Development of starter cultures for mahewu fermentation: affordable solutions for low and medium-income countries

Very few starter cultures were specifically developed for African cereal foods. This study aimed to develop starter cultures for cereal fermentations that can be stored at ambient temperature. Model mahewu fermentations were conducted with two starter culture combinations. The starter cultures competed at 15 °C and 25 °C with strain cocktails of finger millet malt isolates that were formulated based on the bacterial abundance in finger millet malt. Fermentations were analysed by plating and sequencing of 16S rRNA gene amplicons. Without starter cultures, Enterobacteriaceae were dominant members of the microbial community for 24 h (25 °C) and 72 h (15 °C), respectively. Because 16S rRNA gene amplicon sequencing identified Salmonella spp. with more than 0.1% abundance in all six finger millet malt samples, the persistence of Enterobacteriaceae at low temperatures represents a risk for food safety. At 25 °C, the starter cultures Limosilactobacillus fermentum and Lactiplantibacillus plantarum dominated the microbial community. At 15 °C, Lp. plantarum and Weissella confusa were dominant. Starter cultures were produced by air-drying and by freeze-drying and stored at 4 °C and 20 °C. Results provide an alternative approach to the production of starter cultures.