Application of refrigerated and frozen sorghum malt slurries in preservation of starter cultures of traditional fermented cereal-based beverages - a case of Obushera from Uganda

Abstract

Industrial production of traditional fermented beverages in developing countries is limited by lack of commercial starter cultures. Saccharomyces (S.) cerevisiae MNC 21Y and Lactobacillus (L.) plantarum MNC 21 were identi􀂦ed as starter cultures for a Ugandan cereal beverage, Obushera. However, they are commercially unavailable due to lack of affordable appropriate propagating and preservation methods. In this study the starters were propagated in sorghum malt slurries (30 °C for 24 h) and stored at 5 °C and − 18 °C for 90 days. Viability and fermentation ability of the cultures was monitored. Results Viability was higher for starters stored at 5 °C (S. cerevisiae: 6 log cfu/g and L. plantarum: 7–9 log cfu/g during 90 days) than those at -18 °C (S. cerevisiae: 2 cfu/g and L. plantarum: 4 log cfu/g after 30 days). Refrigerated starters acidi􀂦ed Obushera (pH ≤ 4.5) faster (10–20 h) than frozen ones (18–24 h). Refrigerating the starters in sorghum malt slurries preserves them for at least three months. This provides an affordable option for starter commercialization and industrial production of traditional fermented foods.