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Anthocyanins contribute to the attractive color of fruit wine, and their excessive degradation is deleterious to quality, especially for wine with an inherently low anthocyanin content, such as Sanhua plum wine. Ultrasonic treatment is well recognized for wine color maintenance. In the present study, fresh Sanhua plum wine was ultrasonic-treated and aged in barrels for three months. Our results demonstrate that ultrasonic treatment at 28 and 40 kHz improves color performance, as expressed by an increase in a*, b*, and C* values and color intensity, which is highly related to copigmentation. This successful conservation was attributed to the inactivation of polyphenol oxidase and the corresponding reduction in anthocyanin degradation. Finally, the increased antioxidative ability was verified due to the hydrogen donating ability of the surviving anthocyanins. This study indicates the reliability of ultrasonic treatment for providing superior colorfastness during Sanhua plum wine aging, which is also of great potential in processing different fruit wines.

Hydroxyphenyl-pyranoanthocyanins (PACNs), derived from anthocyanins (ACNs) reacted with hydroxycinnamic acids, have higher practical application value because of better physicochemical stability than their precursors. However, the slow formation rate restricted their broader applications. In the present study, cyanidin-3-O-glucoside (C3G) was chosen to react with four kinds of hydroxycinnamic acids in a model solution. Changes of color and the production of hydroxyphenyl-PACNs were monitored. The formation of derivatives was time-dependent, and the orange-yellow changing trend was correlated with the formation of PACNs and the consumption of C3G. In addition, high-pressure processing (HPP) as a widely-used non-thermal processing method in the food industry was conducted to investigate its impact on hydroxyphenyl-PACNs formation. The results showed that HPP significantly improves the yield of two types of hydroxyphenyl-PACNs (C3G-4-vinylcatechol and C3G-4-vinylphenol) and the retention of total residual pigments during 56 days of storage. Therefore, HPP contributed to color-protecting and the transformation of hydroxyphenyl-PACNs.

In this study, eight different levels of commercial blueberry wines were studied to establish the comprehensive quality evaluation method of blueberry wine. Eleven physicochemical indexes (total carbohydrates (TC), total acids (TA), total esters (TE), total phenols (TP), total anthocyanins (ANT), color density (CD), tint (T), alcohol by volume (ABV), total soluble solids (TSS), Ph value, total dry extracts (TDE)) were used to establish the quality evaluation model and conduct the principal component analysis (PCA). Based on the results from PCA, the first three principal components accounted for 85.73% of the total quality variability. The consistent ranking of blueberry wines between quality evaluation model and sensory evaluation test verified the reliability of this model. In addition, ultrasonic-treated blueberry wine showed a higher score than the untreated group, which reflected the sensory quality changes of blueberry wine during ultrasonic treatment with high sensitivity. This study provides a theoretical basis for the comprehensive quality evaluation of blueberry wines and reasonable instruction for consumers' choices.

Anthocyanin accounts for wine color performance, while it is susceptive to saccharomyces cerevisiae, causing threatened stability. Considering pyranoanthocyanin performed better color and stability, converting anthocyanins to pyranoanthocyanins in advance during fermentation was an ideal way for color improvement. Thus, pyruvic acid (PA) as the precursor of vitisin A was applied to fermentation with cyanidin-3-O-glucoside (C3G). Results showed that PA-stress leads to a color loss associated with a decrease in C3G and cyanidin. However, the content of pyranoanthocyanins under PA stress is unvaried. LC-MS-based non-target metabolomics revealed that superfluous PA can disturb the process of glycolysis and tricarboxylic acid cycle. Importantly, 1291 molecular features were increased and 1122 were decreased under PA-stress, in which several anthocyanins derivatization and isomerization were changed, contributing to color performance. This study indicated that extra PA is unfriendly to anthocyanins during fermentation, playing an adverse effect on color, which should be avoided in wine production.