Processing steps and lactic acid bacteria involved in traditional cultured milk (Kwerionik) production in Uganda

The production process of traditionally fermented milk (Kwerionik) from Eastern Uganda and the lactic acid bacteria (LAB) involved were investigated. Viable plate count method was employed for enumeration and isolation of LAB, coliforms and mesophilic aerobes from both the field and laboratory fermentation samples. Representative LAB isolates from the various stages of fermentation were grouped by PCR fingerprinting of the 16S-23S rRNA internal transcribed spacer region; and identified by carbohydrate fermentation tests using API 50 CH kit; and by sequencing of the 16S RNA gene. Fermentation was spontaneous; carried out in gourds and involves periodic removal of whey and addition of fresh milk. The field and the laboratory Kwerionik samples had comparable parameters. The pH ranged between 3.5 and 4.5; LAB levels were 10 9 cfu g-1 after one day but later decreased to 10 5 –10 6 cfu g-1. Mesophilic aerobes ranged from 10 6 to 10 10 cfu g-1 while coliform levels up to 10 7 cfu g-1 were detected, but not later than 11 days. The pH and microbial counts at the different fermentation durations were significantly different (p<0.005) except for the coliforms. Lactobacillus plantarum, Enterococcus faecalis, Lactobacillus paracasei subsp paracasei, Lactobacillus casei subsp casei, Lactococcus lactis subsp lactis, Enterococcus faecium and Leuconostoc mesenteroides subsp mesenteroides were involved.