Technische Universität München, Lehrstuhl für Technische Mikrobiologie, Weihenstephaner Steig 16, D-85350 Freising, Germany.
Food Microbiol. 2012 Apr;29(2):224-8. doi: 10.1016/j.fm.2011.06.010. Epub 2011 Jun 21.
Lactobacillus sakei belongs to the main flora of raw fermented sausages and is used as starter culture. Bacterial starter cultures can convert amino acids to α-keto acids by aminotransferases. These α-keto acids are the precursors of aroma active aldehydes, alcohols and carboxylic acids. In this study the formation of aldehydes, alcohols and carboxylic acids from leucine, isoleucine, valine and the corresponding α-keto acids are analysed in model fermentations with two different strains of L sakei. In the absence and upon addition of leucine, isoleucine and valine they produced 1 μg/ml 3-methylbutanoic, 0.2 μg/ml 2-methylbutanoic acid and 3 μg/ml 2-methylpropanoic acid, respectively. Upon addition of α-ketoisocaproic acid, α-keto-3-methyl-pentanoic acid or α-ketoisovaleric acid the amount of the corresponding carboxylic acid was increased to 40 μg/ml 3-methylbutanoic acid, 20 μg/ml 2-methylbutanoic acid and 35 μg/ml 2-methylpropanoic acid. The response patterns of the strains and amounts of carboxylic acids produced were similar. This behaviour was typical when compared with other strains of L. sakei and suggests general lack of transaminase activity and a limit in the transport of branched chain amino acids and their conversion to volatiles, some of which can contribute to the aroma of fermented sausages.
清酒乳杆菌属于生发酵香肠的主要菌群，被用作发酵剂。细菌发酵剂可以通过转氨酶将氨基酸转化为α-酮酸。这些α-酮酸是香气活性醛、醇和羧酸的前体。在这项研究中，两种不同的清酒乳杆菌菌株在模型发酵中分析了从亮氨酸、异亮氨酸、缬氨酸和相应的α-酮酸形成醛、醇和羧酸的情况。在没有添加亮氨酸、异亮氨酸和缬氨酸的情况下，它们分别产生了 1μg/ml 的 3-甲基丁酸、0.2μg/ml 的 2-甲基丁酸和 3μg/ml 的 2-甲基丙酸。当添加α-酮异己酸、α-酮-3-甲基戊酸或α-酮异戊酸时，相应羧酸的量增加到 40μg/ml 的 3-甲基丁酸、20μg/ml 的 2-甲基丁酸和 35μg/ml 的 2-甲基丙酸。菌株的反应模式和产生的羧酸量相似。与其他清酒乳杆菌菌株相比，这种行为是典型的，表明普遍缺乏转氨酶活性，以及支链氨基酸的转运和转化为挥发性物质的能力有限，其中一些物质可以为发酵香肠的香气做出贡献。
