Screening of Enterobacterial Contamination During Gelatin Production and its Effect on Pharmaceutical Grade Gelatin

Summary Gelatin, an animal protein derived from collagen has many industrial applications; mainly in food and pharmaceutical products. In this study, enterobacterial contamination of gelatin during different stages of its manufacturing was examined. Since gelatin is extracted in the form of liquor by hot water treatment of ossein and undergoes a complex series of processing stages before being finally blended and packaged off as dry gelatin product, contamination at any stage affects the quality of the final product. In total, 142 samples of gelatin were analysed for the presence of enteric bacteria, which were obtained from different stages of gelatin processing. The Enterobacteriaceae-positive samples were processed and these enterobacterial species were isolated and identified as Proteus mirabilis, Serratia marcescens, E. coli, Salmonella typhi, Klebsiella oxytoca, Klebsiella pneumoniae, Shigella flexneri and Serratia liquefaciens. These were tested for gelatinase activity. The eight species producing maximum gelatinolysis were selected and protease zymography was performed using 1% (w/v) gelatin as a substrate in 7.5% (w/v) acrylamide gel and their molecular weights were determined. The effect of these bacteria on the quality of gelatin was assessed chromatographically in terms of change in amino acid content of gelatin broth inoculated by these species, which showed a marked change with length of incubation. Since these enteric bacteria possess pathogenic properties, some of them are gelatinolytic and also have a significant effect on the quality and amino acid content of gelatin, they are of great concern both for the manufacturers as well as for the consumers.     

海藻酸钠明胶协同固定化的研究

目的:研究不同因素对固定化微胶囊的影响以及不同物质向微胶囊扩散的规律。方法:采用海藻酸钠与明胶协同固定化制备微胶囊,考察了海藻酸钠、明胶浓度等因子对微胶囊直径与机械强度的影响,以及牛血清蛋白与葡萄糖向微胶囊扩散的状况,并利用非稳态传递模型计算了这两种物质在微胶囊中的有效扩散系数。结果:随着海藻酸钠质量浓度的升高,微胶囊的直径与机械强度逐渐增大。制备的最优条件是CaCl2浓度为10%,滴定速度为180滴/min,最优浸泡时间为30min。在此条件下,葡萄糖与牛血清蛋白的有效扩散系数分别为4.63×10-5cm2/min、1.01×10-7cm2/min。结论:海藻酸钠明胶协同固定化制备的微胶囊作为一种生物载体,非常适合细胞或酶的固定化。     

基于串联质谱的鱼皮明胶鉴别研究

在胶原蛋白序列比对基础上,以虹鳟鱼明胶、猪明胶和牛明胶为模型,利用高效液相色谱－串联质谱技术（HPLC-MS/MS）研究了3种明胶降解多肽组成的差异。使用胰蛋白酶将鱼皮明胶进行了酶解处理,使用HPLC-MS/MS对酶解产物中的多肽组成进行了分析,并与猪和牛明胶酶解产物中的多肽进行了比较。结果表明鱼明胶酶解产物中存在特征多肽,通过特征多肽的种类可区别鱼明胶与猪和牛明胶,研究了明胶多肽中脯氨酸羟基化修饰、明胶分子量范围和脱酰胺化对特征多肽识别的影响。研究表明利用HPLC-MS/MS技术通过识别明胶酶解产物中的特征多肽进行鱼皮明胶鉴别具有可行性。