Value-added processing of peanut meal: aflatoxin sequestration during protein extraction

Detoxification of Aflatoxin B1 by magnetic graphene composite adsorbents from contaminated oils

Safety concerns pertaining towards fungal occurrence in oil commodities have been a significant threat to human health. In this research, magnetic composite adsorbents were fabricated for the removal of aflatoxin B₁ (AFB₁) from contaminated oils. To this goal, graphene oxides (GO) were synthesized using Hummer's method, and graphenes (rGO) were obtained by the reduction of GO by sodium borohydride. Thereafter, magnetic graphene oxides (MGO) and magnetic graphenes (MrGO) were prepared by coprecipitation of iron oxides on GO and rGO nanosheets, respectively. The as-prepared MGO and MrGO were characterized by SEM, TEM, FT-IR, XRD, VSM, and nitrogen adsorption-desorption techniques. Results showed that MGO had two-dimensional layered nanostructure with many wrinkles on its surface, and the Fe₃O₄ nanoparticles were essentially encapsulated onto the composite. The adsorption behaviors for the composite adsorbents especially for the removal of AFB₁ from contaminated oils were systematically explored by varying adsorbent dosage, contact time, adsorption temperature and initial AFB₁ concentration. The MGO adsorbent could have great potential in the application of AFB₁ removal from contaminated oils, with the merits of facile magnetic separation and high removal efficiency. However, the removal process also causes a loss of the triglyceride, pigment, and beneficial micronutrients in the oil feedstocks.

Common African cooking processes do not affect the aflatoxin binding efficacy of refined calcium montmorillonite clay

Aflatoxins are common contaminants of staple crops, such as corn and groundnuts, and a significant cause of concern for food safety and public health in developing countries. Aflatoxin B1 (AFB1) has been implicated in the etiology of acute and chronic disease in humans and animals, including growth stunting, liver cancer and death. Cost effective and culturally acceptable intervention strategies for the reduction of dietary AFB1 exposure are of critical need in populations at high risk for aflatoxicosis. Fermented gruels consisting of cornmeal are a common source for such exposure and are consumed by both children and adults in many countries with a history of frequent, high-level aflatoxin exposure. One proposed method to reduce aflatoxins in the diet is to include a selective enterosorbent, Uniform Particle Size NovaSil (UPSN), as a food additive in contaminated foods. For UPSN to be effective in this capacity, it must be stable in complex, acidic mixtures that are often exposed to heat during the process of fermented gruel preparation. Therefore, the objective of the present study was to test the ability of UPSN to sorb aflatoxin while common cooking conditions were applied. The influence of fermentation, heat treatment, acidity, and processing time were investigated with and without UPSN. Analyses were performed using the field-practical Vicam assay with HPLC verification of trends. Our findings demonstrated that UPSN significantly reduced aflatoxin levels (47-100%) in cornmeal, regardless of processing conditions. Upon comparison of each element tested, time appeared to be the primary factor influencing UPSN efficacy. The greatest decreases in AFB1 were reported in samples allowed to incubate (with or without fermentation) for 72 hrs. This data suggests that addition of UPSN to staple corn ingredients likely to contain aflatoxins would be a sustainable approach to reduce exposure.

Evaluation of the effect of mycotoxin binders in animal feed on the analytical performance of standardised methods for the determination of mycotoxins in feed

Recently, the use of substances that can suppress or reduce absorption, promote the excretion of mycotoxins or modify their mode of action in feed, so-called mycotoxin binders, has been officially allowed in the European Union as technological feed additives. The influence of the addition of mycotoxin binders to animal feed on the analytical performance of the official methods for the determination of mycotoxins was studied and the results are presented. Where possible standardised methods for analysis were applied. Samples of 20 commercial mycotoxin binders were collected from various companies. The following mycotoxins were included in the study: aflatoxin B₁, deoxynivalenol, zearalenone, ochratoxin A, fumonisins B₁ and B₂, T-2 and HT-2 toxins. A binder (or binders combined in a group) was mixed with feed material containing the mycotoxin, and the feed material was analysed. For data evaluation, the mean values were compared by Student's t-test (an independent two-sample t-test with unequal sample sizes and equal variance). The repeatability standard deviation of each method was used as an estimate of method variability. No significant differences (p = 0.05) in mycotoxin levels between binder-free material and the material containing different binders were found. Further, the possible effects of binder addition in combination with processing (pelletising) on the amount of aflatoxin B₁ determined in feed were studied. Three commercial mycotoxin binders containing hydrated sodium calcium aluminosilicate (HSCAS) as the main component were used in these experiments. Feed samples with and without mycotoxin binders were pelletised with and without steam treatment. After pelletising, materials were analysed for AFB₁. Only the combination pelletising and a mixture of binders added at a total level of 1.2% had a significant effect (41% reduction) on the amount of AFB₁ determined.

Isolation and characterization of an oxygen radical absorbance activity peptide from defatted peanut meal hydrolysate and its antioxidant properties

Defatted peanut meal hydrolysate (DPMH) was purified using ultrafiltration, gel filtration chromatography, and high-performance liquid chromatography. A tripeptide with strong oxygen radical absorbance capacity (ORAC) was isolated and identified as Tyr-Gly-Ser by ESI-MS/MS. It was then synthesized to measure its antioxidant properties in different systems. The ORAC value of Tyr-Gly-Ser was 3-fold higher than that of glutathione (GSH), and it displayed a stronger protective effect on linoleic acid peroxidation and H(2)O(2)-induced oxidative injury in rat pheochromocytoma line PC12 cells than GSH (p < 0.05). However, Tyr-Gly-Ser showed negligible DPPH radical scavenging activity, reducing power, and no metal chelating ability. The results suggested that Tyr-Gly-Ser displayed antioxidant activity via the hydrogen atom transfer mechanism, and the Tyr at the N-terminal was the hydrogen donor. The ORAC assay was recommended as a reliable and effective method to measure the antioxidant activity in the course of antioxidant peptide isolation.

Substances for reduction of the contamination of feed by mycotoxins: a review

The global occurrence of mycotoxins is considered to be a major risk factor for human and animal health. Contamination of different agricultural commodities with mycotoxins still occurs despite the most strenuous prevention efforts. As a result, mycotoxin contaminated feed can cause serious disorders and diseases in farm animals. A number of approaches, such as physical and chemical detoxification procedures, have been used to counteract mycotoxins. However, only a few of them have practical application. A recent and promising approach to protect animals against the harmful effects of mycotoxin contaminated feed is the use of substances for reduction of the contamination of feed by mycotoxins. These substances, so-called mycotoxin binders (MB), are added to the diet in order to reduce the absorption of mycotoxins from the gastrointestinal tract and their distribution to blood and target organs, thus preventing or reducing mycotoxicosis in livestock. Recently, the use of such substances as technological feed additives has been officially allowed in the European Union. The efficacy of MB appears to depend on the properties of both the binder and the mycotoxin. Depending on their mode of action, these feed additives may act either by binding mycotoxins to their surface (adsorption), or by degrading or transforming them into less toxic metabolites (biotransformation). Biotransformation can be achieved by mycotoxin-degrading enzymes or by microorganisms producing such enzymes. Various inorganic adsorbents, such as hydrated sodium calcium aluminosilicate, zeolites, bentonites, clays, and activated carbons, have been tested and used as MB. An interesting alternative to inorganic adsorbents for the detoxification of mycotoxins is the use of organic binders, such as yeast cell wall components, synthetic polymers (cholestyramine, polyvinylpyrrolidone), humic substances and dietary fibres. This paper gives an overview of the current knowledge and situation in the field of MB. The most important types of MB, mechanism of their action, and their application as a part of general strategy to counteract mycotoxins are described in this review. Recent advances in the use and study of MB, as well as data of their in vitro and in vivo effectiveness are given. Problems, potential, current trends and perspectives associated with the use of MB are discussed as well in the review.

Aflatoxin toxicity reduction in feed by enhanced binding to surface-modified clay additives

Animal feeding studies have demonstrated that clay additives, such as bentonites, can bind aflatoxins in ingested feed and reduce or eliminate the toxicity. Bentonite deposits are found throughout the world and mostly consist of expandable smectite minerals, such as montmorillonite. The surfaces of smectite minerals can be treated with organic compounds to create surface-modified clays that more readily bind some contaminants than the untreated clay. Montmorillonites treated with organic cations, such as hexadecyltrimethylammonium (HDTMA) and phenyltrimethylammonium (PTMA), more effectively remove organic contaminants, such as benzene and toluene, from water than untreated clay. Similarly, montmorillonite treated with PTMA (K_d = 24,100) retained more aflatoxin B1 (AfB1) from aqueous corn flour than untreated montmorillonite (K_d = 944). Feed additives that reduced aflatoxin toxicity in animal feeding studies adsorbed more AfB1 from aqueous corn flour than feed additives that were less effective. The organic cations HDTMA and PTMA are considered toxic and would not be suitable for clay additives used in feed or food, but other non-toxic or nutrient compounds can be used to prepare surface-modified clays. Montmorillonite (SWy) treated with choline (K_d = 13,800) and carnitine (K_d = 3960) adsorbed much more AfB1 from aqueous corn flour than the untreated clay (K_d = 944). A choline-treated clay prepared from a reduced-charge, high-charge montmorillonite (K_d = 20,100) adsorbed more AfB1 than the choline-treated high-charge montmorillonite (K_d = 1340) or the untreated montmorillonite (K_d = 293). Surface-modified clay additives prepared using low-charge smectites and nutrient or non-toxic organic compounds might be used to more effectively bind aflatoxins in contaminated feed or food and prevent toxicity.