Elimination of aflatoxins from peanut meal

Application of ozone for degradation of mycotoxins in food: A review

Mycotoxins such as aflatoxins (AFs), ochratoxin A (OTA) fumonisins (FMN), deoxynivalenol (DON), zearalenone (ZEN), and patulin are stable at regular food process practices. Ozone (O₃ ) is a strong oxidizer and generally considered as a safe antimicrobial agent in food industries. Ozone disrupts fungal cells through oxidizing sulfhydryl and amino acid groups of enzymes or attacks the polyunsaturated fatty acids of the cell wall. Fusarium is the most sensitive mycotoxigenic fungi to ozonation followed by Aspergillus and Penicillium. Studies have shown complete inactivation of Fusarium and Aspergillus by O₃ gas. Spore germination and toxin production have also been reduced after ozone fumigation. Both naturally and artificially, mycotoxin-contaminated samples have shown significant mycotoxin reduction after ozonation. Although the mechanism of detoxification is not very clear for some mycotoxins, it is believed that ozone reacts with the functional groups in the mycotoxin molecules, changes their molecular structures, and forms products with lower molecular weight, less double bonds, and less toxicity. Although some minor physicochemical changes were observed in some ozone-treated foods, these changes may or may not affect the use of the ozonated product depending on the further application of it. The effectiveness of the ozonation process depends on the exposure time, ozone concentration, temperature, moisture content of the product, and relative humidity. Due to its strong oxidizing property and corrosiveness, there are strict limits for O₃ gas exposure. O₃ gas has limited penetration and decomposes quickly. However, ozone treatment can be used as a safe and green technology for food preservation and control of contaminants.

Ozone Effectiveness on Wheat Weevil Suppression: Preliminary Research

Insect infestations within stored product facilities are a major concern to livestock and human food industries. Insect infestations in storage systems can result in economic losses of up to 20%. Furthermore, the presence of insects and their waste and remains in grain and stored foods may pose a health risk to humans and livestock. At present, pests in commercial storage are managed by a combination of different methods ranging from cleaning and cooling to treatment of the stored material with contact insecticides or fumigation. The availability of pesticides for the treatment of grain and other stored products is decreasing owing, in some cases, to environmental and safety concerns among consumers and society, thus emphasizing the need for alternative eco-friendly pest control methods. One of the potential methods is the use of ozone. Although the mechanism of action of ozone on insects is not completely known, the insect's respiratory system is a likely the target of this gas. The main goal of this investigation was to determine the efficacy of ozone in the suppression of adult wheat weevils Sitophilus granarius. In the experiments conducted, different durations of ozone exposure were tested. In addition to ozone toxicity, the walking response and velocity of wheat weevils were investigated. The results showed the harmful effects of ozone on these insects. In addition to mortality, ozone also had negative effects on insect speed and mobility. The efficiency of the ozone treatment increased with increasing ozone exposure of insects. The ability of ozone to reduce the walking activity and velocity of treated insects is a positive feature in pest control in storage systems, thereby reducing the possibility of insects escaping from treated objects. The results of this investigation suggest that ozone has the potential to become a realistic choice for suppressing harmful insects in storage systems for humans and livestock, either alone or as a complement to other control methods.

Detoxification of aflatoxin in corn flour by ozone

BACKGROUND

Corn, which is one of most important agricultural products worldwide, is prone to pollution by aflatoxins (AFs) in many areas, thus seriously jeopardizing human health and threatening economic growth. This study evaluated the effects of ozone on the detoxification of AFs in corn flour (CF) and the moisture content (MC) thereof.

RESULTS

The detoxifying effects of ozone on CF became more obvious as the ozone concentration and exposure time increased. After CF was treated with 75 mg L(-1) ozone for 60 min, the contents of AFB1 , AFG1 and AFB2 decreased from 53.60, 12.08 and 2.42 µg kg(-1) to 11.38, 3.37 and 0.71 µg kg(-1) , respectively, which are lower than the maximum limits of AFB1 , AFG1 , AFB2 and total AFs (20 µg kg(-1) ) for CF regulated by the Chinese government. Ozonation significantly affected the MC of CF, and ozone at a higher concentration decreased the MC more drastically. After CF was exposed to 15, 30, 45 and 75 mg L(-1) ozone for 60 min, the MC of CF decreased from 17.4% to below 15%, fulfilling the long-period storage requirements for CF.

CONCLUSION

Ozone is potentially applicable in effectively degrading the AFs in CF and in greatly decreasing the MC of CF.

The effect of chemical treatment on reduction of aflatoxins and ochratoxin A in black and white pepper during washing

The effect of 18 different chemicals, which included acidic compounds (sulfuric acid, chloridric acid, phosphoric acid, benzoic acid, citric acid, acetic acid), alkaline compounds (ammonia, sodium bicarbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide), salts (acetate ammonium, sodium bisulfite, sodium hydrosulfite, sodium chloride, sodium sulfate) and oxidising agents (hydrogen peroxide, sodium hypochlorite), on the reduction of aflatoxins B(1), B(2), G(1) and G(2) and ochratoxin A (OTA) was investigated in black and white pepper. OTA and aflatoxins were determined using HPLC after immunoaffinity column clean-up. Almost all of the applied chemicals showed a significant degree of reduction on mycotoxins (p < 0.05). The lowest and highest reduction of aflatoxin B(1), which is the most dangerous aflatoxin, was 20.5% ± 2.7% using benzoic acid and 54.5% ± 2.7% using sodium hydroxide. There was no significant difference between black and white peppers (p < 0.05).

Effect of Oxygen-Reducing Atmospheres on the Safety of Packaged Shelled Brazil Nuts during Storage

This work reports the application of oxygen-(O(2)-) reducing atmosphere methods on stored shelled Brazil nut (Bertholletia excelsa H.B.K.) packs aiming to evaluate the degree of aflatoxin degradation, nuts lipid oxidative stability, fungi control, and hygienic conditions improvement. The methods applied were (a) ozone: O(3), (b) carbon dioxide: CO(2), and (c) O(2) absorber pads with and without vacuum. From all modified atmospheres evaluated, the best performance was obtained with O(3), either with or without vacuum. It was the only nut treatment that was able to degrade aflatoxins. None of the spiked (AFLs: 15 μg·kg(-1)) nut samples O(3)- treated had aflatoxins detected up to the LC-MS/MS method LOQ (0.36 μg·kg(-1) for total AFLs), thus producing safer nuts. Also it kept the fatty acid oxidation indicator-malondialdehyde stable and improved the sensory attributes for consumer acceptance. In addition, the destruction of fungi and yeast was observed since the O(3) application (from 1.8 × 10(4) cfu/g to NG = no growth). All other treatments stabilized and/or inhibited microorganisms' growth only. By adding CO(2) gas also played an important role in the nut quality. Regarding cost, gaseous O(3) showed to be of low cost for application in the nut packs.

Role of lactone ring in structural, electronic, and reactivity properties of aflatoxin B1: a theoretical study

This study involved quantum mechanical calculations to explain the chemical behavior of the lactone ring of aflatoxin B1, which is a carcinogenic hazardous compound. The aflatoxin B1 compound, produced by the fungi Aspergillum flavus, was studied with the B3LYP/6-311+G(d,p) method; its reactivity properties were accounted for by means of the calculated geometrical and electronic parameters. The results obtained indicate that the fused A, B, C, and D rings of aflatoxin adopt a continuous planar conformation. The carbon atom of the lactone group presents a highly electrophilic character, since the population analysis yields a high positive charge for this atom, whereas high negative charges were recorded for both oxygen sites of that group. Thus, in an acidic aqueous medium, the oxygen atoms could be protonated and the carbon site may suffer a nucleophilic attack by water. Accordingly, the OC-O bond length has been lengthened substantially. So it was demonstrated that the lactonic ring of aflatoxin B1 is hydrolyzed under acidic conditions by an acid-acyl bimolecular mechanisms, A(AC)2, suggesting the deletion of its carcinogenic properties.

Lutein from ozone-treated corn retains antimutagenic properties

The present study was conducted to determine the influence of an ozonation process on lutein and protein in clean and contaminated corns. This study aimed to determine the levels of lutein and protein in corn before and after ozonation and to verify the antimutagenic potential of the extracted lutein against aflatoxin using the Ames test. The lutein content was analyzed by high-performance liquid chromatography. Nitrogen analysis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis were used to analyze protein. Clean ozone-treated corn had a total lutein content of 28.36 microg/g, which was higher than that of 22.75 microg/g in the untreated clean corn. However, the lutein content was 11.69 microg/g in the ozone-treated contaminated corn, which was lower than that of 16.42 microg/g in the untreated contaminated corn. In both corn samples, the protein content of ozone-treated corn was lower than that of untreated corn, indicating that protein could be destroyed by the ozonation process, which may influence the nutritious value of the corn. Lutein extracts alone showed no mutagenic potential against Salmonella typhimurium tester strains TA100. Lutein extracts from corn inhibited the mutagenicity of AFB1 in a dose-response manner more efficiently than lutein standard. Lutein extracts from different corn samples had similar antimutagenic potentials against AFB1, so the ozone treatment did not affect the antimutagenic potentials of lutein extracts.

Safety of Oxygreen®, an ozone treatment on wheat grains. Part 2. Is there a substantial equivalence between Oxygreen-treated wheat grains and untreated wheat grains?

The Oxygreen process is a new process based on wheat grain treatment by ozone (produced in situ), in a closed sequential batch reactor. The Oxygreen process offers a close, homogeneous, and controlled contact between the gas and the grain. It is proposed for use for wheat grain decontamination (insects, fungi, bacteria, mycotoxins, pesticides). It takes place in classical milling diagram, and occurs after grain cleaning and before milling. The aim of the study reported here was to determine if Oxygreen treatment could induce in the grain the formation of processing-related compounds, and if these compounds are specific or could be recognized as classical modifications already used in the cereal industry (milling, baking). Studies were performed in order to evaluate any effect of Oxygreen treatment on vitamins, ferulic acid, phytates, proteins, carbohydrates, and lipids. It was concluded that there was no detectable substantial difference between ozone-treated grains and the untreated ones, although some quantitative differences can occur. The more detectable differences concern concentration of free sugars, and inhibition of some oxidative enzymes. These quantitative differences are very slight compared to the modifications that occur in dough, after addition of oxidative products directly in flour, or during kneading and dough fermentation.

Ozone and its current and future application in the food industry

The food industry is interested considerably in using ozone to enhance the shelf-life and safety of food products and in exploring new applications of the sanitizer. This interest was recently accompanied by a US governmental approval of ozone for the safe use, in gaseous and aqueous phases, as an antimicrobial agent on food, including meat and poultry. Ozone has a strong microbicidal action against bacteria, fungi, parasites and viruses when these microorganisms are present in low ozone-demand media. Readily available organic constituents in food, however, compete with microorganisms for applied ozone and thus efficacy of the treatment is minimized. Ozone is suitable for washing and sanitizing solid food with intact and smooth surfaces (e.g., fruits and vegetables) and ozone-sanitized fresh produce has recently been introduced in the US market. Use of ozone to sanitize equipment, packaging materials, and processing environment is currently investigated. Efforts to decontaminate bean sprouts and remove biofilm with ozone have not been successful. The antimicrobial efficacy can be enhanced considerably when ozonation is combined with other chemical (e.g., hydrogen peroxide) or physical (e.g., ultraviolet radiation) treatments. Mechanical action is also needed as a means to dislodge microorganisms from the surface of food and expose them to the action of the sanitizer. The food industry also is interested in using ozone to decontaminate processing water and decrease its chemical and biological oxygen demand. This application improves the reusability of processing water and allows for environment-friendly processing operations.

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 8.9tonnes (350bu) of maize with 50ppm ozone for 3d 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 0.03m/s, a velocity that is achievable in typical storage structures with current fans and motors. At this velocity 85% of the ozone penetrated 2.7m into the column of grain in 0.8d during Phase 1 and within 5d a stable degradation rate of 1ppm/0.3m was achieved. Optimum velocity for Phase 2 was 0.02m/s. At this velocity, 90% of the ozone dose penetrated 2.7m in less than 0.5d. These data demonstrate the potential usefulness of using ozone in managing stored maize and possibly other grains.

Aflatoxicosis in turkey poults is prevented by treatment of naturally contaminated corn with ozone generated by electrolysis

Previous studies have demonstrated that a novel source of ozone gas (O3) maybe used to chemically degrade numerous mycotoxins, including aflatoxin (AF) B1. Subsequent in vitro analyses demonstrated detoxification of AFB1, suggesting a potential method of remediate AF-contaminated grain. The objective of this study was to evaluate the capability of electrochemically produced ozone to degrade AFB1 in naturally contaminated whole kernel corn and confirm detoxification in turkey poults. Corn was procured from the southern coastal areas of Texas and HPLC revealed 1,220 +/- 73.3 ppb AFB1. Control and contaminated corn were treated for 92 h with O3 at 200 mg/min in 30 kg batches; greater than 95% reduction of AFB1 in contaminated corn was achieved. One-day-old female turkey poults were fed 1) control corn, 2) control corn + O3, 3) AFB1 corn, or 4) AFB1 corn + O3 mixed in rations (46% by wt.) and consumed ad libitum for 3 wk. When compared with controls, turkeys fed AFB1 corn had reduced body weight gain and relative liver weight, whereas turkeys fed control corn + O3 or AFB1 corn + O3 did not differ from controls. Furthermore, alterations in the majority of relative organ weight, liver discoloration, serum enzyme activity, hematological parameters, and blood chemistry caused by AFB1 were eliminated (no difference from controls) by treatment with O3. These data demonstrate that treatment of contaminated corn with electrochemically produced O3 provided protection against AFB1 in young turkey poults. It is important to note that treatment of control corn with O3 did not alter the performance of the turkey poults.

Oxidative degradation and detoxification of mycotoxins using a novel source of ozone

Practical methods to degrade mycotoxins using ozone gas (O3) have been limited due to low O3 production capabilities of conventional systems and their associated costs. Recent advances in electrochemistry (i.e. proton-exchange membrane and electrolysis technologies) have made available a novel and continuous source of O3 gas up to 20% by weight. It is possible that the rapid delivery of high concentrations of O3 will result in mycotoxin degradation in contaminated grains--with minimal destruction of nutrients. The major objectives of this study were to investigate the degradation and detoxification of common mycotoxins in the presence of high concentrations of O3. In this study, aqueous equimolar (32 microM) solutions of aflatoxins B1 (AfB1), B2 (AfB2), G1 (AfG1), G2 (AfG2), cyclopiazonic acid (CPA), fumonisin B1 (FB1), ochratoxin A (OA), patulin, secalonic acid D (SAD) and zearalenone (ZEN) were treated with 2, 10 and/or 20 weight% O3 over a period of 5.0 min and analysed by HPLC. Results indicated that AfB1 and AfG1 were rapidly degraded using 2% O3, while AfB2 and AfG2 were more resistant to oxidation and required higher levels of O3 (20%) for rapid degradation. In other studies, patulin, CPA, OA, SAD and ZEN were degraded at 15 sec, with no by-products detectable by HPLC. Additionally, the toxicity of these compounds (measured by a mycotoxin-sensitive bioassay) was significantly decreased following treatment with O3 for 15 sec. In another study, FB1 (following reaction with O3) was rapidly degraded at 15 sec, with the formation of new products. One of these appeared to be a 3-keto derivative of FB1. Importantly, degradation of FB1 did not correlate with detoxification, since FB1 solutions treated with O3 were still positive in two bioassay systems.

Inactivation of aflatoxin B1 in corn meal, copra meal and peanuts by chlorine gas treatment

More than 75% degradation of aflatoxin B1 (AFB1) was achieved after treatment of AFB1-spiked corn meal, spiked copra meal (the residue of the kiln-dried coconut kernels after mechanical expulsion of oil) and peanuts artificially infected with Aspergillus parasiticus, with 11, 16 and 35 mg chlorine gas per g meal or peanuts, respectively. At these chlorine gas treatment levels, extension of the exposure period of the corn meal and copra meal beyond 2.5 hr, and the peanuts beyond 1 day, did not increase the percentage degradation of AFB1. The mutagenicity of chlorine-treated copra meal and peanuts spiked with AFB1 was greatly reduced compared with untreated controls, as determined in Salmonella typhimurium strain TA98 in the presence of rat liver S-9 mix; the reduction in mutagenicity was found to be highly correlated with the reduction in AFB1 levels. Reactions of chlorine with AFB1 or constituents of the meals or peanuts did not appear to generate new mutagenic compounds. The moisture content of the meals and peanuts appeared to be an important factor affecting the degradation of AFB1 by chlorine gas.

Aflatoxins in food: occurrence, biosynthesis, effects on organisms, detection, and methods of control

Aflatoxins are secondary metabolites produced by species of Aspergilli, specifically Aspergillus flavus and Aspergillus parasiticus. These molds are ubiquitous in nature and grow on a variety of substrates, thereby producing aflatoxins. Aflatoxins are of great concern due to their biochemical and biological effects on living organisms. In this article, the occurrence of aflatoxins, their biosynthesis, factors influencing their production, their effects on living organisms, and methods of detection and control in food are reviewed. Future areas of research involving mathematical modeling of factors influencing aflatoxin production and alternative methods of control, such as modified atmosphere packaging, are also discussed.

Reduction of mutagenicity and toxicity of aflatoxin B1 by chlorine gas treatment

Chlorine gas was used to treat aflatoxin B1 (AFB1). The time-related exposure study showed that 4 ml (15 mg) pure chlorine gas caused about 90% destruction of 100 micrograms AFB1 within 10 min, at standard temperature and pressure. Four fluorescent reaction products were produced, two of which were identified as 8,9-dichloro-AFB1 and 8,9-dihydroxy-AFB1 (diol). The use of [14C]AFB1 confirmed the 90% destruction of the compound by chlorine gas. An increased destruction of AFB1 also occurred when an increased amount of chlorine gas was used. The mutagenic activity of the AFB1 sample treated for 10 min was reduced to about 5% of the untreated control using the Salmonella typhimurium strain TA98 in the presence of a rat-liver S-9 mix. A similar time-related reduction in AFB1 toxicity after chlorine treatment was also achieved using the chicken embryo toxicity assay.

The effect of feeding aflatoxin-contaminated groundnut meal, with or without ammoniation, on the development of gamma-glutamyl transferase positive lesions in the livers of Fischer 344 rats

The detoxification of aflatoxin-containing groundnut meal by ammoniation has been investigated using weanling male and female Fischer 344 rats. Rats were fed a pelleted diet consisting of 75% groundnut meal and 25% powdered rat diet, with vitamin supplement, for a period of 90 days. The groundnut meal was either aflatoxin-free or naturally contaminated with aflatoxins, and was used untreated or after ammoniation. Body weights and food consumptions were monitored throughout the experimental feeding period. After 90 days the animals were sacrificed and the gamma-glutamyl transferase (GGT) levels in the livers assayed fluorimetrically, and the distribution of the enzyme activity determined histochemically. The results indicated that ammoniation of the aflatoxin-containing meal eliminated the development of focal GGT positive lesions in both male and female animals. However, in the female, histochemical GGT staining of hepatocytes in the periportal areas was increased by all the experimental diets compared with the unammoniated, aflatoxin-free diet. This observation was supported by the fluorimetric assays. Ammoniation of the diet led to a decreased body weight gain in all cases compared with the corresponding unammoniated diet-fed groups.

An overview of aflatoxicosis of poultry: its characteristics, prevention and reduction

Aflatoxicosis represents one of the serious diseases of poultry, livestock and other animals. The cause of this disease in poultry and other food-producing animals has been attributed to the ingestion of various feeds contaminated with A. flavus. This toxigenic fungus is known to produce a group of extremely toxic metabolites, of which aflatoxin B1 (AFB1) is most potent. Avian species especially chicks, goslings, ducklings and turkey poults are most susceptible to AFB1 toxicity. The toxic effects of AFB1 are mainly localized in liver as manifested by hepatic necrosis, bile duct proliferation, icterus and hemorrhage. Chronic toxicity in those birds is characterized by loss of weight, decline in feed efficiency, drop in egg production and increased susceptibility to infections. The incidence of hepatocellular tumors, particularly in ducklings, is considered to be one of the serious consequences of aflatoxicosis. Even though prevention and avoidance are the best way to control aflatoxicosis, natural contamination of crops with A. flavus is sometimes unavoidable. Such aflatoxin-contaminated feeds can be decontaminated using various methods which mainly focus on physical removal or chemical inactivation of the toxins in the feeds. Moreover, dietary additives such as activated charcoal, phenobarbital, cysteine, glutathione, betacarotene, fisetin and selenium have also been reported to be effective in the reduction of aflatoxicosis in poultry.

Survey of aflatoxin-producing fungi in certain fermented foods and beverages in Thailand

Aflatoxin-producing fungi were found in fermented foods and beverages: fermented rice (kaomak), soybean sauce (taotjo), peanut butter, soy sauce (shoyu), Thai red and white wine, and rice sugar wine. These foods were extracted directly and tested for aflatoxins by thin-layer chromatography (TLC) and high pressure liquid chromatography (HPLC). Four strains of aflatoxin-producing fungi were isolated from peanut butter, taotjo, and shoyu. Direct extracts of 10% of the peanut butters tested and 5% of the kaomak tested contained large amounts of aflatoxins. The HPLC procedures used in this experiment utilized chloroform-ethyl acetate (3:1).