Abstract: In order to solve the problems of rapid degradation of anthocyanins and significant color deterioration of Summer Black grape juice during storage, the effects of 0.5 g/L antioxidant of bamboo leaves (AOB), a natural plant extract, and grape seed extract (GSE) on the juice’s color, anthocyanin stability and sensory quality during storage were investigated. The results showed that AOB significantly enhanced the color (31.6%) and redshift (6.0 nm) of grape juice, the effect being more pronounced than that of GSE (4.2% enhancement and 0.3 nm redshift), and the color of grape juice changed from ruby red to purplish red after AOB addition. At 25 ℃, AOB significantly prolonged the half-life of anthocyanins (from 12.80 d to 15.15 d) and improved color stability, while GSE accelerated the degradation of anthocyanins (with the half-life shortened to 11.36 d). Sensory evaluation results showed that AOB improved the flavor and overall acceptability of grape juice, while GSE reduced the sensory acceptability due to its sour and astringent taste. In conclusion, AOB exhibits a significant co-pigmentation effect on Summer Black grape juice, indicating promising application prospects. The findings of this study provide a theoretical basis and technical support for the processing of dark grape juice.

Key words: grape juice; antioxidant of bamboo leaves; copigmentation effect; anthocyanin stability