Concentration of grape juice (Vitis labrusca) by reverse osmosis process

Abstract

The objective of this work was to evaluate the concentration of grape juice by reverse osmosis (RO). The experiments were carried out in two steps. First, three transmembrane pressures (40, 50 and 60 bar) and four temperatures (20, 30, 40 and 50oC) were evaluated without juice concentration. The following parameters were analyzed: acidity and pH, soluble solids content, concentration of phenolic compounds and concentration of monomeric and total anthocyanins, color index, color density, as well as the permeate flux. Under the evaluated conditions, the process conducted at 50oC and 60 bar presented the higher permeate fl ux and the maintenance of all the physical and chemical parameters of the product. In the second step, the grape juice was concentrated at three temperatures, 20, 30 and 50oC, always at 60 bar of transmembrane pressure. The temperature of 30oC resulted in an adequate value for the permeate flux besides maintaining the physical-chemical and nutritional characteristics of the concentrated pr...