反相高效液相色谱法测定玉米须中尿囊素的含量

目的:采用反相高效液相色谱对玉米须中尿囊素的含量进行测定。方法:选用DiamonsilTM(钻石)C18色谱柱(5μm,150 mm×4.6 mm),氯仿-甲醇-水(0.012∶0.5∶100)为流动相,紫外检测波长为224 nm条件下对尿囊素进行含量测定。结果:尿囊素的含量在0.108~0.972μg范围内,进样量与峰面积积分值呈良好的线性关系,r=0.999 9,平均回收率97.5%,RSD=1.62%。结论:所建立的方法能准确、快速地进行定量检测,可作为玉米须中尿囊素的质量控制方法。     

Lipid utilization of human adults as affected by dietary bran supplementation

Twenty-one adult men and women participated in two studies to compare the effects of selected brans on the utilization of dietary fat. Fecal fat excretion was measured as well as total weight of feces. Blood serumcholesterol, triglycerides, and phospholipids were determined. Results indicated that fecal fat excretion tended to increase with bran supplementation of diets. Wheat bran had a greater effect than did either rice or corn bran. No statistically significant changes in blood lipids were associated with the various types of fiber. However, serum lipids of subjects were substantially lower when subjects received the experimental diets than when they were consuming their self-selected diets prior to the start of the study. The experimental diet was moderately low in fat and very low in cholesterol. The effectiveness of added bran in influencing lipid utilization may vary with the kinds of bran employed and also with the total amount of dietary fat or other dietary parameters.     

A Comparative Study of Indirect Competitive ELISA and HPLC for Fumonisin Detection in Corn of the State of Paraná, Brazil

The performance of a monoclonal antibody (MAb)-based indirect competitive ELISA (ICELISA) for fumonisin detection in corn was evaluated using 150 post-harvest corn samples from the April 1995 and March-April 1996 crop, in the State of Paraná, Brazil. Compared to high performance liquid chromatography (HPLC), the correlation coefficient (r) of the results from the two methods was 0.94. The IC-ELISA detected total fumonisin levels of 1.1 to 1.5-fold higher than HPLC in 85 samples (56.6%). The concentration range of 1.0 to 5.0 μg g^?1 was observed in 26% of samples analysed by ELISA and in 29% by HPLC. In addition, four samples (2.7%) showed an ELISA/HPLC ratio of 0.7 to 0.99 and seven samples (4.7%) a 1.0 ratio. In 29 (13.3%) samples, IC-ELISA detected 1.6 to 2.0-fold higher values than HPLC. These data showed high correlation (r = 0.91) of IC-ELISA and HPLC for fumonisin concentration in corn contaminated with ≤ 10 μg g^?1, with a detection limit of 93 ng g^?1. Matrix interference was minimized by diluting the sample before the ELISA assay. MAb-based IC-ELISA may be effectively applied for fumonisin screening in corn, with advantages of simplicity, ease of sample preparation and sensitivity.     

超高效液相色谱-串联质谱法测定面粉、玉米及其制品中的伏马菌素研究

目的建立面粉、玉米及其制品中3种伏马菌素的超高效液相色谱-串联质谱(UPLC-MS/MS)检测方法。方法样品用乙腈-水(50∶50,V/V)溶液提取,经MultiSep 211净化柱富集净化后,用甲醇-甲酸(99∶1,V/V)溶液洗脱,洗脱液用UPLC-MS/MS进行测定。UPLC-MS/MS检测伏马菌素的条件为梯度洗脱,流动相为0.2%甲酸水和乙腈;质谱采集模式为电喷雾正离子多反应监测模式。结果 UPLC-MS/MS检测方法对3种伏马菌素的检出限均为0.2μg/kg,最低定量限为0.6μg/kg。不同加标水平的3种伏马菌素平均回收率为69.44%～114.69%。用所建方法对2011年甘肃及天津生产的39份玉米及30份面粉样品进行了分析,结果以伏马菌素B1的检出率最高,污染水平最为严重。结论 UPLC-MS/MS法具有操作简单、灵敏度高、重现性好等特点,可用于面粉、玉米及其制品中伏马菌素的检测。     

部分市售食品中总黄曲霉毒素污染的监测结果

目的了解我国部分食品（玉米、花生、大米、核桃、松子）中黄曲霉毒素B1、B2、G1、G2的污染情况,为国家食品限量标准及国际相应控制规范的制定提供基本科学依据。方法2003年10月从重庆、福建、广东、广西、湖北、江苏、上海、浙江等地区共采集市售玉米、花生、大米、核桃、松子等样品284份。碾磨后经乙腈／水提取、过滤,提取液净化后,经三氟乙酸衍生,进行高效液相色谱测定。结果玉米中黄曲霉毒素的检出率为70．27％,平均含量为36．51μg／kg,最高为1098．36μg／kg,并有14．86％的玉米样品中黄曲霉毒素B1含量超出国家限量标准。花生中黄曲霉毒素的检出率为24．24％,平均含量为80．27μg／kg,最高为437．09μg／kg,且有3．03％的花生样品中黄曲霉毒素含量超出国家及国际食品法典限量标准。大米、核桃、松子的污染情况较轻,全部符合国家限量标准。结论玉米和花生是我国受黄曲霉毒索污染的主要食品。食品中黄曲霉毒素B。并不能全面代表总黄曲霉毒素的污染情况。进行食品中总黄曲霉毒素的污染监测,对国家制定食品限量标准及国际相应控制规范具有重要的现实意义。     

高效液相色谱法检测谷物中赭曲霉毒素A的方法评价与应用

目的:评价高效液相色谱定量检测谷物中赭曲霉毒素A的分析方法,为监测粮谷类食品中赭曲霉毒素A的污染水平提供技术支持。方法:利用液-液分离前处理技术,选用C18反相柱(250×4.6 mm),以乙腈:水:乙酸=99:99:2为流动相,流速1 ml/min,荧光检测器(激发波长333 nm,发射波长460 nm)定量,柱温25℃。结果:以准确度和精密度评价该方法,其中变异系数均低于10%,回收率介于77.61%~95.66%之间。结论:与文献中所采用免疫亲和柱净化样品的方法比较,本法操作简便、灵敏度高、重现性好、结果可靠、经济,可用于谷物中赭曲霉毒素A定量检测。     

玉米须多糖治疗糖尿病作用研究

目的研究玉米须多糖治疗糖尿病的作用。方法采用四氧嘧啶快速造模法,研究玉米须多糖对糖尿病小鼠血糖及糖代谢的影响,同时研究玉米须多糖对正常小鼠血糖的影响。结果玉米须多糖对糖尿病小鼠有明显的降糖作用,能够促进肝糖元合成,同时对正常小鼠有一定降糖作用。结论玉米须多糖对治疗糖尿病小鼠有明显作用。     

Non-targeted method to detect honey adulteration: Combination of electrochemical and spectrophotometric responses with principal component analysis

Detecting adulteration in honey is not an easy task and most of the traditional methods are usually unaffordable. Thus, we describe the use of cyclic voltammetry using Cu/CuO electrode and UV–vis spectrophotometry along with chemometric tools to detect adulteration of honey with corn syrup. Both honey and corn syrup samples presented an anodic peak at +1.1 V, but the current is variable and depends on the sample composition in relation to the honey and syrup content. A cathodic peak at +0.42 V arises at higher scan rates, which is more pronounced for syrup samples and can be used to discriminate between pure and adulterated samples. This response can be combined with UV/vis absorbance peaks at 285 and 216 nm to identify adulteration. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) allowed differentiating between honey and corn syrup samples and simulated mixtures of them, in which the first two principal components together explain 100.0 % of the data variability, specifically 98.47 % by PC1 and 1.53 % by PC2. The method requires a minimum amount of sample and generates a low amount of waste. Furthermore, it is possible to use portable and cheap equipment, making it more accessible to the beekeeper sector.     

玉米须制剂抗疲劳、耐缺氧实验研究

目的探讨玉米须制剂的抗疲劳、耐缺氧作用。方法通过测定小鼠游泳时间及血清尿素氮、肝糖原,耐缺氧时间等指标,研究其抗疲劳、耐缺氧作用。结果玉米须制剂的两个剂量组均能显著降低小鼠肝糖原的储备量;不影响运动后血清尿素氮含量,可以提高小鼠的游泳时问,延长小鼠的耐缺氧时间。结论玉米须制剂具有抗疲劳,耐缺氧作用。     

Mycological survey and ochratoxin A natural contamination of swine feedstuffs in Rio de Janeiro State, Brazil

Mycotoxin contamination of animal feeds represents a hazard to human and animal health due to potential transmission to meat and milk. Barley by-products are alternative feeding supplies for animal production. The aims of this assay were to study the mycobiota of feedstuffs and finished swine feed, to determine the ability of Aspergillus and Penicillium isolates to produce ochratoxin A (OTA) and to evaluate OTA occurrence in these substrates. Corn, brewers' grains and finished swine feed samples were collected from different factories. Fungal counts were higher than 2.8 × 10⁴ CFU g⁻¹. Fusarium, Aspergillus and Penicillium genera were isolated at high levels. A 23.7% of the isolates produced 9-116 μg kg⁻¹ of OTA in vitro. Corn samples (44%) were contaminated with 42-224 μg kg⁻¹ of OTA. Finished feed (31%) and brewers' grains samples (13%) were contaminated with 36-120 μg kg⁻¹ and 28-139 μg kg⁻¹ of OTA, respectively. This is the first scientific report on contamination by OTA-producer molds and OTA in swine feedstuffs from Brazil. The presence of OTA in raw materials and finished feed requires periodic monitoring to prevent mycotoxicoses in animal production, reduce economic losses and minimize hazards to human health.