To improve tannin assay in cashew apple, several parameters were examined, including (1) extraction solvents, (2) effects of water and boiling time on butanol acid reaction and (3) correlation between vanillin and butanol acid assay of tannin in cashew apples. The 50-70% acetone extracted the greatest amount of tannin from cashew apples. Concentrations of water in butanol reagents were adjusted and boiling time of butanol reaction was reduced at 15 min. Tannin of unripe cashew apples was purified on Sephadex LH-20, aiming to obtain tannin standard for butanol assay. The vanillin assay presented high correlation with the butanol acid assay.
tannin; cashew apple; vanillin assay
