Abstract

The production of Nigerian indigenous yoghurt (kindirmo) using Lactobacillusbulgaricus and Streptococcus thermophilus mutants as starter culture was investigated. The results of milk fermentations using L. bulgaricus and S. thermophilus mutant isolates when compared with their wild-type strains (control) indicated that the pH values of “kindirmo” produced at different incubation periods (h) and the mean percentage titratable acidity were not significantly different (p > 0.05) when compared with the control. The pH values of “kindirmo” produced usingL. bulgaricus mutant isolates at different incubation periods (h) and the mean percentage titratable acidity were not significantly different (p > 0.05) when compared with the control. Also, these physicochemical properties of color [yellow (9/12) and white (3/12)], consistency [(thick and uniform (2/12), thick (6/12), not so thick (1/12), very thick (1/12), very thick and uniform (1/12)] and presence of water [trace amount of water (4/12), water present (4/12), water moderately present (2/12), water in large amount present (1/12)] were observed. The pH values of “kindirmo” produced by S. thermophilus mutant isolates at different incubation periods (h) and the mean percentage titratable acidity were not significantly different (p > 0.05) when compared with the control. Also, these physicochemical properties of color [yellow (5/6) and white (1/6)], consistency [(thick and uniform (1/6), thick (3/6), not so thick (2/6)] and presence of water [(water present (3/6), trace amount of water present (2/6), water moderately present (1/6)] were observed. It should be noted that, the “kindirmo” produced in this work was not from a mixed culture of L. bulgaricus and S. thermophilus mutant isolates when compared with the normal procedures known. It is possible that if these mutant isolates are to be used in dairy industry as a mixed culture, it will give better and high quality yoghurt.

Key words: Starter culture, titratable acidity, consistency, physicochemical properties, kindirmo.