烟梗与叶片氨基酸组成差异和相关性研究

为了解烤烟烟梗中氨基酸含量和组成特点,选择了国内18个代表性产地,对上、中、下部位烤烟烟梗和对应叶片样品氨基酸进行了测定,比较了烟梗和叶片20种氨基酸含量差异,分析了烟梗与对应叶片氨基酸含量的相关性,并考察了不同部位烟梗氨基酸差异规律。结果显示,烟梗中氨基酸总量略高于叶片,烟梗中异亮氨酸、酪氨酸、天冬氨酸等11种氨基酸含量显著高于对应叶片,色氨酸、组氨酸等4种氨基酸含量显著低于叶片;不同烟梗间氨基酸含量变异性大于叶片间变异性;除缬氨酸、苏氨酸和胱氨酸,烟梗其他氨基酸含量与对应叶片氨基酸含量有显著相关性;上部烟梗氨基酸含量高于中部和下部烟梗。总之,烟梗与对应叶片氨基酸含量具有正相关性,但组成有显著差异。     

鲤鱼肌肉蒸制过程中的品质变化

采用理化检验、光学显微镜和质构分析法(TPA)对新鲜鲤鱼肌肉组织在蒸制过程中理化性质、微观结构和质构特性进行了分析,并采用SDS-PAGE电泳法分析了流失液的蛋白形式,以期明确鲤鱼肌肉在蒸制过程中品质变化规律,提出鲤鱼肌肉组织蒸制的最佳工艺条件。研究表明:随加热时间延长,肌肉组织失重率、失水率和p H值呈上升趋势,肌原纤维蛋白提取率在2 min内迅速降低,而后缓慢降低。鱼肉蒸制后肌浆蛋白等水溶性蛋白流失,随时间延长蛋白质变性程度加深。加热过程中肌肉组织微观结构变化明显,纤维间隙逐渐增大直至纤维断裂。硬度、咀嚼性、回复性及剪切力均随加热时间延长而降低,在4 min后趋于平稳。综合分析,为保证营养价值和质构特性,规格为1.5 cm3的鲤鱼肌肉组织蒸制时间为4 min较好。     

打顶后供钾水平对烟草体内钾素积累分配的影响

本试验采用砂培和营养液培养的方式,探索了打顶后供钾水平对烟草体内钾素积累分配的影响。结果表明,打顶能够促进烟株的生长,增加生物量。钾素在烟株体内移动活跃,无钾培养烟株的根部有大量钾素向叶片运输;提高供钾水平,烟株的钾浓度和钾含量显著提高。打顶后烟株的钾浓度和钾含量下降,但钾素在叶片的积累量增加,上部叶片的钾含量显著提高。     

胡柚精油提取工艺优化与理化特性研究

采用水蒸气蒸馏法提取胡柚精油,以单因素试验为基础设计正交试验L9(33),考察了液料质量比、蒸馏时间及氯化钠添加量作为主要影响因子对胡柚精油得率的影响,并对所得精油的理化性质进行了分析。结果表明,蒸馏时间120 min,提取液料质量比4∶1,氯化钠添加量5%是胡柚精油提取的最佳工艺参数,精油的得率可达最大值1.28%;同时所得精油经气-质分析,共鉴定出含有47种化合物,主要成分为柠檬烯(33.78%)和γ-松油烯(31.08%),与其它柑橘类精油有较大的差别。     

培养条件对银耳菌丝体及胞外多糖产量的影响

研究了不同培养条件对银耳菌丝体生物量及多糖产量的影响,结果显示,最适合银耳菌丝体生长及胞外多糖(EPS)分泌的碳源分别是葡萄糖和半乳糖,氮源分别是硝酸铵和谷氨酸钠。菌丝体EPS产量最高的碳氮比是70∶1,且生物量均随碳氮比的增加而增加。菌丝体的EPS产量在第10d达到最大值,其pH随之降至最低。     

干红葡萄酒下胶澄清后两种分离方式的比较

结合实际生产需要,研究红葡萄酒下胶澄清后两种分离方式对酒的感官和理化指标的影响。试验证明两种分离方式对酒的感官和理化指标几乎没有差别,干红葡萄酒在下胶澄清后采用离心的方式分离悬浮颗粒比过滤方式更能提高容器的利用率,缩短生产周期和降低运行成本。     

水样中氨态氮含量的不同测定方法比较

分别采用纳氏试剂比色法、苯酚—次氯酸盐(或水杨酸—次氯酸盐)比色法和凯氏定氮仪蒸馏—滴定法对两种水样进行氨态氮含量的测定,比较了不同方法的检测精确度和准确度。结果显示,凯氏定氮仪蒸馏—滴定法的准确度和精确度最高,适用于有浊度或颜色的水样。     

游泳时间、采血时间对小鼠血乳酸浓度的影响

为研究运动时间、采血时间对动物血乳酸浓度的影响，通过对动物的基础性研究，测得小鼠在不同游泳时间、不同运动强度下血乳酸的变化及不同取血时间对血乳酸测定值的影响。研究结果表明，小鼠在运动时随游泳时间延长及运动强度增大，血乳酸浓度逐渐升高，而后缓慢下降，随运动强度继续增大，血乳酸浓度继续升高，长时间运动后即刻取血，测得的血乳酸浓度显著高于运动后１５ｍｉｎ取血（Ｐ＜０．００１）。     

Uptake and utilization of ectoine by halotolerant Brevibacterium sp. JCM 6894 subjected to osmotic downshock

The concentration changes of the cyclic amino acid ectoine (1,4,5,6-tetrahydro-2-methyl-4-pyridine carboxylic acid) in Brevibacterium sp. JCM 6894 cells subjected to an osmotic downshock were investigated. When the cells grown in the presence of 2 M NaCl were suspended in deionized water, they immediately released about 60% of the ectoine synthesized intracellularly. During the subsequent incubation, we observed that both the extra- and intracellular concentrations of ectoine were reduced almost linearly with the incubation time. When ectoine was provided externally to the downshocked cells, a similar reduction in both intra- and extracellular ectoine concentrations was recognized. In addition, we observed an increase in ectoine accumulation at about 10 h of incubation, which indicates that ectoine was taken up by such downshocked cells in the absence of external Na+. Furthermore, the downshocked cells showed higher levels of survival, respiration, and growth in the presence of ectoine than in its absence. The ability to take ectoine up was induced in the cells grown in the presence of >0.25 M NaCl for >12 h. Thus, we conclude that even under the lower osmotic condition ectoine might be taken up and subsequently utilized by strain JCM 6894 subjected to the osmotic downshock, indicating that the uptake of ectoine by such cells occurred for the survival and growth of the cell itself rather than for cellular osmoregulation.     

Physiochemical Properties of Polysaccharides Extracted from Tofu Processing Wastewater

ABSTRACT: Yield, gelation, viscosity, emulsifying properties, and sugar composition of polysaccharides extracted from tofu processing wastewater under acidic conditions at different temperature levels and incubation times were determined. Optimum extraction for water-soluble polysaccharides was at pH 1.5 and 100 °C over an incubation period of 6 hours. Extraction ratio (%) and yield of high-molecular-weight polysaccharides were higher at pH ranges of 1.5 to 3.0 with extraction temperatures of 80 to 100 °C. Most water-soluble polysaccharides extracted under strong acidic conditions and above 80 °C remained fluid, while most extracted within the range of 45 to 80 °C gelled. Pure polysaccharides exhibited better emulsifying properties than water-soluble polysaccharides. Apparent viscosities of water-soluble polysaccharides were dependent on sugar concentration.