Abstract: The distribution of phenolic compounds and the relationship between the content of phenolic compounds and the taste of astringency and bitterness in apple (Malus domestica Borkh. ) fruits were studied by high-performance liquid chromatography (HPLC). The results showed that the contents of phloridzin and catechin were more than 30 times, and epicatechin, procyanidins and chlorogenic acid were about 10 times in young fruits with strongly astringency and bitterness compared to that in ripe fruitswith no taste of astringency
and bitterness. In ripe fruits with astringent taste, the contents of chlorogenic acid, catechin, epicatechin, and procyanidinswere much higher than that with no astringent taste. In fruits with bitter taste, the contents of chlorogenic acid, phloridzin, and procyanidinswere much higher than that with no bitter taste. In fruits with both astringent and bitter taste, the contents of chlorogenic acid, catechin, epicatechin, phloridzin, and p rocyanidins were the highest. The levels of phloridzin and procyanidins in the bitter pit tissue were fifteen and three times higher than those in normal tissue, respectively. These results indicated that the astringency of apple fruitswas due to the increase of chlorogenic acid, catechin, epicatechin, and procyanidins, while the bitter taste was associated with the accumulation of phloridzin, catechin, and p rocyanidins. Chlorogenic acid mainly exists in seed, core, and flesh. Catechin, epicatechin, and quercetin are mainly in the peel. Procyanidins are also mainly in the peel with small amount in the flesh and core, and phloridzin is mainly in the seed, peel, and core.

Key words: Apple, Phenolic compounds