Production of Nigerian Yoghurt Using Lactic Acid Bacteria as Starter Cultures

Abstract

Aim: This work was carried out to investigate the influence of Lactic Acid Bacteria (LAB) on organoleptic quality and proximate composition of yoghurt, and viability of starter cultures in yoghurt.
 Methods: The LAB starter cultures were selected based on their ability to produce diacetyl and lactic acid.
 Results: Lactobacillus caseiN1 produced the highest quantity (2.72 g/L) of diacetyl at 48 hrs of incubation while Pediococcus acidilacticiG1 had the lowest amount (0.50 g/L). The pH of produced yoghurt ranged between 4.40 and 5.58 while the corresponding lactic acid contents ranged between 0.70 and 0.96 g/L. Yoghurt produced with cow milk inoculated with L. PlantarumN24 and L. BrevisN10 had the lowest pH (4.40) at significant level of P≤0.05. Yoghurt with mixed culture of L. PlantarumN24 and L. PlantarumN17 had the highest protein content (5.13%) while spontaneous fermentation (control) produced the least (0.48%). Yoghurt produced from cow milk inoculated with L. PlantarumN24 and L. PlantarumN17 was rated best with overall acceptability (9.0) during first day of storage while the commercial yoghurt (5.8) and spontaneous fermentation (6.8) had least overall acceptability at P≤0.05.
 Conclusion: Yoghurt samples stored in refrigerator had more viable LAB counts for a period of 21 days while the samples stored at room temperature had a day count except for yoghurt produced with cow milk inoculated with L. plantarumN24 which retained its viability at the second day. The yoghurt produced with selected LAB starters are better than commercial yoghurt in terms of sensory properties, proximate composition, pH and viability.