Effects of variety, maturity and processing on pear juice quality and protein stability
1990
Hsu, J.C. | Heatherbell, D.A. | Yorgey, B.M.
d'Anjou, Comice, and Bartlett pears were processed into clarified juices from hard green and soft ripened fruits. Processing trials with and without SO2 were conducted. Effects of variety, maturity and processing on browning, turbidity, proteins, and stability were investigated. Browning increased with heat treatment, and was reduced by processing with SO2. Total soluble protein content increased with fruit maturity and processing with SO2. Protein fractions from a clarifying enzyme preparation (mainly arabinase and amylase) with MW in the range of 64,000-92,000 and containing glycoproteins were not removed by fining/clarification. They contribute to protein instability in the clarifed pear juices, but could be removed by heat treatment (pasteruization) prior to final filtration and bottling. Our results indicate some enzymes added for clarification during processing may contribute to post-clarification haze and sediment formation.
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