Effects of Fruit Maturity, Juice Storage, and Juice Extraction Temperature on Quality of ‘Concord’ Grape Juice

A factorial study was designed to examine the effects of fruit maturities, juice extraction temperatures, storage time, and storage temperature on the quality of ‘Concord’ grape ( Vitis labrusca L.) juice. Mature grapes produced juice with superior sensory quality and better objective color initially than less-mature grapes, but juice from grapes at both maturities had similar sensory quality after 18 months. The high extraction temperature (99°C) resulted in juice with better color initially than extraction at 60°, but juice extracted at 85° or 99° resulted in greater browning and loss of total anthocyanins during storage than extraction at 60°. High storage temperature (35°) greatly accelerated quality loss. Sensory color ratings correlated better with a ratio of absorbances at 520/430 nm ( r = 0.95) and a/b ( r = 0.92) than other objective color measurements.