Effect of pre-rigor temperature incubation on sarcoplasmic protein solubility,calpain activity and meat properties in porcine muscle

The aim of the study was to investigate the effect of pre-rigor temperature incubation on sarcoplasmic protein characteristics in relation to meat properties within porcine muscle. Porcine Longissimus dorsi muscles were incubated at temperatures of 0, 10, 20, 30 and 40 °C to 6 h post mortem. Incubation at 40 °C induced a significant decrease of sarcoplasmic protein solubility and an increase in proteins in the myofibrillar fraction. The protein relocation was followed till 72 h post mortem but had largely been completed by the end of the temperature incubation at 6 h. SDS-PAGE and Western blot analyses suggested that phosphorylase and creatine kinase precipitated onto the myofilaments during incubation at 40 °C. Drip loss increased following incubation at 40 °C, indicating that the precipitation of phosphorylase and creatine kinase may be a factor of reduced water-holding capacity at the combination of high temperature and low pH. Incubation at 40 °C resulted in substantially lower shear force in parallel with loss of extractable activity of μ- and m-calpain, suggesting a rapid activation of both enzymes at high temperatures and low pH early post mortem.     

Rheology of cellulosic N‐methylmorpholine oxide monohydrate solutions of different degrees of polymerization

Preparation and shear and elongational rheology of cellulose solutions of different degrees of polymerization (DP) in N‐methylmorpholine oxide monohydrate (lyocell) were investigated. The dissolution process takes place in two stages, depending on the content of low and high DP fractions from the dissolving pulp blends. The influence of the DP of cellulosic chains on elongational and shear viscosity is greater at low deformation rates. Low DP solutions behave more like viscous fluids and the increase of the chain length brings about an increase of the elastic component. Orientation induced by the convergence flow is enhanced by the higher DP cellulosic chains. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 396–405, 2001     

脱水法制备无水N-羟基丁二酰亚胺

介绍了制备N 羟基丁二酰亚胺的一般方法 ,研究了采用丁二酸酐与盐酸羟胺制备N 羟基丁二酰亚胺水合物的工艺方法 ,以及从一水合N 羟基丁二酰亚胺出发制备高纯度无水N 羟基丁二酰亚胺的方法     

The Regulation and Expression of the Creatine Transporter: A Brief Review of Creatine Supplementation in Humans and Animals

Creatine monohydrate has become one of the most popular ergogenic sport supplements used today. It is a nonessential dietary compound that is both endogenously synthesized and naturally ingested through diet. Creatine ingested through supplementation has been observed to be absorbed into the muscle exclusively by means of a creatine transporter, CreaT1. The major rationale of creatine supplementation is to maximize the increase within the intracellular pool of total creatine (creatine + phosphocreatine). There is much evidence indicating that creatine supplementation can improve athletic performance and cellular bioenergetics, although variability does exist. It is hypothesized that this variability is due to the process that controls both the influx and efflux of creatine across the cell membrane, and is likely due to a decrease in activity of the creatine transporter from various compounding factors. Furthermore, additional data suggests that an individual's initial biological profile may partially determine the efficacy of a creatine supplementation protocol. This brief review will examine both animal and human research in relation to the regulation and expression of the creatine transporter (CreaT). The current literature is very preliminary in regards to examining how creatine supplementation affects CreaT expression while concomitantly following a resistance training regimen. In conclusion, it is prudent that future research begin to examine CreaT expression due to creatine supplementation in humans in much the same way as in animal models.     

蓖麻酸正丁酯的催化合成研究

用NaHSO4.H2O作催化剂,对蓖麻酸与正丁醇酯化反应进行了研究。在回流温度(油浴温度145~150℃)下,分别考察了催化剂用量、醇酸摩尔比、反应时间对酯化反应的影响。得出的优化工艺条件为:催化剂用量1.01%(催化剂与蓖麻酸的质量比)、醇酸摩尔比2.5(蓖麻酸0.2mol)、反应时间2h。在该工艺条件下,蓖麻酸的平均酯化率可达95%。红外光谱表明:反应过程蓖麻酸中的羟基和双键保存完好,催化剂表现出了很好的活性和很高的选择性。该方法的产物后处理工艺简单且不污染环境。     

一水合硫酸氢钠催化合成丙酸苄酯的研究

用一水合硫酸氢钠催化苯甲醇与丙酸的酯化反应合成了丙酸苄酯。研究结果表明:一水合硫酸氢钠具有较高的催化活性。考察了催化剂用量、苯甲醇与丙酸摩尔比、反应时间、反应温度和带水剂环己烷用量对丙酸苄酯收率的影响。在典型反应条件下(苯甲醇与丙酸摩尔比=0 1∶0 2,1 0g催化剂/0 2mol丙酸,反应时间2 5h,反应温度95～110℃,15mL环己烷/0 2mol丙酸),丙酸苄酯的收率可以达到82 3%。该催化剂易于回收且可重复使用,具有良好的活性及稳定性,是合成丙酸苄酯的理想催化剂。     

高压微波催化合成对硝基苯甲酸乙酯

以一水合硫酸氢钠为催化剂，利用高压微波技术，快速合成了对硝基苯甲酸乙酯。用正交试验研究了各反应因素对产品收率的影响，确定最佳反应条件为：以2．0g对硝基苯甲酸为准，醇酸物质的量比为4：1，催化剂用量为1．0g，微波时间为9min，微波功率为522w，产率达97．8％。