Effects of storage conditions and periods on glycoalkaloid content and nutritional value of Solanum tuberosum

A study was carried out to investigate the effects of storage conditions and periods on glycoalkaloid content and nutritional value of Solanum tuberosum. Freshly harvested tubers of Solanum tuberosum were purchased from terminal market in Jos and the glycoalkaloids contentand proximate evaluation of the stored tubers were carried out based on the length of storage. The tubers were randomly grouped into 9. Groups 1-4 represent tubers stored for a period of 1-4 week(s) respectively under sunlight at room temperature while group 5 represents the control, inwhich the glycoalkaloids content was determined immediately after purchase. Tubers in groups 6- 9 were stored in the dark for 1-4 weeksrespectively. The results showed that the concentration of glycoalkaloid (900mg/100g ±0.01) in gr oup 5 tubers is significantly low (p<0.05) when compared with groups 1-4 tubers. Also the glycoalk aloids concentrations (1050mg/100g±0.01, 1100 mg/100g±0.01, 1200mg/100g±0.01 and1350mg/100g±0.01) of groups 1-4 respectively were significantly elevated (p<0.05) when compared with the control and tubers stored in the dark. However, there was no significant difference (p>0.05) in the concentrations of glycoalkaloids of groups 6-9 and the control. Nutritional evaluation revealed considerable amount of measured nutrient without significantdifference (p>0.05) in all the tubers stored in darkness, but there were significant reductions (p<0.05) in the proteins of groups 1-4 tubers when compared with the control and tubers stored under the dark condition. The increase in the glycoalkaloids content of Solanum tuberosum storedunder sunlight could be attributed to exposure to light causing greening, mechanical stress and damage to the tubers, one of which is depletion of protein concentration. Such tubers can predispose consumers to acute symptoms, such as gastrointestinal disorders. Storage in the dark ishereby suggested

Effect of Addition of Moringa Leaf By-Product (Leaf-Waste) on Proximate and Sensory Characteristics of Cookies.

The effects of incorporation of Moringa leaf fibre (a by-product of leaf processing which contains 24% Crude Fibre by dry weight at 0, 5 and 10 % substitution of wheat flour in cookies was investigated. Three products containing wheat flour: Moringa leaf fibre ratios of 100:0, 95:5, and 90:10 respectively were prepared, and a commercial cookie was used as a standard. Proximate composition of each of the products was determined and sensory evaluation of the cookies was performed on a 7-point hedonic scale (with the standard commercial cookie as control) using a 20- man sensory panel. There was no significant (P< 0.05) difference in the dry matter content of the four samples. The 10% Moringa leaf fibre cookie blend had the highest moisture, fat and crude fibre content (0.57 % CF, relative to 0.44 and 0.54% CF observed in the 0:100 and 5:95 recipes respectively), while the commercial cookie had the lowest values for these parameters (0.36% CF) but with highest value for protein. The 100% wheat flour cookie ranked best in sensory evaluation, followed by the 5% fibre substituted cookie. All the cookies were acceptable; scoring above 4 on the 7-point hedonic scale. Addition of moringa leaf waste up to 10 % in cookies is feasible, though better at 5%. Cookies with Moringa leaf by-product have the advantage of being good sources of some of the daily requirements of dietary fibre.Keywords: Moringa leaf waste fibre, by-product, cookies, dietary fibre, sensory evaluation