On the carbohydrate composition and nutritive value of some cereals

The contents and the distribution between the different grain parts of starch, hemicellulose, cellulose, crude lignin, crude protein and ash have been determined for oat, barley, rye and two wheat species. The relative proportions of the different structural units of the hemicellulose have also been determined. Furthermore, a method is proposed for the determination of the cell-wall complex in cereals. Oat and barley differ from wheat and rye to an appreciable extent only in respect of the hull. The hulls consist of strawlike material rich in lignin, cellulose and xylan; they are richer in xylan than the straw proper. The fruit and seed coat enveloping the seed (viz. the bran) contains relatively small amounts of lignin and cellulose. The bran is chiefly composed of hemicellulose with xylose and arabinose as the main components. The main compound of the endosperm is starch, although some hemicellulose and protein are present, whereas only minor amounts of cellulose and lignin can be found. In the samples investigated only small differences were noted between the compositions of wheat, rye, dehulled oat and dehulled barley; wheat had the highest starch content, rye the highest hemicellulose content, and oat the highest contents of crude protein and lignin. The cell-wall complex determined as the residue after enzymatic hydrolysis of the starch agreed well with that obtained by fractionation. On the other hand, the detergent-fibre values differed from the fractionation results considerably, and the conventional crude fibre analysis yielded results which were about 1.5 times that of cellulose. The feed-values of the different grain parts are discussed on the basis of the analysis results obtained.