Effect of fermentation time on nutritional, antinutritional factors and in-vitro protein digestibility of macrotermes nigeriensis-cassava mahewu

Abstract

Fermented Macrotermes nigeriensis-Cassava mahewu (MECM) has the potential to contribute substantially to nutrition security due to its enhanced protein and micronutrient contents. However, changes related to fermentation time during processing are important factors that could affect the nutritional quality. This study determined the influence of fermentation time (0 h to 48 h) on nutritional (protein, Fe, Zn, Ca and ascorbic acid), anti-nutritional factors (phytate oxalate and tannins) and protein digestibility of freeze-dried fermented MECM using in-vitro digestion methods and standard procedures. Cassava flour was replaced with M. nigeriensis powder at 70:30% and fermented for 0, 12, 24, 42 and 48 h to obtain MECM. Results showed a decrease (P < 0.05) in pH (6.45–3.65) and increase in titratable acidity (TTA) (0.10–0.38%) with increasing fermentation time. Fermentation for 42 h enhanced (P < 0.05) protein (21.02%), Fe (52.69%), Zn (69.46%), ascorbate (125.71%) and protein digestibility (62.42%) higher than other fermented samples. Fermentation for 48 h resulted in highest reduction (P < 0.05) in Phytate (64.16%), oxalate (76.11%) and tannins (41.32%). Fermenting MECM at 42 h is an effective means of improving its nutritional qualities, while at same time providing better conditions for degrading inhibitors of minerals absorption.