Functional properties, in vitro protein digestibility and mineral contents of extruded flour developed from maize-cassava leaf composites

Abstract

Application of extrusion cooking technology in product development is getting a high priority due to its effectiveness in quality improvement. Response surface methodology has been used extensively to optimize extrusion variables. The objective of this study was to evaluate the functional properties, in vitro protein digestibility and mineral contents of maize-cassava leaf composite extruded instant porridge flour using response surface methodology. Box-Benkhen design was used for formulation and optimization of the process variables. Extrusion variables; extrusion temperature (80oC – 120oC), feed composition (cassava leaf flour proportion) (5% -15%) and feed moisture (14% - 18%) were used as input variables whereas, water absorption index (WAI), water solubility index (WSI), in vitro protein digestibility (IVPD), and minerals were used as responses. Results obtained showed that, WAI and WSI increased significantly (p<0.05) as a result of increase in extrusion temperature and feed composition. WSI showed a significant (p<0.05) positive correlation with IVPD and mineral contents. IVPD was significantly (p<0.05) improved by extrusion temperature and feed composition. Calcium, potassium, magnesium and iron contents were significantly (p<0.001) increased as a result of increase in feed composition. Supplementation of cassava leaf flour during extrusion of maize based products improved its functional properties, IVPD and mineral contents, hence suitable for formulation of nutritious extruded food products.