The composition of polyphenols (tannins) and the properties of an associated enzyme, polyphenol
oxidase (PPO), in the Nigerian mango (M. indica) kernel were investigated. Tannins were
qualitatively and quantitatively analysed. PPO activity of "ltered extract of the fresh mango
kernel suspension (40% w/v) was studied spectrophotometrically at 420 nm using catechol as
substrate. Results showed that a 6.4% (w/v) gravimetric yield of tannin from dry mango kernel
meal contained tannic acid, gallic acid, and epicatechin in the ratio 17:10 : 1, respectively. Acid
hydrolysis of the condensed tannins indicated the presence of ellagic acid, gallocatechin, and an
acylated cyanidin in the ratio 11:7:5. Moist heat at 903C inactivated PPO by 50% of its
maximum activity within 3 min. Furthermore, up to 90% inactivation could be achieved after
5 min of water blanching, thereby reducing signi"cantly the rate of undesired browning leading
to tannin formation. Water-blanching would advantageously leach soluble tannic substances
into the soak-water