Effect of co-fermentation on nutritive quality and pasting properties of maize/cowpea/sweet potato as complementary food

Abstract

Traditional complementary foods based on cereals have inadequate nutrients required by infants. This study developed a co- fermentation process of maize (50%), cowpea, (30%) and sweet potato (20%w/w) to produce a complementary food for infants. The control was fermented whole grain maize. Gruel of fermented cereal is called ‘ogi’ in Yoruba native language of south-west Nigeria. Analyses of proximate composition,
minerals, amino acids and ß-carotene contents were done using standard methods. Pasting properties were determined using Rotatory Viscometer. Crude protein content was higher in maize/cowpea/sweet potato (p > 0.05) than fermented maize but both values were lower than Recommended Daily Allowance (RDA) for complementary infant food. Most of the amino acids (AA) analyzed were higher in co-fermented mixture. Total AA were higher in co-fermented mixture than maize but lower the standard: egg reference protein of 556mg/g crude protein (cp). Fermented maize had
higher calcium, magnesium, potassium and sodium contents than co-fermented mixture: This might be due to the utilization of these minerals by the various microbes in the co-fermented mixture for their metabolic activities however the values in both samples met RDA for 9-11months old infants, and are in excess for 11-23months old.
The K/Na ratio was lower in both samples than recommended ratio value of 0.61. In Mineral Safety Index (MSI); magnesium, calcium, sodium, zinc, iron and copper were comparable to recommended MSI value for infants aged 6-23 months. The calcium and iron values in both samples were lower than RDA value based on nutrient need from complementary food by level of usual breast milk intake. Co-fermentation of maize/cowpea/sweet potato reduced some essential minerals, increased crude protein and total amino acid contents. Carotenoid value in co-fermented mixture was
comparable to estimated need from complementary foods level of usual breast milk intake for 11-23 months infant, while maize carotenoid value was comparable to that of 6-8 months old infant. Essential minerals values in both samples met the requirement for 9-11months.The MSI for magnesium, sodium, zinc and copper in cofermented mixture met the RDA for 6-23 months. Co-fermentation of maize/cowpea/sweet potato resulted in a product of improved nutritional quality than fermented maize.

Key words: Co-fermentation, maize, cowpea, sweet-potato, ß-carotenoid