Evaluating the feasibility of commercial arabinoxylan production in the context of a wheat biorefinery principally producing ethanol. Part 1. Experimental studies of arabinoxylan extraction from wheat bran

Arabinoxylans (AX) are a component of wheat bran that could have application as a food ingredient or for non-food uses if a commercial source could be established at a reasonable price. AX can be co-produced with ethanol in an integrated process, which could enhance the economics of a wheat-based biorefinery principally producing ethanol, and thus facilitate the introduction of commercial wheat-based fuel ethanol production in the UK. A study was therefore undertaken to investigate the economic feasibility of co-producing AX with ethanol from wheat. Pearling is an advanced wheat fractionation technology that preferentially recovers bran from the outer layers of the wheat kernel. The practical feasibility and economic benefit of recovering wheat bran for AX extraction via pearling was also investigated. This paper describes experimental studies to investigate the AX content in bran fractions obtained by pearling, the yields of AX extracted from pearling fractions, and the feasibility of recovering starch from the removed bran via washing, in order to minimise the reduction in ethanol yield due to starch losses with the bran. The following paper describes simulation and economic analysis of ethanol–AX co-production with and without the use of pearling to obtain the bran for AX extraction.

AX was more concentrated in the outer bran layers of the wheat kernel, and the yield and purity of AX extracted from pearling fractions of these layers were greater than for fractions arising from the inner bran layers. This suggests that recovery of bran for AX extraction by pearling would give advantages in terms of yield. However, the quality and functionality of the AX extracted from the outer bran layers, compared with AX arising from other parts of the wheat kernel, need to be investigated. Enzyme treatment of AX extracts significantly enhanced the purity of the extracts. Washing bran with water prior to AX extraction resulted in 71–77% starch recovery for return to the ethanol production section.