CHEMICAL COMPOSITION OF PROCESSED TENDER LEAVES AND HUSKS OF COWPEA AND ORGANOLEPTIC ATTRIBUTES OF THEIR SOUPS

Thesis Abstract

The study examined the chemical composition of fresh, sundried tender leaves and husks of cowpea‘Adengee’ (Vigna unguiculata) and organoleptic attributes of their traditional soups. Information onprocessing, preparation and utilization of soup meals based on cowpea leaves and husks were obtainedduring the focus group discussion. The tender leaves and husks were parboiled and sundried.Proximate, micronutrients, phytochemicals and antinutrient levels were determined using standardprocedures. The soups based on fresh and sundried leaves and husks were analysed prior to sensoryevaluation. The data collected were statistically analysed using means, standard deviation and standarderror. All values were based on residual moisture. Protein for dried leaves was higher (p<0.05) (39.24vs. 21.98 and 13.95%) than those of fresh leaves and dried husks. Dried leaves and husks had lower fatthan the control (1.31 and 0.75 vs. 9.10%) (p<0.05). Sun drying increased ash in both dried leaves andhusks (14.74 and 10.86 vs. 4.82%). The lower value for fibre in the dry samples was rather surprising(14.20 and 20.42 vs.25.13%) (p<0.05). Carbohydrate significantly increased more in dried husks thanin dried leaves. (53.76 Vs. 30.22%) (p<0.05).The micronutrients in both dried leaves and husks werereduced due to their volatile nature. Tannins, saponins, flavonoids and polyphenols decreasedsignificantly (p<0.05) in processed samples due to drying. Soups based on dried leaves (DS) hadhigher protein (p<0.05) relative to the soup based on dried husks (HS) and fresh leaves (FS) (34.40vs.34.10 and 33.30%).Similarly, husks based soups had higher fat (34.10 vs.34.05 and31.44%)(p<0.05) Ash was higher in dried leaves based soup(7.83%) and fresh leaves soup (7.20%).Fibre for the husks based soup was higher (p<0.05) relative to fresh and dried leaves based soups(6.13 vs.5.58 and 6.11%, respectively). The carbohydrate levels were generally appreciable. All soupshad appreciable levels of calcium, phosphorus and iron. These minerals varied significantly amongstthe soups (p<0.05). Zinc and iodine also differed (p<0.05).β-carotene content of soup based on freshleaves was higher (p<0.05) relative to those based on dried leaves and husks (6.08 vs.5.07 and5.46RE).Vitamin C varied significantly (0.90 to 1.10mg) in soups based on fresh leaves and driedhusks. Tannins, saponins, polyphenols and flavonoids in soups based on fresh leaves and dried huskswere comparable. Anti nutrients levels in all soups were generally low. Scores for all organolepticattributes of the three soups were more than half (6.17 to 7.70) of the 9-point scale. The soups weregenerally acceptable. As judged by the results, cowpea leaves, husks and their soups have highnutrient potentials to justify its cultivation, consumption promotion and diversification. Consumptionrelated information such as nutritional properties should be packaged and extensively promoted tobroaden the knowledge of health and nutritional benefits of consuming cowpea leaves and husks. Theresults demonstrate that, there is a potential in developing multi-purpose varieties with goodperformance, which are well-yielding in both leaves and seeds. Therefore, production relatedinformation, such as variety, yields and cultivation practices as well as processing should be packagedand made available to extension personnel and governmental agricultural research institutes that oftenhave a good outreach to farmers.