Partial dehydration of 'Niagara Rosada' GRAPES (Vitis labrusca L.) targeting increased concentration of phenolic compounds and soluble solids

Abstract

The partial dehydration of grapes after harvest and aimed wine-making, has been shown to be a process that brings increased concentration of sugar and phenolic compounds in the must, which results in the quality of the wines produced. However, the works developed so far studied the process for temperatures up to a maximum of 25°C and air velocity less than 1 m.s^-1. This study aimed to analyze the physical and chemical changes (concentration of total soluble solids (TSS) and phenolic compounds (CPC)) after partial dehydration of 'Niagara Rosada' grapes at the temperature subjected to two treatments combining two temperatures and one air velocity (T₁= 22.9°C/1.79 m.s^-1 and T₂ = 37.1°C/1.79 m.s^-1), and relative humidity of approximately 40%. The loss of water in the grapes was approximately 14% and the drying process lasted between 20 to 50 h for the treatments T₁ and T₂, respectively. We experimentally and statistically verified that the treatments promoted significant increase in TSS and CPC; however, for CPC at the temperature of 37.1°C, the increase accounted for approximately 29%, whereas, for the temperature of 22.9°C, it was only 5%. For TSS, the increase was on average 14.4 ± 3.9% between both treatments.

Key words: Chaptalization, temperature, air velocity, winemaking.