Enzymatic acivity



A major contributor to undesirable browning effects in fruit and vegetables is the enzymatic browning caused by PPO, polyphenol oxidase (Martinez & Whitaker 1995). Enzymatic browning can henceforth be expressed by the dioxygen consumption of PPO, as this is directly related to the activity of PPO. To avoid enzymatic browning of fruits and vegetables it is important to store them under conditions that suppress the enzymatic activity.

The activity of PPO was investigated as a function of different levels of O2, CO2, temperature, pH, and substrate according to a factorial design. A traditional ANOVA model of the data did not shed much light on the relation between these factors and the activity, while a multiplicative model based on GEM­ANOVA/PARA­FAC was easy to interpret. The problem presented here is part of an investigation conducted by Hanne Heimdal and described in detail in [Bro & Heimdal 1996, Heimdal et al. 1997].

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The data are available in zipped MATLAB 5.x format as a standard data object. Download the data and write load data in MATLAB. If you use the data we would appreciate that you report the results to us as a courtesey of the work involved in producing and preparing the data. Also you may want to refer to the data by referring to

Bro R, Heimdal H, Enzymatic browning of vegetables. Calibration and analysis of variance by multiway methods, Chemom Intell Lab Syst, 1996, 34, 85-102


Data (Matlab format)



See description of GEMANOVA algorithm and application

Copyright © 1996-01 Rasmus Bro (rb@kvl.dk). All rights reserved