Study On The Optimization Of The Process Of Making Sweet Rosé Wine From Syrah By Split Juice Method

The juice separation method,also known as"bleeding"from the French"Saignee",is a process that varies the intensity of maceration in the fermentation mash by changing the ratio of peel to juice;it can be used to obtain both dry red wines and roséwines.The process can be used to obtain both dry red wines and roséwines.Given the unique climatic conditions and geographical characteristics of Xinjiang,problems such as the poor color stability of its wines are prominent.Therefore,some improvements in the winemaking process can not only compensate for the defects caused by ecological conditions on raw materials,but also improve the quality of wines to a certain extent.The experiment was conducted to make Syrah sweet roséwine by cold maceration combined with juice separation using Syrah grapes from the Heshuo appellation in Xinjiang,China,and to provide theoretical basis and technical reference for the production of high quality sweet roséwine through an in-depth study of the effects of different treatments on its quality.The main research results are as follows.1.Sweet roséwines were made by cold maceration treatments(12℃,8 h,16 h,24 h)and controlled temperature fermentation(12℃,16℃,20℃).The results showed that all treatments met the requirements of national standards and the content of polyphenolic compounds in the wines was significantly increased after cold maceration treatment.Cold maceration for 16 h and 24 h increased the content of total flavonoids,total anthocyanins,total tannins and total phenols in the wines;the increase in fermentation temperature made the anthocyanins extremely unstable and easily changed the color of the wines.2.By studying the color quality and monomeric anthocyanins in roséwines,it was found that the coloring substances in the grape mash were easy to accumulate after the extended maceration time,the wine color(WC)deepened,the red tones(a~*)increased,the wine color difference saturation(C~*ab)and chromaticity(CI)increased,but the wine brightness(L~*)decreased.A total of six basic anthocyanins and five acylated anthocyanins were detected in Syrah sweet roséwines.3.Comparing the effects of different clarifying agents on color parameters and sensory characteristics of roséwines,it was found that the best dosage of each clarifying agent was 0.08 g/L for egg white powder,0.6 g/L for Cross-linked polyvinylpyrrolidone(PVPP)compound clarifier,0.09 g/L for cold-soluble gelatin and 0.09 g/L for hot-soluble gelatin,in which PVPP compound clarifier improved the clarification effect and reduced the loss of color of the wine at the same time.Fuzzy mathematical sensory evaluation of roséwine appearance,aroma,taste and overall was conducted,and the results showed that the treatment group with cold maceration at 16 h fermentation temperature of 16℃performed more outstanding in all aspects,mainly in the improvement of color quality,taste quality,aroma intensity and overall balance.