Quality Assessment of Commercially Processed Carbon Monoxide‐Treated Tilapia Fillets

Carbon monoxide (CO) has been used to stabilize the color of fish muscle during frozen storage and distribution. This study compared changes in the quality profiles of CO‐treated and untreated (UT) tilapia fillets stored at 21 to 22 °C (room temperature), 4 to 5 °C (refrigerated), and 0 °C (iced). Samples (n = 3) were analyzed at different time intervals for chemical, lipid oxidation, microbiological, color, and expert sensory profiles. CO samples contained greater (P < 0.05) apparent ammonia and total volatile base nitrogen (TVB‐N) at day 0, with greater (P < 0.05) TVB‐N throughout refrigerated and iced storage. At time 0, peroxide values (POV) and thiobarbituric‐acid‐reactive substances were lower (P < 0.05) for CO samples and continued to have lower trends throughout all storage temperatures. Microbiological analysis at time 0 did not show any differences between UT and CO samples. Redness (a*) color values were greater (P < 0.05) in CO tilapia at time 0; however, treated product showed a more rapid decline in a* throughout all storage temperatures. While expert sensory evaluation showed no statistical differences between UT and CO tilapia at time 0, CO product failed sensory assessment sooner than UT product when stored refrigerated and in ice.     

Viscoelastic Behavior of Commercially Processed Soy Isolate Pastes During Heating and Cooling

The viscoelastic properties of soy isolate dispersions of Prolina and Brim cultivars, commercially processed, were compared during heating and cooling utilizing small deformation rheology. All isolates formed gels upon hydration. Heating to 90 °C yielded less rigid gels, as evidenced by a decreasing G'. Holding at 90 °C induced an increase in G' for Brim isolate, possibly as a result of increased hydrophobic and/or covalent bonding. Cooling to 25 °C generated a G' increase above initial levels for both cultivars, likely due to enhanced intermolecular hydrogen bonding. Mechanical spectra at 25 °C before and after heating, and at 90 °C before and after holding, confirmed these observations. A lower G' was consistently exhibited by Prolina gels throughout testing.     

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。     

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.     

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.     

Sensory Profiles for Dried Fig (Ficus carica L.) Cultivars Commercially Grown and Processed in California

A trained sensory panel evaluated the 6 fig cultivars currently sold in the California dried fig market. The main flavor and aroma attributes determined by the sensory panel were “caramel,” “honey,” “raisin,” and “fig,” with additional aroma attributes: “common date,” “dried plum,” and “molasses.” Sensory differences were observed between dried fig cultivars. All figs were processed by 2 commercial handlers. Processing included potassium sorbate as a preservative and SO₂ application as an antibrowning agent for white cultivars. As a consequence of SO₂ use during processing, high sulfite residues affected the sensory profiles of the white dried fig cultivars. Significant differences between dried fig cultivars and sources demonstrate perceived differences between processing and storage methods. The panel‐determined sensory lexicon can help with California fig marketing.     

超高压对泡萝卜的杀菌效果及其动力学研究

研究300～600 MPa超高压条件下处理四川泡萝卜5～25 min,对其细菌总数的影响、对霉菌、酵母菌及大肠菌群的杀灭效果的影响。并采用3 种模型对不同压力条件下杀菌动力学过程进行分析比较。结果表明：随处理压力和时间的增加,超高压对泡萝卜的杀菌效果增强;霉菌和酵母菌对压力较为敏感,500 MPa处理5 min可被全部杀死;Weibull模型能很好地拟合泡萝卜超高压杀菌的动力学过程（决定系数R2＞0.99）,且相较Log-logistic模型更简洁、灵活实用。尺度参数b随处理压力的增加而增大,形状参数n则随压力的增加而减小。     

Nature Abhors a Vacuum: Highly Diverse Mechanisms Enable Spoilage Fungi to Disperse,Survive, and Propagate in Commercially Processed and Preserved Foods

Fungal spoilage in processed foods remains a challenge for food manufacturers despite the increasing availability of diverse processing and formulation strategies used to control foodborne microorganisms. Physiological features of yeasts and molds contribute to their tolerance to thermal processing, acidity, desiccation, and oxygen and nutrient limitations. These features variably include growth form, cell wall structure, cytoplasmic composition, cell membrane‐bound proteins, and secretion of secondary metabolites. Collectively, these mechanisms contribute to the ability of fungi to disperse, survive, and propagate in highly restrictive food environments. The diversity of fungal growth and survival mechanisms has resulted in organisms adapted to nearly all food environments; although, only a small subset of fungi are particularly suited for spoilage of a given product. The relationship between the individual physiology and metabolic capabilities of a yeast or mold and the product's specific physicochemical attributes and processing history determines spoilage potential. Explicit characterization of the fungal features responsible for this extremotolerance contributes to more targeted and effective control strategies.     

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.     

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。     

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.     

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.     

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.     

乳源外泌体对微生物的作用

外泌体是纳米级(直径40~160 nm)的胞外囊泡,在细胞信号转导、免疫应答和抗原递呈过程中发挥作用,并存在于多种体液,包括血清、唾液、尿液、脑脊液和乳液等。乳外泌体携带蛋白质、miRNA等多种功能分子,很多与人体免疫功能相关。摄取乳液后,乳外泌体中的内容物可被人体肠道吸收,从而发挥健康作用。本文总结国内外有关乳源外泌体与微生物关系的研究报道以及本团队的研究成果,阐述外泌体的生物发生过程,主要组成成分,外泌体与病原微生物感染的关系以及乳外泌体对肠道微生物的作用,为研究乳外泌体对人体的营养和健康功效提供参考。     

加工食品对ACE活性的影响

目的:了解不同加工食品对ACE活性的影响,为筛选具有降血压作用的食品提供数据支撑.方法:选择15种饮料、5种坚果及8种其它固体加工食品进行水提取、乙醇提取和胃蛋白酶解,采用高效液相色谱法(HPLC)检测马尿酸含量变化,了解提取物对体外血管紧张素转化酶(ACE)活性的影响.结果:绝大多数食品的乙醇提取物能促进ACE活性,...     

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.     

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。     

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。