Thermal dynamic properties of isoflavones during dry heating

Document Type

Article

Publication Date

9-1-2010

Abstract

Thermal stabilities of major soya isoflavones at different dry-heating temperatures were determined in this study. The conversion of glucoside isoflavones to aglycone isoflavones was monitored as well. The thermal degradation of the isoflavones: glucoside form daidzin, glycitin, and genistin and aglycone form daidzein, glycitein, and genistein followed first-order reaction kinetics at heating temperatures 100, 150, and 200 °C. The degradation rate constants of the six isoflavones were not significantly different at 100 °C. However, the constants increased with increasing heating temperature. The half-life for the glucoside and aglycone isoflavones was from 144 to 169 min and 139 to 176 min at 100 °C, respectively. They decreased rapidly to 15.7-54.7 and 36.0-90.7 min when temperature increased to 150 °C. When heated at 200 °C, they further decreased to 5.8-6.0 and 15.7-21.2 min, respectively. The order of thermal stability from lowest to highest was glycitin < genistin < daidzin < glycitein < genistein < daidzein at temperature below 150 °C. However, their thermal stabilities were not different at 200 °C. The conjugated glucosides were cleaved from the isoflavones to produce their corresponding aglycones when heated at 150 °C or higher. The production of glycitein increased constantly and was the highest among the three aglycone isoflavones. © 2010 The Authors. Journal compilation © 2010 Institute of Food Science and Technology.

Publication Source (Journal or Book title)

International Journal of Food Science and Technology

First Page

1878

Last Page

1882

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