Effect of variety and maturity stage of cassava (Manihot esculenta) on flour properties and sensory characteristics of wheat-cassava composite bread

Abstract

Cassava (Manihot esculenta) grows well in Tropical and Sub-Tropical regions of Sub-Saharan Africa. It is used as a food and raw material for many industrial applications, including food, feed and starch. Cassava has several varieties whose physico-chemical properties and functional properties of flour are hardly known. The aimed at characterizing physico-chemical and functional properties of cassava flour from different varieties harvested at different maturity stages and to determine their suitability for baking. Cassava tubers from 5 improved varieties; MH95/0183, MH95/0193, MH96/093, MH95/6484 and Migyera and 2 indigenous varieties; Selele and Merry go round were obtained from farmers in Migori County. Dry matter content and cyanide content of the fresh tubers and functional properties of cassava flour were analyzed. Wheat- cassava composite flour blends were prepared from three cassava varieties; MH95/0183, MH95/0193 and Selele that had wheat: cassava ratios as 95:5, 90:10, 85:15, 80:20, 75:25 and 70:30 with baker’s wheat flour as the control. These flour blends were analyzed for proximate composition, rheological properties and the physical properties of the bread. Sensory evaluation was done for every composite blend after baking using 25 semi-trained panelists and shelf life of the bread was determined. The roots that were harvested at 12 month had the highest dry matter, swelling power and low water binding capacity thus more suitable time for harvesting. Selele, MH95/0183 and MH95/0193 had the best dry matter content at 46.69%, 47.21% and 47.05% respectively at 12 months and functional properties for baking. The protein and gluten content of the blended breads reduced with increase in cassava substitution for all the cassava varieties with the 100% wheat flour having the highest content of 13.2 % and 63.20 % respectively. Composite flours with MH95/0183 variety were found to have better rheological properties while composite bread with Selele variety had the highest specific volume, form ratio of 3.07 cm3/g and 1.34 respectively and sensory properties. The sensory acceptability of composite bread made from 5%, 10% and 15% cassava flour didn’t have significant (P<0.05) difference from that of the control Bread (100% wheat flour). The external loaf characteristics were the major factors the panelist used to rate the acceptability of the bread. Results of this study show that cassava flour from different varieties have different physico-chemical and functional properties and that it can be used in the substitution of bread wheat flour at 15%.