Isolation and characterization of lactic acid bacteria isolates that degrade Maillard reaction products from coffee

Abstract

In this study, melanoidin-degrading bacteria were isolated, and the optimal parameters of their degradation ability were examined. Five isolates were inoculated into a GYP broth containing model melanoidin (MM) or coffee melanoidin (CM) and incubated at 30 ℃ for 1 week. Five strains showed maximum decolorization rates of 31 % for MM and 50 % for CM. 16S rDNA sequencing identified Lactococcus garvieae (3 strains), L. lactis, and Enterococcus faecalis. In DAD-HPLC analysis, substances with molecular weights (MW) greater than 10 000 decreased, and substances with MW less than 500 were observed. Based on the IR spectrum of CM after microbial decomposition, an absorption suggestive of a carbonyl group was detected. microbial decomposition products showed radical scavenging activity. These results indicate that the compounds produced from melanoidin after degradation by strains may increase radical scavenging activity. Thus, conducting further studies is necessary to examine the mechanism of the microbial degradation of melanoidins.