臭氧降解玉米中黄曲霉毒素B1效果及降解动力学研究

玉米是我国重要的食品和饲料原料,当收获、加工和储藏等措施不当时,可能会造成黄曲霉毒素B1（aflatoxin B1,AFB1）污染玉米这一突出问题,AFB1已被国际癌症机构定为1级致癌物。尽管目前已建立了一些物理、化学和生物降解AFB1的方法,但高效、安全、经济的绿色降解方法仍很少。本研究以AFB1污染的玉米为试样,研究臭氧对玉米中AFB1的降解效果。结果表明：AFB1降解率随着臭氧质量浓度的增加和处理时间的延长而显著提高;当水分质量分数为20.37%的玉米经90 mg/L的臭氧处理40 min后,AFB1含量由77.6 μg/kg降低到21.42 μg/kg,降解率达72.4%。臭氧降解AFB1的动力学模拟结果表明,臭氧降解AFB1符合一级动力学模型。玉米中AFB1降解速率常数按以下次序递减：k90 mg/L＞k65 mg/L＞k40 mg/L。实验得到臭氧降解AFB1的动力学方程、反应速率常数、决定系数和半衰期,为最优地控制臭氧降解AFB1的反应条件奠定了理论和实践基础,也为臭氧降解AFB1污染玉米的应用提供了技术保障。     

玉米霉变及黄曲霉毒素的图像处理检测方法

为准确快速识别出仓储玉米是否包含霉变以及感染黄曲霉毒素的玉米颗粒,提出基于图像处理技术的定性、定量检测方法。基于感染霉菌的玉米颗粒表层会发生颜色褐变、发黑等特点,通过MATLAB对灰度图像二值化、区域填充、去干扰、连续膨胀等操作,统计出霉变颗粒数目;同时,基于感染黄曲霉毒素的玉米颗粒在365 nm紫外光照射下会发出独特的黄绿色荧光(bright greenish-yellow fluorescence,BGYF)特性,通过对彩色图像进行增强、形态滤波、彩图二值化、去除干扰、图像连续膨胀等,统计出感染黄曲霉毒素玉米颗粒的数量。用4组共112粒玉米对所提方法进行检测验证的结果表明,霉变玉米颗粒的正确检出率达93.75%以上,感染黄曲霉毒素玉米颗粒的正确检出率亦可达87.5%以上,能够达到区分检测的要求。     

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。     

Comparison of two Analytical Methods (ELISA and LC-MS/MS) for Determination of Aflatoxin B1 in Corn and Aflatoxin M1 in Milk

The aim of this paper is to assess the closeness of agreement between results of ELISA and LC-MS/MS methods for determination of aflatoxin B₁ in corn and aflatoxin M₁ in milk. Samples of corn (n=100) and milk (n=250) were simultaneously analyzed using ELISA and LC-MS/MS methods, after the severe drought that affected Serbia in summer 2012 resulting in occurrence of aflatoxin B1 in corn and aflatoxin M₁ in milk. Regression analysis showed higher level of agreement between aflatoxin B₁ samples (R²=0.994), compared to aflatoxin M₁ samples (R²=0.920). However, both techniques were satisfactory in meeting the requirements for official control purposes.     

Mutagenicity and Acute Toxicity Evaluation of 2-Dodecylcyclobutanone

ABSTRACT: Mutagenicity and acute toxicity of 2-dodecylcyclobutanone (2-DCB), a unique radiolytic product, were evaluated. Mutagenicity was evaluated by the Ames assay using 5 standard Salmonella tester strains with S9 enzyme activation and 5 concentrations of 2-DCB. Sodium azide (NaN₃), fenaminosulf, and2-aminofluorene (2-AF) served as positive controls. The Ames assay showed no difference between the 5 concentrations of 2-DCB and the controls, including samples incubated with S9. The results indicate that 2-DCB does not produce point or frameshift mutations in Salmonella and is not activated by S9. Acute toxicity of 2-DCB was evaluated by the Microtox acute toxicity system and compared with cyclohexanone and 2-nonenal (both GRAS additives). The effective concentrations that caused a 50% reduction in light emission by Vibrio fischeri cells (EC₅₀) were; 21.72 6 14.57 ppm for 2-DCB, 37.40 6 0.45 ppm for cyclohexanone, and 1.65 6 0.26 ppm for 2-nonenal. The maximum number of cells affected by 2-DCB was 65% 6 4%, while it reached 90% to 100% for the other 2 compounds. Our results suggest that even though the EC₅₀ for 2-DCB is lower than that for cyclohexanone, it was not toxic enough to decrease light emission of V. fischeri beyond 60% to 70%. These results indicate that the potential risk from 2-DCB, if any, is very low.     

热处理对玉米粉中黄曲霉毒素B1含量变化的影响

黄曲霉毒素B1(AFB1)是霉菌的次级代谢产物,是玉米的主要污染物之一,对人类和家畜的健康均有较大危害。研究热处理对玉米粉中黄曲霉毒素B1(AFB1)含量变化的影响,建立玉米粉中AFB1含量变化与处理条件的动力学模型。试验结果显示在热处理过程中,玉米粉中AFB1的残留率随着处理温度的升高而降低,随着处理时间的延长而降低。依据阿伦尼乌斯方程,玉米粉中AFB1含量变化属于一级反应,其活化能为42.2 kJ/mol,在100～200℃范围内,该模型可以有效预测玉米粉中AFB1在热处理过程中含量变化规律,模型预测值与实测值相关系数高于0.80。     

基于颜色特征的含黄曲霉毒素玉米颗粒的检出方法

为快速准确识别出感染黄曲霉毒素的玉米颗粒,基于黄曲霉毒素在365 nm紫外光照射下可发出黄绿色荧光(bright greenish-yellow fluorescence,BGYF)的特性,提出了一种以颜色为特征量的感染毒素颗粒的检出方法。首先针对同一组玉米颗粒样本分别获取其在紫外光和可见光下的2幅图像,对可见光图像进行二值化、颗粒区域填充等预处理操作,得到玉米颗粒的轮廓与位置信息;然后将进行彩色增强后的紫外光图像与预处理后的可见光图像掩膜;最后在掩膜图像中通过RGB模型中G通道下的阈值作为分割参数识别玉米颗粒上的感染区域。结果表明,所提出的识别方法对能够发出荧光的含黄曲霉菌玉米颗粒识别准确率达到84%以上,对含有黄曲霉毒素的正确检出率可达77.8%以上,能够达到区分检测的要求。     

Aflatoxin determination in peanut butter by enzyme-linked immunosorbent assay

High specificity, high titre antisera to aflatoxins B₁ and G₁ have been produced by immunisation of rabbits with a bovine serum albumin-aflatoxin B₁ conjugate. The antiserum has been used to set up an indirect, double antibody microtitration plate enzyme-linked immunosorbent assay with a limit of detection of 0.1 pg toxin per well. The assay has been validated for application to peanut butter, and demonstrates many advantages over conventional methodology, including the requirement for minimal sample preparation before assay, its technical simplicity, and its potential high sample through-put.     

胶体金免疫层析法快速检测黄曲霉毒素B1的研究

本文应用胶体金免疫层析技术,建立了一种快速检测食品中黄曲霉毒素B1的方法。采用柠檬酸三钠还原法制备胶体金颗粒,标记抗黄曲霉毒素B1单克隆抗体并喷于玻璃纤维上,黄曲霉毒素B1偶联抗原和二抗鼠抗驴分别结合于硝酸纤维膜上,依次将样本垫、胶金垫、硝酸纤维膜和吸水纸组装切割成胶体金试纸条并装入检测卡中。测试结果表明黄曲霉毒素B1快速检测试纸条的灵敏度为5ng/ml,检测时间为10min,批内和批间重复性为100%,假阳性率和假阴性率均为0。使用简单方便,非常适合现场快速检测黄曲霉毒素B1。     

玉米胚芽油食用安全性评价

目的评价玉米胚芽油的食用安全性。方法依据食品安全性毒理学评价程序和方法进行急性毒性试验、骨髓细胞微核试验、精子畸形试验、沙门菌回复突变试验(Ames试验)和30 d喂养试验。结果小鼠经口最大耐受量20.0 g/kg,属无毒物;骨髓细胞微核试验、精子畸形试验和Ames试验结果均为阴性;30 d喂养试验各项指标均未见异常。结论该试验条件下,食用玉米胚芽油是安全的。     

Assessment of Groundnut Varietal Tolerant to Aflatoxin Contamination in Indonesia

Aflatoxin is secondary metabolite produced by Aspergillus flavus and A. paraciticus that grow on the seed coat (testa) of groundnut. This toxin is a serious food safety issue throughout the world. The availability of resistant genotype to A. flavus infection and/or aflatoxin contamination urgently needed. The experiment found one genotype had aflatoxin contamination under the safe level (≤ 10 ppb), with <15% of seed number infected by A. flavus. Recently, the biggest peanut industry, where the main production is roasted-peanut (in shell) produced from fresh pods, grows and develops that variety.     

Rapid Methods for Lipoxygenase Assay in Sweet Corn

Potential methods for rapid assay of sweet corn lipoxygenase (LPO) were evaluated and compared by visual inspection. Both model system (partially purified) and vegetable (LPO extract) system studies were carried out. Model system studies indicated that LPO had maximum activity at pH 6.0 and 2.0 mM linoleic acid. Methylene blue bleaching (MBB), carotene bleaching (CB), and potassium iodide-starch (KI-S) methods were evaluated both spectrophotometrically and visually. Both MBB and KI-S methods were effective for the model system. For the vegetable LPO extract systems (sweet corn and green beans), the MBB method indicated positive results for both, the CB method was not effective for either, and the KI-S method was very effective for green beans but not for sweet corn.     

Susceptibility of Date Fruits (Phoenix dactylifera) to Aflatoxin Production

Segments of fruits from 12 varieties of date (Phoenix dactylifera) and three stages of maturation were inoculated with a toxigenic strain of Aspergillus parasiticus. During growth at 28°C for 10 days, 8 varieties supported appreciable aflatoxin production at the Khalal stage—the most popular stage for direct human consumption, with a maximum value in excess of 300 μg g^-1 of fruit. Marked differences in susceptibility to infection and/or aflatoxin production were observed between varieties and/or stage of maturation. It was concluded that toxigenic aspergilli could proliferate on any date fruits that suffered mechanical damage in the field or during harvesting, and hence that such fruits should be considered as likely to be unfit for human or animal consumption. © 1997 SCI.     

食品中黄曲霉毒素B1的抽查检验与安全评价

采用酶联免疫法对市售几类食品花生油、花生糖、月饼等的黄曲霉毒素B1(简称AFTB1)进行检测,分析其AFTB1超标的原因及安全性,结果表明大部分食品中AFTB1的含量在安全限量之内,少数几类产品存在安全隐患.     

玉米中黄曲霉毒素B1测定的不确定度评定

采用超高效液相色谱法对玉米中黄曲霉毒素B1的不确定度进行评估。根据CNAS-GL006-2018《化学分析中不确定度的评估指南》和JJF1059.1-2012《测量不确定度评定与表示》中的有关规定,建立测定玉米中黄曲霉毒素B1不确定度的数学模型,逐层对不确定度来源进行分析。通过对不确定度分量进行量化和合成,得出当玉米中黄曲霉毒素B1为3.60μg/kg时,其相对扩展不确定度为0.14μg/kg(k=2)。结果表明,影响检测结果的主要因素为样品非均匀性、回收率、校准过程及样品处理液定容;其量化结果分别为0.0140、0.009、0.007、0.0058。     

臭氧及催化臭氧氧化法处理制浆废水的研究进展

介绍了臭氧及催化臭氧氧化技术降解去除废水中有机物的机理,分析了影响臭氧处理制浆废水效果的主要因素。综述了近年来臭氧及催化臭氧氧化技术处理制浆废水的研究进展;指出此领域尚存在的问题,并对未来的发展方向进行了展望。     

同时检测玉米中黄曲霉毒素B1和赭曲霉毒素A的时间分辨荧光免疫层析试纸条的研制

研究制备了一种可同时快速定量检测黄曲霉毒素B1 (aflatoxin B1,AFB1)和赭曲霉毒素A(ochratoxin A,OTA)的二联时间分辨荧光免疫层析试纸条.采用铕系时间分辨荧光微球分别标记AFB1和OTA单克隆抗体,优化荧光微球活化pH值、标记的抗体浓度、荧光探针使用量、检测线包被原浓度、质控线羊抗鼠Ig...     

构建下转换荧光-适配体的免疫层析试纸条用于快速检测黄曲霉毒素B1

构建下转换荧光-适配体免疫层析试纸条用于食品中黄曲霉毒素B1 (aflatoxin B1,AFB1)的快速高效检测.体系中AFB1存在会减弱下转换荧光-适配体纳米颗粒层析至T线时与AFB1半抗原的结合能力,从而导致下转换荧光信号衰减,进而实现对AFB1的高效检测.该方法在AFB1质量浓度1～40 ng/mL范围内与荧光...