Improvement of colour stability of pear juice concentrate by heat treatment |
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| Authors: | H J PETROPAKIS† M W MONTGOMERY‡ |
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| Affiliation: | Department of Chemical Engineering, School of Engineering, University of Thessaloniki, Thessaloniki, Greece;Department of Food Science and Technology, Oregon State University, Corvalis, OR 97331, U. S. A. |
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| Abstract: | Clarified pear juice concentrates were prepared from ascorbic acid treated juices that had been boiled for 0, 1, 2, 3 and 5 min and an unheated control. Boiling of pear juice for 1 min was required for complete inactivation of pear juice polyphenol oxidase (EC 1.14.18.1, monophenol monooxygenase). During 6 months of storage at 0,20 and 38°C concentrates prepared from boiled juice were characterized by greater colour stability as indicated by slower rates of browning and changes in the Hunter 'L' values when compared to these changes in concentrates prepared from unheated juice.
Colour stability of the concentrates was also improved by storage at 0°C. |
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