The juice incorporation from grape pomace pressing positively influence the yield and chemical composition without affecting its sensory profile

Abstract

The quality of juice obtained by pressing grape pomace and the viability of its incorporation into whole grape juice was investigated for the first time on an industrial scale. Two pressing systems were tested: hydraulic and pneumatic and the evaluated treatments were as follows: whole grape juice (CJ - control), juice 100% from hydraulic press (HP), juice 100% from pneumatic press (PP), juice with a blend of 87% CJ + 13% HP (CJHP), and 87% CJ + 13% PP (CJPP). Analyses were conducted to determine the physicochemical profiles of the juices, levels of primary and secondary metabolites, antioxidant capacity, sensory profile, and consumer acceptability. Pressing increased the yield in the hydraulic and pneumatic systems by 20.5% and 27.3%, respectively, the concentration of phenolic compounds, especially flavanols, flavonols, and stilbenes, and the antioxidant capacity. However, HP and PP juices obtained the lowest overall sensory acceptability scores compared with the control, whereas CJPP and CJHP did not differ from CJ. The pneumatic press stood out for providing better results in juice quality and yield. In this study, the incorporation of juice from pressing grape pomace collected during the maceration stage positively influenced the product's chemical composition without altering its sensory profile or negatively affecting its acceptance by consumers.