Acid adaptation affects the viability of Salmonella typhimurium during the lactic fermentation of skim milk and product storage

In this study, Salmonella typhimurium was acid adapted at pH 5.5 for 4 h. The viability of the acid-adapted and non-adapted cells of S. typhimurium was investigated both during the lactic fermentation of skim milk with Streptococcus thermophilus or Lactobacillus bulgaricus, and during the storage of lactic fermented milk products at 5 degrees C. It was found that the viable population of S. typhimurium, regardless of acid adaptation, increased in skim milk during the initial 24 h of lactic fermentation and then declined. However, the viable population of acid-adapted S. typhimurium was significantly higher (P<.05) than that of non-adapted cell at the end of 48 h of fermentation. Acid-adapted cells of S. typhimurium were also found to have survived better than non-adapted cells in the S. thermophilus-prepared fermented milk and two commercial lactic fermented milk products. The viability of the acid-adapted and non-adapted S. typhimurium at 5 and 37 degrees C in cell-free fermented milks that had their pHs adjusted to 6.4 and skim milk (pH 6.4) was further investigated. Results revealed that acid adaptation, in addition to enhancing acid tolerance, reduced the susceptibility of S. typhimurium to refrigerated temperature and other detrimental factors which might be present in lactic fermented milk products. These responses all contribute to the enhanced survival of acid-adapted S. typhimurium in the lactic fermented milk products observed in the present study.     

影响草毒果汁红色素变化的因子研究

通过试验对草莓果汁在加工及继后贮藏过程中,影响红色素变化的因子进行了研究。结果表明,迅速加热果实温度到60℃,有利于提高果汁中红色素含量;向果汁中分别加入0.1%~0.4%的抗坏血酸、酒石酸和柠檬酸对果汁具有明显的增色作用;而加入1.0%~15.0%的葡萄糖和蔗糖对果汁颜色没有影响;调整果汁pH值到4.0以下有助于保持果汁的固有颜色;采用低温避光贮存果汁可延缓草莓果汁红色素的降解。     

植酸在黄酒酿造中的应用研究初探

本文通过添加植酸于黄酒酵母菌生长发酵基质中,研究植酸在黄酒酿造中的应用,初步得出如下结论:①最适植酸添加浓度为0.10%,至主发酵结束,酒精度最大可提高13.16%;②植酸能促进黄酒酵母菌细胞增殖,使酵母菌提前进入对数生长期,提高出芽率,降低死亡率,并表现出较好的同步性,从而加快发酵速度;③植酸使黄酒酵母菌的耐酒精度从16%提高到20%;④黄酒醪中添加植酸,发酵周期缩短且各项理化指标均有较大改善,从而提高了黄酒产量和质量。     

生物微胶囊固定化Candida krusei的研究

以一种新型NaCS/PDMDAAC(sodium cellulose sulfate/poly[dimethyl(diallyl)ammonium chloride])生物微胶囊体系包埋耐高渗型产甘油酵母Candia krusei ICM-Y-05。较详细研究了C.krusei在囊内的生长曲线,以及葡萄糖和甘油在囊内外随培养时间变化的情况。结果表明,经生物微胶囊包埋后的细胞在囊内具有二次生长现象。对固定化细胞培养过程中传质系数的测定表明,细胞在囊内的生长对胶囊传质特性有较大的影响,而囊内活细胞数随培养时间的变化并没有减少的趋势,从侧面证明了传质会部分改变囊内细胞生理代谢特性。     

2010中国国际网印及数字化印刷展

由中国印刷技术协会和中国网印及制像协会共同主办的2010中国国际网印及数字化印刷展／2010中国国际纺织品印花展／2010中国（广州）标签印刷技术展将于2010年12月2—4日在广州·琶洲·保利世贸博览馆（广州市海珠区新港东路1000号）举行。本届展会将以“绿色环保、自主创新”为主题,     

Hexachlorocyclohexanes in the North American atmosphere

Annually integrated air concentrations of alpha- and gamma-hexachlorocyclohexane (HCH) were determined in 2000/2001 at 40 stations across North America using XAD-based passive air samplers to understand atmospheric distribution processes on a continental scale. Elevated levels of gamma-HCH in the atmosphere of the Canadian Prairies are consistent with the ongoing use of lindane as a seed treatment on canola and confirm the feasibility of detecting the agricultural use of a pesticide using long-term integrated passive air sampling. In contrast to gamma-HCH, the atmospheric concentrations of alpha-HCH show a rather uniform distribution across Canada and the United States, which is expected for a chemical with no current use on the continent. Higher levels in the atmosphere over Atlantic Canada can be explained by alpha-HCH evaporating from the waters of the Labrador Current, which is supported bythe chiral composition of alpha-HCH and the temperature dependence of its atmospheric concentrations along the east coast of Canada. Similarly, alpha-HCH is volatilizing from Lake Superior. Atmospheric HCH levels increase with elevation in the Canadian Rocky Mountains. The results suggest that evaporation, in particular from cold water bodies, is an important source of alpha-HCH to the North American atmosphere. Low levels of HCHs in Central America hint at efficient degradation under tropical conditions. Chiral analysis shows that (+)-alpha-HCH is often enriched in air over continental areas and at the Pacific Coast, which is opposite to the enantiomeric enrichment in the proximity to the Great Lakes and the Atlantic Ocean. Passive air sampling is a powerful tool to discern the large-scale variability of semivolatile and persistent organic chemicals in the atmosphere.     

A potential contribution of the less negatively charged cell wall to the high aluminum tolerance of Rhodotorula taiwanensis RS1

Rhodotorula taiwanensis RS1 (Rt) is a high‐aluminum (Al)‐tolerant yeast that can survive Al at concentrations up to 200 mM. In this study, we compared Rt with an Al‐sensitive congeneric strain, R. mucilaginosa AKU 4812 (Rm) and Al sensitive mutant 1 (alsm1) of Rt, to explore the Al tolerance mechanisms of Rt. The growth of Rm was completely inhibited by 1 mM Al, but that of Rt was not inhibited until Al concentration was more than 70 mM. The growth of alsm1 was inhibited much more by 70 mM and 100 mM Al than that of Rt. Compared with Rm cells, Rt cells accumulated less Al in the cell wall and cytoplasm. A time‐course analysis showed that Al was absorbed by Rm cells much more rapidly than by Rt cells when exposed to the same Al concentration. Meanwhile, the Al content of alsm1 was higher than that of Rt. Although the cell wall of Rt was thicker than that of alsm1 and Rm under control and 0.1 mM Al, that of Rt was thinner than that of alsm1 under 70 mM Al despite that their cell walls were thickened. The alcian blue adsorption was lower and cell wall zeta‐potential was higher in Rt and alsm1 than in Rm, indicating a less negative charge of cell wall of Rt and alsm1 than that of Rm. Taken together, the less negatively charged cell wall of Rt may restrict the adsorption of cationic Al in cells, potentially contributing to its high Al tolerance. Copyright © 2016 John Wiley & Sons, Ltd.     

绿松石结构的致密性对其颜色量化研究的影响

绿松石的结构致密性对其颜色量化研究工作存在重要影响。采用国际公认的色度学变量CIE 1976色差(ΔE)来表征绿松石样品在特定区域内颜色的不均一性,通过静水称重法和原子力显微镜(AFM)来表征结构致密性的体相和表相特征。结果发现,质地疏松绿松石存在较大色差、较大的表面粗糙度及较小的相对密度。激光剥蚀电感耦合等离子质谱仪(LA-ICP-MS)研究绿松石成分显示,疏松绿松石样品中致色元素含量呈现较大的测量不确定性,存在很严重的随激光剥蚀时间延长而迅速衰减的现象,而致密绿松石样品并无此现象。出土疏松绿松石样品的受沁程度和色差也明显大于致密样品。相对而言,高致密性绿松石具有相对密度较大、表面平滑度较高、颜色分布较为均一、致色元素分布较为规律、抗污染能力较强等优良特征。因此,在后续绿松石颜色量化分级工作当中,对致密性进行严格定量显得尤为必要。     

低沸点溶剂萃取植物营养油

利用低沸点溶剂萃取技术 ,对 3种植物油进行提取和精炼试验 ,获得高质量的精制油。结果表明 :紫苏籽精制油中含α 亚麻酸 5 5 % ,油酸 2 0 % ,亚油酸 1 2 % ,是富含α 亚麻酸的油品之一 ;紫草籽精制油中含γ 亚麻酸 1 3 5 % ,α 亚麻酸 3 1 % ,油酸 1 2 % ,亚油酸 2 1 6% ,是迄今为止发现的γ 亚麻酸含量最高的油品之一 ;碱蓬籽精制油中含亚油酸 70 % ,油酸 1 1 % ,α 亚麻酸 6% ,说明碱蓬籽油具有很好的营养价值。     

微生物酶与肉组织酶对干发酵香肠中游离脂肪酸的影响

以戊糖乳杆菌31-1和木糖葡萄球菌为发酵剂生产干发酵香肠,就发酵剂对干发酵香肠成熟过程中游离脂肪酸的影响进行了研究。研究结果表明,在灌肠后的1周内,脂肪的水解主要是由组织酶引起的,微生物对脂肪微弱的水解能力主要表现在干发酵香肠成熟的后期,并且发酵剂不能改变发酵香肠中游离脂肪酸的变化模式。