Influencing TSS/Sugar Content and Acidity in Table Grape

Sugar level in the TSS content of the table grape berry is usually measured by oBrix. The sugar content has to be maintained at best level for both flavor and storage qualities when they are harvested, because grapes have no starch reserve that could be hydrolyzed after harvest to increase sugar content. Various regions or individual importing countries set defined standards for sweetness.

Sugar is accumulated during ripening. The amount of sugar depends on the length of ripening and crop management practices. Sugar content increases towards maturity, while grape acidity decreases over the same period. 

A good oBrix/acid ratio is 25:1 or above, though certain varieties are marketable with brix/acid ratios as low as 20:1. Brix/acid ratio of 20:1 is accepted as the normal standard for most varieties in Europe.

Crop Nutrition and TSS/Sugar Content and Acidity in Table Grape

Nitrogen

Nitrogen is needed to produce better quality berries; it enhances growth and development of the crop. Application of nitrogen fertilizer resulted in higher sugar content of table grape berries.

Potassium

Potassium influences the flavor and taste of table grapes by increasing the sugar content and sweetness of the berry as measured by the TSS:Acid ration. Application of potassium fertilizer resulted in increase of sugar/acid ratio of table grape berries.

Boron

Foliar boron also helps improve grape quality by increasing the TSS content and reducing acidity of table grapes.

Iron

Optimum levels of iron increased TSS contents in grapes according to Indian research. Iron is essentially required for early leaf production and photosynthesis to ensure better berry development and quality. Supply of sufficient amount of iron fertilizer resulted in an increased sugar content.

Zinc

Zinc is involved in the process of chloroplast development, thus it is essential for improvement of grape quality. Foliar zinc application resulted in the increase in sugar content.