Use of a Commercial Yoghurt Starter Culture in the Production of Motsena, a Fermented Non-alcoholic Sorghum-Maize Gruel from Botswana

Abstract

Motsena is a fermented, non-alcoholic cereal gruel traditionally prepared in Botswana from a mixture of leftover sorghum and maize porridges. Because leftover food is used as the fermentation substrate, the product is prone to spoilage and quality variability. The objective of the study was to investigate the feasibility of using a commercial dairy starter culture to improve product quality compared with the traditional product. Two batches of cultured motsena were prepared, whereas four independent samples of traditionally prepared motsena were obtained from two villages in Central Botswana, where it is commonly produced and consumed. Lactic acid bacteria (LAB), yeasts and coliforms were enumerated, while pH and total titratable acidity were measured for both products and compared statistically using pairwise Student’s t-tests. The mean pH of cultured motsena was 4.06, while traditional motsena had a significantly higher mean pH of 4.81 at P = .05. Cultured motsena was significantly less acidic, with a mean titratable acidity of 0.36% compared with 0.46% for traditional motsena. Cultured motsena supported a significantly higher LAB population of 6.82 log10 CFU/mL compared with 6.12 log10 CFU/mL in traditional motsena, and it had a significantly lower yeast population of 4.52 log10 CFU/mL compared with 6.08 log10 CFU/mL in traditional motsena. Total coliforms were nevertheless detected at 4.48 log10 CFU/mL in cultured motsena and 6.43 log10 CFU/mL in traditional motsena; the difference was statistically significant at P = .05, indicating that use of the starter culture alone was insufficient to ensure the safety of motsena. Nevertheless, because the yoghurt starter culture produced motsena with significantly higher LAB and lower yeast counts than the traditional product, it may have potential to improve the microbial quality of motsena. The process should be optimised to increase final acidity, further lower the final pH, reduce the yeast population and eliminate coliforms as target control variables