Optimization of the de-starching step in fractionation of wheat bran

Sammanfattning: With continuous growth of the human population and limited resources for food pro-duction, there is a need to optimize the utilization of already produced food. Wheat bran is the outer layer of the wheat kernel and a side stream product from flour mill-ing, containing multiple potential functional ingredients. A fractionation process for wheat bran with mild and non-destructive extraction methods is needed to keep all compounds intact. The initial process step is generally to de-starch the wheat bran through one swell part with a 1:10 (bran:water) ratio and several washing steps with a 1:6 (bran:water) ratio. The aim of this project was to decrease the water usage of the de-starching in wheat fractionation, as well as investigate if and to what extent that any functional ingredi-ents are lost into the water used, called slurry, during the process. De-starching was made with three different water ratios (1:6, 1:8, 1:10; bran:water) for the swelling step and three different water ratios (1:4, 1:5, 1:6; bran:water) for five washing steps. For all bran:water treatments the starch content decreased from 9,00 % to below 1,00 % in the bran after three washing steps. The amount water needed have been narrowed down to 1:6-1:8 (bran:water) for swell water ratio and to 1:5 or below (bran:water) for the wash water ratio, without any impact on the process efficiency. The total water use was thereby decreased with at least 20 %. Small concentrations of arabinoxylans (< 0,4 mg/g slurry) and proteins (<0,3 mg/g slurry) were found in the water extractable part of the slurries. At least 40 % of the water unextractable part was non-starch and have potential to be valuable chemical compounds. Future studies need to focus on the water unextractable part of the slurries from the de-starching process of wheat bran. This project could bring useful information for the industry when planning to de-starch wheat bran and extract its nutrients, leading to a decrease of the environmental impact and targeting the most economically efficient nutrients to extract. Thus, being a part of optimizing the utilization of already produced food.