Effect of variety, maturity and season on composition and quality of musts and wines

Abstract

The effect of variety and maturity on the composition of grapes and wines of Bangalore Blue, Thompson Seedless, Black Champa and Malvasia Bianca Di-wapolis was studied. Fruits from these four varieties were harvested at five different maturity levels and the wines were prepared. Both the musts and wines were analyzed for various organic and inorganic constituents. Distinct variation in organic and inorganic constituents was noticed due to variety, maturity and season. Among the nitrogenous compounds, total nitrogen, protein and proline showed an increasing trend with maturity. Ammonia content was found to decrease in Thompson Seedless and Black Champa whereas in Bangalore Blue and Malvasia Bianca Di-wapolis it increased with maturity. Tannin content increased in Thompson Seedless, Bangalore Blue and Malvasia Bianca Di-wapolis while in Black Champa it did not show much variation with maturity. Inorganic constituents such as phosphorus, calcium and magnesium increased with maturity in all the varieties. Potassium content increased in Thompson Seedless and Bangalore Blue while in Black Champa and Malvasia Bianca Di-wapolis, it remained unchanged. Iron content increased in Thompson Seedless but not in other varieties. Zinc and Manganese remained constant while copper showed variation between samplings. In wine samples total acidity, tartaric acid and malic acid decreased while pH increased with maturity. The wine prepared from third, fourth and fifth stage of maturity scored higher rankings than wines from earlier samples. The results suggested that a Brix/Acid ratio of about 30±5 is near optimum for making good quality dry wines from these varieties for this region.