Wheat gluten phenolic acids: Occurrence and fate upon mixing

Ferulic acid (FA, 4.9-17.7 mug/100 mg), sinapic acid (SA, 1.4-3.5 mug/100 m g), and traces of p-coumaric acid and vanillic acid were detected after sap onification of six wheat glutens from industrial and pilot-scale origins. F A and SA occurred mostly as soluble-bound and insoluble-bound forms accordi ng to their extractability by acetone/methanol/water (7:7:6, v/v/v). The ma jor part of FA (50-95%) was found in the unextractable fraction, whereas SA was mostly extractable (64-85%). The carbohydrate contents of the glutens were determined also after acid hydrolysis. The highest levels of glucose, arabinoxylan, and FA were obtained from the unextractable fractions of the pilot-scale extracted glutens, probably in relation with a lower efficiency of washing during extraction compared to industrial processes. On the othe r hand, SA compounds were in similar concentrations in all samples, suggest ing their involvement in specific interactions during gluten protein agglom eration. Saponification of the soluble-bound phenolic acids released mainly glucose, whereas a P-glucosidase treatment had no effect. FA and SA extrac tability, especially that of soluble-bound ones, decreased strongly in over mixed gluten/water doughs. These low molecular weight conjugates of phenoli c acids could be involved in the dough breakdown phenomenon.