Influence of spontaneous fermentation on some quality characteristics of maize-based cowpea-fortified nixtamalized foods

Abstract

Spontaneous fermentation has been identified to improve the quality characteristics of foods derived from them. When combined with cowpea fortification and nixtamalization, it is expected to improve the nutritional, functional, physico- chemical and sensory qualities of maize based foods thereby improving the qualities as well as broadening the food processing techniques in sub-Saharan Africa. This study was therefore aimed at investigating the influence of spontaneous  fermentation on the functional, physico-chemical and sensory characteristics of maize-based cowpeafortified nixtamalized foods. A 3x3x2 factorial experiment with fermentation time (0, 24, 48 h), cowpea (0, 10 and 20%) and alkaline treatment (nixtamalized and nonnixtamalized maize) was used. Samples were analyzed for pH, titratable acidity and water absorption capacity (27°C and 70°C). The blends were dried using the cabinet drier, milled into flour and processed into a snack food. The cylinder probe test was used in a TA-TX2 Texture Analyzer to measure the  hardness of processed snack foods and sensory analysis was conducted to  determine the acceptability of the snack products. The pH of all the nixtamalized samples decreased with fermentation time and cowpea fortification with concomitant increase in titratable acidity. Cowpea addition caused decreases in the pH from 9.68 to 6.12 in the unfermented nixtamalized samples. Contrary to this trend,  general increases in titratable acidity were observed with fermentation and cowpea addition of the products. The water absorption capacities at both 27°C and 70°C of all the nixtamalized blends generally decreased with fermentation time and cowpea fortification. The texture (hardness) of the formulated products were acceptable. Sensory evaluation indicated that the techniques of nixtamalization, fermentation and cowpea fortification used for the processing of the products did not influence their acceptability by the panel. Nixtamalized maize can therefore be subjected to spontaneous fermentation with cowpea fortification to enhance the functional, physico-chemical and sensory properties of products derived from them, thereby serving as alternative food technologies to maize processing in sub-Saharan Africa.

Keywords: Maize, fermentation, cowpea-fortification, nixtamalization, functional
properties.