Comparative Effects of Drying on the Drying Characteristics, Product Quality and Proximate Composition of Some Selected Vegetables (Published)
This study investigated the effects of drying on the drying characteristics, product quality and proximate composition of some selected vegetables. The vegetable investigated were Ocimum gratissimum (Scent leaf), Vernonia amygdalina (Bitter leaf), Moringa oleifera and Heinsia crinite (Atama leaf). These vegetables were collected fresh, sorted, oven dried at 50oC for 12 h and evaluated for drying kinetics, rehydration properties, proximate composition, and total chlorophyll content. The result of drying kinetics indicated that the rate of moisture loss was at its highest in the first and second hour of drying; however the moisture loss was slowed down in the subsequent drying period. The removal of moisture at the end of drying was found to be at a faster rate in the following order: bitter leaf>scent leaf>Moring oleifera leaf>atama leaf. Results of the rehydration properties showed that significantly (p<0.05) higher rehydration ratio and rehydration capacity was obtained in atama leaves (10.56 and 0.223, respectively) while Moringa oleifera recorded the lowest (10.56 and 0.097, respectively). The results revealed that the drying significantly (p<0.05) affected the proximate composition of the dried vegetables with bitter leaf having the highest ash and protein content (11.31% and 29.28%, respectively), atama had the highest fat and carbohydrate content (17.36% and 50.33%, respectively) while Moringa oleifera was highest in crude fibre (19.98%). Total chlorophyll content was higher in the dried vegetables (1.75-3.22mg/100g) than in the fresh vegetable (0.80-1.39mg/100g). In its fresh and dried forms, bitter leaf had the highest chlorophyll content (1.39 and 3.22mg/100g) while chlorophyll retention was highest in scent leaf (67.21%) after drying. This study therefore indicates that drying affects the nutritional composition and product quality of the vegetables differently and that these vegetables in its dried forms are recommended as they supply adequate nutrients.
Keywords: Bitter Leaf, Drying, Moringa oleifera, Scent leaf, atama leaf
Effect of Cassava (Manihot Esculenta Crantz) Variety, Drying Method and Blending Ratio on the Proximate Composition and Sensory Properties of Cassava-Wheat Composite Bread (Published)
The use of composite cassava-wheat flour for commercial bread making purposes and consumption of composite cassava-wheat bread are relatively new in Ethiopia. This experiment was conducted to explore the effects of cassava variety, drying methods and blending ratio on chemical compositions and sensory properties of cassava-wheat composite bread. Two levels of cassava verities (Qulle and Kello), two levels of drying methods (sun and oven) and three levels of blending rations (11.12g, 25.00 g and 42.90 g of cassava in 100 g of control wheat flour) were used and the treatments were factorial arranged in complete randomized design with three replications. Blending with Qulle and Kello varieties had reduced crude protein content to 9.18 and 8.84 %, respectively as compared to the protein content (10.05 %) in the control (100% wheat bread). Similarly, the crude fat dropped to 1.18 to 1.12 % from 2.33%, the crude fiber increased to 2.05 and 2.03 % from 1.17 %, the carbohydrate (%) increased to 80.13 and 81.10 from 77.33, the ash increased to 2.21 and 2.10 % relative to 1.82 % in wheat bread. No significant (P>0.05) differences were detected in proximate compositions attributed to the two drying methods. With increase in blending ratio the carbohydrate, the crude fiber and the ash contents increased whereas the protein content decreased significantly (P<0.05). No significant (P>0.05) differences were observed in overall acceptability of the composite breads due to varieties and drying methods. However, as the blending ratio increased the overall acceptability dropped significantly (P<0.05). It could be concluded that the substitution of cassava flour with wheat flour in bread making with substitution level up to 25 g did not adversely affect the quality properties of the bread and produce bread comparable to that produced from wheat flour in terms of proximate composition and sensory acceptability. Further studies are required to investigate the impacts on anti-nutrients and storage period on cassava-wheat composite bread.
Keywords: Blending, Composite Bread, Drying, Proximate and Sensory Acceptability., cassava