Mi. Rubino et al., EVALUATION OF ALKALINE CONVERSION OF SINAPIC ACID TO THOMASIDIOIC ACID, Journal of agricultural and food chemistry, 44(6), 1996, pp. 1399-1402
Conditions which promote the alkaline conversion of sinapic acid (SA),
the main phenolic acid in canola, to the lignan thomasidioic acid (TA
) were investigated as the presence of TA could affect nutritional and
functional properties of canola products. Reaction rates were studied
using ultraviolet spectroscopy under oxygen, nitrogen, and air and in
the presence of antioxidants. High-pressure liquid chromatography was
used to quantify the conversion of SA to TA. This reaction appears to
involve an oxidative coupling of SA molecules which can be controlled
by purging with nitrogen. By including ascorbic acid, the reaction wa
s slowed but not completely controlled, and the presence of sodium bis
ulfite accelerated the reaction. In the presence of air, there was com
plete conversion of SA to TA at pH 8.5 and 30% conversion at pH 7.