Physicochemical stability of grape juice produced on industrial scale by different commercial enzyme preparations

The present work evaluated the analytical characteristics. total phenolic contents (TPC), antioxidant activities (AOX), sugars and organic acids by RP-HPLC/DAD/RID of grape juices produced on an industrial scale, with three different commercial pectinases. They were evaluated by colour, total monomeric anthocyanins (TMA) and AOX of the juices stored for six months. Newly produced juices did not present differences in the classical parameters such as pH, degrees Brix, titratable acidity, colour and yield. There was no difference in the organic acids profile of the obtained juices. The juice obtained with predominant presence of hemicellulases presented rhamnose in its composition, indicating degradation of polysaccharides of the grape peel. The juices showed no difference in TPC and AOX between the studied pectinases. In storage studies, there were fast colour evolution, TMA and AOX in all samples. The juice obtained with the predominance of hemicellulases presented more accelerated loss of TMA and AOX. The results obtained in the present work demonstrated the importance of knowing the influence of the use of commercial pectinases in the process of producing grape juice, not only at the time of production, but during its shelf life. The comparison of the different pectinases used under real processing conditions showed that choice of enzymes used in the preparation could be decisive for the shelf life after bottling the product. (C) All Rights Reserved