Browning of Alcoholic Beverages Containing Ascorbic Acid and Catechin

Non-enzymatic browning commonly occurs during wine storage and downgrade the quality. In order to improve color quality of fruit fermented liquor, ascorbic acid is usually used as an antioxidant in wine industry. On the contrary, some researchers reported that the addition of ascorbic acid may increase browning in wine. In the present study, we used reconstituted white wine as real alcoholic beverages to evaluate the effect of ascorbic acid induce on browning in fruit fermented liquors. Furthermore, the storage test in various conditions was conducted for understanding the effect of ascorbic acid on wine browning.

The results shown that the addition of ascorbic acid does not increase browning in wines contain low catechin content. The ascorbic acid was found to undergo aerobic degradation in alcoholic solution during dark storage. The final aerobic degradation products of ascorbic acid include 2-furoic acid (2-FA) and 3-hydroxy-2-pyrone (3OH2P). The production of 2-FA and 3OH2P increase with the increase of alcoholic concentration, whereas, the browning of alcoholic solution decrease with the increase in alcoholic concentration. According to the above result, we postulate that ascorbic acid degradation end products shouldn’t be the major factor to cause browning in alcoholic beverages. L-xylosone, the medial product of ascorbic acid degradation, was considered to interact with catechin and form browning pigments. The degradation of ascorbic acid and catechin, and browning index were significantly decreased in alcoholic solutions during anaerobic storage. However, none ascorbic acid degradation products were detected including 2-FA and 3OH2P during anaerobic storage. We postulate that after ascorbic acid and catechin degraded, they still stay in the medial of pathway, cause the final browning pigment substance wasn’t formed and decreases the browning index. The amounts of ascorbic acid, catechin and ascorbic acid degradation products drop rapidly in alcoholic solution during storage under light exposed. We postulate that light promotes the degradation of ascorbic acid and catechin, accelerates the interaction between those products to form high molecular weight aggregates, and significantly accelerate the browning in alcoholic beverages.

The above-mentioned results suggest that the content of catechin should be considered before added ascorbic acid into wine for its preventive/ antioxidant advantages. After bottling, the wine/ liquor products should choose the dark containers to keep away from exposure to light and oxygen, thus prevent the browning during storage.