Madurez de uva (Vitis vinifera) negra criolla, moscatel y quebranta: Análisis del color de bayas sobre el contenido de azúcar y acidez total

Abstract

Grape maturation was evaluated in black creole, muscatel and quebranta varieties, through color in berries, related to their sugar content and total acidity. The color was obtained through digital image, using a 21-megapixel camera with natural lighting and a white background; later analyzed by numerical values RGB (red, green and blue) using Imagej software; variation of distance with Euclidean equation from RGB, HSL (tone, saturation and brightness), HSV (tone, saturation and value) and L*a*b* (black and white luminosity, red to green, blue gradient). The sugar was evaluated with Abbe R12 refractometer in Brix degrees. Total Acidity valued with 0.1 N sodium hydroxide until pH 7. The data was verified by regression analysis. The black Creole and muscatel varieties had a direct relationship with the sugar content and total acidity, but not the quebranta variety. The progressive coloring of color grapes during the ripening process, predict the content of sugar and total acidity, so that the generation of a range of colors is useful for the deduction of the state of maturity of the grape

Keywords

• maturity
• color
• sugar
• total acidity.