Functional and Sensory Characteristics of Sorghum-Cocoyam-Cassava (SCC) Composite Flour Bread
Abstract
This study was carried out to evaluate the bread characteristics and sensory attributes of sorghum-cocoyam-cassava flour composite bread using simplex lattice of experimental design of response surface methodology (RSM). The sensory evaluation results from semi-trained panelists were generated into a 3D plot for color, taste, aroma, texture and overall acceptability. Wheat bread was used as control for comparison. The loaf weight of the bread samples ranged from 216.0g by sorghum-cocoyam-cassava bread to 177.5g of wheat bread(control); the loaf specific volume ranged from 251.9cm3 of wheat to 187.2cm3 of sorghum bread while loaf specific volume ranged from 1.42cm3/g to 1.10cm3/g. The linear mixture components of sorghum-cocoyam, sorghum-cassava, cocoyam-cassava and sorghum-cassava-cocoyam flours were not significant on the attributes. The mean hedonic score values for all tested attributes were different from the bread sample (control) at p<0.05. The overall acceptability of the samples showedp>0.05 indicating poor acceptance of the composite bread. Generally the samples understudy showed dark brown external and internal colour with increased coarseness and firmness. However, a successful use of sorghum, cocoyam and/or cassava with improved processing methods leading to production of indigenous bread would save many less developed countries from importation of wheat.
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Introduction
Bread is the second most consumed non-indigenous food product after rice in Nigeria (Idowu, et al., 1996). Wheat flour is a major component of bread with the proteins glutein and glutenin giving it unique baking properties. Glutein is responsible for the elasticity of the dough by causing it to rise and trap the carbon dioxide generated by yeast during fermentation (Mepba et al; 2007). Wheat production in tropical countries vis-à-vis Nigeria is inadequate, hence the heavy reliance on importation thus depleting the lean foreign reserve.
Efforts have been made to promote the use of composite flours using locally grown crops to replace wheat flour in bread making thereby decreasing demand for imported wheat and stimulating production and use of locally grown non-wheat products. Studies on the use of various oilseeds, legumes, and high protein seeds in bread making have been reported (Yue et al., 1991 and Olaoye et al; 2006).
According to Mongi et al; (2011), 2-10% non-wheat flour can be used without undesirable changes in bread characteristics. Cocoyam, cassava, plantain and other tubers have been reported as alternative sources of major raw materials for bread making (Mepba, et al 2007; Udofia et al; 2013; Idowu et al; 1996). Casier et al; (1976) reported the production of good quality bread from pure millet and sorghum flour as well as mixtures of maize and cassava flour. Well structured bread from pure seed sorghum flour was obtained using 3% rye pentosan. The pentosan acted as a binding agent simulating the role of gluten from wheat. Certain bread improvers such as calcium stearate or relatively high percentage of fat and sugar are used to improve the bread characteristics of non-wheat flour (Idowu et al; 1996).
Sorghum flour is made from Sorghum bicolor and is rich in protein, B Vitamins, dietary fibre and antioxidant. (Tekle, 2009) Sorghum flour would be an excellent substitute for wheat flour in which some consumers are gluten-intolerant. Cocoyam are commonly consumed as energy giving foods. The mainly edible varieties are Colocasia Esculenta (taro) and Xanthosoma Sagittifolium (tannia). Cocoyam contains minute size starch which enhances digestibility and is ideal for people with digestive problems especially the elderly, invalids, and the diabetics (Idowu et al., 1996). According to Idowu et al., (1996) Cocoyam is nutritionally superior to other roots and tubers in terms of digestibility, crude proteins content, and minerals such as calcium, magnesium, and phosphorus. A major limiting factor in the utilization of cocoyam is the presence of oxalates which cause acridity and irritation when eaten (Bradbury and Holloway, 1988; Bencini, 1991). Proper processing methods however would diminish the acridity. Cassava is a tropical crop with high content of carbohydrate. Though some varieties contain cyanide, improved processing methods are capable of alleviating the cyanide content. Physio-chemical properties of cassava starch are suitable for supplementation of wheat flour in bread making without compromising its sensory attributes (Eduardo et al; 2013).
The use of substitutes for wheat flour in bread making if feasible would lower the dependency of developing nations on imported wheat. The major objective of this study therefore was to examine the effect of selected experimental variables (levels of sorghum, Cocoyam, cassava flour) using response surface analysis (RSA) on the physical characteristics of bread (bread volume, loaf volume, organoleptic) of the composite flour bread.
The overall aim was to produce an acceptable indigenous bread like the Pita bread of Arabia and Syria, Roti Bread of Asia, (wheat, millet, cocoyam), Rye bread of Europe (Rye/Wheat); Ezekiel bread, Rye/Wheat. Krisa bread of Sudan (Sorghum), Chapatti bread of India (Sorghum), Tortilla bread of Central and South America (Sorghum). (Asiedu, 1989).
Conclusion
It was observed that all parameters failed to meet the important attributes of pure wheat bread which hindered general acceptability of the bread sample. However sorghum–cassava bread showed much acceptability. Levels of brownness were shown by the weight increase which consumers are familiar within all wheat flour bread which would easily be accepted. It is envisaged that regular supply, publicity, nutritional and health claims on the products may improve production and acceptability of sorghum-cocoyam-cassava flour bread as an indigenous food product.