ABSTRACT

This study was aimed at isolating, characterizing and optimizing lactic acid bacteria from

„nono‟ for use as starter culture in yoghurt production. The Lactic acid bacteria were grown

on de Mann Rogosa and Sharpe medium agar (MRS agar, Oxoid) and β-disodium

glycerophosphate agar (M17 agar, Oxoid). After several presumptive tests which included

microscopy and conventional biochemical tests, the isolates were further characterized base

on their different sugar fermentation profiles using Analytical profile index (API KIT,

Biomereux, France). Six different strains were obtained and identified as Lactococcus

lactis     sub    specie lactis,     Streptococcus    thermophilus,     Pediococcus    pentasaceus,

Lactobacillus fermentum, Lactobacillus brevis, and Lactobacillus pentosus. These lactic

acid bacteria were further subjected to tests for exopolysaccharide (EPS) production where

Streptococcus thermophilus and Lactococcus lactis were discovered to be EPS producing

strains which is a desirable quality in yoghurt production. The co-culture of these two

strains was then termed the “local starter culture” and the specific growth rates, doubling

times and acidification rates in cow, soy and goat milk fermentations were determined.

Comparatively, findings from this study showed no variation (p ≥ 0.05) in the acidification

rates of the local starter culture with that of foreign starter cultures which further affirmed

the potentials of the local starter culture in yoghurt production. The yoghurt samples

produced with the local starter cultures were compared with their counterparts produced

from foreign commercial starter culture and compared base on their physicochemical,

proximate, microbiological, viscosity, sensory properties and shelf-life. Profile of the

physicochemical analysis of the yoghurts produced with the local starter culture showed

decrease in pH from 5.74 to 4.27 while titratable acidity increased from 0.38% to 1.32%

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