SENSORY STABILITY OF CONCORD AND ISABEL CONCENTRATED GRAPE JUICES DURING STORAGE

The study evaluated the sensory characteristics and phenolic contents of concentrated red grape juice of two cultivars (Concord and Isabel), over 8 months of storage. To approach the sensory aspects, modified descriptive analysis was used. Total phenols were quantified by the Folin–Ciocalteu assay and catechins ([+]-catechin and [−]-epicatechin) by high-performance liquid chromatography with fluorescent detection. The results showed fairly stable sensory behavior of both grape juices with a higher stability of Concord. Total phenols of Concord and Isabel juices depicted retention of 93 and 88%, respectively, and total catechins of 60 and 85%, respectively. Concord concentrated juice was more stable to storage with sensory characteristics of astringency, bitterness and higher color intensity, while Isabel juice was characterized by sweetness and juice flavor. Concentrated juices, under the investigated storage conditions were capable of maintaining sensory standards. PRACTICAL APPLICATIONS Sensory aspects of phenolic-rich beverages such as wine and grape juice are greatly impaired by storage conditions. Color, for instance, is an aspect of great importance to producers for it impacts perceived quality by consumers. This study demonstrates that proper storage of grape juice is capable of preserving sensory characteristics. Moreover, cultivar differences of the same fruit species affect the sensory stability of juices. In practical terms, the use of blends may be useful for commercial grape juice producers for an optimal product that combines high quality taste and stability.