Synthesis of carbon quantum dots-doped dummy molecularly imprinted polymer monolithic column for selective enrichment and analysis of aflatoxin B1 in peanut.

In this study, a novel method was proposed to sensitively determine aflatoxin B1 (AFB1) in peanut sample by using a carbon quantum dots-coated dummy molecularly imprinted polymer (CDs-DMIP) monolithic column for pretreatment coupled with high performance liquid chromatography-fluorescence detection (HPLC-FLD). The CDs-DMIP monolithic column was prepared by in-situ polymerization in a water bath using 5,7-dimethoxycoumarin as dummy template molecule. The CDs-DMIP monolithic column was applied to determine AFB1 by HPLC-FLD. Satisfactory linearity was obtained over 0.5-2000ngmL-1, with a high correlation coefficient of 0.9999. The recoveries of AFB1 in peanut sample ranged from 79.5% to 91.2%, and the intraday and interday relative standard deviation ranged from 1.2% to 4.9%. Limit of detection (S/N=3) and limit of quantitation (S/N=10) were 0.118ngmL-1 and 0.393ngmL-1, respectively. Under the optimized conditions, the enrichment factor was over 71-fold. AFB1 in peanut sample and even some other samples could be sensitively determined by CDs-DMIP-HPLC-FLD method.

Aflatoxin testing in peanuts: a proficiency assessment scheme for Chinese analytic laboratories.

This national assessment program was established by the China National Accreditation Service for Conformity Assessment (CNAS) to evaluate the aflatoxin-testing proficiency of a cross-section of Chinese laboratories. The Shan Dong Inspection and Quarantine Bureau of China conducted the assessment according to ISO 13528:2005 (E) and the International Harmonized Protocol for Proficiency Testing. The 77 laboratories that participated in the study had either been previously accredited by CNAS or were candidates for CNAS accreditation. The analytic samples for this testing scheme were prepared from naturally contaminated peanuts and diluted to approximately 10 microg/kg for aflatoxin B1 and 18 microg/kg for total aflatoxins. The Ss/sigma p test (with a required result of Ss < or = 0.3 sigma p) was used to evaluate the homogeneity of the test samples; sample stability was confirmed with a t-test. The performance of each laboratory was designated by a z-score that was calculated using robust statistics. The robust mean of the participants' results in this study was nearly coincident with the median. A modified Horwitz equation was used to determine the standard deviation. The study compared analytic results obtained by 5 different methods: high-performance liquid chromatography (LC), enzyme-linked immunosorbent assay, thin-layer chromatography, fluorometry, and LC with tandem mass spectrometry. A satisfactory performance rating required z-scores between -2 and +2 for the target analytes. Of the 73 laboratories that reported results for aflatoxin B1, 66 (90.4%) performed satisfactorily. Of 32 laboratories that reported total aflatoxins (B1 + B2 + G1 + G2), 30 (93.8%) performed satisfactorily. Laboratories whose performance ratings were questionable or unsatisfactory were re-evaluated in a second interlaboratory comparison.

The importance of dietary control in the development of a peanut allergy model in Brown Norway rats.

This report describes the further development of a peanut allergy model in Brown Norway (BN) rats and in particular the importance of allergen-free breeding of the laboratory animals for the allergen to be used. For this purpose BN rats were bred for 3 generations on soy- and peanut-free feed since it is known that the legumes peanut and soy are cross-reactive. In addition, the effect of cholera toxin (CT), an oral adjuvant often used to increase the sensitivity of food allergy models, was investigated in the BN rat model. BN rats that were bred on both soy- and peanut-free feed could be sensitized orally to peanut (all exposed rats developed peanut-specific IgE, IgG2a and IgG1) and the adjuvant CT could only enhance this sensitization to a limited extent. We also found different protein recognition patterns against purified peanut allergens (Ara h1, Ara h2 and Ara h3) between intraperitoneally (i.p.) and orally sensitized BN rats. Orally sensitized rats recognized all tested allergens whereas i.p. sensitized rats only recognized Ara h1 and Ara h2. Our conclusion is that a model for food allergy should preferably be (A) oral and (B) if possible without the use of adjuvantia. Our model in BN rats unites these preferred characteristics. In addition, we show the importance of dietary control when conducting oral sensitization studies. Special attention must be paid to unscheduled dietary pre-exposure of the animals to the protein under investigation to obtain optimal oral sensitization.

Does severity of low-dose, double-blind, placebo-controlled food challenges reflect severity of allergic reactions to peanut in the community?

BACKGROUND: The severity of allergic reactions to food appears to be affected by many interacting factors. It is uncertain whether challenge-based reactions reflect the severity of past reactions or can predict future risk. OBJECTIVE: To explore the relationship of a subject's clinical history of past reactions to the severity of reaction elicited by a low-dose, double-blind, placebo-controlled food challenge (DBPCFC) with peanut. METHOD: Cross-sectional questionnaire assessment of community-based allergic reactions and low-dose DBPCFC in self-selected peanut-allergic subjects. Reaction severity was assessed using a novel scoring system, taking account of the dose of allergen ingested. RESULTS: Forty subjects (15 males, 23 children, 23 asthmatics by history) were studied. Only the most recent community reaction predicted the severity of reaction in the DBPCFC, but even this association was weak (r=0.37, P=0.03). Peanut-specific IgE (PsIgE) and skin prick test (SPT) weal size were not associated with community score but PsIgE level correlated well with the challenge score (r=0.6, P=0.001). Asthma did not affect the eliciting dose or challenge score directly but the association of PsIgE and challenge score was stronger in those without asthma (r=0.72, P=0.001) than in those with asthma (r=0.48, P=0.02). CONCLUSIONS: The scoring system developed appears to improve the sensitivity of assessment of reactions induced by DBPCFC. This is the first prospective study showing an association between PsIgE levels and clinical reactivity in DBPCFC, an effect that is more pronounced in non-asthmatics. This finding has important implications for the clinical care of subjects with food allergy. There is a poor correlation between the severity of reported reactions in the community and the severity of reaction elicited during low-dose DBPCFC with peanut.

Post harvest control of aflatoxin production on in-shell moist peanuts by sodium ortho-phenylphenate. II. Harvester tests

O objetivo deste trabalho foi o de otimizar o sistema de pulverizaçäo, em campo, da soluçäo de ortofenilfenato de sódio (OFS) sobre amendoim em casca, para verificar a eficiência desta substância no controle da produçäo de aflatoxinas. Em trabalho realizado anteriormente por Fonseca et al. (6) verificou-se que a pulverizaçäo sob condiçöes de campo foi deficiente uma vez que a cobertura completa da vagem, com a soluçäo de OFS näo foi conseguida, indicando assim a necessidade de otimizaçäo desta operaçäo. Deste modo, na safra das águas de 1988, a pulverizaçäo foi realizada na própria colhedora mecânica onde o sistema de ulverizaçäo foi adaptado. A concentraçäo da soluçäo de OFS utilizada foi de 0,5 por cento. Nesta safra, a despeito da melhor cobertura das vagens com a soluçäo ocorreu o acúmulo de vagens na bica de saída da colhedora, por ocasiäo da troca da sacaria já cheia pela vazia, o que prejudicou a pulverizaçäo, dificultando a cobertura de todas as vagens com a soluçäo. Observou-se que o teor inicial de aflatoxinas aumentou durante o período de armazenamento, tanto nos lotes tratados como nos lotes de controle. A alta contaminaçäo com aflatoxinas pode ter ocorrido por näo se ter obtido ainda uma pulverizaçäo perfeita de todas as vagens e/ou devido à concentraçäo insuficiente da soluçäo de OFS para o controle da produçäo da toxina

Aflatoxin removal from peanut meals with commercial aqueous ethyl alcohol

A remoçäo de aflatoxinas (AF), com álcool etílico aquoso comercial (carburante), de farelo de amendoim contaminado em vaso extrator de escala real foi testada em 2 experimentos (testes 1 e 2) realizados numa indústria de extraçäo de óleo no Estado de Säo Paulo, Brasil. No teste 1, álcool 90oGL (diluído a partir do 96oGL) aquecido a 75oC, foi utilizado para fazer 3 extraçöes de uma hora cada (sempre com álcool novo), tendo sido retiradas amostras após cada extraçäo, para análise de AF e de proteína. No teste 2, álcool 96oGL foi utilizado em 4 extraçöes de uma hora, nas mesmas condiçöes porém, sem parar o processo para retirada de amostras intermediárias mas, introduzindo um período de 30 minutos de maceraçäo entre as extraçöes. Neste experimento, pedaços de cerca de 2 cm de espessura e farelo grosseiramente moído, foram utilizados para testar a influência do tamanho da partícula na eficiência da extraçäo de AF pelo solvente. Vinte amostras (10 de cada tipo) foram retiradas no fim do processo para anólises de AF. Os resultados mostraram que a extraçäo de AF com álcool etílico aquoso carburante, em escala real, é dependente do tempo e tecnicamente possível. Alcool 96oGL removeu, em média 87,3 por cento do farelo em pedaços e 95,3 por cento do moído, após 4 extraçöes de uma hora. Houve uma melhor extraçäo na parte inferior do que na parte superior do vaso. O conteúdo de proteína foi avaliado antes e durante o TESTE 1 e mostrou um pequeno aumento de 60,19 por cento para 63,79 por cento

Survey of selected mycotoxins in food.

The contamination of a variety of foods with the mycotoxins aflatoxins B1, B2, G1, M1, ochratoxin A, patulin, and byssochlamic acid was investigated. With the developed methods, the identification was made possible by in situ fluorescence spectral analysis with a far reaching exclusion of substances which simulate sycotoxins. Aflatoxin B1 was detected in 2 samples of 105 spontaneously moulded food specimens and only in 1 of a group of 198 food samples that were obviously not moulded. Aflatoxin M1 was identified in 4 of 60 samples of the so-called wintermilk. Investigated dairy products did not contain aflatoxin M1. Ochratoxin A could be detected twice in 49 spontaneously moulded corn samples, aflatoxin, however, was not found. Further investigations of 50 samples of moulded food revealed ochratoxin A in 2 samples of raw coffee. Food samples obviously not moulded did not contain ochratoxin A. Patulin was detected in 19 of 110 samples of fruit and fruit products, especially in commercial apple juice, in rotten parts of apples, and in moulded fruit products. Byssochlamic acid was not detected in fruit juices or in fruit. The toxicological consequences of mycotoxins in food and possibilities to reduce mycotoxins are discussed.