Aflatoxin Removal from Pistachio Nuts by Natural Natrolite

ABSTRACT: Natrolite was used to explore a physical and safe method to decontaminate aflatoxin-containing pistachio lots. Pistachio nuts with low, medium, and high levels of aflatoxin were subjected to a washing process with a slurry of 5% natrolite. Using thin-layer chromatography and scanning, the aflatoxin contents of the samples were measured. Aflatoxins B₁ and B₂ were found in pistachio nuts. The majority of total aflatoxins was aflatoxin B₁ Natrolite treatment resulted in a 38% to 100% reduction in aflatoxin B₁, depending on the initial aflatoxin level. Although natrolite was demonstrated to be an effective candidate to reduce aflatoxin B₁, its efficacy against aflatoxin B₂ was limited.     

REDUCTION OF FUNGI AND MYCOTOXINS FORMATION IN SEEDS BY GAMMA-RADIATION

Ninety samples of maize, chick-peas and groundnut seeds collected from the Egyptian market were found to be heavily contaminated by molds. Alternaria, Aspergillus, Cladosporium, Eurotium, Fusarium, Mucor, Penicillium and Rhizopus were the most common fungal genera isolated from nondisinfected seeds . Aspergillus alutaceus, A. flavus, Fusarium verticillioides and F. oxysporum were isolated from all surface-disinfected seeds and were reported to produce ochratoxin A, aflatoxin B₁ and zearalenone, respectively. Irradiation at a dose 4.0 kGy reduced the mold growth greatly relative to unirradiated controls. There was no growth at dose 5.0 kGy. On the basis of the radiation survival data, the decimal reduction values D₁₀ for A. alutaceus, A. flavus and F. verticilliodies were 0.70. 2.10 and 0.93 kGy in maize. A dose of 5 kGy inhibited the toxigenic molds and mycotoxin formation in seeds. Aflatoxin B₁ and ochratoxin A were detected in maize and chick-peas, whereas zearalenone was detected in maize samples. Application of radiation at a dose of 6.0 kGy detoxified aflatoxin B₁ by 74.3–76.7%, ochratoxin A by 51.3–96.2% and zearalenone by about 78%.     

COMBINED EFFECT OF pH AND HEAT TREATMENT ON DEGRADATION OF AFLATOXINS IN DRIED FIGS

Dried figs are sensitive commodities to aflatoxin contamination. Although preventive methods are the logical solution to aflatoxin problems, once the product is contaminated, decontamination procedures are inevitable. In this study, the effectiveness of a procedure consisted of acidification/alkalization, and heat treatment in degradation of aflatoxins was evaluated. The pH of dried fig extracts was adjusted to 3.1, 3.5, 6, 8 or 10 by adding acid or base. Extracts were heated at 50, 75 or 98C for 1 or 2 h, and then the residual aflatoxin B₁, B₂, G₁ and G₂ were determined. The highest level of degradation for aflatoxin B₁ (97  ±  1%) and B₂ (87  ±  1%) were observed at pH 10 in samples heated at 98 and 50C, respectively. Some treatments resulted in 100% degradation of aflatoxin G₁ and G₂ so that they could not be detected.

PRACTICAL APPLICATIONS

Aflatoxin contamination is a serious problem for a number of processed and non-processed foods, including dried figs. This not only presents severe risks to human and animal health but also causes economic problems for countries such as Turkey, U.S.A., Greece and Spain, which produce and export dried figs. It is clear that detoxifying studies are unavoidable when the amount of crop contaminated by toxins is considered. Therefore, the food industry is in search of applications that are effective in mycotoxin detoxification and adaptable to food processes. This is the first report on degradation of aflatoxins in naturally contaminated dried figs by such a promising method.     

INHIBITION OF ASPERGILLUS PARASITICUS GROWTH AND TOXIN PRODUCTION BY GARLIC

Mycelial growth and toxin production by Asperigillus parasiticus were inhibited by garlic concentrations of 0.3–0.4%. When the fungus was grown in broth, aflatoxin B₁ production was inhibited at a garlic concentration of 0.3% while aflatoxin G₁ production was inhibited by 0.25% garlic. When growth on rice, aflatoxin B₁ was detected at garlic concentrations of up to 2.5%. Aflatoxin G₁ was detected at 1.25% garlic concentration but not above this level.     

EFFECT OF GAMMA IRRADIATION ON AFLATOXIN B1 PRODUCTION BY ASPERGILLUS FLAVUS IN GROUND BEEF STORED AT 5C

The effect of γ-irradiation for controlling the production of aflatoxin B₁ by Aspergillus flavus in ground beef stored at 5C for 2 weeks was investigated. Aspergillus, Penicillium, Cladosporium, Mucor, Scopulariopsis, Candida and Rhodotorula were the most common fungal genera contaminating ground beef. A. flavus and A. niger were the most common Aspergillus spp. Aspergillus flavus isolates were able to produce aflatoxin B₁ in ground beef. Only 3 (20%) samples of ground beef were contaminated with aflatoxin B₁ (25–45 μg/Kg). Gamma irradiation dose levels resulted in an immediate reduction in the total numbers of A. flavus. No growth or aflatoxin B₁ production occurred at 1.50 kGy during storage.     

INFLUENCE OF OTHER FUNGI ON AFLATOXIN PRODUCTION BY ASPERGILLUS FLAVUS IN MAIZE KERNELS

Experiments were designed to determine whether certain nontoxigenic fungi commonly isolated from maize kernels can affect aflatoxin B₁ development when inoculated with A. flavus onto individual unsterilized, and autoclaved maize kernels . Trichoderma viride and Aspergillus niger were found to be strongly antagonist inhibiting the growth of A. flavus by 87 and 66% respectively, whereas Aspergillus versicolor, Fusarium moniliforme, Paecilomyces variotii and Emericella quadrillineata inhibited the growth of A. flavus by less than 51%. Less aflatoxin B₁ was detected when A. flavus was paired with A. niger or T. viride than with the other test fungi. When A. niger or T. viride was introduced onto the kernels 72 h before inoculation with A. flavus, no aflatoxin B₁ was detected in unsterilized kernels and the levels of aflatoxin B₁ were greatly reduced from 700 ppb to 160 and 140 ppb in autoclaved kernels, respectively. When inoculation of A. flavus followed 72 h of incubation of either A. niger and T. viride, no aflatoxin B₁ was detected. However, when both A. niger and T. viride were introduced 72 h after inoculation with A. flavus, the levels of aflatoxin B₁ were reduced to 385 and 560 ppb, respectively in unsterilized and autoclaved maize kernels . Trichoderma viride and Aspergillus niger may be useful in biological control of aflatoxin contamination of maize kernels .; Accepted for Publication June 11, 1997     

Aflatoxin levels in dried figs, nuts and paprika for export from Turkey

Three hundred and thirteen of 2643 dried fig, two of eighty hazelnut, sixteen of twenty-eight pistachio, five of ten peanut and nineteen of twenty-three paprika samples for export from Turkey were contaminated with total aflatoxins in the range of 0.2–162.76, 5.46–6.55, 2.31–63.11, 0.75–26.36 and 1.79–6.55 μg kg⁻¹, respectively. Samples were collected from January to August 2007 and tested for aflatoxins (B₁, B₂, G₁ and G₂) by immunoaffinity column extraction using RP-HPLC. Fifty-six of the 313 dried fig, all of the contaminated hazelnut and pistachio, two of the sixteen peanut and three of the nineteen paprika samples exceeded the regulatory limits of the European Union. The ratio of the different types of aflatoxin present in each sample exhibited great variability. For example, of 313 contaminated fig samples, 159 contained only aflatoxin B₁, eighty-five contained B₁ (49.7%) + G₁ (50.3%), twenty-two contained only G₁, twenty contained B₁ (89.4%) + B₂ (10.6%), thirteen contained B₁ (73.7%) + B₂ (10.8%) + G₁ (15.5%) and fourteen contained all four types, B₁ (26%) + B₂ (2.5%) + G₁ (66.5%) + G₂ (5%).     

PREPARATION AND CHARACTERIZATION OF AFLATOXIN B2a-HEMIGLUTARATE AND ITS USE FOR THE PRODUCTION OF ANTIBODY AGAINST AFLATOXIN B1

Hemisuccinate (HS) and hemiglutarate (HG) of aflatoxin B_2a (afla B_2a) were prepared by refluxing afla B_2a with the corresponding anhydride and 4-N, N-dimethylaminopyridine in tetrahydrofuran. Two epimers of the respective HS or HG which show different chromatographic behavior and physiochemical properties were isolated and characterized. Afla B_2a-HS hydrolyzes very rapidly in aqueous solution and was not used for further study. Afla B_2a-HG hydrolyzes at a much slower rate and was selected for the coupling to protein. Using the mixed anhydride method, as much as 12 moles of afla B_2a-HG were conjugated to each mole of bovine serum albumin (BSA). The antibody obtained from rabbits immunized with afla B_2a-HG BSA is most specific to afla B₁ and shows little cross reaction with afla G₁ and aflatoxicol. The lower limit for detection of afla B₁ by radioimmunoassay using this antibody is in the range of 30–50 pg per assay.     

RESEARCH NOTE: MYCOTOXINS IN FENNEL SEED

Ten samples of fennel seed from fields in India were examined for the presence ofaflatoxins B₁, B₂, G₁ and G₂. Five of the samples were fluorescent or became fluorescent during a 12 month storage period. Only aflatoxins B₁, B₂ and G₁ were identified. One nonfluorescent sample contained detectable aflatoxin B₁ after 12 months of storage.     

A SIMPLE SOLID-PHASE RADIOIMMUNOASSAY FOR AFLATOXIN B1

A solid-phase radioimmunoassay (RIA) for aflatoxin B₁ (afla B₁) was developed. This method involved the incubation of afla B₁, both labelled and unlabelled, with immunoglobulin (IgG)-sepharose gel which was prepared by conjugation of the IgG highly specific to afla B₁ with CNBr-activated sepharose gel, followed by a filtration step. The binding capacity was determined by counting the radioactivity in the filtrate. Studies with different afla B₁ analogues revealed that the IgG-gel bound most effectively with B₁. Binding of afla B₂, G₁, G₂, and aflatoxicol to the IgG-gel was less effective in comparison with the IgG before coupling. Between 0.5–5.0 ng per assay, the displacement of radioactivity from the gel was directly proportional to the amount of afla B₁ present. Using a simple extraction procedure without clean-up step, the recovery yields for afla B₁ in the contaminated corn or wheat at levels of 5 ppb or above were above 60%.     

Natural maize phenolic acids for control of aflatoxigenic fungi on maize

ABSTRACT:  Natural phytochemicals may be an alternative to synthetic chemicals for controlling fungal growth and mycotoxin production in stored maize. A key to progress in this field is to select the best natural maize phytochemicals to be applied in a storage maize ecosystem. This research was undertaken to evaluate the effects of the natural phytochemicals trans-cinnamic acid (CA) and ferulic acid (FA) alone at concentrations of 20 to 30 mM and in 5 combinations on Aspergillus flavus Link and A. parasiticus Speare populations and aflatoxin B₁ production. Studies on Aspergillus population and aflatoxin B₁ production were carried out in maize grain in relation to a water activity a_w of 0.99, 0.97, 0.95, and 0.93. CA and FA at concentrations of 25 to 30 mM, respectively, and CA-FA mixture T9 (25 + 30 mM) were the treatments most effective at inhibiting A. flavus and A. parasiticus population at all a_w assayed after 11 d of incubation. At all a_w values, the mixture CA-FA T9 (25 + 30 mM) completely inhibited (100%) aflatoxin B₁ production by both strains at a_w= 0.99, 0.97, 0.95, and 0.93. Decreased aflatoxin B₁ levels in comparison with the control were observed with mixtures CA-FA T6 (10 + 25 mM), T7 (20 + 20 mM), and T8 (20 + 30 mM) of both strains in the majority of a_w assayed. The data show that CA and FA could be considered as effective fungitoxicants for A. flavus and A. parasiticus in maize in the a_w range 0.99 to 0.93. The information obtained shows promise for controlling aflatoxigenic fungi in stored maize.     

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.     

AFLATOXIN PRODUCTION ON TWO MUSHROOM SUBSTRATES

Two fungi, Boletus edulis and Agaricus bisporus, were tested as substrates for two known aflatoxigenic fungi, Aspergillus flavus ATCC 15548 and A. parasiticus NRRL 2999. Both autoclaved substrates supported mycelial growth, sporulation, and aflatoxin production; however, the B. edulis substrate allowed more rapid mold growth and greater toxin production than did the A. bisporus substrate under laboratory conditions. Both aflatoxins B₁ and AFG₁ were produced with AFG₁ being the predominant toxin. Aflatoxins B₂ and AFG₂ were not detected. Although toxin was produced at low levels, the highest mean being 0.55 μg/g substrate for AFB₁ and AFG₁, both mushrooms apparently contained minimal nutrients for toxigenic mold growth and failed to cause antimycotic or antiaflatoxigenic responses. Routinely used aflatoxin extraction and analytical procedures appear applicable for such testing of mushrooms.     

Degradation of Vitamin A Palmitate in Corn Flakes During Storage

ABSTRACT: The amounts of vitamin A palmitate lost and isomers formed in corn flakes fortified with a vitamin A palmitate were determined during storage at ambient (avg. 23 °C) and elevated (45 °C) temperatures. Two vitamin A palmitate isomers, 9-cis and 13-cis, were found. The initial vitamin A palmitate consisted of 5% of 13-cis and less than 1% of 9-cis with the remaining being all-trans. In corn flakes fortified with either a complete vitamin mixture or vitamin A palmitate only, the distribution of these compounds was nearly constant throughout storage irrespective of sample type and storage conditions. The rate constant and reaction kinetics on the degradation of vitamin A palmitate were also obtained. After 6–8 wk storage, more than 90% of vitamin A palmitate was lost in all samples except corn flakes fortified with complete vitamin mixture and kept at ambient temperature. This study showed that the loss of vitamin A palmitate fortified in corn flakes was substantial even at ambient temperature. The presence of other vitamins including vitamin A, B₁, B₆, B₁₂, C, and D reduced the loss of vitamin Abut the loss was still significant.     

Essential Oil of Aegle marmelos as a Safe Plant-Based Antimicrobial Against Postharvest Microbial Infestations and Aflatoxin Contamination of Food Commodities

ABSTRACT:  The essential oil of  Aegle marmelos  L. Correa (Rutaceae) showed strong fungitoxicity against some storage fungi-causing contamination of foodstuffs. The oil also showed efficacy as aflatoxin suppressor at 500 μL/L as it completely arrested the aflatoxin B₁ production by the toxigenic strains (Navjot 4NSt and Saktiman 3NSt) of  Aspergillus flavus  Link. Keeping in view the side effects of synthetic fungicides,  A. marmelos  oil may be recommended as an antimicrobial of plant origin to enhance the shelf life of stored food commodities by controlling the fungal growth as well as aflatoxin secretion. This is the 1st report on aflatoxin B₁ inhibitory nature of this oil.  A. marmelos  oil may be recommended as a novel plant-based antimicrobial in food protection over synthetic preservatives, most of which are reported to incite environmental problems because of their nonbiodegradable nature and side effects on mammals. The LD₅₀ of  Aegle  oil was found to be 23659.93 mg/kg body weight in mice ( Mus musculus  L.) when administered for acute oral toxicity showing nonmammalian toxicity of the oil. GC-MS analysis of the oil found DL-Limonene to be major component.     

Aflatoxin Inactivation Using Aqueous Extract of Ajowan (Trachyspermum ammi) Seeds

ABSTRACT: Aqueous extract of ajowan seeds was found to contain an aflatoxin inactivation factor (IF). Thin layer chromatography analysis of the toxins after treatment with IF showed relative reduction of aflatoxin G₁ > G₂ > B₁ > B₂. Quantification of toxin using a fluorotoxin meter as well as the Enzyme Linked Immuno s orb ent Assay (ELISA) confirmed these findings. An approximate 80% reduction in total aflatoxin content over the controls was observed. This observed phenomenon of reduction in total toxin was referred to as toxin inactivation. Temperature was found to influence the rate of toxin inactivation. At 45 °C, it was found to be rapid during the initial 5 h and slowed later. The IF was found to retain considerable activity even after boiling and autoclaving, indicating partial heat stability. The activity was lost below pH 4.0. Above pH 4.0, it increased gradually, reaching the maximum at pH 10.0. IF was found to be stable to gamma irradiation. Toxin decontamination in spiked corn samples could be achieved using IF. This study emphasizes the potential of ajowan IF in aflatoxin removal from contaminated food commodities. However, the biological toxicity, if any, of the IF inactivated aflatoxins needs to be confirmed, and the work in this direction is in progress.     

Aflatoxins in imported edible nuts: some data 1982–84

Results of 188 analyses for aflatoxin in edible nuts imported into the U.K. during 1982–84 are presented. Most samples (140/188, 74%) had aflatoxin B₁, content ≤ 5 μg/kg. Brazilian peanuts may be identified as consistently unreliable as regards aflatoxin contamination.     

Fate of Aflatoxin M1 during Manufacture and Storage of Feta Cheese

ABSTRACT:  The effect of feta cheese manufacture on aflatoxin M₁ (AFM₁) content was studied using an enzyme immunoassay technique. Feta cheese was made from milk spiked with 1 and 2 μg AFM₁ per kilogram milk. Pasteurization at 63 °C for 30 min caused <10% destruction of AFM₁. During cheese making, the remaining AFM₁ in milk was partitioned between curd and whey with two-thirds retained in the curd and one-third going into the whey. Cheeses were then stored for 2 mo in 8%, 10%, and 12% brine solutions at 6 and 18 °C. There was a 22% to 27% reduction of AFM₁ during the first 10 d of storage, with slightly more loss as salt concentration increased and when the cheese was stored at 18 °C. Further storage caused only slight decrease in AFM₁ and after 30 d of brining there was no difference in AFM₁ content of the cheese based upon salt concentration of the brine. At 18 °C, no further losses of AFM₁ occurred after 30 d, and at 6 °C, there was continued slight decrease in AFM₁ levels until 50 d. After 60 d of brining, there was a total loss of 25% and 29% of the AFM₁ originally present for cheese brined at 6 and 18 °C, respectively. Thus, the combination of pasteurization, conversion of milk into feta cheese, and at least 50 d storage of cheese in brine caused a total loss of about 50% of the AFM₁ originally present in the raw milk.     

Efficacy of extract and essential oil of Lantana indica Roxb. against food contaminating moulds and aflatoxin B1 production

The study investigates the antifungal and antiaflatoxigenic efficacy of Lantana indica against Aspergillus flavus , a key storage fungus. The leaf essential oil of L. indica was found more active than leaf extracts. The oil absolutely inhibited the growth of A. flavus at 1.5 mg mL⁻¹ while ethanolic and chloroform extracts of leaf show MIC at 7.5 and 10.0 mg mL⁻¹ concentrations respectively. The oil also showed pronounced antiaflatoxigenic efficacy and completely inhibited the aflatoxin B₁ production at 0.75 mg mL⁻¹. The ethanolic and chloroformic extracts inhibited the aflatoxin B₁ production at 5.0 and 7.5 mg mL⁻¹, respectively while other extracts exhibited poor efficacy. The L. indica essential oil exhibited broad fungitoxic spectrum against twelve different storage moulds. The present findings may recommend the L. indica essential oil and its bioactive leaf extracts as natural preservative would of immense significance in view of the environmental and toxicological implications by indiscriminate use of synthetic pesticides .     

SYNERGISTIC EFFECT OF VITAMIN B1 ON SANITIZER AND DISINFECTANT TREATMENTS FOR REDUCTION OF BACILLUS CEREUS IN RICE

The synergistic bactericidal effects of vitamin B₁ (thiamine dilauryl sulfate) and the efficacy of commercial sanitizers for minimization of Bacillus cereus contamination in cooked rice were investigated. Sanitizer-treated rice exhibited a greater reduction than water-treated rice, while sanitizer-treated rice with Vitamin B₁ produced an even greater reduction. The treatments for B. cereus in rice included (1) 100 ppm hydrogen peroxide with 500 ppm vitamin B₁; (2) 200 ppm hydrogen peroxide with 100 ppm vitamin B₁; (3) 400 ppm hydrogen peroxide; (4) 50 ppm chlorine with 500 ppm vitamin B₁; (5) 60 ppm chlorine with 300 ppm vitamin B₁; (6) 70 ppm chlorine with 100 ppm vitamin B₁; (7) 80 ppm chlorine; and (8) 100,000 ppm ethanol with 500 vitamin B_1. All treatments completely eliminated B. cereus in rice. The sensory properties of all sanitizer-treated cooked rice did not differ significantly from the same properties for water-treated cooked rice.

PRACTICAL APPLICATIONS

The prevalence of Bacillus cereus in rice and rice products has been documented and control of the growth of B. cereus in rice is an important consideration. The results obtained from this study can be of use to rice producers in the manufacture of safe products. Although chemical disinfectants can be used to reduce the amount of B. cereus in rice, vitamin B₁ can also be used as an effective additive that reduces the amount of disinfectant use via a synergistic antimicrobial effect. The increasing use of chemical disinfectants for safety in the food industry can be reversed using our method.