Abstract:

【Objective】This study was aimed to investigate the effects of gallic acid treatment on color and aroma preservation during the aging process of Hutai-8 rosé wine, in order to optimize the design of color and aroma enhancement techniques for rosé wine production. 【Method】In this study, Hutai-8 grape was used as raw material. Gallic acid was added at three different stages, including pre-fermentation (Pr), mid-fermentation (M), and post-fermentation (Po), with the concentrations of 200 and 300 mg∙L^-1. After a 6-month storage period following fermentation, the aroma compounds of the wine samples were analyzed by headspace solid-phase microextraction-Gaschromatography-mass spectrometry (HS-SPME-GC-MS). The color parameters (L^*, a^*, b^*, C^*_ab, H_ab, and Δ^*E_ab) were determined by the CIELab color space parameters, and the color indices were measured by ultraviolet spectrophotometer (UV). Finally, the sensory evaluation was conducted to analyze the influences of different treatments on the aroma characteristics of the wine samples. 【Result】The post-fermentation treatments significantly increased the content of fermentation aroma compounds compared with CK, with an increase of approximately 16%. However, there was little difference between treatments of the two additive concentrations. The pre-fermentation treatments positively contributed to the preservation of varietal aroma compounds, with an increase of approximately 65%-73% compared with CK. The mid-fermentation treatments had a lesser stabilizing effect on the aroma compounds of the wine. Sensory evaluation results showed that post-fermentation treatment had the best effect on improving the overall aroma of the wine, and the pre-fermentation treatment was more effective than the mid-fermentation treatment. PLSR models revealed that terpenols, fatty acids, higher alcohols, acetates and fatty acid ethyl esters were the main aroma contributors (regression coefficients>0.1) to floral and citrus attributes (R²c>0.80 & R²v>0.70), with fatty acid ethyl esters and acetates being particularly prominent contributors. The color analysis results showed that pre-fermentation had a significant color-preserving effect, and the treatment with 200 mg∙L^-1 (Pr1) was more effective than the treatment with 300 mg∙L^-1 (Pr2). Comparied with CK, Pr1 treatment group’s, L^* value decreased by 0.58% and a^* value increased by 45.38%. Furthermore, the color characterization results showed that pre-fermentation treatment enhanced the purple-red tone of Hutai-8 rosé wine and the treatment with 200 mg∙L^-1 was more effective than the treatment with 300 mg∙L^-1. 【Conclusion】The addition of 200 mg∙L^-1 gallic acid before fermentation had a significant effect on stabilizing the color of Hutai-8 rose wine, while the post-fermentation treatments could significantly increase the fermentative aroma content of wine.

Key words: grapes, wine, gallic acid, color, aroma, winemaking