Fermentation of a composite finger millet-dairy beverage

Abstract

Fermented composite beverages of finger millet and milk are popular, nutritious, traditional foods in many parts of Zimbabwe. With the aim of commercial production, we determined what type of microbial cultures can be used to ferment a composite finger millet and skimmed milk powder gruel and the optimum conditions for its production. Composites containing between 0 and 100% finger millet gruel by volume were inoculated and incubated at various temperatures. The desired pH of 4.5 or less was obtained with incubation at 30 to 45 °C (but not at lower temperatures) with lower pH values being obtained as the temperature increased. YC380 (a yoghurt type bacterial starter culture) produced a pH of 4.5 or less only when skim milk was also present; V2 (another yoghurt type bacterial starter culture) did so at all levels of finger millet gruel and JC (a mixed strain culture developed to ferment cereals) only when finger millet gruel was present. A clear relationship between incubation temperature and syneresis could not be established but syneresis decreased significantly (p < 0.05) with increasing proportions of finger millet gruel. A thick product with a set consistency was obtained with YC380 at an incubation temperature of 45 °C and a storage temperature of 7 °C regardless of proportion of finger millet gruel. V2 produced a thick product with a set consistency at an incubation temperature of 45 °C, and storage temperature of 7 °C and when the proportions of finger millet gruel were between 0 and 50%. It appears that yoghurt type bacterial cultures can be successfully used to produce a composite fermented beverage from finger millet and skim milk, but cultures developed for fermentation of cereals are not suitable.