Optimizing tannin precipitation in cashew apple juice

Abstract

The juice extracted from cashew apples contains tannins that must be reduced due to their astringency and anti-nutritional properties. This study investigated reducing the tannins in cashew apple juice by mixing gelatin at 0.0 to 1.0% (w/v) with the juice for 5 to 15 min. Response surface methodology was used to simulate tannin concentration, turbidity, and weight of precipitate as a function of gelatin concentration and mixing time. All models were significant (P<0.01) and residuals exhibited normal distribution. Increasing the gelatin concentration decreased tannins and juice turbidity. Optimal conditions for minimum concentration of tannins and turbidity were obtained by adding gelatin at 0.67% (w/v) for 15 min. Cashew apple juice with the tannins reduced could be used in the subsequent production of wine and bioethanol.