Prevention of conglomerate formation in not-from-concentrate single-cultivar cloudy apple juice by using different treatment methods.

Conglomerates may form at the bottom of bottles containing not-from-concentrate (NFC) cloudy apple juice obtained from a single apple cultivar. Since dissociation or dispersion of these conglomerates cannot be achieved by shaking, the juice appears unsightly, and consumers can mistake the product as being spoilt. Juice from Elstar and Braeburn apples was treated with selected enzymes (gluco-amylase, alpha-amylase, pectin lyase, polygalacturonase and protease) and by using bentonite and a separator. The effects of these treatments on the formation of conglomerates in cloudy apple juice have been studied, and the treatment effects on turbidity and cloud stability have been documented. Conglomerates were observed in juices treated with protease or bentonite and in control juices. However, no conglomerates were observed in the juice samples treated with gluco-amylase, alpha-amylase, pectin lyase or pectin lyase in combination with polygalacturonase. The results obtained after treatment with a separator were not consistent. It is supposed that carbohydrate fractions play a more important role in conglomerate formation than proteins and phenols. Gluco-amylase and alpha-amylase treatment also provides good cloud stability, and thus can be a suitable method for preventing conglomerate formation in single-cultivar NFC cloudy apple juice.