Polyphenol Contents and Polyphenol Oxidase Activities of Some Nigerian Kolanuts

The levels of polyphenol and activities of polyphenol oxidases in some Nigerian kolanuts were investigated. Garcina cola had the least polyphenol content of 15.60±1.70 (mg/g), while Cola nitida (red) recorded the highest value of 33.50±2.51mg/g. Polyphenol oxidase from Garcina cola had its optimum pH of activity in the acidic region (pH 3), but the white and red species of Cola nitida had a neutral (pH 7) optimum pH. With catechol as substrate, polyphenol oxidase activity was highest in Cola nitida (white) (55.70±2.60) and lowest in Garcina cola (2.22 ± 0.04). Whilst the values of polyphenol obtained may explain the high incidence of enzymatic browning in some Nigeria kolanuts, the white cultivar of Cola nitida could be further explored as a good source of polyphenol oxidase.