Isomers of c18:1 and c18:2 Acids in Fresh and Stored Fermented Milks Produced with Selected Starter Cultures

Abstract

The effect of the applied starter cultures and storage time of fermented milk drinks on the content of cis-9, trans-11 octadecadienoic acid (CLA), as well as trans isomers of C18:1 and C18:2 acids were evaluated. The analysed fermented milk drinks were produced by the thermostat method and with three different starter cultures. Analyses were carried out for freshly produced fermented milk drinks and for stored drinks (analyses after 6, 13, and 21 days of storage). The study demonstrated that the type of applied starter culture and storage time affected the content of CLA and of trans isomers of C18:1 acid in fermented milk drinks. Among the starter cultures applied, only the Ceska-star Y508 culture caused a significant increase in CLA content in the stored fermented milk drinks. The mean content of CLA in fresh drinks reached to 3.60 mg/g fat. The significantly higher CLA contents (3.85 and 3.89 mg/g fat) were found in drinks after 6 and 13 days of storage, respectively. The content of trans isomers of C18:1 acid in fresh products was 15.92 mg/g fat. In drinks analysed after 6 days of storage it was 17.14 mg/g fat.