Malonylgenistin and Malonyldaidzin Conversion Kinetics
J. Agric. Food Chem., Vol. 55, No. 9, 2007 3413
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The relative simplicity of the kinetic equations, the accuracy
of the fittings, the trends in reaction rates, and the similarities
in activation energies as analyzed above suggested that the
proposed kinetics adequately described the chemical reactions
involved in the conversion of malonylglucosides, with a low
number of parameters. Results indicated that the small difference
in molecular structure of both malonylglucosides did not affect
the rate of conversion into â-glucosides. However, as pH and
heat increase, the difference in molecular structure affected
significantly the rate of degradation of each malonylglucoside
and its respective â-glucoside. This work confirmed that, along
with conversion, degradation occurs, resulting in loss. In real
heated systems, similar degradation might be occurring, leading
to loss that is independent of waste streams and protein matrices.
To confirm this assertion, complementary kinetic work ought
to be done in real systems, taking into account the protective
effect of proteins on isoflavone chemical modification, as well
as the effect of protein denaturation (due to pH and temperature)
on the rate of extraction of each type/form of isoflavone.
Overall, the findings of this work highlighted the importance
of the chemical structure of isoflavone with respect to stability
and provided useful information to manufacturers aiming to
minimize loss of isoflavones to enhance the nutritional value
of their soy products, without sacrificing the quality character-
istics. Therefore, while nutritionists investigate the biological
significance of each type/form of isoflavone, it is a necessity
to fully understand their distinct reaction to typical processing
conditions and thus minimize loss.
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glycosidic forms of isoflavones. J. Agric. Food Chem. 2005, 53,
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Received for review December 5, 2006. Revised manuscript received
February 22, 2007. Accepted February 22, 2007.
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