engleski

Influence of harvest date on the primary metabolites of ˝Plavac mali˝ (Vitis vinifera L.) grapes

Choosing the best harvest date is the most important decision of the viticulturists upon which the balance of must before fermentation as well as the quality of future wine depends. We determined the changes in the composition and concentration of organic acids (malic, tartaric and citric acid), total acidity, potassium content, sugar components (fructose and glucose) and the change of pH value in „Plavac mali“ grape during four different harvest dates within Central and Northern Dalmatia conditions. The separation and quantitative determination of organic acids was done with high performance liquid chromatography, while fructose and glucose were determined by applying ultraviolet-visible spectrophotometry. Significant differences of four harvest dates in concentration of individual primary metabolites were found in both target locations as well as between the two observed locations. Delaying the harvest date showed an increase in sugar content (°Oe), equatation in the mass portion of glucose and fructose and the decrease in the total content of acids in grape berries. The concentration of malic acid decreases sharply, while the changes in concentration of tartaric acid remain less marked during the ripening.

glucose ; fructose ; HPLC-DAD ; organic acids ; ˝Plavac mali˝

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