对粮油食品中黄曲霉毒素B1测定方法的探讨

本文对国标规定的薄层荧光法和自选的EAB1—95型黄曲霉毒素测定仪法检验粮油食品中黄曲霉毒素B1的操作方法及其结果进行了探讨,从而得出后者比前者操作简便、省时、省力。     

酱油中黄曲霉毒素B1的测定意义及测定方法比较

黄曲霉毒素是一种真菌毒素，其存在严重影响农作物的产量及农产品的质量。酱油产品无论在原料上还是在工艺上都有感染黄曲霉毒素的可能性。食品质量安全市场准入制度也将黄曲霉毒素列为酱油产品的必检项目。本文阐述了黄曲霉毒素的测定意义，并将国标中两种测定方法进行比较，供同行参考。     

黄曲霉毒素B1检测方法的分析

黄曲霉毒素B1是一种致癌物质 ,许多国家已将其限量标准提高 ,黄曲霉毒素B1检测方法的检出限已因其毒性而提高 ,并已成为国际贸易中新的技术壁垒。文中介绍了黄曲霉毒素B1的几种常见检测方法 ,并对其特点及检出限进行了概括性的分析。     

黄曲霉毒素B1检测方法的研究分析

黄曲霉毒素B1是黄曲霉毒素中毒性最强、危害最大的一种。由于国内外限量标准的不统一,在出口食品中由于黄曲霉毒素不合格而被通报的食品占了相当大的比例。这也对我国检测黄曲霉毒素B1的技术提出了更高的要求,在众多检测方法中酶联免疫法也因其快速、方便等特点,逐渐被认可,成为了黄曲霉毒素B1检测工作初筛的工具。     

干红辣椒中黄曲霉毒素B1的判定

在遵循实验测定原理，不影响测定结果的前提下，对样品的前处理，提取的过程、测定的方式进行适当的改变和调整，并利用黄曲霉毒素B1的特性进行确证，从而对干红辣椒中的黄曲霉毒素B1进行定性，定量分析，效果明显，结果满意。     

酱油中黄曲霉毒素B_1的测定意义及测定方法比较

黄曲霉毒素是一种真菌毒素,其存在严重影响农作物的产量及农产品的质量。酱油产品无论在原料上还是在工艺上都有感染黄曲霉毒素的可能性。食品质量安全市场准入制度也将黄曲霉毒素列为酱油产品的必检项目。本文阐述了黄曲霉毒素的测定意义,并将国标中两种测定方法进行比较,供同行参考。     

粮油中黄曲霉毒素B1的监测

利用简单的仪器设备监测粮油中的黄曲霉毒素B1，此法直接、快速，利于推广普及。     

云南省十县市粮油食品黄曲霉毒素B1污染调查

黄曲霉毒素B1是一种强烈的致癌物质,自20世纪60年代初在英国发现以来,全世界有不少食用霉变食品引起人类中毒的报道。流行病学调查发现肝癌发病率在地区上的分布与当地粮油食品受黄曲霉毒素污染程度有密切关系,在污染严重的地区,肝癌发病率较高。我站在我省十个县市采集花生、花生油、玉米等样品137件进行黄曲霉毒素B1的检测结果如下。     

紫玉米中黄曲霉毒素B1和富马毒素B1的脱毒研究

为脱除紫玉米中富马毒素B1(FB1)和黄曲霉毒素B1(AFB1),分别采用紫外、超高压、微波和NaCl处理,利用高效液相色谱方法进行检测。结果表明：紫外和超高压处理对两种毒素含量无影响,微波处理12min能去除90%以上的毒素,而30%以上NaCl浸泡10min即可去除99%的毒素。结论：NaCl浸泡是一种简单经济的脱毒方法。     

OCCURRENCE OF AFLATOXINS IN VARIOUS NUTS COMMERCIALIZED IN TURKEY

Nuts are important agricultural commodities in Turkey as they are exported and largely consumed domestically. Two hundred and seventeen samples of hazelnuts, pistachio nuts and peanuts were randomly collected from public markets, bazaars, supermarkets and retail stores in several regions of Turkey and analyzed for the incidence of aflatoxin (B1, B2, G1, G2) contamination by high-performance liquid chromatography. The levels of aflatoxin B1 (AFB1) and the total aflatoxins in the majority of samples analyzed (87.09%) were so low that they were not quantifiable. Thirty-one samples (14.28%) were found to have low levels of aflatoxins, below the Turkish National regulatory limits of 5 µg/kg for AFB1 and 10 µg/kg for total aflatoxins. However, four samples (1.84%) showed a level of contamination that exceeded the maximum tolerated levels set in the Turkish regulations. The highest value of AFB1 was 36.81 µg/kg in pistachio nuts. This article reports the data of the first survey on the presence of aflatoxins in nuts sampled in three distinct regions of Turkey.

PRACTICAL APPLICATIONS

The formation of aflatoxins depends not only on the genetic potential of mold strains but also on environmental factors, especially during post-harvest transportation and storage. Although further national surveys must be performed on a regular base, the results of the present study indicate a reduced level of aflatoxin contamination of nut-based products compared to earlier observations. The results conclude that implementation of stricter quality control measures, technical assistance to private sector actors and regulatory initiatives to support employment of these strategies undertaken in recent years by the National Authorities have paid back.     

A MINI-COLUMN SCREENING TEST FOR AFLATOXINS IN SORGHUM MALT

The development of a mini-column screening test for aflatoxins in sorghum malt and the finally adopted method is described. The method is based on a silica cartridge clean-up of a chloroform extract of malt followed by detection by means of an alumina/Florisil mini-column. The method is rapid, economical, more sensitive than published methods and suitable for use by semi-skilled personnel. It was deliberately designed to maximise test readings, thereby obviating false negative findings. Validation trials indicated that the method had a detection limit of approximately 3 μg aflatoxin B_t/kg and was robust enough for routine use. The method is recommended for industrial use, provided that positive samples are confirmed by conventional analysis.     

INSTRUMENTAL DETERMINATION OF ELASTICITY OF MARSHMALLOW 1

Marshmallows of a national and supermarket brand were subjected to four successive compression-decompression cycles using a computer interfaced Universal testing machine and the total and recoverable work in each cycle determined. The two brands were significantly different. Differences were maintained irrespective of the deformation rate (10 and 20 mm.min^–1), the magnitude of imposed strain in the range of 15–40% and the time between the cycles (0, 30 and 60 s). It appears that the discriminatory power of the test decreases as the magnitude of the imposed strain increases.     

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.     

回归神经网络——分光光度法同时测定混合体系中多种维生素B

提出了一种将回归神经元网络与分光光度法相结合，同时测定吸收波峰重叠的维生素Ｂ类化合物（ＶＢ１，ＶＢ２，ＶＢ６，ＶＢ１２）含量的新方法，其相对误差均＜２％．     

DETERMINATION OF NON-STARCH POLYSACCHARIDES IN BARLEY BREEDING PROGRAMMES1

A technique is described for the selection of low extractable non-starch polysaccharide content in early generations of barley breeding programmes. An estimate of extractable β-glucan is obtained from the viscosity of an extract prepared by mashing barley at 50°C in an α-amylase-papain solution. The procedure is calibrated using solutions of known concentration of β-glucan precipitated from barley extract by ethanol.