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Food Microbiol

Title:		Production of volatile compounds by Lactobacillus sakei from branched chain alpha-keto acids
Author(s):		Gutsche KA; Tran TB; Vogel RF;
Address:		"Technische Universitat Munchen, Lehrstuhl fur Technische Mikrobiologie, Weihenstephaner Steig 16, D-85350 Freising, Germany"
Journal Title:		Food Microbiol
Year:		2012
Volume:		20110621
Issue:		2
Page Number:		224 - 228
DOI:		10.1016/j.fm.2011.06.010
ISSN/ISBN:		1095-9998 (Electronic) 0740-0020 (Linking)
Abstract:		"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 alpha-keto acids by aminotransferases. These alpha-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 alpha-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 mug/ml 3-methylbutanoic, 0.2 mug/ml 2-methylbutanoic acid and 3 mug/ml 2-methylpropanoic acid, respectively. Upon addition of alpha-ketoisocaproic acid, alpha-keto-3-methyl-pentanoic acid or alpha-ketoisovaleric acid the amount of the corresponding carboxylic acid was increased to 40 mug/ml 3-methylbutanoic acid, 20 mug/ml 2-methylbutanoic acid and 35 mug/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"
Keywords:		"Amino Acids, Branched-Chain/*metabolism Keto Acids/*metabolism Lactobacillus/*metabolism Volatile Organic Compounds/*metabolism;"
Notes:		"MedlineGutsche, K Amelie Tran, Thi Bich Thao Vogel, Rudi F eng Research Support, Non-U.S. Gov't England 2011/12/29 Food Microbiol. 2012 Apr; 29(2):224-8. doi: 10.1016/j.fm.2011.06.010. Epub 2011 Jun 21"