the classification for commercialization both in the domestic and international markets, with the exception of the hybrids H36.45, H36.56, and H45.56, which have yellow pulp, which is not favored in the consumer market.
... PE was determined according to Jen and Robinson (1984) where the assay determines the ability of the enzyme to catalyze the demethylation of pectin corresponding to 1 μmol of NaOH per min under the test conditions. The results were expressed as EAU/g min. ...
... This was correlated with the increase and decrease in firmness. Also on pepper fruit showed that polyglacturonase activity increased during fruit ripening till it reached its maximum at the turning stage (Jen and Robinson, 1984) and this in turn decrease the fruit firmness during its ripening. ...
... The activity of the enzyme pectin methyl esterase (PME) was determined using a method described by Jen and Robinson (1984), and the results are expressed in μmol of NaOH g −1 min −1 . The activity of the enzyme polygalacturonase (PG) was measured using Pressey and Avants (1973) approach and the results are presented as enzymatic activity unit (EAU) g −1 min −1 . ...
Article
The buriti (Mauritia flexuosa L.f.) is a highly nutritious fruit with a yellowish-orange pulp and a bittersweet taste. Its endocarp is surrounded by a spongy material made of starch and oil, while the fruit skin is hard, consisted of small reddish-brown scales. This work aimed to characterize the bioactive compounds and the antioxidant activity of buriti fruits, during the postharvest time, harvested at different ripening stages. The fruits were harvested in a transitional environment savannah/forest at private properties in the city of Boa Vista, Roraima, Brazil. Fruits were analyzed for five consecutive years (2012–2016), at three different ripening stages: immature (with up to 75% green color between the scales), mature (with up to 50% green color between the scales) and ripened (with up to 25% green color between the scales). The selected fruits were standardized on the basis of their appearance, such as color of the epidermis and phytosanitary conditions, and later sanitized. Different fruit variables were analyzed every 2 days during a 10-day postharvest period including loss of fresh mass, pH, total acidity, soluble solids, total pectins, pectin methyl esterase and polygalacturonase enzyme activity, respiratory behavior (CO2 and ethylene), and functional activity such as phenolic compounds, carotenoids and antioxidant activity (ORAC and DPPH). High antioxidant activity, in both methods, was observed in buriti fruits at different ripening stages during the postharvest storage period, characterized by high phenolic and carotenoid compounds. Fruits harvested at mature and immature stages showed a longer postharvest shelf life. It was observed a climacteric behavior of the buriti fruits here analyzed, that showed an increase in the respiration rate and ethylene production, indicated by the peak of CO2 and ethylene production. Similar changes were observed in the fruit pH, total acidity and soluble solids, as well as in the activity of peptic enzymes whereas a decrease was observed in the total pectin contents. The fruits showed reasonable amount of phenolic compounds, carotenoids and antioxidant activity, thus confirming the functional potential of these fruits.
... A unit of enzymatic activity (UAE) of pectin methyl esterase was defined as the amount of enzyme able to catalyze the pectin demethylation corresponding to the consumption of 1 nmol NaOH for 10 minutes. The results were expressed in UAE per gram of fresh mass per minute (Jen & Robinson 1984). ...
... Soluble pectins were extracted according to McCready & McComb (1952), and quantified by the Bitter and Muir (1962) technique, with results expressed as mg 100 g -1 of galacturonic acid f.w. Pectinamethylesterase (PME) activity was determined according to Jen & Robinson (1984), where one unit of PME was defined as the amount of enzyme capable of catalyzing pectin demethylation corresponding to the NaOH consumption per gram of fresh pulp per minute. Results were expressed as units per gram of fresh fruit per minute (U min -1 g -1 f.w.). ...
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Jabuticaba (Plinia cauliflora) is a native Brazilian Atlantic Rainforest fruit tree. Its fruits are purplish berries with a short shelf life, due to fermentative processes that begin shortly after harvest. Recently, commercial jabuticaba exploitation has intensified, justifying the application of postharvest technologies. In this context, this study aimed to evaluate the chemical characteristics and nutraceutical compounds of "ponhema" jabuticabas stored at room and cold temperatures. Chemical analyzes (soluble solids (SS), titratable acidity (TA), pH, soluble sugars, soluble pectins and pectinamethylesterase (PME) activity), and nutraceutical compounds (total anthocyanins (TA), yellow flavonoids (YF), total phenolic compounds (TFC)) were performed. A completely randomized experimental design was applied. Analyzes were performed every 2 days, at days 0, 2, 4 for the room temperature (25° C) assay and at days 0, 2, 4 and 6 for the cold temperature (13° C) experiment. Fruits stored under cold temperature presented lower acetaldehyde and ethanol contents, as well as high soluble sugar, total anthocyanin, and total phenolic compound levels. Fruits stored at room temperature displayed marked wilting and fermentation on the fifth day of storage, preventing their consumption after this period. Fruits presented a shelf-life gain of up to two days when stored at cold temperature, displaying better characteristic maintenance, such as soluble solids, titratable acidity, pH and soluble sugars, which were verified by the acetaldehyde and ethanol tests. Total anthocyanin and phenolic compound levels were higher in fruits stored at cold temperature.
... Pectin methyl esterase (PME) activity was measured according to the method described by Jen and Robinson (1984). Briefly, we measured the ability of the enzyme to catalyze the demethylation of pectin, i.e., to produce 1 mol of NaOH per minute under the assay conditions. ...
... For example, pectinases enzymes can degrade pectic substances through hydrolases [30,31]. These enzymes that produce the hydrolysis of pectin (pectinesterases) are present in sweet pepper during the different ripping stages [32]. Ascorbic acid is recognized as a competitive inhibitor of enzymes affecting browning properties [33] [-] [35]. ...
Article
Serious difficulties in evaluating the fungicides captan and folpet by the usual chromatography systems coupled to mass spectrometry are well known. These compounds are highly prone to degradation due to different conditions into tetrahydrophthalimide (THPI) and phthalimide (PHI). Such an effect can be produced at different stages of the analytical procedure or during the growing crop, making their evaluation troublesome. As a consequence, the quantification of captan and folpet is typically performed through or together these metabolites. However, imide ring metabolites can be produced by other unknown sources, including other phthalimide derived pesticides enabling false positive results. For this reason, in the last decade, laboratories demand a robust method to quantify captan and folpet, that overcomes such a situation. In the present work, various operational parameters were optimized to ensure the no degradation of captan and folpet facilitated by supercritical fluid chromatography coupled to mass spectrometry (SFC-MS/MS). A direct comparison with reverse-phase LC-MS/MS and GC-MS/MS was conducted for comparative purposes. The representative commodities selected for this evaluation were pepper and tomato. Furthermore, possible oxidative degradation during the sample milling step was also evaluated and avoided by the application of crio-milling conditions and ascorbic acid addition. By the proposed procedure, captan and folpet were recovered in both matrices at the 84%–105% range and with an RSD below 8% at two concentration levels: 10 and 50 μg/kg. On the contrary, with GC-MS/MS, captan and folpet were not recovered, and, as a consequence, their evaluation was possible only by THPI and PI. In the case of LC-MS/MS a significant decrease in the sensitivity was observed compared to SFC-MS/MS. Other validation parameters evaluated were satisfactory. This new approach can assess the correct analysis of captan and folpet at low concentrations in fruits and vegetables.
... 2.1.6. PG and PME enzymes Pectinametilesterase (PME) was determined according to Jen and Robinson (1984) by analyzing the capacity of the enzyme to catalyze the demethylation of pectin corresponding to 1 mol of NaOH per minute under test conditions. The results were expressed in mol of NaOH/g/min. ...
... A unit of PME activity was defined as the amount of enzyme capable of catalyzing pectin demethylation corresponding to the consumption of 1 mmoL NaOH per min. Results were expressed as mmoL/L (Jen & Robinson, 1984). ...
Article
This study evaluated physicochemical and roughness surface characteristics of edible coatings formulated with chitosan (Chi, 5 g/L) and Mentha x villosa Huds (MVEO, 0.6 and 1.2 mL/L) or M. piperita L. essential oil (MPEO, 0.6 and 1.2 mL/L) and measured the effects of these coatings on quality parameters of papaya during cold storage. MVEO and MPEO affected positively coating thermal stability. Chi + MVEO or MPEO coatings had homogeneous surfaces. Papaya coated with Chi + MVEO or MPEO had decreased firmness, weight loss, total soluble solids and enzymatic activity, as well as delayed evolution of pulp and peel colour during storage when compared to uncoated papaya. Formulated coatings did not affect papaya sensory acceptability. These results indicate occurrence of interactions and molecular compatibility among Chi and MVEO or MPEO to form coatings. Application of Chi + MVEO or MPEO coatings caused delayed maturation without negative effects on papaya postharvest quality. Industrial relevance Papaya is a fruit with important market value and good acceptance by consumers, but with short shelf life due to a fast maturation process and susceptibility to phytopathogenic fungi, being necessary the use of effective strategies to preserve this fruit. Edible coatings formulated with antifungal additive or synergistic mixtures of Chi and MVEO or MPEO had satisfactory thermal stability, homogeneous surfaces and ability to form physical barriers on papaya, causing maintenance or improvements of physical, physicochemical and sensory characteristics of papaya during cold storage. Formulated edible coatings could be innovative strategies to preserve papaya with functionalities related to the control of fungal rot and parameters indicative of postharvest quality and more prolonged fruit storability.
... Harvesting peppers in the fully developed but green condition enables a higher yield, as it stimulates production of more flowers. A study on pectolytic enzymes ( Jen and Robinson 1984) in sweet bell peppers showed that polygalacturonase activity increased during ripening, accompanied by softening of texture, while pectin esterase activity declined. ...
Chapter
This chapter provides an overview of production, varieties, postharvest handling and storage, utilization, quality characteristics, processing, and food safety issues of Capsicum peppers. Global production of Capsicum peppers mainly comprises: the mild to highly pungent chili peppers; bell and sweet peppers utilized as vegetables; and paprika, primarily traded as a spice. The world production of fresh and dry chilies and green bell peppers in 2014 was 32.32 and 3.82 million metric tons (MMT), respectively. China was the leading producer of green types with 16.12 MMT, followed by Mexico, Turkey, Indonesia, and Spain. Postharvest handling and storage practices have a major impact on the quality and shelf-life of peppers. The postharvest storage quality and shelf-life depends on the types of storage regime involved—for example, normal refrigerated and controlled atmosphere (CA) storage, modified atmosphere packaging (MAP), and a variety of postharvest treatments.
... Wild accessions, which soften to some extent, have detectable PG activity, but this is much reduced in commercial lines (Rao and Paran, 2003). Jen and Robinson (1984) found bell pepper PG activity was 0.01 % of that in tomato. There are a number of more recent reports of ripeningrelated increases in PG activity (Priya Sethu et al., 1996;Cheng et al., 2008;Ahmed et al., 2011;Rao et al., 2011) although activity is often low or appears at the end of a long postharvest period. ...
Article
We have investigated the cell wall polysaccharides of a commercially grown blocky-type red bell pepper (Capsicum annuum L. ‘Funky’) during on-plant growth and ripening, and after postharvest water loss. There was no evidence of substantial depolymerisation of cell wall pectic polysaccharides or hemicelluloses at any ripening stage. The onset of fruit ripening was accompanied by a slightly increased solubilisation of very high molecular weight polyuronides. Measurable polygalacturonase activity was absent, despite an endo-polygalacturonase mRNA being present as fruit turned red. The largest cell wall change was a substantial loss of galactose (primarily from Na2CO3-soluble rhamnogalacturonan-I) as green fruit approached full size, which could not be directly correlated with conventionally assayed β-galactosidase/galactanase activities. The majority of β-galactosidase/galactanase gene expression and enzyme activity was found in fully ripe fruit, although by this stage galactose loss was comparatively minimal. This suggests that the upregulation in activity has significance beyond wall rheology, or is vestigial. Severe water-stress applied to harvested ripe fruit did not result in any cell wall changes suggestive of cell wall breakdown, compared with cell walls of fruit stored under high humidity conditions. We conclude that this commercial line of bell pepper, which was bred for intensive glasshouse production, has wall characteristics that result in retention of typical crisp texture and extended postharvest storage life.
... A unit of enzymatic activity (UAE) of pectin methyl esterase was defined as the amount of enzyme able to catalyze the pectin demethylation corresponding to the consumption of 1 nmol NaOH for 10 minutes. The results were expressed in UAE per gram of fresh mass per minute (Jen & Robinson 1984). ...
Article
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The green pepper (Capsicum annuum L.) is an important Brazilian vegetable and it is very much appreciated, besides being a source of vitamins, minerals and fibers. However, it has serious post-harvest shelf-life problems, such as tissue softening. The exogenous application of pectin methyl esterase and calcium has been shown to be efficient in maintaining the firmness of several fruits. Thus, the present study had as objective to evaluate the effects of the application of exogenous pectin methyl esterase (PME) and calcium in post-harvest conservation of the cv. Yolo Wander. For this, the green peppers were submitted to vacuum infusion with water, vacuum infusion with 7% of calcium chloride and vacuum infusion of PME associated to 7% calcium chloride, fruits without infusion were used as control. Loss of fresh mass, fruit firmness, peel color, soluble solids content, pH, total acidity and PME activity were evaluated. In relation to the loss of fresh mass there was a significant increase over time in all treatments. Also, according to the results, the fruits not immersed or those immersed in calcium chloride showed greater maintenance of the firmness, as well as smaller variations in the activity of the SME and low levels of organic acids. The vacuum infusion with 7% calcium chloride maintained the firmness and the physicochemical characteristics of the green pepper. However, the application of PME + CaCl2 did not promote the maintaining desirable firmness characteristics for the green pepper.
... Polygalacturonase (PG) activity was related to the loss of firmness in tomatoes [13], green peppers [14] and cucumbers [15]. Two types of PG have been identified (endo and exo) [29]. ...
... A unit of PME activity was defined as the amount of enzyme capable of catalysing the demethylation of pectin corresponding to the consumption of 1 mmoL of NaOH per min. The results were expressed as mmoL L −1 min −1 (Jen & Robinson, 1984). ...
Article
This study assessed the effects of the application of coatings formed by mixtures of chitosan (Chi; 5 g L⁻¹) and Mentha piperita L. essential oil (MPEO; 1.25 and 0.6 mL L⁻¹) on physicochemical and sensory characteristics of mango cv. Tommy Atkins during 30 d of cold storage (12°C, 85% relative humidity). Decreases in titratable acidity and increases in pH values during storage were overall less accentuated in Chi-MPEO coated mango. Chi-MPEO coated mango showed lower and higher contents of sugars and organic acids, respectively, than uncoated mango from day 15 of storage onward. Chi-MPEO coatings decreased weight and firmness losses and reduced polyphenol oxidase, peroxidase and pectin methylesterase activity in mango. Chi-MPEO coatings delayed peel and pulp colour development in mango. Chi-MPEO coatings delayed changes in contents of catechin, procyanidin B1 and B2 during storage. Uncoated and Chi-MPEO coated mango received similar scores for all assessed sensory attributes on day 7 of storage. Chi-MPEO coated mango received smaller scores for colour, taste and aftertaste on days 15 and/or 30 of storage. These results indicate that coatings formed by synergistic antifungal mixtures of Chi and MPEO should be effective to improve postharvest quality characteristics in mango cv. Tommy Atkins.
... Pectin methylesterase (PME; EC: 3.1.1.11) enzyme activity was determined according to the methodology described by Jen and Robinson (1984) in sweet bell pepper, and expressed in enzyme activity unit per min (EAU min −1 ). ...
Article
This study’s main goal is to use hydrocooling and edible coating, associated with calcium, to preserve com-mercial fresh fruit quality, and extend the shelf life of cashew apples (Anacardium occidentaleL.). The Cashewswere subjected to four treatments: hydrocooling at 5 °C (HY), hydrocooling at 5 °C combined with calciumchloride application (HYCa), edible corn starch-based coating (EC), and edible corn starch-based coating en-riched with calcium (ECCa). All treatments maintained under refrigeration for 25 days at 5 °C. The calciumapplication resulted in afirmer fruit, in lower pectin methylesterase and polyphenol oxidase activity, and theincrease of soluble solids content. Hydrocooling was effective in reducing the peroxidase activity, in weight lossdelay, in greater conservation of vitamin C, color, carotenoids and anthocyanins content, and, as consequence, indelaying the loss of visual quality. Corn starch-based coating 4% was not effective in maintaining the cashewapples quality, independently of the Ca presence.
... The activity of pectin methylesterase (PME) was determined according to the technique described by Jen and Robinson (1984). A 1% citrus pectin solution in 0.2N NaCl, pH=7.0, was used as the substrate at room temperature. ...
Article
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Guava is a highly perishable fruit due to its rapid metabolism during maturation, suffering a loss of firmness a few days after harvesting, which prevents its storage for long periods. Thus there is great interest in the development of new types of packaging that extend its useful life, providing desirable sensory and nutritional characteristics. This study investigated the softening of “Pedro Sato” guavas subjected to treatment with chitosan films of different molecular weights (132, 228 and 245 kDa), at concentrations of 0.5% and 1.5%. Thus the loss of mass, firmness, pectin content and activities of the hydrolytic enzymes pectin methylesterase and β-D-glucosidase were evaluated for eight days of storage at room temperature. The results showed that the product treated with chitosan 245kDa at a concentration of 1.5% showed lower weight loss and loss of soluble pectin content, as well as greater firmness and total pectin content, as compared to the other treatments. The treatment with chitosan 245 kDa at a concentration of 0.5% resulted in lower activities of the hydrolytic enzymes analyzed. When compared with the control, the treatments with chitosan at different concentrations were effective in maintaining the postharvest quality of guavas, extending their life by eight days.
... In some capsicum cultivars, pectin depolymerisation was essentially absent during ripening (Harpster et al. 2002), and this would appear to be the situation in most domesticated cultivars bred for improved storage life. Jen and Robinson (1984) found that PG activity was less than one-hundredth the activity in tomato. In a wild Indian accession and in two Chinese-developed capsicum cultivars, PG activity peaked at the turning stage but persisted into the red ripe stage, and showed some correlation with softening and increased pectin solubility (Priya Sethu et al. 1996;Cheng et al. 2008). ...
Article
Capsicums (bell peppers) are an important international crop that has specific postharvest handling requirements due to a high susceptibility to quality deterioration from water loss. When harvested green, capsicums are susceptible to chilling injury if stored below ∼7°C for long periods, although red fruit can withstand lower temperatures. Chilling injury usually manifests as spots of surface pitting that can develop into large regions of pitted areas. Extending storage life to enable sea freight from countries distant from their final market (such as New Zealand) means that fruit must be exceptionally well cleaned to allow high humidity to be maintained during storage so that rots do not develop. A range of postharvest treatments that might reduce chilling injury is discussed, although few if any of these have entered commercial practice. This review also covers biology and consumer attributes including colour, taste and flavour, and texture.
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O presente estudo teve por objetivo determinar os efeitos da associação de tratamentos hidrotérmicos, cloreto de cálcio e atmosfera modificada sobre a atividade enzimática do abacaxi cv. Smooth Cayenne. Os frutos provenientes de Canápolis-MG (BRASIL) foram colhidos em estádio de maturação “de vez” e tamanho uniforme, com peso médio variando de 1,8 a 2,1 kg. Testaram-se tratamentos hidrotérmicos a temperatura de 40°C, com e sem cloreto de cálcio a 2%, nos tempos de imersão de 10, 20, 30, 40 e 50 minutos, além de armazenamento ou não em emalagens de polietileno. Após os tratamentos, procedeu-se o armazenamento refrigerado em temperatura de 8°C ± 2 e umidade relativa de 90% ± 3 durante 20 dias. Em seguida, os frutos foram deixados em temperatura ambiente (20°C ± 2) e umidade relativa de 80% ± 10 por 5 dias. Após esse período, avaliaram-se as atividades das enzimas fenilalanina amônio liase (FAL), peroxidases (PER), polifenoloxidases (PFO), poligalacturonase (PG) e pectinametilesterase (PME). O uso da embalagem reduziu a atividade de todas as enzimas analisadas e o cálcio provocou aumento na atividade das peroxidases. Maior tempo de imersão ocasionou aumentos nas atividades das peroxidases e polifenoloxidases.
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The objective of this study was to evaluate the changes in the activity of pectinases (pectinesterase and polygalacturonase), dietary fiber content (alcohol-insoluble solids, pectin, and total fiber), and physicochemical indices related to the flavor (pH, titratable acidity, soluble solids, Brix/acid ratio, and reducing and nonreducing sugars) of cubiu fruits (Solanum sessiliflorum Dunal) at different stages of ripening (green, turning, ripe, and fully ripe). Alcohol-insoluble solids and pectin were very similar, with the highest levels detected at the green and turning stages, and the lowest levels occurring at the fully ripe stage. The amount of total fiber was consistent at the green, turning, and ripe stages, but declined at the fully ripe stage. These changes correlated with the pectinase activities, the profiles of which resembled those of other species of the Solanaceae family during fruit ripening. However, cubiu fruits were significant sources of dietary fiber at all stages. The reducing sugar content reached the highest level at the turning stage, with glucose as the major sugar. The content of nonreducing sugars, such as sucrose, remained low at all stages. The other physicochemical indices displayed increases during ripening, characterizing cubiu as a very acidic fruit with a small degree of sweetness. © 2015, Eduem - Editora da Universidade Estadual de Maringa. All rights reserved.
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Objetivou-se com este trabalho avaliar o efeito de pressões parciais de O2 e CO2 (1,0 kPa+2,5 kPa, 1,0 kPa+2,0 kPa, 0,8 kPa+2,0 kPa, 0,8 kPa+2,5 kPa e 20,8 kPa+0,03 kPa, respectivamente) em maçãs `Gala´ (Malus domestica Baumg.) armazenadas por 8 meses em atmosfera controlada (AC) sobre a perda de suculência, firmeza de polpa, conteúdo de pectina solúvel (PS) e atividade das enzimas pectinametilesterase (PME) e poligalacturonase (PG). A temperatura de armazenamento foi de 0,5°C e umidade relativa do ar, em torno de 96%. Ao final do período em AC e mais 7 dias a 20°C, foram avaliadas a suculência, firmeza de polpa, conteúdo de PS e atividades da PME e PG. As pressões parciais de 1,0 kPa de O2 + 2,0 kPa de CO2 e 0,8 kPa de O2 + 2,0 kPa de CO2 conferiram maior suculência após 8 meses em AC; e as maçãs mais firmes foram as mais suculentas, independente da concentração da atmosfera.
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The storage of fresh-cut mangoes is limited by the enzymatic browning and the loss of firmness due to the various operations of process. This work proposes a new approache to improve the storage of fresh-cut mangoes by: application of heat treatments by dipping with, or not, a storage under modified atmosphere: passive or active (5% O2 - 5% CO2) or using coatings (chitosane). The first step of this work was to determine the traitement 50 °C/30 min as an optimal treatment which maintian the quality of several varieties of mango (Keitt, Kent, Tommy Atkins). Effects of the heat treatment on the respiratory intensity, the color, firmness, the contents antioxydants: vitamin C, carotenoids and phenols total, and on the activity of several enzymes (PME, PG, b-GAL: for firmness; and PPO and PAL for colour changes) were studied. This work showed that during 9 days at 6 °C, the heat treatment maintains mainly the color by reduction of the activity of PPO and reduces the loss in firmness by reduction of the activity of the pectolytic enzymes (PME et b-GAL). In addition, the modified atmospheres seem less effective for the maintenance of the color and the firmness of freshcut mangoes. Combination of heat treatment with a modified atmosphere storage and have less additional effects and has even sometimes an inhibiting effect
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No manejo pós-colheita, os frutos podem estar expostos a injúrias que depreciam sua qualidade e vida útil. Assim, avaliou-se o efeito da atmosfera modificada em goiabas var. Paluma submetidas a diferentes tipos de danos mecânicos. Depois de colhidos, os frutos foram selecionados, sanitizados e submetidos aos tratamentos: T1 (testemunha) - sem injúrias nem acondicionamento em sacolas de polietileno de baixa densidade (PEBD); T2 - sem injúrias + PEBD; T3 - queda de 1 m + PEBD; T4 - compressão de 9 N + PEBD; T5 - queda de 1 m + compressão de 9 N + PEBD e T6 - queda de 1 m + compressão de 9 N + sem PEBD. Os tratamentos foram frigoarmazenados a 10 ± 1oC e 94 ± 2% de U.R. As análises da produção de CO2/etileno, atividade enzimática, pectina total/solúvel, firmeza de polpa, acidez titulável (AT), sólidos solúveis (SS), açúcares redutores e ácido ascórbico foram realizadas a cada 10 dias de refrigeração mais um dia fora da câmara frigorífica (22 ± 1 oC e 75 ± 3% de U.R.), durante 30 dias. As goiabas acondicionadas em sacolas de PEBD, não submetidos às injúrias mecânicas, apresentaram os melhores padrões de qualidade. Os frutos submetidos apenas a um tipo de injúria, quando embalados, apresentavam qualidade satisfatória em comparação aos frutos sem embalagem e não submetidos às injúrias. Na aplicação dos dois tipos de injúria, simultaneamente, o uso da embalagem não foi suficiente para reduzir a velocidade metabólica desses frutos, tornando-os inaptos à comercialização.
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Colletrotrichum gloesporiodies is the causal agent of anthracnose in guava, and proliferates during the storage period. One of the major changes occurs in the cell wall, affecting appearance, making this fruit more susceptible to the attack of this pathogen, significantly affecting marketing and storage. The antifungal effect of the 0.01% cinnamon essential oil, associated or not with 2% cassava starch, was studied for the physical, chemical and enzymatic properties, as well as cell wall changes occurred in the fruit stored at 25 °C and 76% ± 5 RH for 8 days. The treatment 2% starch + 0.01% cinnamon essential oil (S + EO) reduced mass loss by 30.23%, had a firmness of 12.23 N at the end of storage and the green color was maintained on the 8th day of storage, when compared with treatment control (C). The increase in the contents of soluble pectin was observed in all treatments, but more sharply in treatment C, with values of 0,62 mg 100 g−1; for treatment 2% starch (S) and S + EO, these values were 0.32 mg 100 g−1 and 0.33 mg 100 g−1, respectively, at the end of the evaluation. The activity of the enzyme PME was lower in the treatment S + EO, presenting a value of 233.38 U.g.min−1 on the 8th day, showing that there was lower fruit tissue softening. The cell wall degradation of the fruits was observed in treatment C, confirming firmness loss. The treatments S and S + EO were effective in maintaining the quality of guava at room temperature and modified atmosphere, extending the useful life of such a perishable fruit.
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The purpose of this research was to study the effect of delayed storage in the preservation of the quality, as well as the control of chilling injuries during cold storage of late peaches from Brazil. The research was carried out over the course of two years (2003 and 2004), using yellow pulp peaches and white pulp peaches. All the cultivars were exposed to temperatures of 20°C and 75±3% of U.R., in a B.O.D., for 0, 24 and 48h and then kept in a cold chamber at 0±0.5°C and 92±3% of R.H., for 28 d. The analyses were carried out at harvest period (day 1 - initial stage), after one day of delayed storage and, on 7, 14, 21 and 28 d and after two days of each day, that is 7+2, 14+2, 21+2 and 28+2 d. After 28 d of cold storage plus 2 d under no controlled temperature and humidity, the yellow pulp cultivars, regardless of delayed storage, did not present any symptom of internal browning. At the same time, at the end of the experiment, these fruits also showed the appropriate qualities for commercialization and/or later consumption. When not submitted to delayed storage, after 14 d of cold storage plus 2 d out of the cold chamber, the white pulp fruits already presented some pulp browning. High activity of polyphenol oxidase was verified in the fruits with pulp browning. The phenol content was also higher in those fruits. From the results observed in the analyses of soluble solids, titratable acidity and rotting development, we can assume that these fruits showed an advanced ripening. Also, the delayed storage of white pulp fruits, for 48h, provided advances in maturing. The same behavior was observed in yellow pulp fruits. Delayed storage for 24h was effective in controlling pulp browning and quality maintenance of the white pulp peach cultivars.
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The objective of this work was to evaluate the effects of humic substances and of different organic substrates on the textural quality of tomato fruit of the Vênus hybrid, in a protected environment. Four types of substrates were used: coconut fiber; coconut fiber and carbonized coffee husk 1/3 (v/v); coconut fiber and carbonized coffee husk 2/3 (v/v); and carbonized coffee husk. The humic substances (humic acid, 10% + fulvic acid, 10,2%) dosages of 0, 20, 40 and 80 L ha -1 were applied onto the substrates fortnightly from the eighth day after transplanting. The experimental design was in randomized block in a 4x4 factorial arrangement. Evaluations were done for fruit firmness, percentage of pectin solubilization, and enzymatic activity (pectinmethylesterase and polygalacturonase). Different enzymatic activities of pectinmethylesterase and polygalacturonase were observed according to the doses of humic substances added to the different substrates. The humic substances dosage effects of the humic substances in fruit firmness, pectin solubility and enzymatic activity were dependent upon the substrate used. Fruit grown in coconut fiber had an increase in firmness and a reduction in the percentage of pectin solubilization with the application of increasing doses of humic substances.
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The indian jujube (Ziziphus mauritiana) is a native fruit of South Asia and East Africa. In Brazil, it is an exotic and endemic fruit specie, brought by the colonizers in the 18th century to the state of Roraima, Brazil. In its native region presents damaging aspect, it demands severe control to prevent its invasion in the pastures and other agricultural fields. Nevertheless, it is considered a very nutritious fruit, but so far has been studied very little. Thus, the aim of this study was to find out its exact harvest time based on its physicochemical and functional properties. The study was conducted between the years of 2012 and 2016, and the fruits were collected from the individual trees in the urban area of Boa Vista city, Roraima sate, Brazil, and analyzed at 7-day interval after the anthesis (DAA). The analysis included physical analysis (diameter and fresh weight), chemical analysis (pH, total acidity, soluble solids, total sugars, reducing sugars, starch, total pectin, soluble pectin, pectin methylesterase and polygalacturonase enzymes), antioxidant activity (phenolic compounds, anthocyanins, flavones, flavonols, carotenoids, ascorbic acid, ORAC and DPPH), and pattern of respiration (CO2 and ethylene). A completely randomized design was used for the experiment with 10 phenological fruit stages and three replications, with a total of 30 sample units per each replication. For the best fit of regression model, F test was performed with a 5% probability level. At the end of the experiment, a clear fruit climacteric behavior was observed, and the antioxidant activity was connected with the presence of phenolic compounds, and based on other analyses, it was determined that the best point of harvest is 56 DAA.
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The study investigated the effects of individual and combined preharvest applications of gibberellic acid (GA3, 180 mg L−1) and aminoethoxyvinylglycine (AVG, 180 mg L−1) at 34, 40 and 45 days after anthesis (DAA) on preharvest fruit drop, postharvest quality and antioxidant metabolism of ‘BRS 189’ cashew. AVG treatment at 45 DAA reduced significantly preharvest cashew drop to 26% while control presented 90% of fruit drop, moreover, without detrimental effects on peduncle and nut physical and physicochemical quality, except for 60% reduction in total antioxidant activity due to 50% reduction in total vitamin C content. GA3 treatments did not reduce cashew drop significantly when compared to control, although they incremented significantly total cashew weight (27%) due to increases in peduncle weight (29%) and length (14%), especially GA3 treatment at 40 DAA that also promoted significant increases in peduncle SS/TA ratio (23%) and firmness (33%) due to inhibition of PME cell wall hydrolytic activity. Peduncles treated with GA3 at 40 DAA also presented statically higher total carotenoid (16%) and polyphenol (59%) contents, despite the reduction in total vitamin C (25%) and total antioxidant activity (70%). Thus, AVG at 45 DAA was effective in reducing fruit drop, while GA3 treatment at 40 DAA promoted cashew quality with increases in peduncle weight and size, in SS/TA ratio, in firmness and in total carotenoid and polyphenol contents.
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Factors such as suitable substrate and packaging may increase the shelf life of greenhouse bell pepper. In this study, the greenhouse bell pepper plants grown in the substrates containing 0, 25, 50, 75 and 100% compost tea in hydroponic culture were packaged in two types of film using the modified atmosphere method. Firmness of fruit texture, total soluble solids, pH, titratable acidity, vitamin C, and respiration were measured immediately after harvesting and during storage time with three replications. Then, the data obtained from the above tests were analyzed in a completely randomized design with factorial arrangement (three factors: substrates containing different amounts of compost tea, type of packing material, and storage time). Although the results showed that characteristics of the bell peppers grown on the substrates containing different amounts of compost tea were significantly different (p<0.05) from the substrate without compost, no significant result was obtained as to which percentage of compost tea had the most impact. With regard to storage time, most of the tested characteristics had a decreasing trend, but still laid within the standard ranges. In terms of the type of film, with a slight difference, nanofilm was superior to polyethylene film. As a conclusion, the bell peppers grown on the substrates containing compost tea and packaged in the nanofilms with the modified atmosphere method had acceptable shelf life more than one month.
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The effects of ultrasound treatment at different temperatures (4, 10, and 25 ℃) on the brining process of Chinese cabbage were investigated based on their salt diffusion coefficients and texture profiles. Salt weight increased significantly, but water weight decreased in Chinese cabbage treated with ultrasound at increasing temperatures. According to Fick's second equation, the effective diffusion coefficient of Chinese cabbage showed a notable increase as temperature was increased. High temperature caused unfavorable texture properties, and among these, hardness showed the most significant decrease when brining temperature was set at 25 °C. Consequently, results from the texture profile analysis and brining kinetics modeling suggest that optimal brining conditions could be achieved at 10 °C. At this temperature, the diffusion coefficient of Chinese cabbage is higher, the brining time is reduced, and the preferred qualities of kimchi are preserved. Practical Application Ultrasonication is an effective technology that can be utilized in kimchi manufacturing. It presents the advantage of reducing brining time while maintaining the acceptable textural properties of kimchi. This study investigated the impact of different temperatures on the texture properties and brining times of Chinese cabbage during brining and reveal a practical application worthy of further study in food industries and provide valuable information for improving the quality of kimchi.
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The objective of the present study was to evaluate the physical and chemical changes, pectinases activity, and cell wall pectin in melon varieties Acidulus (access 16), Momordica (access 2), Inodorus (cv. ‘Iracema’) and Cantalupensis (cv. ‘Olympic’), in the relation of ripening degree at harvest. Melon fruits were planted and evaluated with different ripening degree at harvest, from 15 to 35 days after anthesis (DAA). The fruits, arranged in a completely randomized design, had been evaluated on the harvest days to physical and chemical characteristics. We evaluate pectin methylesterase, polygalacturonase, beta-galactosidase, and pectin contents (water-soluble, chelate soluble, and sodium carbonate soluble). The ideal harvest for each melon was, 35 days after anthesis for cv ‘Iracema’, 30 days after anthesis for cv. ‘Olympic’, 30 days after anthesis for access 16, and 20 days after anthesis for access 2. High pulp firmness of access 16 is associated with the high levels of sodium carbonate soluble pectin and low levels of polygalacturonase and beta-galactosidase activity. Momordica melon fruit cracking is related to the high levels of pectinases activity, as well as pectin degradation.
Chapter
The aim of this work was to evaluate the possible use of high-pressure treatments to substitute the conventional thermal blanching applied to bell pepper fruits prior to freezing, to obtain a final product with better quality. In order to compare both blanching and pressure processes, the soluble protein content, the activity of the enzymes PME, POD, and PPO, the ascorbic acid content, and the firmness were quantified. These are the main parameters quantified at the industrial level, to evalu - ate the adequacy of thermal blanching of peppers fruits. The effect of freezing on firmness, as carried out in industrial conditions to produce commercial frozen pep - pers, was also evaluated for both thermally blanched and high-pressure-treated pep- pers. The physicochemical characterization of the peppers used was also carried out.
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A new assay for nanomole amounts of reducing sugar using 2-cyanoacetamide has been modified and adapted to assay for exo- and endo-polygalacturonase in fruit extracts of tomato ( Lycopersicon esculentum Mill. cv. Heinz 1350) with increased sensitivity (140%) and simplicity over currently used methods. Linearity was observed with galacturonic acid as a standard up to 250 nmol; the lower limit of detection was 1 nmol. Polygalacturonase product formation was linear for 3 hours and was proportional to the amount of enzyme in the reaction. Thin-layer chromatography of reaction products revealed a range of uronic acid oligosaccharides as well as galacturonic acid. Thus, both exo- and endo-polygalacturonase were active in the extracts.
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Firmness measurements made on tomato fruit at various degrees of ripeness by means of a machine recently described have been compared with those produced by an established instrument. Highly significant correlations were obtained between results from the two types of apparatus. Because of its greater ease of operation the newer instrument was used to compare the firmness of six varieties of tomato fruit, all judged to be in a uniform condition known as the “ commercial picking stage ”. The polygalacturonase activity in the same tomato samples was also measured, and a highly significant positive correlation established between the activities of the enzyme and the compression of the different varieties of fruit under a standard load. These results strongly suggest that pectolytic enzyme activity is one of the predominant factors governing the firmness of different varieties of tomato fruit.
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The cell wall degrading enzyme polygalacturonase (E.C. 3.2.1.15) is not detectable in green tomatoes (Lycopersicon esculentum Mill). Activity appears at the onset of ripening and in ripe fruit it is one of the major cell-wall-bound proteins. Radioimmunoassay results, employing an antibody against purified polygalacturonase, suggest that during ripening the enzyme is synthesised de novo. Radioimmunoassay data also show that the low level of polygalacturonase in "Never ripe" mutants and the lack of activity in "ripening inhibitor" mutants can be correlated to the levels of immunologically detectable polygalacturonase protein.
Article
Four forms of pectinesterase have been identified in extracts of tomatoes by chromatography on DEAE-Sephadex A50. Green fruit of the variety Marion contained two pectinesterases. On ripening, the level of one of the enzymes decreased while the second increased several fold and a third component developed. Fruit of the variety Pixie also contained three pectinesterases, but one of the Pixie enzymes was not present in the other varieties. The pectinesterases were different in terms of MW, stability to heat, and their responses to pH and cation concentration.
Article
Changes in the isoenzymes of pectinesterase were studied during the development of normal tomato fruit and of fruit from two near isogenic lines containing the ‘Never ripe’ (Nr) and ‘ripening inhibitor’ (rin) alleles. Nr fruit ripen slowly to an orange-red while rin is even more extreme, eventually turning yellow. Enzyme activity present in normal green fruit increases during ripening, as did that in Nr fruit. No comparable increase was observed in rin fruit. Pectinesterase activity was resolved into two major forms by ion-exchange chromatography. One of these isoenzymes (PE 2) accumulated during the ripening of normal and Nr fruit, but did not change in the rin fruit. PE 2 was purified to homogeneity, judged by electrophoresis in dodecyl sulphate-polyacrylamide gels.
Two polygalacturonidases, (poly--1, 4-galacturonide glycanobydrolase, EC 3.2.1.15) (polygalacturonases I and II) have been separated from extracts of ripe tomatoes by chromatography on DEAE-Sephadex A-50. Polygalacturonase II was the predominant enzyme in all of the samples examined. The enzymes differed in stability with respect to both temperature and pH. The molecular weights determined by gel filtration were 84 000 and 44 000 for polygalacturonases I and II, respectively. The activities of both enzymes were shifted to the acid side as the substrate size decreased and on addition of NaCl to the reaction mixture, but polygalacturonase I was less dependent on these factors. At levels of enzymes forming reducing groups at equal rates, polygalacturonase II was much more effective than polygalacturonase I in reducing the viscosity of pectic acid.
Article
In 4 cultivars of tomato (Lycopersicon esculentum Mill.), the early detachment of fruits advanced ripening and considerably reduced the threshold value of endogenous C2H4. This indicates a supply from the vegetative parts of (a) labile ripening-inhibiting substance(s) antagonizing the action of C2H4. The endogenous level of CO2 increased shortly after the rise in C2H4, and maximum levels of C2H4 and CO2 occurred almost simultaneously. The activity of PE showed no connection with ripening, but PG activity did not occur until the onset of ripening. However, this activity increased at considerably higher C2H4 concentrations than the rise in WSP, and was independent of the possible presence of ripening inhibitor(s). Hence PG is considered not to be involved in the primary events leading to fruit ripening. Exposure of fruits to different C2H4 concentrations in the ambient atmosphere also showed PG activity to increase only after the rise in WSP had started. Other pectin degrading or synthesizing enzymes may be involved. In the non-ripening Rin mutant of cv. Rutgers, no rise occurred in C2H4, CO2, WSP, and PG activity.
Article
Polygalacturonase is extractable from ripe tomatoes in two isoenzyme forms, polygalacturonase 1 and 2. These isoenzymes have previously been shown to have substantially different properties although their polypeptides appear similar. Green fruit contain a heat-stable, non-dialysable factor capable of the conversion of polygalacturonase 2 in vitro into another isoenzyme which, on the basis of heat stability, molecular weight and density in caesium chloride, is equivalent to polygalacturonase 1. The amount of this factor extractable from tomato tissue increases during ripening.
Article
1. Polygalacturonase activity is not detectable in mature green tomato fruits but appears as fruits begin to change colour and continues to increase during the ripening period. There is a sequential appearance of two isoenzymes, polygalacturonase 1 and 2, during ripening. These isoenzymes have been purified and their properties compared. Polygalacturonase 1 has a Mr of 100,000, is 50% inactivated at 78 degrees C and has a density of 1.343 g cm-3 in caesium chloride. Polygalacturonase 2 has a Mr of 42,000, is 50% inactivated at 57 degrees C and has a density of 1.300 g cm-3 in caesium chloride. 2. Fruits from isogenic lines homozygous for the 'Neverripe' (Nr) mutation do not ripen normally and contain reduced amounts of polygalacturonase. Only polygalacturonase 1 is produced in Nr fruit. Tomatoes from isogenic lines homozygous for the 'ripening inhibitor' (rin) mutation do not ripen normally and produce very little detectable polygalacturonase. 3. Although polygalacturonases 1 and 2 have different properties they both give rise to a single polypeptide on electrophoresis in polyacrylamide gels in the presence of sodium dodecyl-sulphate (Mr = 46,000). A comparison of the major fragments produced by limited proteolysis of polygalacturonase 1 and 2 with chymotrypsin suggests that the polypeptides from the two isoenzymes are similar. The same conclusion was reached from a comparison of polygalacturonase 1 and 2 by radioimmunoassay, using antibody prepared against polygalacturonase 2 and 125I-labelled polygalacturonase 2. 4. The results from radioimmunoassay of extracts from green and ripening fruits suggest that the increase in polygalacturonase activity during ripening is due to net synthesis of protein.
Pectic substances in fresh and reserved fruits and vegetables
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The molecular bi-ology of ripening A rapid and sensitive spectrophotometric method for assaying lygalacturonase using 2-cyanoacetamide
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