THERMOSTABILITY AND ORANGE JUICE CLOUD DESTABILIZING PROPERTIES OF MULTIPLE PECTINESTERASES FROM ORANGE

Authors

  • C. VERSTEEG,

    1. Authors Versteeg, Rombouts, Spaansen, and Pilnik are with the Dept. of Food Science, Agricultural University, De Dreijen 12, 6703 BC Wageningen, The Netherlands.
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  • F. M. ROMBOUTS,

    1. Authors Versteeg, Rombouts, Spaansen, and Pilnik are with the Dept. of Food Science, Agricultural University, De Dreijen 12, 6703 BC Wageningen, The Netherlands.
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  • C. H. SPAANSEN,

    1. Authors Versteeg, Rombouts, Spaansen, and Pilnik are with the Dept. of Food Science, Agricultural University, De Dreijen 12, 6703 BC Wageningen, The Netherlands.
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  • W. PILNIK

    1. Authors Versteeg, Rombouts, Spaansen, and Pilnik are with the Dept. of Food Science, Agricultural University, De Dreijen 12, 6703 BC Wageningen, The Netherlands.
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ABSTRACT

Three forms of pectinesterase, accounting for 95% of the activity in Navel orange, showed considerable differences in heat stability and orange juice cloud destabilizing properties. Pectinesterase I and II (isoenzymes) and a so-called high molecular weight pectinesterase were rapidly inactivated at 70°C, 60°C, and 90°C, respectively. In chilled juices (5°C) the high molecular weight pectinesterise was the only enzyme which rapidly produced methanol and destabilized the cloud. Although this enzyme represents only 5% of the total pectinesterase activity in Navel orange, it is thought that it is largely responsible for gelation which may occur in concentrates produced by the cut-back process.

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