LAUSR

Fermented products with a pleasant aroma and with strong honey, rose, and fruit odor notes were developed through the biotransformation of a medium containing sour or sweet whey with the addi-tion of L-phenylalanine by Galactomyces geotrichum mold. In order to obtain the strong honey-like aroma, G. geotrichum strains were screened and fermentation conditions were optimized to achieve a preferable ratio (>1) of phenylacetaldehyde (PAAL) to 2-phenylethanol (2PE) by the Ehrlich path-way. This allowed postfermentation products with the ratio of concentrations of PAAL to 2PE was 1.7:1. Additionally, the use of gas chromatography-olfactometry (GC-O) analysis and the calculation of odor activity values (OAVs) allowed 10 key odorants to be identified in postfermentation prod-ucts. The highest OAVs were found for PAAL with a honey odor in both sour and sweet whey cul-tures (3010 and 1776, respectively). In the variant with sour whey, the following compounds with the highest OAVs were: 3-methyl-1-butanol (131), 3-(methylthio)-propanal (119), 3-methylbutanal (90); dimethyl trisulfide (71), 2,3-butanedione (37) and 2-phenylethanol (29). In the postfermentation product with sweet whey, the following compounds with the highest OAVs were: 3-(methylthio)-propanal (112), dimethyl trisulfide (69), and 2,3-butanedione (41).