Innovations in the production of kenkey, a traditional fermented maize product of Ghana : nutritional, physical and safety aspects

Kenkey is traditionally made from a dough obtained by soaking maize (1-2 days, room temperature), milling and then fermenting naturally for 2-4 days. This thesis was aimed at improving not only the nutritional quality of kenkey, but also the production process. The traditional method for making kenkey was scaled down to a laboratory process and the microbiological, physical and nutritional quality of both maize and maize- cowpea kenkey were investigated. Natural fermentation for 48h or 72h at 30°C was sufficient to obtain properly acidified maize (pH 4.07) or maize-cowpea (pH 4.08) doughs, respectively. Lactic acid bacteria were mainly responsible for acidification. Supplementation of maize (on a replacement basis) with 20% white cowpea resulted in significant increases in protein (by 20.5%) and available lysine (by 74%) contents. This also resulted in significant increases in biogenic amines (total amines < 500 ppm, mainly putrescine and tyramine) compared with maize kenkey (total amines < 60 ppm). Histamine was absent (< 5 ppm). Acceptability tests in Ghana, however, showed that only a 10% cowpea level was comparable with the traditional kenkey in terms of flavour and texture. Process options for producing a dehydrated kenkey meal (kenkey dry- mix) were investigated with the aim of developing a product with a longer shelf-life than traditional kenkey. An in vitro method was developed for determining the digestibility and flatulence potential of kenkey. Soaking of grains effected the highest increase in in vitro digestibility. Clostridium perfringens strain NCTC 8239 produced more gas from the solid residue left over from the in vitro digestion of maize-cowpea samples than from the resulting supernatant which contained low molecular weight oIigosaccharides, traditionally held responsible for intestinal flatus induction, suggesting that non-starch polysaccharides contribute significantly to the flatulence potential of cowpea-supplemented kenkey.