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Facile spectrophotometric quantification method of sinapic acid in hexane-extracted and methanol-ammonia-water-treated mustard and rapeseed meals

Naczk, M., Wanasundara, P.K.J.P.D., Shahidi, F.
Journal of agricultural and food chemistry 1992 v.40 no.3 pp. 444-448
spectroscopy, Brassica juncea, Brassica napus, cultivars, mustard meal, rapeseed meal, extraction, hexane, phenolic acids, sinapic acid
The contribution of sinapic acid to the free, esterified, and insoluble bound phenolics of a number of Brassica oilseeds, namely Triton (B. napus), Midas (B. napus), and Hu You 9 (B. napus) rapeseed and Domo mustard (B. juncea), was determined according to a simple spectrophotometric method. Sinapic acid constituted 65-86% of free and 71-97% of esterified phenolic acids of defatted meals. The contribution of sinapic acid to insoluble bound phenolic was 7-32%. Treatment of defatted meals with 10% ammonia in 95% methanol (MeOH-NH3-H2O) resulted in the removal of 41-75% of their total free phenolics and 45-79% of the content of sinapic acid in this fraction. This process also removed 82-93% of the total esterified phenolics and 86-93% of their corresponding sinapic acid. In all cases, MeOH-NH3-H2O extraction enhanced the protein content of the resultant meals.