Effect of Oak Chips on Evolution of Phenolic Compounds and Color Attributes of Bog Bilberry Syrup Wine During Bottle-Aging

This study investigated the evolution of phenolic compounds of bog bilberry syrup wine during a bottleaging process, and further estimated the oak chip treatment on the wine color alteration. The wine was macerated with oak chips (2 or 5 g/L under light or medium toasting level) for 20 d and then bottle-aged for 6 mo. Results showed that the oak chip treatment significantly increased the content of phenolic compounds and enhanced the copigmented anthocyanin level before aging. It also resulted in an increase on a* and C* but a decrease on L*, b*, and H* of the wine. During aging process, a content decrease of total phenol and antioxidant capacity of the wine was observed. Phenolic acids, flavonol glycosides, and anthocyanins reduced the content, whereas flavonol increased the content. Free and copigmented anthocyanin levels decreased, whereas polymerized anthocyanins level increased. This process caused an increase on L*, b*, and H*, but a decrease on a* and C*. The oak chip treatment delayed the wine color change and its effect was mainly depended on the addition amount. Partial least square regression revealed that flavonol glycosides, phenolic acids, and anthocyanins displayed a positive correlation with L*, b*, and H*, but a negative correlation with a* and C*. Quercetin-3-O-glucuronide, myricetin-3-O-galactoside, chlorogenic acid, and quercetin exerted a more important effect on the color alteration in wine.