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.     

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.     

Assessment of hot peppers for aflatoxin and mold proliferation during storage

Aflatoxin contamination and mold proliferation in three hot pepper hybrids (Sky Red, Maha, and Wonder King) were studied during 5 months of storage at three temperatures (20, 25, and 30°C) and under different packaging conditions (low-density polyethylene bags and jute bags). The presence of aflatoxins in hot pepper samples was determined by high-performance liquid chromatography with a UV-Vis detector. Sampling for analysis of aflatoxins, total mold counts, and Aspergillus counts was carried out at 0, 50, 100, and 150 days of storage. Hot peppers packed in jute bags were more susceptible to aflatoxin contamination than those packed in polyethylene bags; aflatoxin concentrations were 75% higher in peppers stored in jute bags. The effect of storage temperature resulted in aflatoxin concentrations that were 61% higher in hot peppers stored at 25 and 30°C than in those stored at 20°C. Of the three pepper hybrids, Wonder King was more susceptible to aflatoxin contamination, with a maximum of 1.50 μg/kg when packed in jute bags and stored at 25°C for 150 days. However, no sample exceeded the maximum permitted level for total aflatoxins in spices established by European Union regulations (10 μg/kg). Total mold counts and Aspergillus counts increased with storage duration, but all counts were significantly lower in peppers stored in polyethylene bags. A gradual increase in temperature during prolonged storage of hot peppers in combination with aeration may be the main reasons for increases in fungal biomass and Aspergillus proliferation with the subsequent aflatoxin production.     

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%.     

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.     

The effects of post-harvest handling on physical,chemical and functional properties of cowpea (Vigna unguiculata) seed

Damage by insects and mould, proximate composition, cooking rate and functional properties of sun-dried and stored cowpea (Vigna unguiculata) seeds were evaluated. Cowpea samples spread between black polythene films were placed on cement (CS), Wooden (WS) and corrugated iron sheet (CIS) surfaces, respectively, and sun-dried for 5 h. Storage lasted 6 months in jute and polythene bags. Results show that sun-drying and storage in polythene bags significantly (p < 0.05) lowered the extent of insect and mould damage, moisture-loss at drying, emulsion activity and stability, foaming capacity and foam stability. Treated cowpea seeds could be stored safely for about 5 months. In contrast, storage in jute bags significantly (p < 0.05) lowered only foam stability. Moisture loss during sun-drying principally lengthened cooking time as storage duration progressed. Therefore, assessment of moisture content before and during storage is a preferred quality index of cowpea seeds stored in polythene bags. © 1999 Society of Chemical Industry     

Efficacy of mint and eucalyptus leaves on the physico-chemical characteristics of stored wheat against insect infestation

Wheat treated with mint and eucalyptus leaves powder was stored for six months in four different storage structures viz., jute bags, peru (made from bamboo strips), metal bins and polythene bags. Samples were analysed at monthly intervals for physico-chemical characteristics. After six months of storage, per cent damage increased, whereas weight and density decreased in untreated wheat, but no significant (P < 0.05) changes were observed in treated grains. Proximate principles increased signficantly (P < 0.05) in untreated grains except crude fat which decreased, but no significant changes were observed in their treated counterparts. Mint leaves powder was able to protect wheat stored in different storage structures for 6 months, whereas eucalyptus leaves had their protective effects only for 5 months.     

Evaluating of hermetic bags for long-term storage of turmeric (Curcuma longa L.) rhizomes

Hermetical and traditional storage bags were evaluated for their effect on the postharvest storage of turmeric at laboratory conditions. The traditional Polypropylene (PP) woven bags and the jute bags were compared with Purdue Improved Crop Storage (PICS), Super Grainpro, Savegrain bags, and Ecotect bags. Every month, for eleven months, the levels of oxygen and carbon dioxide, moisture, insect damage, live insect count, weight loss of turmeric rhizomes were monitored. A slight change in moisture was observed for turmeric stored in PICS, Grainpro, Savegrain, and Ecotect bags. But, a significant decrease in moisture was observed for turmeric stored in jute bags. The levels of oxygen in PICS and Ecotect bags decreased from 20% to 8% while carbon dioxide content increased in PICS bags from 0.2% to 12% during the period of storage. In jute bags, the level of oxygen was approximately 19.3% but the level of carbon dioxide increased from 0.05% to 0.43% due to insect activity. In all hermetic bags, the risk of insects has decreased over time, and weight loss has also decreased as compared with jute bags. In Polypropylene woven and jute bags, damage by insects and weight loss increased during storage while the curcumin content reduced. Our study showed the effectiveness of PICS, Grainpro, Savegrain, and Ecotec bags in controlling insects and weightloss in turmeric rhizomes over the traditional bags. All the four hermetic bags performed well in long-term storage of turmeric rhizome and can be recommended.     

Low permeability triple-layer plastic bags prevent losses of maize caused by insects in rural on-farm stores

Participatory on-farm trials were conducted to assess effectiveness of Purdue Improved Crop Storage (PICS?) bags for storage of maize in small-scale farmers’ stores in rural villages in eastern Kenya. A PICS bag is a three-layered hermetic bag-system that forms a barrier against the influx of oxygen and the escape of carbon dioxide. Jute, woven polypropylene or PICS bags were filled with shelled maize grain, purchased from the participating farmers, and the three sets of bags kept in the farmers’ own stores for 35 weeks. Oxygen and carbon dioxide levels in the PICS bags were monitored, as well as the temperature and relative humidity in all the bags. Grain moisture, live insect population, grain damage and weight loss were examined at intervals of seven weeks. Oxygen and carbon dioxide composition demonstrated that PICS bags are capable of sustaining good air-barrier properties under farmer storage conditions. Moreover, moisture content of maize stored in PICS bags did not change throughout the storage period whereas the moisture content of maize stored in polypropylene and jute bags decreased significantly in the final 14 weeks. Maize stored in PICS bags remained free from insect infestation and the weight loss due to insect damage was below 1 %. On the contrary, polypropylene and jute bags permitted profuse build-up of insect populations. At 35 weeks, grain damage reached 77.6 % and 82.3 % corresponding to 41.2 % and 48.5 % weight loss in the polypropylene and jute bags respectively. These findings demonstrate that PICS bags are effective in controlling losses caused by storage pests under farmer storage conditions.     

Storage of chickpea grains (Cicer arietinum L.) in triple layer bags prevent losses caused by Callosobruchus maculatus (F.) (Coleoptera: Chrysomelidae) under laboratory conditions

Present study envisages the potential of triple layer bags for reducing pulse beetle infestation under laboratory conditions over six months of storage. It was observed that when chickpea grain was stored in jute bags with bruchid infestation, the germination percentage decreased significantly from 84.67 to 18.67% in six months of storage. But, the grain stored in jute bags without infestation the germination percentage decreased from 92.00 to 73.33% only. On the other hand, grains stored in triple layer bags with bruchid infestation, the germination percentage merely decreased from 86.00 to 78.33% in six months of storage and triple layer bags without infestation the germination percentage only decreased from 91.67 to 90.67%. The per cent grain damage over a period of six months storage also increased significantly from 14.54 to 70.67% and 0.00–26.45% in jute bag with bruchid infestation and jute bag without infestation, respectively. However, per cent grain damage in triple layer bags with bruchid infestation increased only from 15.15 to 25.70% and triple layer bags without bruchid infestation showed negligible increase from 0.00 to 2.64% grain damage in six months of storage. The corresponding per cent weight loss of infested grain was increased significantly from 8.51 to 55.67% in six months of storage in jute bag with bruchid infestation and from 0.00 to 15.08% in jute bag without infestation. Whereas, per cent weight loss of infested grain in triple layer bags with bruchid infestation increased only from 7.83 to 15.70 in six months of storage and triple layer bags without bruchid infestation recorded a mere per cent increase in weight loss from 0.00 to 1.48%. Benefit cost ratio showed that grains stored in triple layer bags for 6 months has highest benefit cost ratio (1.23) compared to jute bag storage (0.39).     

Comparative effects of hermetic and traditional storage devices on maize grain: Mycotoxin development,insect infestation and grain quality

A large-scale study was conducted to assess which of the five most accessible hermetic storage devices on the Kenyan market fulfill the needs of smallholder farmers by positively impacting three major areas of concern: insect infestation, grain quality, and mycotoxin (aflatoxin and fumonisin) contamination. Efficacy of two hermetic silos (plastic and metal) and three hermetic bags (PICS, GrainPro's GrainSafe™, and Super Grain) was directly compared to current maize storage in polypropylene (PP) bags under local environmental conditions using representative storage volumes during a 6-month storage period. Impact of maize grain stored at typical (∼15%) and recommended (<13.5%) moisture levels and potential efficacy losses through frequent interruption of the underlying hermetic principals was assessed. Hermetic storage significantly reduced the increase in aflatoxin compared to PP bags regardless of the moisture level of the grain. An <5% per month aflatoxin increase was achieved by three of the five devices tested: Metal silo, PICS and GrainSafe™ bag. A strong correlation between grain moisture, storage time and aflatoxin development was found in PP bags, but not in any of the hermetic devices. The same result was not obtained for fumonisin development in stored maize. The rate of Fumonisin increase was similar in all tested devices, including the polypropylene bags, and conditions. The periodic opening of the hermetic devices had no significant effect on the efficacy of the hermetic devices but the repeated disturbance of the PP bags led to a significant increase in aflatoxin levels. The maize weevil Sitophilus spp. was most commonly found with a total incidence of 72%. Grain storage under hermetic conditions reduced insect infestation, grain weight loss and discoloration. However, maize storage above recommended moisture levels led to a distinct odor development in all hermetic devices but not the PP bags. Hence, proper grain drying is a prerequisite for maize storage in airtight conditions.     

Impact of opening hermetic storage bags on grain quality,fungal growth and aflatoxin accumulation

Purdue Improved Crop Storage (PICS) bags are used by farmers in Sub-Saharan Africa for pest management of stored grains and products, including maize. These bags hermetically seal the products, preventing exchange with external moisture and gases. Biological respiration within the bags create an environment that is unsuitable for insect development and fungal growth. This study was conducted to determine the impact of routine opening of the storage bags for maize consumption on fungal growth and aflatoxin contamination. Maize with moisture contents (MC) high enough to support fungal growth (15%, 16%, 18% and 20%) was stored in PICS bags, which were opened weekly and exposed to humid conditions (85% RH) for 30 min over a period of 8 weeks and 24 weeks. Monitors indicated that oxygen defused into the open bags but did not reach equilibrium with the bottom layers of grain during the 30-min exposure period. Fungal colony forming units obtained from the grain surface increased 3-fold (at 15% MC) to 10,000-fold (at 20% MC) after 8 weeks. At both 8 weeks and 24 weeks, aflatoxin was detected in at least one bag at each grain moisture, suggesting that aflatoxin contamination spread from a planted source of A. flavus-colonized grain to non-inoculated grain. The results indicate that repeatedly breaking the hermetic seal of the PICS bags will increase fungal growth and the risk of aflatoxin contamination, especially in maize stored at high moisture content. This work also further demonstrates that maize should be properly dried prior to storage in PICS bags.     

Biological utilization of insect infested wheat stored in different storage structures

Wheat (Triticum aestivum) was stored in jute bag, peru, metal bin and polyethylene bag for 6 months. Infested wheat was fed to the rats for 40 days. Effect of incorporation of uninfested and infested wheat stored in different storage structure on feed intake, weight gain, feed efficiency ratio (FER), protein efficiency ratio (PER), biological value (BV), true protein digestibility (TPD), net protein utilization (NPU), net protein ratio (NPR) and weight of liver, kidney and spleen was observed. Inclusion of insect infested wheat stored in different storage structure had significant (P > 0.05) effect on the biological utilization of wheat protein. Diets prepared from wheat stored in jute bag and peru had significantly higher insect infestation which resulted in lower values for feed intake, weight gain, FER, PER, BV, TPD, NPU, NPR. Weight of liver, kidney and spleen also decreased as compared to the control diets and the diets prepared from wheat stored in metal bin and polyethylene bags.     

Moulds and mycotoxins in sorghum stored in traditional containers in India

Various traditional containers have been used in India for storage of sorghum grains. Sorghum is susceptible to fungal infestation and toxin elaboration. The present study relates to the mould and mycotoxin contamination (aflatoxin B₁ and T-2 toxin) in stored sorghum in different storage containers viz. “Kotlu” (Storage rooms), earthenware pots, gunny bags and reed baskets. Aspergillus sp. and Fusarium sp. were the prominent genera and the “Kotlu” form of storage was most susceptible to fungal attack. Storage treatment had little effect on fungal contamination, but despite the fungal infestation, the mycotoxin contamination was found to be very low.     

Efficacy of phosphine and insect penetration ability in ZeroFly® bags

The deltamethrin incorporated woven polypropylene ZeroFly® storage bag is a promising novel technology for grain storage. However, if grain stored in ZeroFly bags gets infested and has to be fumigated using phosphine (PH₃), data on the effectiveness of such treatments are needed. Additionally, obtaining field data on ability of stored-product insect pests to breach ZeroFly bags would facilitate insect management. Therefore, efficacy of PH₃ in immature and adult Sitophilus zeamais (Motschulsky), Prostephanus truncatus (Horn), Rhyzopertha dominica (F.) and Tribolium castaneum (Herbst) in experimental cages in maize stored in 100-kg polypropylene (PP), jute and ZeroFly bags was investigated. Post-fumigation mortality of adults was recorded after 7 d, and after 7 wk for immatures. The ability of either S. zeamais or P. truncatus to penetrate fabric of PP, jute and ZeroFly bags was assessed. Phosphine efficacy was good in all the three types of bags and resulted in complete mortality of adults and immatures of the four species tested. Sitophilus zeamais and P. truncatus were more successful in penetrating the PP bag fabric and on average made 84 and 780 holes per bag over a 4 mo-period, respectively; this was followed by jute with 37 and 614 holes. The ZeroFly bag was harder to breach and ≤3 holes per bag were made for both species. This study shows that PH₃ is highly efficacious in insects that infest maize stored in ZeroFly bags, and that these bags are not easily penetrated by stored product insect pests. Hitherto, ZeroFly bags are a good technology for storing grain that is not infested, and fumigation using PH₃ can be effectively conducted if infestation occurs. Therefore, ZeroFly bags can be incorporated in integrated stored product insect management (IPM) programs for bagged grains.     

Establishing the value of modern seed storage methods for wheat in diverse production ecologies in Nepal

In the developing-country context of Nepal, farmers often incur seed losses of 15–30% due to improper storage. To evaluate the efficacy and costs of modern storage alternatives, experimental trials were set up among ten farmers each in two contrasting ecologies, i.e. Palpa (hills) and Rupandehi (terai plains) districts of Nepal in 2013. Several wheat seed storage options were contrasted including farmer practices (FP) such as reused fertilizer bags, polythene bags, household metal containers, and mud bins. Modern storage methods that were evaluated included plastic bags (with and without pesticide), metal bins, and hermetic ‘SuperGrain bag’ (SGB). Seed quality and losses were assessed after six months of storage (May–October) with parameters such as grain moisture content, insect damage, seed germination, and seedling vigor. The overall quality of seed with FPs was lower in the hills than in the terai plains. Among the treatments, SGBs were more effective in maintaining acceptable seed moisture levels, controlling insect damage (<1%), preserving germination (>90% lab, >65% field), and promoting seedling vigor. Metal bins and plastic bags without pesticide had higher insect damage (7–15%) compared to FP and plastic bags with pesticide (2–5%). In terms of storage costs, SGBs were comparable with the farmers' storage methods ($5–6 per 100 kg seed storage). Our findings demonstrate that SGBs are better at maintaining seed quality and more economical than not only FP but also the other modern storage methods evaluated in this study across production ecologies in Nepal.     

Impregnated bags for safer storage of legume grains in West and Central Africa

The use of jute bags impregnated with aqueous extracts from two insecticidal plants, Chenopodium ambrosioides and Lantana camara, to reduce damage to stored legume seeds by two major bruchid insect pests, Acanthoscelides obtectus and Callosobruchus maculatus, was compared with a direct seed-treatment method using plant powders. In the first method bags were treated with a 10% concentration of the aqueous plant extract and filled with bean or cowpea seeds, whereas in the second method seeds were thoroughly mixed with leaf powder from the same plants at the rate of 4% (w/w). The bag-treatment method significantly reduced seed damage compared with the untreated control after 6 months of storage (4- to 6-fold decrease in percentage seed damage). Even though relatively low (? 20%), damage by the two insect species controlled by this method was significantly higher than the damage recorded in the seed-treatment method. Orthogonal contrast analysis across test insects showed a significant seed damage difference between treatments with C. ambrosioides and those with L. camara, the latter having the lowest damage profile. The biosafety implication of the use of plant extract-impregnated bags for the protection of food grains against damage by storage bruchid pests is highlighted.     

Quality changes in 12% moisture content canola stored in silo bags under Canadian Prairie conditions

A study was conducted for two storage years (2011–12 and 2013–14) to determine the changes in grain quality while storing 12% moisture content (m.c., wet basis) canola seeds in silo bags under Canadian Prairie conditions. Canola seeds were stored in three silo bags (67 tonnes per bag) and unloaded at three different times (one bag at a time) which represent 20 weeks of storage (unloaded in late winter), 28 weeks of storage (unloaded in spring) and 40 weeks of storage (unloaded after summer storage). Canola seed quality parameters (germination, free fatty acid value (FAV), and moisture content), and intergranular composition (CO₂ and O₂ levels) at different locations in silo bags were analysed every two weeks. Temperature of canola seeds at various locations in the silo bag was recorded every 30 min. The germination of canola seeds at most parts of the silo bags stayed above a safe level up to late winter (20 weeks of storage). At the top layer of the silo bags, germination of canola seeds decreased to below 30% during summer storage (after 40 weeks of storage). Moisture content of canola seeds increased at the top layer in both storage years. The FAV values remained at safe levels until 20 weeks of storage, and increased more than two times the initial values after summer storage. The commercial grades after first, second and third unloading (after 20, 28 and 40 weeks of storage) were Grade 1, Grade 2 and Feed Grade, respectively, in year 1. Whereas for year 2, these were Grade 1, Grade 1 and Grade 2 after first, second and third unloading, respectively. The grain quality analysis and commercial grading results indicated that ambient temperature had a major role in quality of canola during storage.     

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.     

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.