Sentence:  ... the fragments are broken down and the finer particles are collected by sieving; finally, there is the bolting of the assembled fine fractions, with exclusion of the wheat <WSD>offal</WSD> which includes bran and a number of other commercial fractions like red dog and shorts. 
Meaning of the word marked with <WSD> tags:  A by-product of the grain milling process, which may include bran, husks, etc.