Promoting the grinding of wheat bran through treatment by sodium carbonate and its mechanism

Abstract

This work investigated the effect of treatment by sodium carbonate on grinding of wheat bran and the related mechanism. Specifically, wheat bran was treated by sodium carbonate solutions at the ratio of 1:2 to make addition of sodium carbonate at 0.0%, 4.0%, 8.0%, 12.0%, 15.0%, and 30.0% based on the mass of bran, dried, and ground using the universal high-speed grinder. It was found that treatment by sodium carbonate significantly reduced the particle size of ground bran and this effect was positively correlated with the sodium carbonate content, which suggested that treatment by sodium carbonate promoted the grinding of wheat bran. Besides, treatment by sodium carbonate improved the hardness of bran. On the other hand, treatment by sodium carbonate damaged the crystal structure, the cell wall and lignin of bran. Moreover, treatment by sodium carbonate converted bound phenolics, including ferulic acid, into free phenolics and insoluble dietary fiber, including unextractable arabinoxylan, into soluble dietary fiber. These results suggested that treatment by sodium carbonate had already damaged the structure of bran and altered the texture of bran before the mechanical stress during grinding was applied. As a result, treatment by sodium carbonate promoted the grinding of wheat bran.