The Effect of Fermentation on Nutritional Quality of Cassia obtusifolia Leaves (kawal)

Abstract

In this study Cassia obtusifolia leaves and Kawal were obtained from Nyala, west Sudan. The objective of this study was to evaluate the effect of fermentation on chemical composition, protein fractions, in vitro protein digestibility, amino acid contents, mineral content, phytic acid, tannin, and total polyphenol of Cassia obtusifolia leaves. Fermentation was found to cause significant changes in Cassia obtusifolia leaves major nutrients; fat content increased from 3.50 to 4.50 %, protein content from 24.81 to 35.13 %, ash content from 13.67 to 18.00 %, and fiber content decreased from 13.04 to 12.90 %. The effect of fermentation on protein fractions showed an increase in globulin from 58.52 to 63.38 %, albumin 12.59-14.43 %, prolamin 8.69-13.83 %, glutelin 5.03-8.32 %, and a decrease in insoluble protein from 17.81 to 5.41 %. Globulin and albumin are major fraction of kawal protein. The in vitro protein digestibility significantly increased from 49.43 to 61.87 %. Fermentation was found to cause significant changes in amino acid composition; valine increased from 946.6 to 1086.9, methionine 127.188 -147.588, isoleusine 737.388-850.813, leucine 1322.275-1474.613, and threaonine decreased from 664.113 to 574.788, , phenylanine 768.225-96.313, lysine 878.725-766.61, histidine 525.7-407.025, mg100g . Also, the fermentation caused significant change in mineral content, it showed an increase in Ca from 3.87 to 4.17, P 0.27-0.29 gkg, Mn 75.33-112.33 mgkg, and decrease in Na from 1.42 to 0.88, Mg 0.37-0.46 gkg, Fe 533.67-84.33, Zn 536.00-84.67 mgkg. Fermentation was found to cause decrease in anti-nutritional factors. Tannin content decreased from 2.39 to 2.24 %, phytic acid 649.13-340.92 mg100g and total polyphenol 4.77-3.80 %.