Evaluation of Some Biochemical Properties of the Juice of Two Varieties of Sweet Potato Grown in the North of Côte d’Ivoire During a Fermentation Process

Like cassava flour for making “attiéké” (cassava semolina), the sweet potato tuber, after grinding followed by pressing, produces flour and juice. The present work aims to enhance this juice from the sweet potato by a fermentation which leads to an alcoholic drink. The process consists of five steps including juice extraction, gelation, enzymatic hydrolysis by millet malt, pasteurization and fermentation. We have followed the evolution of some chemical and biochemical parameter at each step of the process. The results indicate that enzymatic hydrolysis with millet malt increases the reducing sugar level by 10 times which was 0.074 g/ml ± 0.013 and 0.041 mg/ml ± 0.011 respectively for white-fleshed sweet potato and yellow flesh after extraction. However, the process drops the vitamin C level from 0.1 mg / ml ± 0.013 of white-fleshed potato juice and 0.05 mg / ml ± 0.002 of yellow-fleshed potato juice to 6.6 10-3 mg/ml ± 1.9.10-3 and 5.9.10-3 mg / ml ± 0.8.10-3 in the same order. The optimal production of alcohol during fermentation is obtained with a concentration of 40 mg / L of yeast to reach an alcohol level of 5.56% ± 0.1 and 4.60% ± 0.1 respectively for the potatoes. sweet with yellow flesh and white flesh after 6 hours.