Investigation of the Acid Composition of Sherry-Type Wine Materials Produced from Azerbaijani Grape Varieties and Evaluation of Acidity Regulation Methods

This study investigated the acid composition of experimental sherry-type wine materials produced from Azerbaijani grape varieties and evaluated different acidity-regulation methods under controlled processing conditions. Wine materials prepared from the grape varieties Bayan Shira, Aligote, Riesling, Rkatsiteli, and Chardonnay, cultivated in different soil-climatic zones of Azerbaijan, were used as the research object. Titratable acidity, pH, organic acid composition, acetaldehyde, and other physicochemical parameters were determined in the samples. Chemical, physical, and biological methods were comparatively evaluated for the purpose of acidity regulation. The titratable acidity of the investigated wine materials ranged from 5.75 to 9.1 g/dm³, depending on grape variety and growing region. In wine materials produced under warm-climate conditions, titratable acidity could decrease to 4.76 g/dm³, whereas high-acidity materials from the investigated regions showed values of up to 9.1 g/dm³. Adjustment of the acidity to 5.5– 6.5 g/dm³ and the pH to 3.2–3.4 accelerated the development of the sherry flor, increased
the acetaldehyde content to 526–646 mg/dm³, and ensured the formation of the typical sherry character. During biological deacidification, the conversion of malic acid into lactic acid improved the stability and organoleptic properties of the wine. In wine materials with low acidity, the addition of tartaric acid and the blending method made it possible to achieve an optimal acidity balance. The obtained results demonstrate that the targeted regulation of acidity increases the intensity of the sherrying process in sherrytype wine materials, accelerates flor formation, and improves the quality characteristics of the finished product. These results are of practical significance for optimizing the production technology of sherry-type wines.