纳豆芽孢杆菌Bacillus natto 16-1对小麦粉中呕吐毒素的脱毒机制

采用酶联免疫吸附法(ELISA)及高效液相色谱—质谱(HPLC-mass spectrometry,HPLC-MS)检测纳豆芽孢杆菌Bacillus natto 16-1各细胞成分对小麦粉中呕吐毒素(deoxynivalenol,DON)的清除效果及降解产物,探讨纳豆芽孢杆菌清除呕吐毒素的效果及降解机制。结果显示,培养5h后不同浓度的菌悬液、发酵上清液、全菌裂解液、粗提酶液以及细胞壁悬浮液,对DON清除率均在53%以上,其中不同浓度的菌悬液处理间存在显著差异,高浓度细胞壁悬浮液处理对DON清除率高达62.85%;培养10h后不同菌体成分对DON的清除率在57%以上,其中不同浓度发酵上清液、菌体裂解液以及细胞壁悬浮液处理间存在显著差异。除细胞壁处理组外,其他各组均可将DON降解为分子质量较小的物质。结果表明,纳豆芽孢杆菌Bacillus natto 16-1各细胞成分对DON均有清除作用,且这种作用在一定程度与细胞成分的浓度及作用时间有关;各细胞成分对DON的清除机制主要是生物降解作用,细胞壁可能是通过生物吸附作用来清除DON。     

臭氧对不同基质中呕吐毒素的降解效果研究

为了研究臭氧对不同基质中呕吐毒素（DON）的降解效果及其规律，本研究采用臭氧来处理不同状态下DON纯品和赤霉病小麦，并初步探究了小麦组分对臭氧降解DON效果的影响。结果表明，臭氧可以在短时间内降解水溶液中的DON纯品和固态DON纯品，在处理浓度为10 mg/L、处理时间为60 s时，DON的降解率可达90%；臭氧可以有效降解小麦中的DON，料液比对小麦中DON的降解效果具有显著影响，当小麦粉与水的料液比为1:6时，臭氧可将初始含量为1.82 mg/kg的全麦粉中DON含量降解至国家标准限量 (1 mg/kg)以下。此外，在臭氧降解小麦中的DON时，小麦麸皮、淀粉和蛋白均对其降解效果有着明显的阻碍作用，且蛋白的阻碍作用最大。由此可知，臭氧可以显著降解不同状态下的DON纯品，对小麦各组分中的DON有较好的降解效果，并且臭氧对DON纯品的降解效率要显著高于赤霉病小麦，说明小麦各组分对臭氧降解DON有一定影响，其中蛋白的影响效果最为明显。不同基质中的DON的臭氧降解效果不同，且该降解效果受臭氧处理浓度和处理时间、样品与臭氧接触面积、样品水分含量等因素的影响。     

河南省市售小麦粉微生物及真菌毒素污染状况研究

为了解河南省市售小麦粉的安全状况,收集整理河南省市售小麦粉。采用Filmplate~(TM)测试片法测定样品的菌落总数、霉菌和酵母菌计数及大肠菌群,采用酶联免疫法(Enzyme–Linked Immuno Sorbent Assay,ELISA)测定样品中呕吐毒素(DON)、黄曲霉毒素B_1(AFB_1)及赭曲霉毒素A(OTA)三种常见真菌毒素的含量。结果显示:小麦粉样品受微生物污染面积较广,但程度可控。菌落总数、霉菌酵母菌数、大肠菌群数主要集中范围分别是10~2~10~4、10~2~10~3、10~2~10~3 CFU/g;DON、AFB_1及OTA含量超限率分别为0.00%、13.85%、7.69%,检出率依次为69.23%、52.31%及84.62%,污染程度不同,污染范围均较为广泛。     

臭氧水协同超声波处理对小麦中DON降解效果的研究

为了研究臭氧水协同超声波处理对赤霉病小麦中DON降解效果的影响,采用不同协同方式对赤霉病小麦进行处理,并筛选出臭氧水和超声波协同的最佳方式。随后在最佳联合方式下进行单因素和正交实验来探讨臭氧水浓度、超声振幅和处理时间对赤霉病小麦籽粒中DON降解效果的影响。结果表明:臭氧水和超声波最佳联合处理方式为T5,即先超声波处理5 min再臭氧水处理5 min,此时赤霉病小麦中DON降解率最高(46.99%)。经单因素和正交实验得出,在此联合方式下臭氧水浓度为58.32 mg/L,超声振幅为60%,处理时间比为9:1时赤霉病小麦中DON降解率最高(51.02%)。     

白藜芦醇对不同时间高糖诱导HepG2细胞氧化损伤的保护作用

研究白藜芦醇对不同时间高糖诱导HepG2氧化损伤的保护作用。33 mmol/L高糖作为诱导剂,与不同浓度白藜芦醇(0.1、1、10μmol/L)共同孵育24、48、72 h,采用MTT法检测其对损伤细胞存活率的影响,DCFH-DA荧光探针法检测细胞自由基水平,测定细胞超氧化物歧化酶(SOD)、丙二醛(MDA)、谷胱甘肽过氧化物酶(GSH-PX)、总抗氧化能力(T-AOC)水平,Real-time PCR测定Nrf2、HO-1 mRNA表达水平,探讨白藜芦醇对高糖损伤细胞的保护作用及可能机制。结果表明,白藜芦醇与高糖共同作用48 h以上时,各浓度组均能显著提高损伤细胞存活率,显著降低细胞自由基水平(p0.05);各浓度组均能改善模型氧化还原状态,其中10μmol/L白藜芦醇作用48 h时效果极显著(p0.01);10μmol/L白藜芦醇作用48 h时,极显著上调Nrf2、HO-1mRNA表达水平(p0.01)。因此,白藜芦醇能通过清除细胞自由基、改善细胞氧化还原状态、上调抗氧化通路相关基因表达,抑制高糖诱导HepG2细胞的损伤。     

臭氧处理小麦生产低菌粉的研究

为了保障小麦粉及其制品的食用安全,研究了臭氧处理小麦生产低菌粉的工艺条件.结果表明,臭氧处理小麦的浓度、时间和润麦温度对小麦粉带菌量均有显著性影响,通过正交试验优化的工艺条件为:臭氧处理小麦浓度75 mg/kg、时间20 min、润麦温度10℃,在此工艺条件下生产的小麦粉,菌落总数、需氧芽孢菌数、霉菌总数分别为:470、180、340 CFU/g,蜡样芽孢杆菌和大肠菌群均＜10 CFU/g,比对照小麦粉的带菌量明显下降.     

不同包装材料对储藏小麦粉微生物和脂肪酸值的影响

通过模拟储藏,研究了包装材料对储藏小麦粉微生物和脂肪酸值的影响。结果表明:在70%RH、18～20℃储藏条件下,由于包装材料的阻湿性能不同,不同包装材料储藏小麦粉的水分呈现不同程度的下降,导致储藏小麦粉细菌量、霉菌量和脂肪酸值的变化规律不尽相同,小麦粉的细菌量与储藏时间呈一元线性负相关,霉菌量呈现先上升后下降的趋势,脂肪酸值与储藏时间呈一元线性正相关,但相关程度与包装材料有关。进一步的分析表明脂肪酸值与水分、细菌量(或霉菌量)呈现二元线性关系。通过比较储藏过程中细菌量、霉菌量和脂肪酸值的变化速率,表明在给定的模拟储藏条件下,布袋为最适合储藏小麦粉的包装。     

干热处理对小麦粉热力学特性与面团流变学性质影响

采用不同温度(110、130 ℃和150 ℃)和时间(1、2、3 h和4 h)干热处理小麦粉,研究其热力学性质以及添加干热改性小麦粉对面团流变学特性的影响。研究结果表明,与未处理样品相比,干热处理降低了小麦粉的糊化温度,且在130 ℃和150 ℃下,糊化焓也随之降低。X-射线衍射图谱分析发现,随着干热处理时间的延长,相对结晶度逐渐降低,且在150 ℃时小麦粉的结晶类型发生改变。干热处理使小麦粉糊化黏度增加,并在130 ℃加热1 h时达到最大值;除150 ℃处理3、4 h外,干热处理小麦粉的回升值均小于未处理样品,表明150 ℃处理3、4 h破坏了小麦粉的淀粉结构。此外,干热处理使得小麦粉中的蛋白质发生明显聚集。适度干热处理小麦粉的添加增加了面团的形成时间,改善了面团的稳定性,增强了面团的拉伸阻力,降低了面团的延伸度。论文对深入认识干热处理小麦粉的作用理论知识提供了一定的支撑。     

2014~2018年黑龙江省小麦和小麦粉中脱氧雪腐镰刀菌烯醇污染水平调查与分析

目的 调查分析黑龙江省小麦和小麦粉中脱氧雪腐镰刀菌烯醇(deoxynivalenol, DON)污染状况。方法 样品经乙腈-水(84:16)溶液浸泡提取,净化柱净化后,用液相色谱-串联质谱法对黑龙江省90份收购环节小麦和127份市售小麦粉中DON含量进行检测,并对污染情况进行研究。结果 小麦及小麦粉样品DON平均含量分别为133和417 μg/kg,检出率均为100%。在检测的217份样品中,最大检出值为970 μg/kg,DON含量均低于我国限量标准1000 μg/kg。结论 检测数据表明,小麦和小麦粉易受DON污染;我国东北部产区小麦粉中DON的含量较中部地区低,这可能与中部地区的温湿度条件较东北部地区更有利于真菌生长、产毒有关;小麦粉中DON的含量大于小麦中DON的含量,提示小麦粉的运输及储存过程可能导致其DON含量增加;因此,对市售小麦粉的管理应重点关注其出厂后的运输储存条件。     

臭氧水润麦生产低菌化小麦粉的研究

目的优化臭氧水润麦生产低菌化小麦粉工艺条件。方法用不同浓度臭氧水和温度润麦,并对小麦粉进行微生物和品质指标检测。结果 20℃润麦时,浓度为5.5 mg/L的臭氧水能显著降低小麦粉中微生物含量(P0.05),且对小麦粉脂肪酸值和色彩色差值等品质指标无负面影响;同一臭氧水浓度润麦时,温度与小麦粉中微生物含量之间基本呈极显著的正相关(P0.05),温度较低时,对小麦粉品质指标未产生负面影响。综合考虑减菌效果和对小麦粉品质的影响,润麦时选择臭氧水浓度为5.5 mg/L,温度为10℃,在此工艺下小麦粉中的细菌总数、需氧芽孢数和霉菌量分别为310、210、230 cfu/g,蜡样芽孢杆菌和大肠杆菌均10 cfu/g。结论本方法能够生产低菌化小麦粉。     

Determination of Deoxynivalenol in Wheat Bran and Whole-Wheat Flour by Fluorescence Polarization Immunoassay

A rapid and accurate fluorescence polarization (FP) immunoassay has been optimized for the determination of deoxynivalenol (DON) in wheat bran and whole-wheat flour. A preliminary treatment with activated charcoal was used to eliminate the strong matrix effect due to highly colored interfering compounds present in raw wheat bran extracts. In particular, matrix effect was removed by adding activated charcoal to the wheat bran extract (3.5 mg/mL) and mixing for 3 min of incubation time prior to the FP immunoassay analysis. No preliminary treatment was necessary for whole-wheat flour. Average recoveries from samples spiked with DON at levels of 500, 1,000, and 1,500 μg/kg were 95 % for wheat bran and 94 % for whole-wheat flour, with relative standard deviation generally lower than 13 %. Limits of quantification of the optimized FP immunoassay were 120 μg/kg for both matrices. The overall time of analysis was lower than 15 min for wheat bran and 10 min for whole-wheat flour. Good correlations (r?>?0.971) were observed between DON contents obtained by both FP immunoassay and high-performance liquid chromatography with immunoaffinity cleanup for 37 and 23 samples of naturally contaminated wheat bran and whole-wheat flour, respectively. These results show that the FP immunoassay is suitable for high-throughput screening as well as for quantitative determination of DON in wheat bran and whole-wheat flour.     

Evaluation of the TLC quantification method and occurrence of deoxynivalenol in wheat flour of southern Brazil

ABSTRACT

The study evaluated a QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) extraction method for use with a TLC quantification procedure for deoxynivalenol (DON). It also surveyed DON occurrence in wheat flour from the southern region of Brazil. Forty-eight wheat flour samples were analysed, divided into 2 different harvest lots, each consisting of 24 different brands. The detection and quantification limits of the method were 30 and 100 ng of DON on the TLC plate. The various concentrations of DON presented high linearity (R² = 0.99). A negative matrix effect (?28%) of the wheat flour was verified, with suppression of the chromatographic signal of DON, and 80.2–105.4% recovery. The TLC method was reliable for DON evaluation, with a coefficient of variation of less than 10%. High-performance liquid chromatography of lot 2 samples confirmed the presence of DON in all samples identified DON-positive by the TLC technique. Of the 48 wheat flour samples in lots 1 and 2 analysed by TLC, 33.3 and 45.8% of the samples respectively were above the Brazilian legislation limit. Correlations were observed between the water activity and DON content, and between the fungal count and moisture content of the wheat flours.     

Physicochemical Properties of Wheat Gluten Proteins Modified by Protease From Sierra (Scomberomorus sierra) Fish

The effect of semi-purified trypsin on the physicochemical properties of durum and bread wheat flour and gluten protein fractions was evaluated. Trypsin was partially isolated from sierra (Scomberomorus sierra) guts extracts by affinity chromatography. Treatment with enzyme caused hydrolysis of 1.16–1.40% in both durum and bread wheat gluten and gluten fractions. The effect of hydrolysis on the isoelectric point was more evident in durum that bread wheat gluten. Addition of the trypsin-like enzyme at three different concentrations induced a decrease in the gluten index. The dough consistency fell after 1.5 h of incubation. It was possible to modify wheat flour proteins by varying S. sierra trypsin-like enzyme concentration and incubation time, depending on the wheat species.     

LED蓝光处理对小麦粉的减菌效果及其品质的影响

为减少有害微生物对小麦粉的污染,本研究以不同筋度（低筋、中筋、高筋）小麦粉为原料,对其接种不同菌落数的大肠杆菌和蜡样芽孢杆菌,分析LED蓝光光照处理（430～470 nm,36 W）对3 种筋度小麦粉的减菌效果及其理化性质的影响。结果表明：与对照组相比,5 h LED蓝光处理可显著降低高接菌量小麦粉中的大肠杆菌和蜡样芽孢杆菌菌落数,分别减少4.9（lg（CFU/g））和4.7（lg（CFU/g））,且杀菌效果与光照时间呈正相关;LED光照处理使小麦粉水分质量分数和横向弛豫时间T21、T22均呈现降低趋势,但不会改变小麦粉中水分的主要存在形式;经LED蓝光处理后,小麦粉的亮度、湿面筋质量分数和蛋白质聚合体无显著变化;但绿度和黄度下降,且小麦粉中蛋白与淀粉之间结合更加紧密。因此,LED蓝光处理可有效抑制小麦粉品质劣变,并有利于增加小麦粉的稳定性,改善小麦粉的品质。     

真菌毒素在赤霉病小麦研磨及其湿法加工中的分布研究

小麦赤霉病不仅会导致粮食减产,更会引起多种真菌毒素的高污染风险。将染病小麦进行实验室制粉并湿法分离统粉中的粗淀粉、谷朊粉,采用酶联免疫吸附测定法(Enzyme-Linked Immuno Sorbent Assay,ELISA)测定各系统的呕吐毒素(Deoxynivalenol,DON)、黄曲霉毒素B1(Aflatoxin B1,AFB1)、玉米赤霉烯酮(Zearalenone,ZEN)以及赭曲霉毒素A(Ochratoxin A,OTA)的含量,以探究赤霉病小麦在制粉及其湿法加工中四种常见真菌毒素的分布变化规律。结果显示:研磨制粉及湿法加工对真菌毒素的分布影响显著。制粉加工后,皮磨和心磨系统粉的DON、AFB1、ZEN和OTA含量比原粮显著降低,降低率分别为1.38~16.24%、20.47~71.77%及26.71~69.51%;湿法加工产物中,DON消减为相应统粉的4.88~12.11%,AFB1与OTA浓缩富集,富集率分别可达统粉的2.55、3.65倍,粗淀粉中ZEN消减为统粉的12.70~15.83%,谷朊粉则富集为统粉的4.11倍。研究表明,在工业生产中,可根据赤霉病小麦的感染类型及程度,适当选用研磨或湿法加工等合适的方法加工处理。     

A survey on the occurrence of Fusarium mycotoxins in Bavarian cereals from the 1987 harvest

Bavarian cereals and wheat flour from the 1987 harvest were analysed for nivalenol (NIV) and deoxynivalenol (DON) using high performance liquid chromatography (HPLC) and for T-2 toxin and zearalenone (ZEA) by enzyme-linked-immunosorbent assay (ELISA). The study included 190 field samples of wheat, barley, rye and oat with visibly damaged ears, 45 samples of wheat intended for feed production and two series of wheat flour (type 550) and whole wheat flour collected in October 1987 and June 1988. The field samples examined showed a high DON contamination of wheat (87%) with an average of 3.96 mg/kg and a maximum of 43.8 mg/kg. Mean levels between 0.33 mg/kg and 0.27 mg/kg DON could be detected in barley, rye and oat. Of the wheat samples, 58% contained ZEA with a maximum of 1.560 mg/kg. The highest levels of ZEA were detected in samples which also showed high concentrations of DON. The NIV and T-2 toxin levels were comparatively low. Thirty percent of the samples showed NIV concentrations between 0.04 mg/kg and 0.29 mg/kg and 38% contained between 0.005 and 0.60 mg/kg of T-2. In the wheat samples for feed production, only DON was detected with an average of 0.190 mg/kg and a maximum of 0.75 mg/kg. The highest DON levels (0.58 mg/kg) from October 1987 were found in the wheat flour samples which were lower than the highest DON concentration (3.24 mg/kg) detected in the samples collected during June 1988. This fact was probably due to a substantial amount of non-contaminated wheat from 1986. The toxin concentrations in the whole wheat flour were not higher than in the type 550 flour.(ABSTRACT TRUNCATED AT 250 WORDS)     

Utilization of highly deoxynivalenol-contaminated wheat via extrusion processing

Deoxynivalenol (DON) is a toxic natural metabolite produced by Fusarium graminearum. In this study we investigated the effects of sodium bisulfite and extrusion cooking under high temperature and pressure on DON levels in wheat grain and mill fractions. Samples of highly naturally DON-contaminated soft winter wheat were soaked for 1 h in water or aqueous sodium bisulfite (SB) solutions (0.5, 1.5, 2.5, or 5% SO2 equivalent) and extruded. The soaking treatment with SB solution (5% SO2 equivalent) lowered DON from 7.3 microg/g to 0.8 microg/g without extrusion and to 0.3 microg/g with an extrusion process. When the contaminated kernels were tempered with water or SB solutions (5 or 10% SO2 equivalent) and milled, the flour samples, as expected, showed lower levels of DON (from 7.3 to 3.1 microg/g). Extrusion of milled flour and whole meal samples, both obtained from SB-tempered wheat, did not change DON levels significantly under the studied extrusion conditions as compared to the nonextruded milled flour and whole meal samples. However, the extrusion process can be utilized to remove moisture and/or odor of chemicals used in the soaking solutions and to produce potentially useful extruded products.