Effect of thermal treatments on vitality and physical characteristics of bean,chickpea and lentil

Thermal disinfestation treatments are relatively easy to apply, leave no chemical residues and may have some fungicidal activity. However, temperature and time combinations required to kill insect pests may meet or exceed those that reduce the viability of seeds, nutrients content, shelf life or technological characteristics. The aim of this study was to investigate the effect of thermal treatments (different temperature and time combinations) on physical and biological characteristics of bean, chickpea and lentil. Seed samples of common bean, chickpea and lentil were treated at low (12, 24 or 48 h at −18 °C) or high (30, 60 or 90 min at 60 °C) temperature. Seed germination, mean germination time, physical characteristics: solids loss, electrolytes leached and firmness after cooking, were determined. The use of thermal treatments for disinfesting seeds of bean, chickpea and lentil represent a physical technique of pest control that can be harmless for seeds destined for crop production (especially for organic farming) or to be stored in germplasm banks. Moreover, thermal treatments can be applied also to grain legumes used as food by humans, with no significant effect on lentils and with a reduction of cooking time for chickpeas. Beans should be treated only with cold treatments and for no more than 24 h.     

Investigation of quality attributes of ice-stored Pacific white shrimp (Litopenaeus vannamei) as affected by sequential minimal ozone treatment

Ozone treatment is among non-thermal technologies with great promise to the seafood industry. Additionally, the demand for high quality minimally processed food products is increasing worldwide. However, no research endeavors has explored the quality attributes of sequential minimal ozone-treated ice stored shrimp. Therefore, the present investigation was undertaken to study the quality attributes of ice-stored Pacific white shrimp subject to minimal ozone treatment sequentially applied at days 1, 3, 5, 8 and 11. Quality indicators measured include aerobic plate count (APC), titratable acidity (TA), metric chroma, hue difference (ΔH), total colour difference (TCD), trimethylamine-nitrogen (TMA-N), total volatile basic-nitrogen (TVB-N), peroxide value (PV), p-anisidine value (AnV) and total oxidation (totox). The results indicated that the TA, metric chroma, ΔH, TCD, APC, TMA-N, TVB-N, PV, AnV and Totox values changed significantly with storage. Also, statistical differences in correlations and temporal rates of TMA-N and TVB-N as well as PV and AnV of sequential minimal ozone-treated ice-stored shrimp were obtained compared to control (P < 0.05). The noticeable reductions in APC, TMA-N, TVB-N and PV showed sequential minimal ozone treatment to resemble an anti-oxidant and thus, could within the respective limits of acceptability promise the safety of shrimp for consumption.     

Effect of controlled atmospheres on the insect Callosobruchus maculatus Fab. in stored chickpea

Callosobruchus maculatus (Fab.) is the principal pest of the stored chickpea. The larvae of this insect feed on the grain, causing considerable damage that produces qualitative and quantitative losses. For control of this species, pesticides such as phosphine and methyl bromide have been used; the latter was withdrawn from use due to the reduction of the ozone layer. Therefore, it is important to develop novel, safe, and economical control alternatives such as Controlled Atmospheres (CA). In this study, the mortality was determined on four developmental states of C. maculatus, employing CA at different concentrations (50, 70, and 90% CO₂ with 10, 6, and 3% O₂, respectively) during 48, 72, and 120 h. 100% mortality of adult insects was observed with 50% CO₂ at 48 h. Cases of third instar exhibit higher resistance to CA than adults, with 18.9% mortality at 48 h. There were no significant differences in tests on water absorption, cooking time, texture, and color. Finally, the chickpea germination obtained was 93.5% with 90% CO₂ exposure during 120 h. In this latter treatment, significant differences were not presented between control and CA treatments. On comparison of means of vigor, the treatments are favored in terms of weight, rootlet number, plumule and radicle growth with the increase of CO₂ concentration and exposure time. In conclusion, the effect of CA was lethal on C. maculatus, did not affect chickpea quality, and it favored chickpea vigor.     

Impact of postharvest treatments,chlorine and ozone,coupled with low-temperature frozen storage on the antimicrobial quality of lowbush blueberries (Vaccinium angustifolium)

The additive antimicrobial influence of low-temperature frozen storage and oxidation treatments was investigated using 100 mg/L chlorine or 1 mg/L aqueous ozone sprays applied to lowbush blueberries (Vaccinium angustifolium) destined for individually quick frozen (IQF) markets. Following a 60 s contact time with either oxidant, treated berries were blast frozen at ?30 °C and stored at ?18 ± 2 °C for up to 12 months. Significant differences (p ≤ 0.05) between treatment effectiveness at time 0 were not observed among all populations evaluated (mesophilic bacteria, yeast, and mold), although ozone treatments resulted in the greatest log reductions in each population. In contrast, after 12-months of frozen storage, the greatest microbial reductions in all populations were observed on chlorine-treated berries. Results suggest a significant impact (p ≤ 0.05) of low-temperature frozen storage on microbial counts of both treated and non-treated blueberries yet, chlorine-treated berries stored for up to 12 months exhibited significantly greater reductions (p ≤ 0.05) in bacterial and yeast counts compared to non-treated controls and ozone-treated berries. Study results suggest an additive effect between freezing and chlorine pre-treatments in altering microbial integrity and survival on blueberries.     

Susceptibility of stored product insects to high concentrations of ozone at different exposure intervals

Ozone is a highly reactive gas with insecticidal activity. Past studies have indicated that ozone technology has potential as a management tool to control insect pests in bulk grain storage facilities. The objective of this study was to determine the efficacy of short periods of exposure to high ozone concentrations to kill all life stages of red flour beetle (Tribolium castaneum (Herbst)) (Coleoptera: Tenebrionidae), and Indianmeal moth (Plodia interpunctella (Hübner)) (Lepidoptera: Pyralidae), adult maize weevil (Sitophilus zeamais (Motsch.)) (Coleoptera: Curculionidae) and adult rice weevil (S. oryzae (L)) (Coleoptera: Curculionidae). Insects were treated with six ozone concentrations between 50 and 1800 ppm. The specific objective was to determine minimal time needed to attain 100% mortality. The most ozone-tolerant stages of T. castaneum were pupae and eggs, which required a treatment of 180 min at 1800 ppm ozone to reach 100% mortality. Eggs of P. interpunctella also required 180 min at 1800 ppm ozone to reach 100% mortality. Ozone treatments of 1800 ppm for 120 min and 1800 ppm for 60 min were required to kill all adult S. zeamais and adult S. oryzae, respectively. The results indicate that high ozone concentrations reduce the treatment times significantly over previously described results. Our results also provide new baseline information about insect tolerance to ozone treatment.     

Hermetic storage for control of common bean weevil,Acanthoscelides obtectus (Say)

This study evaluated hermetic storage as a method of controlling Acanthoscelides obtectus (Coleoptera: Chrysomelidae: Bruchinae) in stored beans. Recently harvested “vermelhinho” cultivar of the common red bean was used, which had already been infested by A. obtectus in the field. Beans with a moisture content of 15.0% wet basis were stored in silo bags (3 kg), plastic bottles (1.5 L), or non-hermetic glass containers (3 L) (control) for 120 days. The packages were stored in an acclimatized chamber at 25 °C with a relative humidity of 70 ± 5%. At time intervals of 0, 30, 60, 90, and 120 days, three packages of each treatment were opened, and analyses were performed to assess the infestation percentage by insect pests, moisture content, density, electrical conductivity, germination percentage, and cooking time. There was no increase in infestation by A. obtectus in the grains stored in the silo bags and plastic bottles during the 120 days of storage; however, there was a significant increase in infestation in the grains in non-hermetic storage (control). The quality of the beans correlated with infestation; it was not altered in the hermetic storage systems and decreased in the control sample. Hermetic storage of common beans is an effective tool in the control of A. obtectus.     

Ozone application in a modified screw conveyor to treat grain for insect pests, fungal contaminants, and mycotoxins

Recent efforts have focused on improving the application of ozone technology as a pest management tool for stored grain. This study evaluated the efficacy of a modified screw conveyor to treat grain with ozone in a continuous-flow system. The ozone concentration delivered into the screw conveyor was 47,800 ppm and the average retention time for a corn kernel moving through the system was 1.8 min. Under these conditions, 100% mortality of adult red flour beetle (Tribolium castaneum (Herbst)) and adult maize weevil (Sitophilus zeamais (Motsch.)) was achieved after three passes through the screw conveyor, which equated to a concentration × time (CT) product value of 258,120 ppm-min. The potential effectiveness of the continuous treatment to reduce mold on the surface of corn kernels was also explored. Aspergillus flavus counts were reduced by 96% in a single pass through the screw conveyor. Three passes through the screw conveyor reduced the mold count by more than 2-log units. Ozone treatment also reduced aflatoxin applied to the grain; however, the reduction was not sufficient enough to be of commercial value. The results of this study provide valuable information for estimating the parameters needed for effectively treating grain in a commercial scale continuous-flow treatment system.     

Rice weevil management through application of silica nano particle and physico-chemical and cooking characterization of the treated rice

Nano technology is an alternative method for pest management and can be applied to minimize the post harvest storage losses due to insect infestation. A study was undertaken with an aim to control the stored grain pests, particularly rice weevil using silica nano particle (SNP). The nano-silica of 30 nm size was taken for the experiment. Entomotoxic effect of five different doses of SNP was tested against rice weevil Sitophilus oryzae. The effects of SNP mixing with grain at the rate of 0.25, 0.5, 0.75 and 1.0 g/kg of rice, stored in glass jars and gunny bags were examined. The cumulative mortality rate was studied at 1, 2, 4, 7 and14 days of exposure. Mortality rate of 80 and 97.4% were achieved after 7 and 14 days of storage by application of SNP at the rate of 0.5 g per kg of rice. Residual persistency of samples treated with optimum dose of SNP was studied by washing with distilled water at the ratio of 1:2 (sample to water ratio) for three times and the samples were studied under Scanning Electron Microscope (SEM). Single washing prior to cooking was found to be sufficient enough for removing the SNP from treated rice and can be recommended safe for cooking and consumption. This process can also prove to be an eco-friendly and efficient pest management technology. The technology is suitable for industrial application in large scale warehouses and storage godowns to control stored grain insect pests.     

Efficacy of ozone for Callosobruchus maculatus and Callosobruchus chinensis control in cowpea seeds and its impact on seed quality

The insecticidal efficacy of ozone was evaluated against the adults of Callosobruchus maculatus (F.) and C. chinensis L. on stored cowpea seeds under laboratory conditions. Ozone was assessed at concentrations of 0.25, 0.5, 1.0, 1.5, and 2.0 g/m³. The effect of ozone treatments on the adult mortality after 1, 3, 5 and 7 days of treatment, progeny production after 45 days, cowpea seed weight loss, seed germination and chemical constituents of cowpea seeds were determined. Adult mortality of C. maculatus and C. chinensis was improved with the increase in ozone concentration. Thus, all tested concentrations caused complete adult mortality of C. chinensis after 7 days of treatment, while the concentrations of 1.0, 1.5, and 2.0 g/m³ caused complete adult mortality of C. maculatus after the same periods. Progeny of both species was significantly decreased in all ozone concentrations after 45 days of treatment. Nevertheless, strong suppression in progeny production was achieved at the highest concentration of ozone (2.0 g/m³). Also, the ozone treatment at the highest concentration protected the cowpea seeds from damage caused by C. maculatus and C. chinensis for 45 days. In addition, there was no significant effect of ozone treatments on the cowpea seed germination compared with untreated seeds. Moreover, the chemical analysis of treated cowpea seeds showed a slight decrease in protein, fat, carbohydrate, moisture, total phenolics, total flavonoids and tannins contents, and a slight increase in fiber and ash contents compared with untreated cowpea seeds. Our findings suggest the ozone can be effectively used for the control C. maculatus and C. chinensis and can provide sufficient protection of stored cowpea seeds.     

Thermal resilience of Prostephanus truncatus (Horn): Can we derive optimum temperature-time combinations for commodity treatment?

Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae), is a wood-boring, destructive quarantine insect pest of stored cereal grains and tuber crops. Current disinfestation methods against this pest mainly include fumigants, whose usage in some countries has been contested and discontinued owing to increasing pesticide resistance, public health risks and environmental hazards. Grain temperature treatments thus, offer a sustainable non-chemical and near universally acceptable form of disinfestation for international commodity movement. Currently, blanket temperature treatments are applied regardless of as-yet-unknown P. truncatus developmental stage thermal mortality thresholds that simultaneously optimise grain quality. Here, we used established static and dynamic protocols to determine the low and high thermal profile of P. truncatus larvae and adults measured as critical thermal minima (CT_min), lower lethal temperatures (LLT₀), chill coma recovery time (CCRT), supercooling points (SCPs), critical thermal maxima (CT_max), upper lethal temperatures (ULT₀) and heat knock-down time (HKDT). We tested the adult ULT-time matrices on maize and sorghum grain quality (germination %) to determine the most effective temperature-time combination(s) retaining optimum grain germination quality. Our results showed adults had higher basal heat (CT_max and HKDT), cold (CT_min, CCRT and SCP) and potential thermal plasticity than larvae (P < 0.05). The LLTs and ULTs ranged −1 to −15 °C and 41–49 °C respectively. Using LLT₀ and ULT₀, our results showed that for heat treatment, moderate temperature × long duration matrix; i.e. either 45.5  °C × 4 h or 47  °C × 2  h were more efficacious while retaining commodity quality. Similarly, for cold treatment; −9 °C × 4 h, −11  °C × 2 h, −13  °C × 1 h and −15  °C × 0.5 h were effective for complete mortality. These temperature-time combinations may be a sustainable alternative to fumigants in phytosanitary grain disinfestation against P. truncatus or related pests. Such pest- and commodity -specific thermal profiling is critical for development of effective standardised grain disinfestation protocols.     

Low and high temperatures for the control of cowpea beetle, callosobruchus maculatus (F.) (coleoptera: Bruchidae) in chickpeas

Chickpea (Cicer arietinum L.; Leguminasae) is an important pulse crop grown, around the world. The whole grain of chickpea is damaged by the cowpea seed beetle, Callosobruchus maculatus (Coleoptera: Bruchidae), which is the most important field-carry-over storage pest of pulses. The management of this insect in storage using chemicals leads to insecticide residues in grains and insecticide resistance development in insects. Thermal disinfestation is one of the means of physical insect control. Eggs, larvae, pupae and adults were held at 42 or 0 °C for varying durations. Pupae and adults were equally heat tolerant. The lethal time to reduce survival by 50% (LT₅₀) at 42 °C for eggs, larvae, pupae and adults were 18, 57, 78 and 71 h, respectively. Pupa was the most cold-tolerant stage. The LT₅₀ at 0 °C for eggs, larvae, pupae and adults were 3, 8, 10 and 4 d, respectively. The LT₅₀ for pupae were 4907, 4262, 336, 36 and 13 min at the grain temperature of 42, 45, 50, 55 and 60 °C, respectively. The LT₅₀ of pupae at 0,−5,−10 and −15 °C were 274, 122, 7 and 2 h, respectively.     

Efficacy and fumigation characteristics of ozone in stored maize

This study evaluated the efficacy of ozone as a fumigant to disinfest stored maize. Treatment of 8.9 tonnes (350 bu) of maize with 50 ppm ozone for 3 d resulted in 92–100% mortality of adult red flour beetle, Tribolium castaneum (Herbst), adult maize weevil, Sitophilus zeamais (Motsch.), and larval Indian meal moth, Plodia interpunctella (Hübner) and reduced by 63% the contamination level of the fungus Aspergillus parasiticus Speare on the kernel surface. Ozone fumigation of maize had two distinct phases. Phase 1 was characterized by rapid degradation of the ozone and slow movement through the grain. In Phase 2, the ozone flowed freely through the grain with little degradation and occurred once the molecular sites responsible for ozone degradation became saturated. The rate of saturation depended on the velocity of the ozone/air stream. The optimum apparent velocity for deep penetration of ozone into the grain mass was 0.03 m/s, a velocity that is achievable in typical storage structures with current fans and motors. At this velocity 85% of the ozone penetrated 2.7 m into the column of grain in 0.8 d during Phase 1 and within 5 d a stable degradation rate of 1 ppm/0.3 m was achieved. Optimum velocity for Phase 2 was 0.02 m/s. At this velocity, 90% of the ozone dose penetrated 2.7 m in less than 0.5 d. These data demonstrate the potential usefulness of using ozone in managing stored maize and possibly other grains.     

Optimization of ozone treatment of fresh-cut green leaf lettuce

The optimization of ozone treatment for fresh-cut green leaf lettuce was studied to determine the effects of ozone concentration (0.5–4.5 ppm) and exposure time (0.5–3.5 min) on Listeria monocytogenes counts and the overall visual quality of lettuce. Prior to the optimization study, the effect of temperature on the efficacy of ozone treatment was evaluated in the range of 10–26 °C. No significant effect of temperature on the efficacy of ozone treatment was observed. The quality and safety of lettuce samples treated at the determined optimum ozonation condition (2 ppm) were compared with the chlorinated water (100 ppm), organic acid (0.25 g/100 g citric acid plus 0.50 g/100 g ascorbic acid), and water treatments applied at 10 °C for 2 min. Samples were stored at 4 °C for 12 days. Analysis include aerobic mesophilic count, Enterobactericeae, psychrotrophic bacteria, vitamin C, β-carotene, and sensory quality. Ozone treatment was found to be better than the chlorine and organic acid treatments in maintaining the sensory quality.     

Effects of storage period and temperature on the technological properties,starch digestibility,and phenolic compounds of mung beans (Vigna radiata L.)

This study aimed to evaluate the effects of storage period (0, 2, 4, and 6 months) and temperature (15 °C, 25 °C, and 35 °C) on the germination, vigor, technological properties, starch digestion, and phenolic compound content of mung beans. The germination, vigor, protein solubility, inhibition of the ABTS radicals, and the total free and bound phenolic compound content reduced while cooking time, leached solids, and electrical conductivity increased during storage. Minor changes were observed in grains stored at 15 °C. Starch digestion was higher in stored grains than in freshly harvested beans; however, it decreased on increasing the temperature. The content of bound gallic acid, bound chlorogenic acid, free and bound ferulic acid, free and bound rutin, and free and bound quercetin contents reduced after storage. In contrast, the content of bound caffeic acid, bound vanillic acid, bound myricetin, free coumaric acid, and free catechin contents increased after storage at 15 °C. These results suggested that mung beans could be cooled at 15 °C to reduce the detrimental effects of storage and maintain the nutritional value and germination viability.     

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.     

Assessment of bruchids density through bioacoustic detection and artificial neural network (ANN) in bulk stored chickpea and green gram

Acoustical detection of insects feeding and crawling sounds was used to automatically monitor internal and external grain feeding bruchids in order to assess the growth and density of food legume bruchids (Callosobruchus chinensis and Callosobruchus maculatus) in bulk stored chickpea and green gram. Bruchids hidden inside the grain kernels were detected acoustically through amplification and filtering of their mobility and feeding sounds. The multivariate technique of artificial neural network (ANN) was applied to assess and predict the bruchids’ density in bulk stored legumes. Five levels of bruchids density (0, 5, 10 15 and 20 bruchids per 500 g) were monitored under without insulation and with insulated condition on the basis of formant parameter obtained by analysis of the acoustic sensor data. The K fold validation method with back propagation multilayer perceptron methodology was used for the prediction of bruchids densities. The maximum and minimum values of accuracy (R²) of 0.99, 0.98 and 0.90, 0.89 could be achieved for both bruchids in stored green gram and chickpea under insulation and without insulation for the training and validation dataset, respectively. Least RMSE (0.82 and 0.89) was obtained for C. maculatus in sound insulated stored green gram for training and validation dataset, respectively. The accuracy of prediction and validation of experimental data with low RMSE and high R² values for both the food legumes indicated that the ANN modeling performed well in predicting bruchids density. Hence it can be concluded that, best prediction was obtained for the C. maculatus for green gram under insulated condition. The results further corroborated that bioacoustic detection technique with ANN provided a reliable and accurate monitoring technique for bruchids. The developed technique can be adopted in large bulk storage grain systems for the selected legumes for predicting and assessing the growth of bruchids thereby leading to safer storage.     

Influence of germination techniques on sprout yield,biosynthesis of ascorbic acid and cooking ability,in chickpea (Cicer arietinum L.)

Effects of germination time and illuminations on sprout yield, biosynthesis of ascorbic acid, cooking ability and moisture accumulation in chickpeas were significant (p ? 0.01). Green light had the highest promoting effect on the ascorbic acid level (40.59 mg/100 g) as compared to other illuminations but significantly reduced the sprout yield (188.6 g) as compared to dark, fluorescence and γ-rays illuminations with significantly high sprout yield (196 g) and imbibing moisture (51%). Cooking time was reduced by 43% due to γ-rays in un-soaked seed. Cooking time increased in all treated chickpea samples after 24 h germination and thereafter decreased significantly. Red light significantly increased the cooking time (68.44 min) followed by fluorescent (64.5 min), yellow (61.8 min) and green light (60.9 min). The results indicated that germination of chickpea under green light was an effective process in enhancing ascorbic acid content while dark, fluorescence and γ-rays were effective in promoting sprout growth and to some extent biosynthesis of ascorbic acid.     

A comparison of different chemical sanitizers for inactivating Escherichia coli O157:H7 and Listeria monocytogenes in solution and on apples, lettuce, strawberries, and cantaloupe

Ozone (3 ppm), chlorine dioxide (3 and 5 ppm), chlorinated trisodium phosphate (100- and 200-ppm chlorine), and peroxyacetic acid (80 ppm) were assessed for reduction of Escherichia coli O157:H7 and Listeria monocytogenes in an aqueous model system and on inoculated produce. Initially, sanitizer solutions were inoculated to contain approximately 10(6) CFU/ml of either pathogen, after which aliquots were removed at 15-s intervals over a period of 5 min and approximately plated to determine log reduction times. Produce was dip inoculated to contain approximately 10(6) E. coli O157:H7 or L. monocytogenes CFU/g, held overnight, submerged in each sanitizer solution for up to 5 min, and then examined for survivors. In the model system study, both pathogens decreased > 5 log following 2 to 5 min of exposure, with ozone being most effective (15 s), followed by chlorine dioxide (19 to 21 s), chlorinated trisodium phosphate (25 to 27 s), and peroxyacetic acid (70 to 75 s). On produce, ozone and chlorine dioxide (5 ppm) were most effective, reducing populations approximately 5.6 log, with chlorine dioxide (3 ppm) and chlorinated trisodium phosphate (200 ppm chlorine) resulting in maximum reductions of approximately 4.9 log. Peroxyacetic acid was the least effective sanitizer (approximately 4.4-log reductions). After treatment, produce samples were stored at 4 degrees C for 9 days and quantitatively examined for E. coli O157:H7, L. monocytogenes, mesophilic aerobic bacteria, yeasts, and molds. Populations of both pathogens remained relatively unchanged, whereas numbers of mesophilic bacteria increased 2 to 3 log during storage. Final mold and yeast populations were significantly higher than initial counts for chlorine dioxide- and ozone-treated produce. Using the nonextended triangle test, whole apples exposed to chlorinated trisodium phosphate (200 ppm chlorine) and shredded lettuce exposed to peroxyacetic acid were statistically different from the other treated samples.     

Effect of meat ingredients (sodium nitrite and erythorbate) and processing (vacuum storage and packaging atmosphere) on germination and outgrowth of Clostridium perfringens spores in ham during abusive cooling

The effect of nitrite and erythorbate on Clostridium perfringens spore germination and outgrowth in ham during abusive cooling (15 h) was evaluated. Ham was formulated with ground pork, NaNO₂ (0, 50, 100, 150 or 200 ppm) and sodium erythorbate (0 or 547 ppm). Ten grams of meat (stored at 5 °C for 3 or 24 h after preparation) were transferred to a vacuum bag and inoculated with a three-strain C. perfringens spore cocktail to obtain an inoculum of ca. 2.5 log spores/g. The bags were vacuum-sealed, and the meat was heat treated (75 °C, 20 min) and cooled within 15 h from 54.4 to 7.2 °C. Residual nitrite was determined before and after heat treatment using ion chromatography with colorimetric detection. Cooling of ham (control) stored for 3 and 24 h, resulted in C. perfringens population increases of 1.46 and 4.20 log CFU/g, respectively. For samples that contained low NaNO₂ concentrations and were stored for 3 h, C. perfringens populations of 5.22 and 2.83 log CFU/g were observed with or without sodium erythorbate, respectively. Residual nitrite was stable (p > 0.05) for both storage times. Meat processing ingredients (sodium nitrite and sodium erythorbate) and their concentrations, and storage time subsequent to preparation of meat (oxygen content) affect C. perfringens spore germination and outgrowth during abusive cooling of ham.     

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.