Mold and Aflatoxin Reduction by Gamma Radiation of Packed Hot Peppers and Their Evolution during Storage

The effect of gamma radiation on moisture content, total mold counts, Aspergillus counts, and aflatoxins of three hot pepper hybrids (Sky Red, Maha, and Wonder King) was investigated. Whole dried peppers packed in polyethylene bags were gamma irradiated at 0 (control), 2, 4, and 6 kGy and stored at 25°C for 90 days. Gamma radiation proved to be effective in reducing total mold and Aspergillus counts in a dose-dependent relationship. Total mold counts in irradiated peppers immediately after treatments were significantly lowered compared with those in nonirradiated samples, achieving 90 and 99% reduction at 2- and 4-kGy doses, respectively. Aspergillus counts were significantly reduced, by 93 and 97%, immediately after irradiation at doses of 2 and 4 kGy, respectively. A radiation dose of 6 kGy completely eliminated the population of total molds and Aspergillus fungi. The evolution of total molds in control and irradiated samples indicated no further fungal proliferation during 3 months of storage at 25°C. Aflatoxin levels were slightly affected by radiation doses of 2 and 4 kGy and showed a nonsignificant reduction of 6% at the highest radiation dose of 6 kGy. The distinct effectiveness of gamma radiation in molds and aflatoxins can be explained by the target theory of food irradiation, which states that the likelihood of a microorganism or a molecule being inactivated by gamma rays increases as its size increases.     

Mycofloral changes and aflatoxin contamination in stored chickpea seeds.

Chickpea seeds entering store carry a microflora of 'field' and 'storage' fungi. Field fungi gradually disappear and storage fungi then predominate. These fungi especially Aspergillus flavus, A. niger, A. nidulans, A. ochraceus and Penicillium spp. grow vigorously and initiate grain spoilage and aflatoxin elaboration. The shift in mycofloral spectrum was more rapid in seeds stored in jute bags than those stored in metal bins. Moisture content and aflatoxin contamination in seeds of jute bags was maximum during Sept.-Oct. The internal environment of metal bins is comparatively less influenced by the external conditions and initially restricts fungal growth and aflatoxin elaboration. Prolonged storage however, increases seed moisture content and alfatoxin is increased in chickpea seeds after six months storage in metal bins.     

STORAGE QUALITY OF BELL PEPPERS PRETREATED WITH HOT WATER AND POLYETHYLENE PACKAGING

Treatments of bell peppers (Capsicum annuum, L) with hot water at 45Cfor 15 min or SSC for 4 min prior to storage at 8C markedly reduced the incidence of fungal infections. However, the hot water treatment induced shriveling during storage. When hot water treated pepper fruits were subsequently placed in low density polyethylene bags, storage quality of these peppers improved tremendously including retention of firmness, reduction of water loss, retardation of color change, and alleviation of chilling injury. Total soluble solids, titratable acidity, and pH values in the pepper fruit were generally not affected by these treatment. A 4 min dip at 53C followed by packaging with 0.065 mm low density polyethylene film was very effective in maintaining pepper quality. This treatment inhibited respiration rate, reduced decay, retained turgidity and green color, and maintained excellent overall quality after 28 days of storage at 8C. Hot water treatment combined with polyethylene film packaging is a promising technique for improving the storage quality of bell peppers.     

Assessing Purdue Improved Crop Storage (PICS) bags to mitigate fungal growth and aflatoxin contamination

Storing maize in regions of the world without sufficient drying and storage capacity is challenging due to the potential risk of aflatoxin contamination produced by Aspergillus flavus. This study sought to determine if storage of maize in Purdue Improved Crop Storage (PICS) bags prevents mold growth and aflatoxin accumulation. PICS bags are a three-layer, hermitic bag-system that forms a barrier against the influx of oxygen and the escape of carbon dioxide. Maize conditioned at 12, 15, 18, and 21% grain moisture was inoculated with 50 g of maize kernels infected with fluorescent-marked strain of A. flavus. The grain was stored in either PICS or woven bags at 26 °C, and percent oxygen/carbon dioxide levels, fungal growth, aflatoxin, moisture content, and kernel germination were assessed after 1 and 2 months incubation. Maize stored in woven bags was found to equilibrate with the ambient moisture environment over both storage periods, while PICS bags retained their original moisture levels. Aspergillus flavus growth and aflatoxin accumulation were not observed in maize stored in any PICS bags. No aflatoxin B1 was detected in woven bags containing low-moisture maize (12 and 15%), but detectable levels of aflatoxin were observed in high moisture maize (18 and 21%). The percentage of oxygen and carbon dioxide within PICS bags were dependent on initial grain moisture. Higher carbon dioxide levels were observed in the bags stored for 1 month than for 2 months. High initial moisture and carbon dioxide levels correlated with low kernel germination, with the 18 and 21% treatment groups having no seeds germinate. The results of the study demonstrate that storage of maize in PICS bags is a viable management tool for preventing aflatoxin accumulation in storage.     

Maintaining dryness during storage contributes to higher maize seed quality

Smallholder farmers in Pakistan store their seeds and grains in porous polypropylene (woven) and jute bags or in bulk. Seed stored in these containers is susceptible to fluctuating seasonal relative humidity and temperature, which promote mold and insect growth. The present study assessed the performance of Purdue Improved Crop Storage (PICS) bags for maize seed storage during a two-month period. Seed moisture content increased in polypropylene bags while it remained constant in PICS bags. No change in germination was observed in maize seeds stored in PICS bags while in polypropylene bags it was reduced in half when compared to the initial germination. Seed stored in polypropylene bags had higher insect damage with a weight loss of 35% while in PICS bags the infestation was minimal with a weight loss of about 3%. Higher aflatoxin contamination levels were observed in seeds stored in polypropylene than PICS bags. PICS bags are effective at preserving the dryness of maize seed in storage during high relative humidity conditions, which leads to maintenance of seed quality.     

Potential aflatoxin hazards to human health from direct mold growth on Teleme cheese

Ninety-four commercial Teleme cheese samples were examined for aflatoxins produced by direct mold growth. The mycoflora on the cheese and in the atmosphere of Teleme cheese plants also were monitored. Penicillium and Aspergillus genera were tested for aflatoxin production after growth on Teleme cheese at 25 degrees C. In all cases, over 78% of the molds were Penicillium species. Aspergillus made up 3.8 to 3.9% and 0 to 7.3% of the mold on cheese and in the plant atmosphere, respectively. None of the commercial samples contained aflatoxins and none of the 448 Penicillium isolates was an aflatoxin producer. Of 22 Aspergillus species, one was capable of producing aflatoxins after direct growth on cheese. Because the physicochemical characteristics of Teleme cheese (high moisture, low pH, and medium salt concentration) favor mold growth, care should be taken to avoid contamination of the cheese by aspergilli.     

Antimicrobial effects of a commercial fermentation product on fresh-cut onions

The antimicrobial effects of a commercial fermentation product (CFP) added to fresh-cut onions was assessed. Diced onions without treatment were packed in sealed and vented single-pinhole polyethylene bags, which served as controls. Treated and control samples were then stored at 4 and 7°C. Changes in the microbial loads including total aerobic bacteria, yeasts and molds, and coliforms were determined. Quality parameters including O(2)-CO(2) concentration, pH, soluble solids, and conductivity were also evaluated following 0, 3, 7, 10, 14, and 18 days of storage. After 10 days of storage at 4°C, CFP-treated samples had significantly lower microbial loads (P < 0.001), and aerobic plate counts, yeast and mold counts, and coliform counts were lower by 2.5, 3.2, and 1.4 log, respectively, compared with the controls. The addition of 0.5 or 1% CFP maintained the shelf life of fresh-cut onions for up to 14 and 18 days, respectively, compared with 10 days for the control. In addition, it was determined that storage temperature played an important role in maintaining the quality of fresh-cut onions. Significant (P ≤ 0.05) differences in microbial loads and product quality were found between 4 and 7°C in all treatments.     

Evaluating different hermetic storage technologies to arrest mold growth,prevent mycotoxin accumulation and preserve germination quality of stored chickpea in Ethiopia

Chickpea is an economically important pulse produced by millions of smallholder farmers as a source of food, income and nutrition in Ethiopia. Mold infection and mycotoxin production can potentially lead to significant losses of chickpea during storage. Under laboratory conditions we tested comparative effects of hermetic and traditional storage structures on mold infection, germination and mycotoxin levels of chickpea. Purdue Improved Crop Storage (PICS) bags, Super GrainPro (SGP) bags, and small metal bins were compared to the traditional and popularly used chickpea storage structures such as polypropylene (PP) bags and jute bags over a six-month storage period. Oxygen and carbon dioxide levels, chickpea temperature and moisture, seed infection with molds and percentage germination and mycotoxins levels were determined every two months for six months. In PICS bags, SGP bags and metal bins chickpea temperature and moisture changed very little during storage, whereas in jute and PP bags significant temperature and moisture increases were observed. Oxygen levels in PICS and SGP bags decreased from 20% to 8–10% in six months and carbon dioxide levels increased from 0.4% to 10% in PICS bags and from 0.1% to 17% in SGP bags. In jute and PP bags, oxygen levels were around 20% but carbon dioxide levels increased from 0.05% to 0.1–0.2%, perhaps due to mold activity. Mold infection decreased over time in chickpea stored in PICS bags, SGP bags, and metal bins, and seed germination was high (82–92%). Mold infection increased and seed germination decreased in chickpea stored in jute and PP bags. Increases in levels of aflatoxin, fumonisin, deoxynevalenol, and ochratoxin were observed only for chickpea stored in metal bins, and in jute and PP bags. Our study showed that PICS and SGP bags can effectively arrest mold growth, mycotoxin accumulation and preserve germination of chickpea during six months of storage.     

Effect of triple-layer hermetic bagging on mould infection and aflatoxin contamination of maize during multi-month on-farm storage in Kenya

Field trials were conducted in small-scale farmers' grain stores in an aflatoxin endemic region to assess the effect of storing maize in triple layer hermetic (PICS™) bags on aflatoxin contamination. Shelled maize grain was purchased from farmers, and filled into PICS bags, woven polypropylene (PP) and jute bags and kept in the farmers' own stores for 35 weeks. Grain moisture content, total mould count and mould incidence levels were examined at onset and after every 7 weeks during the 35 weeks of storage. Aflatoxin contamination was examined at onset, and after 14, 28 and 35 weeks. Ambient temperature and r.h. in the trial site and in all the bags, as well as oxygen and carbon dioxide levels in the PICS bags were also monitored. Initial moisture content (m.c.) of maize varied from farmer to farmer and ranged between 12.4 and 15.0%. The m.c. of maize stored in PICS bags remained significantly higher (P < 0.05) than in PP and jute bags in the last 14 weeks of storage. Total mould count and aflatoxin contamination of maize stored at an initial m.c. < 13% and 13% ≤ m.c. ≤ 14% increased significantly in PP and jute bags but not in PICS bags. After 35 weeks, total aflatoxin of maize stored in the PICS bags at an initial m.c. < 13% and 13% ≤ m.c. ≤ 14% did not change where as it increased 5–8 folds in the PP and jute bags. Total mould count and aflatoxin contamination of maize stored at an initial m.c. > 14% increased profusely in the three types of bags. Our findings demonstrate that storing maize in PICS bags can prevent accumulation of aflatoxin in rural farmers' stores if grain moisture is <14%.     

Impact of moisture content and maize weevils on maize quality during hermetic and non-hermetic storage

The objective of this study was to determine the impact of moisture content and Sitophilus zeamais Motschulsky on maize quality during hermetic and non-hermetic storage conditions. Commercial Channel 211-97 hybrid maize kernels were conditioned to 14, 16, 18, and 20% moisture content (wet basis), and then three replications of 300 g of maize grain were stored in glass jars or triple Ziploc^® slider 66-μm(2.6-mil) polyethylene bags at four conditions: hermetic with weevils, hermetic no-weevils, non-hermetic with weevils, non-hermetic no-weevils. All jars and bags were stored in an environmental chamber at 27 °C and 70% relative humidity for either 30 or 60 d. At the end of each storage period, jars and bags were assessed for visual mold growth, mycotoxin levels, gas concentrations, pH level, the numbers of live and dead S. zeamais, and maize moisture content. The maize stored in non-hermetic conditions with weevils at 18 and 20% exhibited high levels of mold growth and aflatoxin contamination (>150 ppb). Conversely, very little mold growth was observed in maize stored in hermetic, and no aflatoxins were detected in any moisture level. CO₂ increased and O₂ gradually decreased as storage time increased for maize stored in hermetic conditions (with or without weevils) in all moisture level. No significant difference in pH was observed in any storage conditions (P < 0.05). Total mortality (100%) of S. zeamais was observed in all hermetically stored samples at the end of 60 days storage. Moisture content for hermetically stored maize was relatively constant. A positive correlation between moisture content and storage time was observed for maize stored in non-hermetic with weevils (r = 0.96, P < 0.05). The results indicate that moisture content and the number of S. zeamais weevils plays a significant role in maize storage, both under hermetic and non-hermetic conditions.     

Ethylene inhibits aflatoxin biosynthesis in Aspergillus parasiticus grown on peanuts

The filamentous fungi Aspergillus parasiticus and Aspergillus flavus synthesize aflatoxins when they grow on a variety of susceptible food and feed crops. These mycotoxins are among the most carcinogenic naturally occurring compounds known and they pose significant health risks to humans and animals. We previously demonstrated that ethylene and CO2 act alone and together to reduce aflatoxin synthesis by A. parasiticus grown on laboratory media. To demonstrate the potential efficacy of treatment of stored seeds and grains with these gases, we tested ethylene and CO2 for ability to inhibit aflatoxin accumulation on Georgia Green peanuts stored for up to 5 days. We demonstrated an inverse relationship between A. parasiticus spore inoculum size and the level of toxin accumulation. We showed that ethylene inhibits aflatoxin synthesis in a dose-dependent manner on peanuts; CO2 also inhibits aflatoxin synthesis over a narrow dose range. Treatments had no discernable effect on mold growth. These observations support further exploration of this technology to reduce aflatoxin contamination of susceptible crops in the field and during storage.     

Incidence of aflatoxin B1 in the Egyptian cured meat basterma and control by gamma-irradiation

In the present studies trials have been carried out to investigate the occurrence of aflatoxin B1 in the Egyptian cured meat basterma and to control such contamination by gamma-rays. Basterma was prepared from fresh salted meat coated with spice paste and stored at room temperature. The total mould counts of basterma samples varied from 10(3) to 10(6) cfu/g in summer months and from 10(2) to 10(5) cfu/g in winter months. Aspergillus, Penicillium, Mucor, Rhizopus, Fusarium and Cladosporium were the most common fungal genera isolated from basterma samples and its components. Basterma samples contained total aflatoxins at levels from 2.8 to 47 microg x kg(-1). Aflatoxins were determined in the spice paste at levels from 9.6 to 120 microg x kg(-1) and in pepper (285.6 microg x kg(-1)), garlic (224.4 microg x kg(-1)), fenugreek (194.2 microg x kg(-1)), coriander (16 and capsicum (42.4 microg x kg(-1)). At an irradiation dose level of 3 kGy, only one sample each of pepper, fenugreek, and spice paste were contaminated with aflatoxins and all basterma samples and its components were free from aflatoxins at an irradiation dose level of 5 kGy.     

Storage of red chili pepper under hermetically sealed or vacuum conditions for preservation of its quality and prevention of mycotoxin occurrence

The effect of storage under hermetically sealed or vacuum storage methods, compared with the traditional method, on important quality indices for Turkish red chili peppers (RCPs) was evaluated at a semi-commercial scale in a warehouse. One tonne lots of flaked and mechanically dried RCP of maximum moisture content 10 ± 1% were stored for six months under a low absolute pressure of 80-100 mm Hg, under sealed, airtight conditions, or under traditional storage conditions (bags stacked in barns; as a control). Basic quality parameters related to microbiological counts, amount of aflatoxins (B₁ and total), pungency properties, colour levels, organoleptic characters and moisture contents were determined before and after 6 months of storage. The experiments indicated that the best quality RCPs were obtained by vacuum storage with quite low losses in quality indicators (capsaicin, colour and aflatoxin). Hermetic storage conditions resulted in major losses of colour, while microbial growth and aflatoxin occurrence were inhibited, and the pungency of RCP was protected. The results supported the feasibility of commercial application of airtight and vacuum storage technologies for long-term storage of RCP. The sealed flexible vacuum-hermetic storage technology introduces substantial advantages over traditional storage methods in the preservation of quality characteristics such as colour, pungency, and aflatoxin of RCP for longer storage periods.     

QUALITY OF MODIFIED ATMOSPHERE PACKAGED "BARTLETT" PEARS AS INFLUENCED BY TIME AND TYPE OF STORAGE

Commercially mature “Bartlett” pears for this study were obtained from local commercial packing facilities. In the first year, pears were packed in modified atmosphere bags and placed in boxes or packed normally (control) with an individual paper wrap around each pear plus a polyethylene liner in the box. Boxed pears from both types of packaging were stored in regular atmosphere (RA) storage at 1C for 30 or 90 days. In the second year, pears were packed normally and stored in both RA or controlled atmosphere (CA) storage for 45 or 90 days, or packed in modified atmosphere bags and stored in RA at 1C. After 45 days, normally packed pears from both RA and CA were removed from their initial storage, placed in modified atmosphere bags and returned to RA storage for an additional 45 days. Pears stored in modified atmosphere bags were superior in quality to normally packed pears stored only in RA storage and equal in quality to pears stored in CA for periods of 90 days. The quality of pears held in modified atmosphere bags under CA conditions deteriorated after only short periods of time (<45 days). Pears in modified atmosphere bags should be stored only in RA. Little or no quality advantage was evident if use of modified atmosphere bags was delayed regardless of prior storage type.     

Purdue Improved Crop Storage (PICS) bags for safe storage of groundnuts

Groundnut seeds are prone to quality deterioration and damage due to improper storage. Hermetic storage of pods offers a novel, sustainable and ecologically safe alternative over traditional methods. In this paper, we demonstrate the efficacy of triple-layer “Purdue Improved Crop Storage (PICS)” bags, (that comprises of two inner high density polyethylene bags and one outer woven polypropylene bag), for protecting pods from quality deterioration, damage by bruchids (Caryedon serratus) and aflatoxin contamination (Aspergillus flavus). Custom made triple-layer bags were used and pods (of cv ICGV 91114) were placed @ 2 kg/bag. Over four months of storage under ambient conditions, triple-layer bags supported retention of seed weight, germinability and oil content significantly better than cloth bags. Further, under both natural and artificial infestations with A. flavus, seed aflatoxins levels were lower in PICS bags compared to cloth bags. Toxin accumulation in PICS bags deliberately infested with bruchids and A. flavus was less compared to cloth bags under similar conditions. Bruchid damage to pods was less in PICS bags versus cloth bags in all cases. Our results suggest the superiority of triple-layer PICS bags over cloth bags in protecting seed viability, seed weight and oil content while safeguarding the groundnuts from bruchids and retarding toxin accumulation.     

Influence of low dose irradiation on the quality of fresh buffalo meat stored at 0-3°C

The effect of low dose irradiation on the microbiological, chemical and sensory qualities of fresh buffalo meat stored at 0-3°C was studied. Meat slices packed in polyethylene bags subjected to 2·5 kGy dose had a shelf-life of 4 weeks with acceptable sensory score, low total volatile basic nitrogen values and remarkable improvement in microbiological quality. Irradiated meat was completely free of Pseudomonas spp. and Enterobacteriaceae throughout storage. In contrast, the unirradiated control meat spoiled within 2 weeks.     

Occurrence of Aflatoxins in Ground Red Chili Pepper and Pistachio Nut

In total, 240 samples were randomly collected from different locations in Gaziantep Turkey, 120 of which were unpacked and packed ground red chili pepper and 120 of which were unpacked and packed pistachio nuts. All samples of the unpacked and packed ground red chili pepper were found to be contaminated with aflatoxins and aflatoxin B1. Three (9.4%) of the packed ground red chili pepper samples were over the legal limit of aflatoxin B1 while 55 (62.5%) of the unpacked samples were over the legal limit. Thirty four (36.2%) of the unpacked pistachio nut samples were contaminated with aflatoxins. There is a need to strictly prohibit the use of batches of ground red chili pepper and pistachio nuts containing aflatoxins.     

Post-harvest physiology and storage of the white oyster mushroom Pleurotus flabellatus

Changes in the post-harvest storage of the mushroom Pleurotus jlabellatus at ambient temperature were studied. There was a decrease in respiratory rate and soluble carbohydrates along with loss in water content. With progress in period of storage, the fresh mushrooms showed an increase in the activities of 0-diphenoloxidases and proteases accompanied with decrease of total phenols and increase in free amino acids respectively. The degree of discoloration increased with the lapse of storage time.
Fresh mushrooms (200 g) packed in 25 μm thick polyethylene bags (16 × 25 cm) with one pin hole on either side stored up to a period of 24 hr at ambient temperature and up to a period of 6 days at 5 ± 2°C in the intact polyethylene bags.     

Effect of application of nontoxigenic strains of Aspergillus flavus and A. parasiticus on subsequent aflatoxin contamination of peanuts in storage

Experiments were conducted to determine the potential for biological control of aflatoxin contamination of peanuts during storage. Florunner peanuts were treated in field plots by applying competitive, nontoxigenic strains of Aspergillus flavus and A. parasiticus, at 76 and 67 days after planting in 1998 and 1999, respectively. After harvest, half the peanuts from both treated and control plots were sprayed with an aqueous conidial suspension containing the nontoxigenic strains; the other half of the peanuts from each group were not sprayed. The peanuts were then placed in separate compartments of a miniature warehouse. Therefore, storage treatments consisted of peanuts that were (1) not treated at all; (2) treated prior to storage only; (3) field-treated only; (4) treated both in the field and prior to storage. Peanuts were stored for 3-5 months under high temperature and relative humidity conditions designed to promote aflatoxin contamination. In 1998, peanuts were not contaminated with aflatoxins prior to storage. After storage, peanuts that were never treated with the competitive fungi contained an average of 78.0 ppb of aflatoxins. Peanuts not treated in the field but receiving the spray treatment before storage contained 48.8 ppb. Peanuts treated in the field only averaged 1.4 ppb, and peanuts treated both in the field and prior to storage contained 0.8 ppb. In 1999, peanuts suffered from late-season drought and were contaminated with aflatoxins at harvest, with controls averaging 516.8 ppb compared with 54.1 ppb in treated peanuts. After storage, non-field-treated peanuts averaged 9145.1 ppb compared with 374.2 ppb for peanuts that had been field-treated, a 95.9% reduction. Spraying of pods with the nontoxigenic strains postharvest but prior to storage provided no additional protection against aflatoxin contamination. Results demonstrated that field application of the nontoxigenic strains had a carry-over effect and reduced aflatoxin contamination that occurred in storage.     

Frequency and behavior of Salmonella and Escherichia coli on whole and sliced jalapeño and serrano peppers

The frequencies of coliform bacteria (CB), thermotolerant coliforms (TC), Escherichia coli, and Salmonella were determined for jalape?o and serrano peppers. In addition, the behavior of four serotypes of Salmonella and three E. coli strains on whole and sliced jalape?o and serrano peppers as well as in blended sauce at 25 ± 2°C and 3 to 5°C was investigated. Chili peppers were collected from markets in the city of Pachuca, Hidalgo, Mexico. CB, TC, E. coli, and Salmonella were detected on serrano peppers in 100, 90, 50, and 10 % of the samples, and on jalape?o peppers in 100, 86, 32, and 12 % of the samples. Concentrations of CB ranged from 3.8 to 7.9 log CFU per serrano sample and from 5.3 to 8.2 log CFU per jalape?o sample, whereas concentrations of TC and E. coli were between < 3 and 1,100 most probable number per serrano and jalape?o samples. On whole serrano and jalape?o peppers stored at 25 ± 2°C or 3 to 5°C, no growth was observed for rifampin-resistant strains of Salmonella and E. coli. After 6 days at 25 ± 2°C, the tested Salmonella serotypes and E. coli strains had decreased from an initial inoculum level of 5 log CFU to 1 and 2.5 log on serrano and jalape?o peppers, respectively, and at 3 to 5°C they decreased to approximately 1.8 and 1.2 log, respectively, on serrano and jalape?o. Both the Salmonella serotypes and E. coli grew on sliced chili peppers and in blended sauce; after 24 h at 25 ± 2°C, both bacteria types had grown to approximately 4 and 5 log CFU on pepper slices and in sauce, respectively. At 3 to 5°C the bacterial growth was inhibited.