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Pectinesterase Activity and Proximate Analyses of Sea Buckthorn Juices
Author(s) -
Harrison Judith E.,
Beveridge Thomas H. J.
Publication year - 2006
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.2006.tb12383.x
Subject(s) - hippophae rhamnoides , pectinesterase , chemistry , food science , pectin , brix , water activity , pectinase , water content , biochemistry , enzyme , sugar , geotechnical engineering , engineering
ASTRACT Three varieties of sea buckthorn fruit were harvested and pressed to obtain juices. These were analyzed for pectin methylesterase activity, moisture, nitrogen, oil, pH, total acid, and °Brix. Yields of press juice for Hippophae rhamnoides ssp. rhamnoides L. varieties Luchistaya, Prozrachnaya, and ssp. mongolica Rousi cv. Indian Summer were 68%, 69%, and 66% w/w, respectively. Differences in juice composition were found to be in moisture content, °Brix, pH, and in total acid with the Luchistaya variety having the highest acid levels and lowest pH. Pectin methylesterase (PME) was present in all sea buckthorn juices with initial activity levels of 6.8 to 14.0 μ equivalents per min per 100 g of juice at pH 8 and 23 °C. Activity was pH‐dependent with little PME activity at pH 3 to 5 and the highest activity at pH 8. The cream, pellet, and serum layers of centrifuged juices all contained PME. Heat treatment reduced PME activity in the juices by 1 decimal reduction or less.