Technische Universität München, Biotechnology of Natural Products, Liesel-Beckmann-Straße 1, D- 85354 Freising, Germany.
Food Microbiol. 2012 Apr;29(2):215-23. doi: 10.1016/j.fm.2011.07.007. Epub 2011 Jul 22.
The microbial degradation of proteins, peptides and amino acids generates volatiles involved in the typical flavor of dry fermented sausage. The ability of three Lactobacillus sakei strains to form aroma compounds was investigated. Whole resting cells were fermented in phosphate buffer with equimolar amounts of substrates consisting of dipeptides, tetrapeptides and free amino acids, respectively. Dipeptides disappeared quickly from the solutions whereas tetrapeptides were only partially degraded. In both approaches the concentration of free amino acids increased in the reaction mixture but did not reach the equimolar amount of the initial substrates. When free amino acids were fed to the bacteria their levels decreased only slightly. Although peptides were more rapidly degraded and/or transported into the cells, free amino acids produced higher amounts of volatiles. It is suggested, that after transport into the cell peptides are only partially hydrolyzed to their amino acids, while the rest is metabolized via alternative metabolic pathways. The three L. sakei strains differed to some extend in their ability to metabolize the substrates to volatile compounds. In a few cases this was due to the position of the amino acids within the peptides. Compared to other starter cultures used for the production of dry fermented sausages, the metabolic impact of the L. sakei strains on the formation of volatiles was very low.
蛋白质、肽和氨基酸的微生物降解会产生挥发性物质，这些物质参与干发酵香肠的典型风味形成。研究了三株清酒乳杆菌菌株形成香气化合物的能力。将休止细胞在磷酸盐缓冲液中发酵，缓冲液中含有等摩尔量的底物，分别由二肽、四肽和游离氨基酸组成。二肽很快从溶液中消失，而四肽则只是部分降解。在这两种方法中，反应混合物中游离氨基酸的浓度增加，但没有达到初始底物的等摩尔量。当向细菌中添加游离氨基酸时，它们的水平仅略有下降。尽管肽被更快速地降解和/或运输到细胞中，但游离氨基酸产生了更多的挥发性物质。因此，建议在运输到细胞后，肽仅部分水解为其氨基酸，而其余部分则通过替代代谢途径进行代谢。这三种清酒乳杆菌菌株在代谢底物生成挥发性化合物的能力上存在一定差异。在某些情况下，这是由于氨基酸在肽中的位置不同。与用于生产干发酵香肠的其他起始培养物相比，清酒乳杆菌菌株对挥发性物质形成的代谢影响非常低。
