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 B₁, B₂, G₁ and G₂ 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 B₁, 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).     

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).     

Aflatoxins’ fate during the nixtamalization of contaminated maize by two tortilla-making processes

The fate of aflatoxin B₁ and B₂ was studied during maize nixtamalization by two tortilla-making processes. High-quality maize seed (AS-900) was used, as well as a toxigenic strain of Aspergillus flavus. The grain moisture content was adjusted to 18%, and the incubation temperature was 27°C. One lot of grain served as the control and so was not inoculated with the fungus. At the end of the 13 d incubation period, this control lot was aflatoxin free (aflatoxin level 1). Two other lots were inoculated with the fungus and incubated for 12 and 14 d. They then had aflatoxin contamination of 29 and 93 ppb, respectively (aflatoxins levels 2 and 3). The quantification of aflatoxins was undertaken according to the AOAC Official Method 991.31 and their identification confirmed by HPLC. The maize grain was processed by the traditional (TNP) and the ecological (ENP) nixtamalization processes. Aflatoxins were quantified at all steps of the tortilla-making processes. The research was conducted under a completely randomized factorial design (2×3). In the case of tortillas processed with TNP, the total aflatoxin content was 2 and 9 ppb corresponding to aflatoxin levels 2 and 3 with a degradation rate of 92% and 90%, respectively. In tortillas obtained through the ENP, the aflatoxin content was 6 and 36 ppb for aflatoxin levels 2 and 3, with degradation rates of 78% and 61%, respectively. The TNP produced higher aflatoxin degradation rates than the ENP.     

Screening of aflatoxins in duck feedstuffs in West Java,Indonesia

During the period 1979-1985, incoming feed ingredients (some of imported origin) for duck diets were screened for their aflatoxin level. As a result. records of aflatoxin data from 533 corn, 88 rice, 136 rice bran, 47 wheat pollard, 207 soya bean meal. 55 copra meal and 166 fish meal samples were obtained. Aflatoxin B ₁ was the predominant form, the incidence of samples containing it ranging from 69 to 94%; then accompanied by aflatoxin G₁, 37 to 81%: by B ₂, 33 to 70%; by G₂, 13 to 66%. Levels of total aflatoxin > 20 μg kg ^?1 were most frequently encountered in corn (71%) and copra meal (58%), followed by soya bean meal (20%), wheat pollard (15%), rice bran (12%), fish meal (10%) and rice (4%). Most feed ingredients contained aflatoxins < 100 μg kg^?1 except in corn of which 202 samples (38%) had a higher level. Corn is concluded to be the main source of alfatoxin contamination in corn-based mixed feeds.     

Mycotoxins in cereal grain. Part IV. Inactivation of ochratoxin A and other mycotoxins during ammoniation

Addition of ammonia to final concentration 2% inactivates ochratoxin A, aflatoxin, citrinin, penicillic acid and partially zearalenon at temperature 20-50 °C. Detoxification of contaminated cereal grain (wheat, corn or barley) can be performed on a farm using ammoniation without special investment during 4 to 6 weeks. Ammoniation changes nutritional value of grain as feed in a small extent.     

Effect of ammonium hydroxide on ultrastructure and tenderness of buffalo meat

This study was conducted with an objective to improve the tenderness of tough buffalo meat using ammonium hydroxide. Buffalo meat chunks from Biceps femoris muscle were marinated with distilled water (control), 0.1%, 0.5% and 1.0% solution of ammonium hydroxide for 48 h at 4±1 °C and subjected to various physico-chemical analysis and ultrastructural studies. Ammonium hydroxide increased (P<0.05) the pH, water holding capacity (WHC), collagen solubility, total and salt soluble protein extractability and cooking yield. Reduction (P<0.05) in Warner-Bratzler shear force values were observed in all ammonium hydroxide treated samples compared to non-treated control. Electrophoretic pattern of muscle proteins exhibited reduction in the intensity and number of certain protein bands for 0.1% and 0.5% ammonium hydroxide treated samples compared to control. Scanning and transmission electron microscopy also revealed breakdown of endothelium layers surrounding muscle fibers and weakening of Z-discs respectively, in treated samples compared to controls. These results suggest that ammonium hydroxide might be used to tenderize tough buffalo meat.     

Comparison of drying behaviour, quality and yield of copra processed in either a solar hybrid dryer on in an improved copra kiln

Drying copra in a solar hybrid dryer reduces the moisture content from around 50% to 7% after 71 h of continuous drying. The copra was graded as 73% white copra, 21% Milling Ordinary Grade II (M.O.GII) and the remaining 6% M.O.GIII (dusty copra). Thermal efficiency was about 10%. In the Coconut Research Institute copra kiln, the moisture content of copra was reduced from around 52% to 8% in 62 h of intermittent dying. The copra was graded as about 82% M.O.GI and the remaining 18% M.O.GIII (burnt copra). Thermal efficiency was about 15.5%. High quality white copra could be processed in solar hybrid drying. However, no white copra could be processed in kiln drying.     

Carry-Over of Aflatoxins to Fig Molasses from Contaminated Dried Figs

The carry-over of aflatoxins to fig molasses produced by using two different processing techniques from contaminated dried figs (> 1000 ppb of total aflatoxins) were examined by using a HPLC technique. The effects of extraction, bleaching and concentration steps on the reduction of aflatoxin levels were also investigated. The reductions in total aflatoxin levels in fig molasses produced by using the two techniques were detected to be 62 and 38%, respectively. Extraction, bleaching and concentration steps were observed to cause 22% reduction in total aflatoxin levels.     

Moisture content,insect pest infestation and mycotoxin levels of maize in markets in the northern region of Ghana

Reliable quantitative data on maize post-harvest losses and factors that cause them in northern Ghana are limited. In this study we assessed maize at six markets in the Northern Region of Ghana, in and around Tamale, during the harvest and storage period of October 2015–June 2016. Across all the markets and sampling periods grain temperature was 32.6 ± 0.2 °C and equilibrium moisture content (EMC) was 9.5 ± 0.2%. EMC tended to decrease to a low in January and February and then increased again, while mean maize temperature was above 30 °C in all months. The primary stored product insects collected from the samples were Tribolium castaneum (Herbst), Sitophilus spp., Rhyzopertha dominica (Fauvel), and Cryptolestes ferrugineus (Stephens). Using all the market and sampling month data, there was a significant correlation between EMC and total number of insects recovered, but not between total number of insects and temperature. The average percentage of insect-damaged kernels (IDK) in the maize sampled across all the markets and sampling periods was 2.7 ± 0.2%, with a range between 0 and 21.4%. Using all the market and sampling month data, levels of insect damage tended to be positively correlated with maize moisture, but not temperature, and levels of insect damage increased with number of stored product insects recovered. The action threshold for aflatoxin in maize in Ghana is 15 ppb, but overall mean aflatoxin level was 19.8 ± 1.5 ppb and aflatoxin levels ranged from 0.3 to 132.2 ppb, with 53% of the samples having levels above 15 ppb. The mean fumonisin level was 1.2 ± 0.0 ppm, which is below the 4.0 ppm action threshold for Ghana. Our results show that aflatoxin levels were high in the market maize in Northern Region of Ghana and insects were prevalent, even though grain moisture tended to be relatively low, especially compared to the Middle Belt of Ghana.     

Mycoflora and Aflatoxin Content of Hazelnuts,Walnuts, Peanuts,Almonds and Roasted Chickpeas (LEBLEBI) Sold in Turkey

In this study, 28 hazelnuts, 24 walnuts, 18 peanuts, 13 almonds, and 11 roasted chickpeas (leblebi) were analyzed for aflatoxin contamination using thin layer chromatography (TLC). Aflatoxin was found in 26 of 94 samples (27.66%) at concentrations ranging from 1 to 113 ppb. Detectable levels of aflatoxin were 33.4 ppb in hazelnuts, 22.1 ppb in walnuts, 43.0 ppb in peanuts, 7.4 ppb in almonds, and 1.7 ppb in roasted chickpeas. The highest level of aflatoxin was 113 ppb in a single hazelnut sample. Aspergillus and Penicillium species were frequently determined in all the samples.     

Decontamination of aflatoxin B1‐contaminated corn by ammonium persulphate during fermentation

The decontamination of aflatoxin B₁(AFB₁)‐contaminated corn, which is required if the corn is to be suitable for alternative use, by an ammoniation–fermentation integrated process was studied. This process could be used for the production of fuel ethanol from aflatoxin‐containing corn. Different concentrations (0.25, 0.50, 1.00, 1.5 and 2.0% w/w) of ammonium persulphate were tested in the detoxification of AFB₁‐contaminated corn during fermentation. In order to increase the decontamination of corn, 0.5 and 1.0% (w/w) azodicarbonamide, benzoyl peroxide and hydrogen peroxide were tested. Peroxides were added at three different stages of the fermentation process: liquefaction, saccharification and fermentation. Levels of AFB₁ and ethanol were determined after each fermentation process. Treated corn was tested for mutagenic potential using the Ames test with TA100 tester strain and pure AFB₁ as positive control. Addition of 2.0% (w/w) ammonium persulphate caused the highest level of decontamination without affecting ethanol production. Addition of peroxides did not significantly (P < 0.05) increase ethanol production or significantly (P < 0.05) improve the decontamination process. The best processes for decontamination of corn and for ethanol production included the addition of 2.0% (w/w) ammonium persulphate for both and of 1.0 and 0.5% (w/w) benzoyl peroxide respectively. All treated corn samples showed no mutagenic potential. Possible industrial use of these processes is discussed. © 2002 Society of Chemical Industry     

Application of hazard analysis critical control points system for the control of aflatoxins in the Brazilian groundnut‐based food industry

This study was conducted to identify and assess the critical control points (CCPs) in groundnut‐based food production in southern Brazil in order to reduce or eliminate aflatoxin contamination. This methodology has been suggested by the Food and Agriculture Organization (FAO) of the United Nations. Reception of prime matter, groundnut storage, roasting and thermal treatment were the main CCPs identified. Critical factors were the determination of aflatoxin, moisture content and water activity (A_w) during groundnut reception and storage, control of temperature, roasting time and thermal treatment in the groundnut‐based food manufacturing. The critical limit for moisture was 8.2% and 0.6 was established for A_w. In Brazil, the limit for aflatoxins B₁, B₂, G₁ and G₂ has been established at 20 ppb. Temperatures of 180 °C/1 h and 80 °C/40 min were established for roasting and thermal treatment stages of groundnut‐based food, respectively.     

INFLUENCE OF MOISTURE CONTENT AND STORAGE TEMPERATURE ON THE PRODUCTION OF AFLATOXIN BY ASPERGILLUS FLAVUS EA-81 IN MAIZE AFTER EXPOSURE TO GAMMA RADIATION

The effect of gamma radiation on aflatoxin production by Aspergillus flavus EA-81 in maize with different initial moisture levels was determined over a 15-day period. The viability of A. flavus on maize decreased over time with increasing moisture contents and storage at 8C. After 45 days at 28C, levels of viable conidiospores of A. flavus increased from 4.5 × 10⁷ to about 3.0 × 10⁸ per gram of maize. Levels of aflatoxin B₁ produced by A. flavus were 10 μg kg^-1 in the maize stored at 8C after 45 days. Production of aflatoxin was highest at 40% moisture and 28C. Irradiation of 1.0 or 2.0 kGy greatly reduced the level of mold growth relative to unirradiated controls. A dose of 4.0 kGy eliminated all viable fungi. Aflatoxin B₁ production decreased with increased levels of irradiation and was negligible at 4.0 kGy. When maize was inoculated after irradiation and stored, the spore counts and aflatoxin levels were higher than in unirradiated and inoculated controls after 30 days. Apparently, the natural competitive microflora prevented growth and thus limited higher concentrations of aflatoxin in maize.     

Effect of gamma irradiation on aflatoxin production in barley

Barley was inoculated with conidia of Aspergillus parasiticus NRRL 2999, and at 0°C was left to equilibrate at three moisture levels: 17, 20 and 25%. Gamma irradiation at five doses, 0, 50, 100, 200 and 400 krad, was applied to the grain either soon after moisture equilibration (3 days after inoculation) or 10 days later (13 days after inoculation). Increasing the radiation dose resulted in decreasing aflatoxin formation, with one exception: 200 krad applied 13 days after inoculation on barley stored at a moisture level of 25% (100% relative humidity) and 25°C led to higher aflatoxin production than at 100 or 50 krad. For the control of aflatoxin contamination in barley, storage at low moisture content appears to be more practical and effective than irradiation.     

Spread of Aspergillus flavus and aflatoxin accumulation in postharvested maize treated with biocontrol products

Maize is a major staple crop and calorie source for many people living in Sub-Saharan Africa. In this region, Aspergillus flavus causes ear rot in maize, contributing to food insecurity due to aflatoxin contamination. The biological control principle of competitive exclusion has been applied in both the United States and Africa to reduce aflatoxin levels in maize grain at harvest by introducing atoxigenic strains that out-compete toxigenic strains. The goal of this study was to determine if the efficacy of preharvest biocontrol treatments carry over into the postharvest drying period, the time between harvest and the point when grain moisture is safe for storage. In Sub-Sahara Africa, this period often is extended by weather and the complexities of postharvest drying practices. Maize grain was collected from fields in Texas and North Carolina that were treated with commercial biocontrol products and untreated control fields. To simulate moisture conditions similar to those experienced by farmers during drying in Sub-Sahara Africa, we adjusted the grain to 20% moisture content and incubated it at 28 °C for 6 days. Although the initial number of kernels infected by fungal species was high in most samples, less than 24% of kernels were infected with Aspergillus flavus and aflatoxin levels were low (<4 ppb). Both toxigenic and atoxigenic strains grew and spread through the grain over the incubation period, and aflatoxin levels increased, even in samples from biocontrol-treated fields. Our molecular analysis suggests that applied biocontrol strains from treated fields may have migrated to untreated fields. These results also indicate that the population of toxigenic A. flavus in the harvested grain will increase and produce aflatoxin during the drying period when moisture is high. Therefore, we conclude that preharvest biocontrol applications will not replace the need for better postharvest practices that reduce the drying time between harvest and storage.     

Aflatoxin reduction in corn through field application of competitive fungi.

Soil in corn plots was inoculated with nonaflatoxigenic strains of Aspergillus flavus and A. parasiticus during crop years 1994 to 1997 to determine the effect of application of the nontoxigenic strains on preharvest aflatoxin contamination of corn. Corn plots in a separate part of the field were not inoculated and served as controls. Inoculation resulted in significant increases in the total A. flavus/parasiticus soil population in treated plots, and that population was dominated by the applied strain of A. parasiticus (NRRL 21369). In the years when weather conditions favored aflatoxin contamination (1996 and 1997), corn was predominately colonized by A. flavus as opposed to A. parasiticus. In 1996, colonization by wild-type A. flavus was significantly reduced in treated plots compared with control plots, but total A. flavus/parasiticus colonization was not different between the two groups. A change to a more aggressive strain of A. flavus (NRRL 21882) as part of the biocontrol inoculum in 1997 resulted in a significantly (P < 0.001) higher colonization of corn by the applied strain. Weather conditions did not favor aflatoxin contamination in 1994 and 1995. In 1996, the aflatoxin concentration in corn from treated plots averaged 24.0 ppb, a reduction of 87% compared with the aflatoxin in control plots that averaged 188.4 ppb. In 1997, aflatoxin was reduced by 66% in treated corn (29.8 ppb) compared with control corn (87.5 ppb). Together, the data indicated that although the applied strain of A. parasiticus dominated in the soil, the nonaflatoxigenic strains of A. flavus were more responsible for the observed reductions in aflatoxin contamination. Inclusion of a nonaflatoxigenic strain of A. parasiticus in a biological control formulation for aflatoxin contamination may not be as important for airborne crops, such as corn, as for soilborne crops, such as peanuts.     

Effect of ammoniation on the carcinogenicity of aflatoxin-contaminated groundnut oil cakes: long-term feeding study in the rat

The efficacy of detoxication by ammoniation of aflatoxin-contaminated groundnut oil cakes was determined in long-term (18 months) feeding experiments with rats. The aflatoxin content of the cake was reduced very considerably by the pressurized application of ammonia, dropping from 1000 to 140 ppb at a gas pressure of 2 bar and to 60 ppb at 3 bar. No reversion was noted during the experiment. The percentage of hepatic tumours obtained was very high for the untreated cakes, but fell sharply with medium treatment and was reduced to zero by the treatment at 3 bar. A satisfactory dose-effect relationship was shown between the residual aflatoxin content of the cakes and the observed incidence of tumours. The results show that ammonia treatment is a practical solution to the problem of the carcinogenic potency of contaminated oil cakes.     

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.     

氨气熏蒸降解玉米中黄曲霉毒素B1 的条件优化

为提高氨气对玉米中黄曲霉毒素B1(AFB1)的降解效率,首先通过单因素试验研究氨熏温度、氨气浓度、氨熏时间及玉米含水量对黄曲霉毒素B1 降解率的影响,然后通过二次回归正交试验设计及响应面分析确定主要影响因素的最优参数组合：温度37℃、玉米含水量20%、氨气体积分数7.05%、氨熏时间96h,在此条件下玉米中AFB1 降解率的模型预测值为90.4%,实测值为92%,两者较接近。     

Effect of sublethal concentrations of propionic or butyric acid on growth and aflatoxin production by Aspergillus flavus

Propionic or butyric acid was added at sublethal doses (0.1–2 mg/ml) to a growth medium supporting growth of Aspergillus flavus and subsequent aflatoxin production. A reduction in growth and aflatoxin production occurred when the acids were added at the time of inoculation. Addition of the acids to cultures at different times resulted in little effect on growth but production of aflatoxin after 12 days was reduced with earlier time of application for both propionic and butyric acid. When the acids were added to rough rice with a moisture content of 21% and inoculated with A. flavus fungal growth and aflatoxin production were reduced relative to non-inoculated controls. Early application of acids resulted in lower yields of aflatoxin.