Enzymatic browning

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Fresh green tea leaves of different sizes.
Fermented Tea (Darjeeling)

The enzymatic browning is a by Enzyme mediated tanning , in various food runs out.

By the penetration of air oxygen into a plant cell, plant diphenols can be converted by the polyphenol oxidase into brown quinones , which the plant simultaneously defends against microorganisms. Quinones are also formed by the laccase . The influence of enzymes distinguishes this type of tanning from the Maillard reaction , in which other chemical processes take place without the participation of enzymes . The discoloration can look unsavory, but is not a health hazard. In the presence of antioxidants such as ascorbic acid , enzymatic browning is slowed down due to the reduction in oxygen concentration.

Enzymatic browning is desirable during the fermentation of tea and cocoa . The dark color and taste result from the oxidation of the catechins originally contained .

Individual evidence

  1. ↑ JR Walker, PH Ferrar: Diphenol oxidases, enzyme-catalysed browning and plant disease resistance. In: Biotechnology & genetic engineering reviews. Volume 15, 1998, pp. 457-498, ISSN  0264-8725 . PMID 9573613 .
  2. ^ JJ Nicolas, FC Richard-Forget, PM Goupy, MJ Amiot, SY Aubert: Enzymatic browning reactions in apple and apple products. In: Critical reviews in food science and nutrition. Volume 34, Number 2, 1994, pp. 109-157, ISSN  1040-8398 . doi : 10.1080 / 10408399409527653 . PMID 8011143 .
  3. ^ John R. Whitaker: Principles of Enzymology for the Food Sciences, Second Edition ,. CRC Press, 1993, ISBN 978-0-824-79148-3 , p. 543.
  4. ↑ M. Friedman: Prevention of adverse effects of food browning. In: Advances in Experimental Medicine and Biology . Volume 289, 1991, pp. 171-215, ISSN  0065-2598 . PMID 1897392 .