Profile of resident microbes causing spoilage in “olewonyo”, a locally produced non-alcoholic beverage in Kumasi, Ghana

Abstract

Samples of olewonyo from two different localities together with a laboratory produced sample were analyzed for microbial changes, pH, titrable acidity and salt tolerance. High total viable counts (TVC) of 9.99 log cfu/ml, 9.23 log cfu/ml and 5.00 log cfu/ml were observed in the Aboabo, Anloga and Lab-simulated samples respectively at room temperature at day 3 (72hours). There was no significant differences in microbial load among the various samples among TVCs, lactic acid bacteria (LAB), lactic-acid cocci, and yeasts and moulds counts as the storage time increases (p<0.001). The pH of samples from Aboabo and Anloga showed a rapid decline from 6.55 and 6.60 to 4.55 and 4.30 respectively within 24-hour of storage. The changes in the Lab-produced sample however, showed a gradual decrease from 6.55 to 4.80 for the entire period of storage. There was no significant increase in titrable acidity of the laboratory sample (p<0.02) compared to the traditional samples. Of the 15 LAB isolates from the three sites, 40% were Lactobacillus fermentatum, 26.6% Lactobacillus plantarum, 20% Lactobacillus acidophilus and 13.4% Lactobacillus brevis. In the API gallaries, the dominant species were able to ferment ribose, galactose, D-glucose, D-fructose and mannitol. The present study shows that Leuconostoc mesenteroides, Lactobacillus plantarum, L. acidophilus, L. brevis, L. fermentatum, Corynebacterium, Saccharomyces cerevisiae, Aspergillus flavus and A. parasiticus may be involved or associated in the spoilage of olewonyo.