Kinetics of the apparent non-enzymic browning of potatoes
1999
Madamba, P.S. (Philippines Univ. Los Banos, College, Laguna (Philippines). Coll. of Engineering and Agro-Industrial Technology)
The kinetics of apparent non-enzymatic browning (NEB) in dehydrated diced potatoes were studied by exposing product samples (known equilibrium moisture contents from 4.4 to 14.7% db) to 40, 60 and 80 deg C and from 7 to 79% relative humidity. The color (O.D./g sample) changes in the potato extract (using 10% NaCl) during storage were determined. No lag phase or initial induction period was observed before the main browning period within the range of the variables studied. A zero-order reaction was found for NEB of potatoes with reaction rate constant, K, increasing with moisture content and temperature. The temperature dependency of the reaction followed a simple Arrhenius type relationship and the calculated activated energy (E sub a = 42.1 plus or minus 0.8 kJ/mol) appeared to be independent of temperature and moisture content over the 40-80 deg C range. Shelf-life studies of dried potatoes were conducted based on k and E sub a and the "limit-of-acceptability", set at 0.45 O.D./g sample. The kinetic model was validated under various temperatures (50, 60, 70, 80, and 90 deg C) and moisture content levels (4.8-17.1% db). The predicted shelf life tended to underestimate the actual shelf life showing consistency of the predictions by less than 10% error
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