胰蛋白酶在合成高分子阴离子交换树脂上的固定化作用

研究了胰蛋白酶在合成高分子聚苯乙烯阴离子交换树脂上的固定化技术,固定化酶的动力学性质以及稳定性特征。阴离子交换树指GM201经预处理除去杂质后与偶联剂成二醛反应,再与胰蛋白酶反应,可把酶固定化在载体上。动力学分析表明:固定化胰蛋白酶的K_m(米氏常数)值高于溶液酶,最适温度及最适pH值均有较大变化。稳定性试验表明:固定化酶的热稳定性低于溶液酶,在微酸性,中性及碱性介质中的稳定性高于溶液酶。用固定化胰蛋白酶水解酪蛋白及提取大豆胰蛋白酶抑制剂的试验结果表明,固定化酶具有良好的操作稳定性。     

Thermomechanical properties of biodegradable films based on blends of gelatin and poly(vinyl alcohol)

The aim of this work was to study the effect of the poly(vinyl alcohol) (PVA) concentration on the thermal and viscoelastic properties of films based on blends of gelatin and PVA using differential scanning calorimetry (DSC) and dynamic-mechanical analysis (DMA). One glass transition was observed between 43 and 49 °C on the DSC curves obtained in the first scanning of the blended films, followed by fusion of the crystalline portion between 116 and 134 °C. However, the DMA results showed that only the films with 10% PVA had a single peak in the tan δ spectrum. However, when the PVA concentration was increased the dynamic mechanical spectra showed two peaks on the tan δ curves, indicating two T_gs. Despite this phase separation behavior the Gordon and Taylor model was successfully applied to correlate T_g as a function of film composition, thus determining k=7.47. In the DMA frequency tests, the DMA spectra showed that the storage modulus values decreased with increasing temperature. The master curves for the PVA–gelatin films were obtained applying the TTS principle (T_r=100 °C). The WLF model was thus applied allowing for the determination of the constants C₁ and C₂. The values of these constants increased with increasing PVA concentrations in the blend: C₁=49–66 and C₂=463–480. These values were used to calculate the fractional free volume of the films at the T_g and the thermal expansion coefficient of the films above the T_g.     

考马斯亮蓝G250染色法测定啤酒中蛋白质含量

以啤酒为原料,利用蛋白质与考马斯亮蓝显色原理,测定啤酒中蛋白质含量,并对测定条件进行优化研究,实验结果表明：波长在595nm处蛋白质有最大吸收峰,反应时间3～5min为最适宜,SDS对马斯亮蓝测定蛋白质含量有干扰。测定所用的标准曲线方程为：v=0．1296x＋0．0907。考马斯亮蓝G-250法测量蛋白质含量与凯氏定氮法相比较误差范围3％～8％。     

Breaking of structural dormancy in seeds of Tetrapleura tetraptera by Aspergillus niger

Aspergillus niger (strain UUF9202) significantly reduced the dormancy period and boosted aggregate germination percentage (AGP) in seeds of Tetrapleura tetraptera. A net reduction in mean germination time (MGT) to 12 days and an increase from 0 to 42% AGP were obtained in 32 days. The optimal spore inoculum of the fungus was 8.5 × 10≥10 ml^?1 per 100 seeds in 96 h pregermination incubation. The potential of some physical factors in combination with this fungal concentration in enhancing AGP was evaluated. The treatments were as follows: (i) hot water scarification at 30°C, 50°C, 80°C and 100°C plus A niger; and (ii) nicking by decoating at either the micropylar or chalazal ends plus A niger. Micropylar scarification plus A niger gave the highest AGP (94%) followed by chalazal scarification plus A niger (86%) and hot water dip at 80°C + A niger (82%). The control seeds which were soaked in presterilised (by autoclaving at 121°C for 15 min) A niger spore suspension at 30°C gave zero germination.     

菜籽粕脱毒提取菜籽蛋白研究进展：Ⅱ菜籽分离蛋白的制取

比较了不同萃取水相、菜籽品种及菜籽加工方法对蛋白质萃取率的影响。介绍了几种具有较高蛋白质得率的菜籽分离蛋白制取工艺，并对降低分离蛋白产品植酸含量进行了讨论。     

优化麦胚蛋白粉制备工艺的研究

本文对麦胚蛋白粉的制备工艺进行了研究，并利用正交实验确定了制备蛋白粉的最佳磨浆工艺条件为：浸泡温度为70℃，浸泡料水比为1：10，磨浆温度为75℃，磨浆料水比为1：9，制得的麦胚蛋白粉蛋白质的含量为45．0％，麦胚蛋白氮可溶解性指数达到52．6％。     

Molecular detection of meat animal species targeting MT 12S rRNA gene

The efficacy of PCR-RFLP analysis of mt 12S rRNA gene in identification of animal species from meat samples of known and unknown origin and adulterated meat samples was evaluated. In PCR, all the samples generated an amplicon of 456 bp. Restriction enzyme digestion of the PCR product with AluI, HhaI, BspTI and ApoI revealed characteristic RFLP patterns. Of the samples of unknown origin few were identified as cattle, few as buffalo and some were admixtures of two, suggesting adulteration. The RFLP pattern of one did not match any of species included in the study, which on sequencing was confirmed as camel meat. Application of this technique on adulterated meat samples could detect both animal species in proportion of 50:50 and 75:25 (except in case of goat+cattle). The technique however could not detect any of the two species when proportion of mixture was 90:10 (except in case of cattle+buffalo).     

Effect of low-voltage electrical stimulation after dressing on color stability and water holding capacity of bovine longissimus muscle

The effect of low voltage electrical stimulation after dressing (ES) on color stability and water holding capacity (WHC) of beef was investigated. Nine Swedish red cattle were slaughtered and the left side was electrically stimulated (80 V, 35 s) approximately 30 min after stunning, whereas the other side was not treated and used as control. Color and its stability, WHC, and protein solubility were evaluated on longissimus lumborum muscles from the two sides. ES produced a brighter red color at 24h mainly by increasing the oxygenation capacity of myoglobin (P<0.01), which was attenuated by postmortem aging. ES did not affect WHC, protein solubility and color stability (P>0.05). Therefore, this technology could accelerate meat tenderization without any negative effect on commercial attributes, such as color or drip of bovine longissimus muscle.     

Isolation and characterization of a new dimeric esterase from Lactobacillus sakei 23K

The M_w of a Lactobacillus sakei intracellular esterase, determined by gel filtration, was compared to those obtained from SDS-PAGE or MALDI-TOF, pointing to a dimeric structure. Its N-terminal sequence and peptide mass fingerprint suggest that it is the putative LSA044 protein from L. sakei 23K genome.