市售鸡蛋三种主要致病微生物的检测与分析

分析了北京市场零售鸡蛋被3种致病微生物污染的情况,结果表明:蛋壳上大肠杆菌的平均带菌率为80%,沙门氏菌的平均带菌率为15%,金黄色葡萄球菌平均带菌率为5%;蛋内容物中大肠杆菌带菌率为55%,少数带有沙门氏菌和金黄色葡萄球菌。     

Preference for Commercially Processed Dill Pickles in Relation to Sodium Chloride, Acid, and Texture

Commercially processed dill pickles from 15 companies were evaluated for levels of NaCl, acetic acid, and texture by objective mcasurements and for preference by a consumer panel. Although differences in preference were significant, the concentrations of NaCl and acid, or the values of texture were not significantly related to these differences. The results indicated that NaCl in processed dill pickles could be reduced from present levels without affecting sensory preference for the product.     

Aerobic Microflora of Commercially Harvested, Transported and Cryogenically Processed Col lards (Brassica oleracea)

Samples of spring and fall harvested collards were obtained at critical stages in a normal harvesting, transportation and cryogenic processing operation and microbiologically analyzed for total plate counts, En-terobacreriaceae counts, and yeasts and molds. Operations that involved extended holding times and mechanical handling tended to increase all counts significantly while blanching and blast freezing with liquid N₂ reduced counts to acceptable levels. Differences were significant in all counts by sampling points and dates. Prominant genera of Enterobacteriaceae isolated from the frozen product were those normally associated with soil contamination and not normally considered pathogenic to humans.     

Yields, Proximate Composition and Mineral Content of Finfish and Shellfish

Yields of edible flesh, proximate composition, and mineral content were determined in two samplings of six finfish and four shellfish from the Chesapeake Bay region. Although there was considerable variation, most species have high protein (above 20%), low fat (less than 5%) and are relatively good sources of macrominerals, including calcium, phosphorus, magnesium and potassium. The ratio of sodium to potassium ranged from 1:4 to 1:15. These species, particularly the shellfish, are excellent sources of the trace elements, including copper, iron, zinc and manganese. Minerals are very high in certain shellfish.     

关于家具产品商业摄影问题的探讨

本文通过对家具商业摄影问题的反思与探讨,指出成功的家具商业摄影在于创新,并阐明了家具产品主题性拍摄多元化的观点。     

Six Northwest Atlantic Finfish Species as a Potential Fish Oil Source

Lipid, cholesterol, and fatty acid data were determined for six species of fish caught off the coast of Massachusetts on several sampling dates. The fattier fish (>5% fat) had low calculated levels of cholesterol per gram of fat (2–14 mg/g). However, low levels of cholesterol in edible flesh (50 mg/100g) amounted to large amounts of cholesterol per gram fat (17–70 mg/g) for lean fish (<5% fat). Wide fluctuations in fat content of the fatty species were paralleled by changes in fatty acid composition. All species would yield about 35% 20-carbon polyunsaturated fatty acids (PUFA) if the 20-carbon monoenes were removed.     

Nitrogen Determination of Commercially Prepared Lactalbumin

Commercially produced denatured whey protein (lactalbumin) was analyzed for total protein using the macro-Kjeldahl technique. The effect of catalyst (CuSO₄, HgO) and preincudation on total nitrogen was determined. Results showed that HgO gave consistently higher and more reproducible results than CuSO₄. Preincubating the sample in concentrated H₂SO₄, for 24 hr prior to digestion improved the recovery of nitrogen.     

Survival of Listeria monocytogenes on Processed Poultry

The potential for Listeria monocytogenes to survive and proliferate on processed poultry was investigated. Chicken breasts were inoculated with L. monocytogenes, cooked to one of five different internal temperatures, then either vacuum-packaged or wrapped in an oxygen permeable film and stored for up to four wk at 4^oC and 10^oC. Survivors were encountered at each cooking temperature employed. The magnitude of lethality was directly related to the cooking temperature. No significant increase in microbial populations occurred through 2 wk of storage. Bacterial populations in samples that were overwrapped increased significantly by week 4, except for the 160^oF (71.1^oC) treatment. For samples which were vacuum-packaged, only the bacterial population in the 150^oF (65.6^oC) treatment significantly increased. Differences due to packaging were observed at 4^oC storage but not at 10^oC storage.     

关于啤酒有害菌培养方式的探讨

本文从伯杰氏细菌鉴定手册[1]整理出常见啤酒有害菌的所属科属及其生理生化特性,并对适合检出啤酒有害菌的方法进行了探讨。试验结果表明,二氧化碳培养箱可以用于啤酒常见有害菌的检出。     

微生物对麦芽品质的影响

大麦作为啤酒酿造的主要原料，其表面或外源的微生物在制麦过程中会影响麦芽的品质，并最终影响成品啤酒的质量。近年来研究发现在制麦过程中添加启动子培养物，既能作为微生物控制剂，抑制有害微生糖的生长；同时又能利用微生物分泌的水解酶系来提高麦芽的品质和安全性。本文介绍了麦芽中的微生物种类及其对麦芽质量的影响，并对添加不同启动子培养物对麦芽品质的改善及其工业化应用的可行性进行了探讨。     

Effect of Diacetyl on Foodborne Microorganisms

A set of 70 organisms consisting of 9 lactic acid bacteria, 14 non-lactic gram positives, 16 yeasts, 6 molds, 12 pseudomonads, and 13 nonpseudomonad gram negative bacteria was tested on plate count agar (PCA) at pH 5.0 to 8.0 and in the presence of varying concentrations of diacetyl. All organisms were more sensitive to diacetyl at a pH of 7.0 and below than at pH 8.0 with the greatest sensitivity at pH 5.0. The lactic acid bacteria were the most resistant while the pseudomonads were the most sensitive. Excluding the lactic acid bacteria, 300 ppm completely inhibited 95, 90, 85, and 43% respectively at pH 5.0, 6.0, 7.0, and 8.0. Using PCA at pH 6.0, three Gram negative bacteria were inhibited by 86 ppm in pour plates while 6 of 7 nonlactic cultures were inhibited by 172 ppm. The compound was shown to be effective in fresh ground beef.     

pH值对再制干酪功能特性的影响

利用质构仪、流变仪、扫描电镜分析pH值对再制干酪产品功能特性的影响,揭示了pH在再制干酪生产过程中的重要作用。结果表明,pH值影响再制干酪的融化性,但是这种影响没有呈现一定的规律性;随着pH值的升高,再制干酪产品的表观黏度也随之升高;在各质构参数中,硬度和咀嚼性随着pH值的升高而降低,pH值对弹性的影响显著(P<0.05);pH值影响水和乳化的过程,pH值越高,越利于水和乳化。     

微生物来源的透明质酸酶

对微生物来源的透明质酸酶的结构、降解机制、分子生物学与应用等研究现状进行综述。     

商品化的新型高活性PET催化剂

Ａｋｚｏ Ｎｏｂｅｌ,即现在的Ａｃｏｒｄｉｓ开发出一种用于聚酯缩聚的新型高活性催倾剂,这种催化剂命名为Ｃ－９４。该催化剂是一种基于耐水解的钛／硅氧化物,其活性比锑基催化剂高６倍￣８倍,适用于所有的常规生产ＰＥＴ的合成路线;以ＤＭＴ或ＰＴＡ为原料的连续和间歇生产模式。评价了用于生产纤维级和瓶级的ＰＥＴ切片,而且中试表明Ｃ－９４同样适用其他聚酯产品如ＰＴＴ和ＰＢＴ,基于其广泛的应用前景,Ａｃｏｒｄｉｓ     

泡菜发酵中微生物的研究

泡菜的产生与形成是由多种天然微生物共同发酵的自然结果,研究泡菜发酵过程中的微生物,对于进一步深入研究和掌握泡菜发酵的生物化学理论,建立一个泡菜微生物发酵的过程并且和泡菜风味物质之间的联系形成一套可控制和相互调节的自动化系统,从而为进一步实现我国泡菜发酵和生产的工业化、自动化过程产生了极其重要的影响和意义.当前国内外的学...     

微生物来源的透明质酸酶

对微生物来源的透明质酸酶的结构、降解机制、分子生物学与应用等研究现状进行综述。     

Effect of Xylitol on Some Food-Spoilage Microorganisms

The effect of 0.5% xylitol, 0.5% glucose, and their mixture on the growth and the pH of the cultures of six food-spoilage microorganisms was studied. 0.1% xylitol inhibited most potently the growth of Clostridium butyricum and Lactobacillus bulgaricus, strongly retarding production of acid by these organisms. 0.5% xylitol also inhibited the growth of Saccharomyces cerevisiae, Escherichia coli, and Salmonella typhii, but not that of Aspergillus flavus. Less inhibition was observed with the sugar mixture than with 0.5% xylitol alone. ¹⁴C(U)-xylitol was not taken up by the cells during growth. Combined with the advantageous organoleptic and physiological properties of xylitol, the present results suggest that xylitol may be of value in the preservation of certain foods.     

微生物生产类胡萝卜素的研究进展

类胡萝卜素广泛存在于自然界中 ,可作为维生素A原 ,能够增强人和动物的免疫力 ,具有抗氧化、着色及防癌抗癌等功效。文中对类胡萝卜素的分布、生物合成、生理功能及基因工程等方面作一综述。     

市售仿水貂毛皮的鉴别方法

水貂毛皮具有很高的经济价值,市售毛皮产品中经常出现以黄狼(黄鼠狼)、河狸(海狸)、麝鼠(青根貂)毛皮来仿冒水貂毛皮的现象,令普通消费者甚至专业人士很难通过感官区分。本文借助现代分析仪器,利用扫描电镜法(SEM)观察水貂、黄狼、河狸、麝鼠毛皮绒毛的鳞片层特征;利用纤维细度仪法(FFI)观察这四种动物毛皮绒毛的内部超微结构。结果表明:通过扫描电镜分析可以有效区分水貂与河狸、水貂与麝鼠的毛皮,但由于黄狼和水貂均属于食肉目鼬科,其绒毛的鳞片形态基本一致,无法被有效区分;通过纤维细度仪分析可以有效区分水貂与黄狼、水貂与河狸的毛皮,但水貂和麝鼠绒毛有部分形态一致,也无法被有效区分。因此,在实际鉴别过程中,使用两种方法互为佐证,可作为水貂毛皮材质鉴定依据。     

强化维生素C的涂抹型再制干酪的研制

使用2个月和7个月的天然契达干酪为原料制作涂抹型再制干酪,对其进行VC强化,测定VC含量及其在产品中的稳定性。同时研究水分、乳化盐添加量对再制干酪质构的影响。使用木糖醇、白砂糖、葡萄糖调整产品口味。结果表明:2个月成熟干酪与7个月成熟干酪以2:1的配比,50%水,2%的乳化盐焦磷酸钠与三聚磷酸钠(1:1),80℃,1 500 r/min搅拌10min,加入VC,2%木糖醇、3%白砂糖与2%葡萄糖搅拌3min,得到易于保存,风味良好的产品。VC含量在储存期间无较大改变。