Optimization of Water Cooking of Sweet Potato (Ipomea batatas) Leaves and Characterization of Three Nutritional Interest Molecules (Folic Acid, Iron and Phytate)

Sweet potato (Ipomea batatas) leaves are among the leafy vegetables most consumed by Ivorian population. In order to preserve iron and folic acid, and to eliminate phytates, a study of optimization of water cooking of these leaves was conducted. Response surface methodology was employed to describe the effects of cooking time and leaf quantity on iron, folic acid and phytate contents of sweet potato leaves using a central composite design. Response surfaces and isoresponse curves were plotted to visualize areas of interest (optimal points). Results showed that the experimental data were adequately fitted into the second-order polynomial model. Cooking time had significant effects (P < .05) on folic acid and phytate contents. The effect of leaf quantity was significant (P < .01) on the three response variables. In addition, the optimal points were located in areas of the experimental domain where iron and folic acid contents were high. Therefore, three optimal conditions for water cooking (cooking time, leaf quantity) were identified: (10 min, 400 g), (7.93 min, 300 g) and (22.07 min, 441.4 g). Under these conditions, iron and folic acid contents (mg/100 g) were: (49.17, 12.58), (37.00, 16.27) and (48.77, 11.26), respectively. These results could be exploited to formulate iron and folic acid supplementation products from sweet potato leaves.

An environmentally friendly organosolv (ethanol-water) pulping of poplar wood.

In this study, pulp production from the fast growing plant, poplar, was examined for organosolv pulping with or without catalysts. In order to find the optimum cooking conditions, 18 different cooking experiments were carried out. The effect of ethanol ratio, cooking time as well as catalyst was studied. It was observed that even at lower temperature (90oC), cooking without catalyst was able to cause sufficient defiberization. It was seen that the increasing proportion of catalyst and cooking temperature resulted in an increased delignification. However in the case of using 0.02% acid catalyst pulp yield and viscosity were lowered to an unacceptable level. The most important cooking factors were found to be the proportion of acid catalyst. Furthermore, the delignification performance was found to be depending on the pH of the black liquor. In a result, the optimum pulp properties were obtained by cooking at 180oC for 90 min with 50 % ethanol mixture without catalyst. The pulp yield was noted as 44.49 %, viscosity was 892 cm2 g-1 and the kappa number was 67.