Incidence of citrinin in red yeast rice and various commercial Monascus products in Taiwan from 2009 to 2012

Red yeast rice, produced by the fermentation of red yeast (Monascus purpureus) with white rice, has long been used in food colouring and meat preservation in Asia. Recently, powdered red yeast rice and its formulated products, used worldwide as dietary supplements, have the ability of reducing blood-lipid levels in humans. However, some Monascus strains could produce the mycotoxin citrinin as a secondary toxic metabolite so that commercial Monascus products are of a serious concern to the public now. The aim of this study was to obtain information about the occurrence of citrinin in red yeast rice and various commercial Monascus products in Taiwan from 2009 to 2012. A simple and rapid HPLC-fluorescence method was developed to detect citrinin in red yeast rice and Monascus products. The method's performance was acceptable in terms of recoveries, which ranged from 81.2% to 94.3% for citrinin-spiked samples at levels of 0.1, 1 and 10 mg/kg, and the relative standard deviation ranged from 2.5% to 5.7%. The limit of quantification of 0.05 mg/kg was achieved. The survey results showed that among total 302 samples, the incidences of citrinin contamination were 69.0%, 35.1% and 5.7% for red yeast rice (raw material), dietary supplements and red yeast rice processed products, respectively. The mean contamination levels were 13.3, 1.2 and 0.1 mg/kg for red yeast rice (raw material), dietary supplements and red yeast rice processed products, respectively. Such high citrinin contamination rate and level is worthy of note.     

Effect of milling on the content of deoxynivalenol,nivalenol, and zearalenone in Japanese wheat

The effect of milling on the content of zearalenone (ZEA), a Fusarium mycotoxin, in a semi-processed wheat product was investigated and compared with that of deoxynivalenol (DON) or nivalenol (NIV). Two grain samples of Japanese soft wheat varieties, norin 61 and chikugoizumi, were milled to obtain three breaking flours (1B, 2B, 3B), three middling flours (1M, 2M, 3M) and two outer-layer fractions (bran and shorts). Patent flour for human consumption was made from 1B, 1M, 2B and 2M flours, while low-grade flour for animal feed was made from 3B to 3M flours. The contents of ZEA in patent flour, low-grade flour, bran and shorts were analyzed by an in-house validated analytical method using solvent extraction, multifunctional cartridge cleanup, and HPLC-fluorescence detection. A greater than 50% reduction in ZEA was observed in the patent flour of both samples, while 4–74% reduction in DON and NIV in the patent flour of the same two samples was observed. The results of this study revealed that the transfer ratios of ZEA had different features from those of deoxynivalenol and nivalenol.     

Detoxification of zearalenone by Lactobacillus pentosus strains

Zearalenone (ZEA) contamination in food samples plays a critical role in food safety, since it causes serious health problems. Usage of microorganisms, such as lactic acid bacteria (LAB), is a promising new approach for detoxification. Eight Lactobacillus pentosus strains were evaluated for their ability to remove ZEA from a sodium acetate buffer solution with initial ZEA concentrations of 5.51–74.70 μg/mL. The adsorption capacity increased with increasing ZEA concentrations. The strain JM0812 showed the highest adsorption capability, at 83.17%, in solution containing 74.70 μg/mL ZEA, followed by UM054 (82.78%) and UM055 (81.69%), respectively. Three adsorption isotherms were applied to predict the removal efficiency of ZEA and the Freundlich isotherm appeared to have the best-fit for ZEA sorption onto bacterial cells. Our results indicate that Lb. pentosus strains are novel promising strains to reduce mycotoxin contamination in food products.     

基于核壳型量子点的生物传感器在真菌毒素检测中的应用进展

真菌毒素是真菌产生的有毒次生代谢物,其广泛存在于被污染的食物中,其中黄曲霉毒素已被认定为天然存在的剧毒致癌物。鉴于真菌毒素污染给人类健康与安全带来的风险与危害,发展低成本、快速、高效的检测方法以确保食品安全,具有重要的现实意义。已有大量研究者构建了基于单一量子点或其他荧光材料为荧光探针的生物传感器用于检测真菌毒素,并且从材料、检测方法和生物传感器等角度进行了详细的检测。然而,目前并没有系统地阐述核壳量子点构建的生物传感器在真菌毒素中的应用报道,因此,本文主要从基于核壳量子点构建的免疫电化学发光传感器、适配体免疫电化学发光传感器、免疫荧光传感器、适配体荧光传感器和试纸条传感器在真菌毒素中的应用进展进行阐述,首次系统地阐述了核壳型量子点生物传感器在真菌毒素分析检测中的研究进展,以期为同类研究提供一定的理论依据。     

2018年中国4省脱粒小麦中9种真菌毒素污染情况调查

目的 调查2018年湖北、安徽、江苏和河北4省脱粒小麦中5种镰刀菌毒素和4种黄曲霉毒素（aflatoxins,AFs）的污染情况。方法 从4省采集2018年5~6月收获的脱粒小麦371份,经乙腈-水（84:16,V:V）提取、Mycosep 226多功能净化柱净化后,采用高效液相色谱串联质谱同时测定样品中脱氧雪腐镰刀菌烯醇（deoxynivalenol,DON）、3-乙酰基-DON（3-acetyl-DON,3-Ac-DON）、15-乙酰基-DON（15-acetyl-DON,15-Ac-DON）、雪腐镰刀菌烯醇（nivalenol,NIV）、玉米赤霉烯酮（zearalenone,ZEN）和4种AF, 共9种毒素的含量。 结果 4省脱粒小麦受多种镰刀菌毒素, 尤其是DON的污染较为严重,而AF污染相对较轻。DON的检出率最高,为90.3%,阳性样品中DON平均污染水平为2706.3 μg/kg,45.3%样品DON的含量超过国家限量标准1000 μg/kg;4种AF的检出率和平均污染水平均较低,其中AFB1和AFB2的检出率最高,均为3.2%,2份样品AFB1含量超过国家限量标准5 μg/kg,仅1份样品检出AFG2,所有样品均未检出AFG1。从地区来看,湖北省脱粒小麦中各毒素污染最严重,尤其是DON、其检出率和平均污染水平分别为100%和6314.9 μg/kg;江苏省样品中ZEN的平均污染水平为1971.2 μg/kg,远高于其它省份。Spearman相关性分析表明,5种镰刀菌毒素的污染具有显著相关性,DON与已检出的3种AF及3种AF间的污染相关性均较弱或无显著相关性。 结论 4省脱粒小麦受5种镰刀菌毒素的污染较为严重且具有显著相关性。污染程度为湖北>安徽>江苏>河北。因此,有必要对4省脱粒小麦中多种毒素的协同污染情况进行持续监测。     

In vitro model to assess the adsorption of oral veterinary drugs to mycotoxin binders in a feed- and aflatoxin B1-containing buffered matrix

Mycotoxin binders are feed additives which are mixed in the feed to adsorb mycotoxins and thereby reducing their toxic effects on animals. Interactions with orally administered veterinary medicinal products, such as antimicrobials or coccidiostats, have been reported previously. This paper describes an in vitro model to screen the interaction between mycotoxin binders and veterinary drugs with respect to the non-specific binding of drugs. It is designed as a static setup using a single concentration of drug and binder in a feed-containing or a feed-plus-mycotoxin-containing matrix, buffered at different pH values. The model was applied to two frequently used antimicrobials in veterinary medicine, doxycycline (DOX) and tylosin (TYL), one major mycotoxin, aflatoxin B1 (AFB1), and four mycotoxin binders. Proportions of feed, DOX or TYL, AFB1, and binder are equivalent to the in vivo situation for broiler chickens, while pH and volume of the buffer are representative of the gastrointestinal tract of chickens. A substantial binding of DOX (~ 88%) and TYL (~ 66%) to the feed-matrix was observed. For the mycotoxin binders, similar results were obtained for DOX and TYL; more specifically up to an inclusion rate of 20 g binder/kg feed, no significant binding was demonstrated, determined as the free concentration of DOX and TYL. A single exception was noticed for TYL and one specific bentonite-based mycotoxin binder, for which no significant interaction could be demonstrated up to 10 g binder/kg but there was an effect at 20 g/kg. In all cases, there was no competition between the tested drugs DOX or TYL and the mycotoxin AFB1 for binding to the bentonite-based mycotoxin binder.     

Removal of aflatoxin B1 by roasting with lemon juice and/or citric acid in contaminated pistachio nuts

Nowadays, aflatoxin B₁ (AFB₁) could be considered as one of the most hazardous mycotoxins for humans, and nuts comprise one of the major responsible food categories for human exposure to this mycotoxin. Thus, complete elimination of AFB₁ or reduction of its content in nut foods, such as pistachio attracted lots of attentions. In the current study, the efficacy of roasting process by incorporation of lemon juice and/or citric acid on the reduction of AFB₁ in contaminated pistachio nuts (AFB₁ at two levels of 268 and 383 ng/g) was investigated. Significant degradation of AFB₁ (up 93.1% for AFB₁) was recorded by applied treatment protocols. Although roasting of 50 g pistachio nuts with 30 ml water, 30 ml lemon juice and 6 g of citric acid at 120 °C for 1 h resulted to a significant degradation (93.1 ± 8.2%) of AFB₁, this treatment altered the desired physical properties. Roasting with 30 ml water, 15 ml lemon juice and 2.25 g of citric acid at 120 °C for 1 h reduced the level of AFB₁ in 49.2 ± 3.5% of the initial level without a noticeable change in desired appearance of pistachios. Hence, a synergistic effect between heating and lemon juice/citric acid in order to AFB₁ degradation was observed. It could be concluded that roasting process with lemon juice and citric acid could be applied as a useful and safe degradation method of AFB₁ in naturally contaminated pistachio nuts.     

Isolation and characterization of Bacillus amyloliquefaciens ZDS-1: Exploring the degradation of Zearalenone by Bacillus spp.

Zearalenone (ZEN) is a mycotoxin produced mainly by various Fusarium species which occur naturally in many crops worldwide. ZEN causes reproductive disorders and hyperestrogenic syndromes in animals and humans. This study aimed to isolate ZEN-degrading bacteria to develop strategies for detoxifying ZEN contamination in cereal crops. We screened approximately 1000 colonies for degrading ability and found four strains were capable of degrading ZEN. We selected one strain ZDS-1 for further study because it showed the high ZEN-degrading ability. On the basis of morphological, physiological and phylogenetic analysis of its 16SrRNA, gyrA gene sequences, strain ZDS-1 was identified as Bacillus amyloliquefaciens. The optimal conditions for the biodegradation of ZEN by ZDS-1 were temperature; 30 °C, pH; 6.0–7.0, and cell concentration; 5 × 10⁸ cfu/mL. ZDS-1 could degrade ZEN efficiently with the concentration from 1 mg/L to 100 mg/L. ZDS-1 not only could remove ZEN in the culture medium, but also could degrade ZEN in wheat. The ZEN removal by ZDS-1 was not due to binding or absorption, and during the process of ZEN degradation, no ZEN derivatives of ZEN were produced. These results suggested that Bacillus amyloliquefaciens ZDS-1 would be explored further for its ability to degrade ZEN in field trials.     

Quantification of the Alternaria mycotoxin tenuazonic acid in beer

Tenuazonic acid (TA) is a major water soluble Alternaria mycotoxin. In the present work, a method for the quantification of TA in beer by liquid chromatography–ion-trap multistage mass spectrometry after derivatization with 2,4-dinitrophenylhydrazine is described. The method is based on a rapid workup procedure and features a LOD of 2 μg/kg without preconcentration using 400 mg of sample. Validation was performed for a working range of 8–500 μg/kg.