Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/50696
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Type: Journal article
Title: Physical-Chemical Analysis of Non-Polyphenol Oxidase (Non-PPO) Darkening in Yellow Alkaline Noodles
Author: Asenstorfer, R.
Appelbee, M.
Mares, D.
Citation: Journal of Agricultural and Food Chemistry, 2009; 57(12):5556-5562
Publisher: Amer Chemical Soc
Issue Date: 2009
ISSN: 0021-8561
1520-5118
Statement of
Responsibility: 
Robert E. Asenstorfer, Marie J. Appelbee and Daryl J. Mares
Abstract: Darkening in yellow alkaline noodles (YAN) was measured over 24 h in a high polyphenol oxidase (PPO) bread wheat ( Triticum aestivum L. cv. Tasman) and a very low PPO durum wheat ( Triticum durum cv. Kamilaroi). Over 24 h non-PPO darkening occurred across a range of pH 3.5-10.5, and in Tasman this was overlaid by darkening from PPO activity. The rate of darkening in YAN was separated into two main time periods, 0-4 and 4-24 h. The first 4 h of darkening was further divided into two stages using a composite first-order rate equation. Several specific inhibitors that partially inhibited non-PPO darkening were identified. These inhibitors, as well as the PPO inhibitors SHAM and tropolone, were used to analyze YAN darkening. The rate of the early stage of darkening was not altered by any inhibitors used; however, the magnitude of darkening was reduced by inhibitors specific for non-PPO darkening. Both the rate and extent of non-PPO darkening of the second stage of darkening were decreased in Tasman and Kamilaroi by inhibitors specific for non-PPO darkening, whereas both PPO inhibitors only decreased darkening in Tasman. The second and third stages of darkening showed similar characteristics. The third stage of darkening was examined in YAN made from Kamilaroi over a temperature range from -4 to 65 degrees C. It followed an Arrhenius relationship indicating non-PPO darkening during this stage was nonenzymatic. The inhibitor data suggested that the reactive component(s) was/were present in a reasonably high concentration(s) and that the soluble protein fraction was involved in the non-PPO darkening process.
Keywords: Triticum; Catechol Oxidase; Plant Proteins; Enzyme Inhibitors; Enzyme Stability; Flour
Description: Copyright © 2009 American Chemical Society
RMID: 0020090924
DOI: 10.1021/jf900485b
Appears in Collections:Agriculture, Food and Wine publications

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