A Study on Changes in Some Physicochemical Properties, Volatile Compounds, Sugar, and Organic Acid Contents of Grape Juice During Molasses Production

Abstract

This study aimed to investigate both qualitative and quantitative changes in the taste and aroma components of grape juice during the production of traditional molasses (pekmez). For this purpose, the changes in some physicochemical properties, such as sugar, organic acid, and volatile compound contents, in fresh Verdani grape (Vitis vinifera L.) juice (FGJ) were evaluated in the production of its traditional molasses. After the production, the total soluble solid (TSS), titratable acidity (TA), glucose, fructose, malic, citric, and succinic acid concentrations were increased (P<0.05) with the rising concentration. However, the level of glucose and fructose in TSS decreased by 4.67% and 11.78%, respectively (P<0.05), based on their degradation. Similarly, as the major organic acids, the rates of tartaric and malic acids in the TSS were decreased by 73.91% and 67.25%, respectively. These reductions raised the pH value of molasses (P<0.05). In addition, the majority of volatile compounds in FGJ disappeared after the production of molasses, whereas some volatile furans were formed in significant amounts.