酶联技术在水产品中呋喃唑酮代谢物AOZ的检测中的应用

用酶联免疫检验技术（ELISA）检测呋喃唑酮（Furazolidone）代谢物AOZ。AOZ经过16h的衍生后和酶联结合物对微孔中的抗体进行竞争反应，利用抗原与抗体的特异性免疫化学反应的基本原理，在酶标仪上450nm处测定吸光强度。进行定性定量分析。     

THE RAPID DETERMINATION OF THE QUALITY POTENTIAL OF MICROMALTS

A rapid method of mashing micromalts, suitable for the selection of crossbreeds in the early generations of a barley breeding programme is described. It uses relatively simple equipment and eighty samples can be tested per day by one operator. The method offers wide differentiation between samples of similar quality potential.     

盐酸萘乙二胺分光光度法测定肉制品中的亚硝酸盐

用盐酸萘乙二胺分光光度法对市售的9种肉制品中的亚硝酸盐含量进行了测定,并选取其中的3种进行了精密度试验和回收率试验,RSD在1.3～1.6之间,回收率在95%～103%之间.所测9种肉制品样品中亚硝酸盐含量在0.64 mg/kg～12.31 mg/kg之间,均符合我国食品添加剂使用卫生标准.散装腊肉腊肠的亚硝酸盐含量高于真空包装的腊肉腊肠中亚硝酸盐含量;在同一种包装制品中,腊肉的肥肉部分亚硝酸盐含量高于瘦肉部分的亚硝酸盐含量.     

DETERMINATION OF THE EFFECTIVENESS OF NOVOBIOCIN ADDED TO TWO AGAR PLATING MEDIA FOR THE ISOLATION OF SALMONELLA FROM FRESH MEAT PRODUCTS

Five plating media, Hektoen enteric (HE) and xylose lysine deoxycholate (XLD) agars with and without 80 and 5 μg/ml of novobiocin (N), respectively, and brilliant greeen sulfadiazine (BGS) agar with 80 μg/ml of the antimicrobial agent, were analyzed for the recovery of salmonellae from various fresh beef, pork, and poultry meat products. Of the total Samonella positive samples, 50.0% and 82.5% were found on XLD and XLD-N agars, respectively, 75.0% and 85.0% on HE and HE-N agars, respectively and 65.0% on BGS agar. HE-N and BGS media isolated three times more false positives than did XLD-N agar, while XLD and HE agars gave the highest numbers of false positives. The major H₂S producing false positive on XLD and HE agars was Proteus mirabilis. With the addition of N, P. mirabilis was eliminated, and the major H₂S producing false positive was almost exclusively Citrobacter freundii. The false positives on BGS agar were predominately distributed among C. freundii, Enterobacter sp., and Klebsiella sp.     

MODEL PREDICTION FOR SENSORY ATTRIBUTES OF NONGLUTEN PASTA

Response surface methodology was used to predict sensory attributes of a nongluten pasta and develop response surface plots to help visualize the optimum region. Optimum regions of xanthan gum, modified starch, and locust bean gum were selected by overlapping the contour plots of sensory properties of nongluten pasta as compared with the control pasta. The formula of nongluten pasta that possessed the most desirable properties was xanthan gum at 40 g, modified starch at 35 g, locust bean gum at 40 g, tapioca starch at 113 g, potato starch at 57 g, corn flour at 250 g, and rice flour at 50 g. The quality of nongluten pasta could be improved by using different levels of nongluten starches and flours, and nonstarch polysaccharides.     

DETERMINATION OF CARBOXYMETHYLCELLULOSE IN FOOD PRODUCTS

SUMMARY –A method was developed to determine sodium carboxymethylcellulose (CMC) in food products containing three or more hydrocolloids after prior removal of interfering substances. Papain was used to digest the proteins; calcium chloride was added to precipitate algin and pectic acid and sulfated hydrocolloids were then precipitated by cetylpyridinium chloride (CPC) in the presence of 0.5M NaCl. Celite 535 or Hyflo Super Cel was added, the mixture filtered over Reeve angel No. 202 paper and the residue washed with 0.01% CPC-0.01M NaCl. The filtrate and washings were collected and diluted with distilled water to attain a final concentration of 0.2M NaCl at which concentration the CMC was precipitated selectively by CPC. The mixture was filtered over a Celite 535 or Hyflo Super Cel column and the residue washed with 0.5M Na₂SO₄ and then with 0.01% CPC-0.01M NaCl until the washings were negative to the phenol-H₂SO₄ reagent. Finally, the residue on the column was washed with hot 30% H₂SO₄ and the hydrolyzed CMC in the eluate determined by the 2,7-naphthalenediol test. Based on the amount added to mixtures, recoveries of 75–86% were obtained from milk and other highly complex and proteinaceous products, with a standard deviation of ± 0.58 mg, when 10 mg of CMC were added. The determination is critically dependent upon the degree of substitution (DS) of the CMC. As a consequence, the method cannot be applied with absolute certainty to unknown samples.     

DETERMINATION OF PIRIMIPHOS-METHYL IN PASTA BY GAS CHROMATOGRAPHY/CHEMICAL IONIZATION MASS SPECTROMETRY

A method for the determination of pirimiphos-methyl residues in pasta has been developed. The pesticide was extracted from pasta using the Luke procedure modified for low moisture, nonfatty food products. The extracts were analyzed by capillary column gas chromatography using an ion trap mass spectrometer in the chemical ionization mode as the detector. Quantification was performed using fluorene as the internal standard. The limit of detection was 0.005 ppm. Recoveries from spaghetti were 83.0% at the 0.100 ppm level and 93.3% at the 0.010 ppm level. Of 48 spaghetti samples analyzed, 38 contained detectable residues between trace (>0.005 ppm) and 0.180 ppm. Electron ionization (EI) was used to confirm residues as low as 0.016 ppm in more concentrated extracts.     

乳粉中蛋白质含量测定结果的不确定度评定

通过建立数学模型,分析乳粉中蛋白质含量测定的不确定度及其影响因素.同时对各分量标准不确定度也进行了分析和计算,得出了样品消耗HCI标准溶液引入的标准不确定度、空白消耗HCI标准溶液引入的标准不确定度以及试验重复测量导致的标准不确定度是不确定度来源的最主要影响因素.最终通过合成和扩展得出了乳粉中蛋白质含量测定的扩展不确定度为(21.7±0.15)%.     

A QUANTITATIVE METHOD FOR THE DETERMINATION OF SHREDDABILITY OF CHEESE

The shreddability of mozzarella cheese was studied by sensory, instrumental and chemical means. This property is normally assessed visually after the cheese is shredded, but none of the compositional parameters alone is able to predict the shreddability. An image analysis system is able to measure accurately the physical characteristics of the shreds and assign values that correlate well with the ability of the cheese to shred. This property seems to be directly related to the length of the shreds produced, indirectly related to the number of fragments present and to the stickiness among the shreds.     

雌酮免疫分析方法的研究

对实验室制得的雌酮特异性抗体A—E1和针对雌酮、雌二醇、雌三醇的广普性抗体A一17E2进行了效能指标的系统评价，建立了雌酮测定的直接竞争ELISA方法。其结果两者检测雌酮的灵敏度分别可达1．3μg／L±0．06μg/L和1．5μg／L±0．05μg／L，检出限分别可达0．04μg／L±0．01μg／L和0．07μg／L±0．01μg／L。此外，A-17E2对于雌二醇和雌三醇的检测灵敏度分别可达1．5μg／L和18μg／L，对两者的检出限分别可达0．04μg／L和0．2μg／L，证明此种广普性抗体可有效检测雌酮，同时对雌二醇、雌三醇也有良好的检测效果。     

NEW METHOD FOR THE DETERMINATION OF HOT-WATER EXTRACT OF MALT

A new method for the measurement of hot-water extract of malt is described. In this method malt grist is continuously extracted in a Soxhlet apparatus under reduced pressure, the pressure being chosen such that the extraction is carried out at 65·5° C. In a comparison of malt extracts by the new method and by the Standard Institute of Brewing method the former gives lower extract values. The new method provides certain advantages: it requires a smaller malt sample, is rather quicker to carry out, requires less manipulation and avoids the problem of accounting for spent grain volumes.