Wheat bran – from a fibre source to a significant protein source: lactic acid and yeast fermentation and enzymes liberates the proteins for nutritional use

Up until now, wheat bran has been primarily used as feed or as a raw material in bioethanol production. Bioprocessing helps to modify proteins in wheat bran to make them bioavailable for human consumption.

Wheat is one of the most important cereals in the world. The inner parts of wheat grains are utilised as food, processed into starchy wheat flour. The outer layers of the grain, known as bran, and the germ located in the stem of the grain are removed during milling, since leaving them in the flour would alter the baking qualities.

Annually, more than a hundred million tonnes of side streams with a relatively high protein content is generated by milling. Yet, these side streams are wasted in the perspective of human nutrition, since the proteins contained in bran, for example, are hard to access.

“They hide inside the cell walls of the tough and fibrous aleurone layer. Human digestion is unable to break down the cell walls, subsequently leaving the proteins unabsorbed as well. With the help of bioprocessing, these proteins can be released and a new type of plant protein food raw material can be produced from industrial sidestreams,” says Elisa Arte who defended her doctoral dissertation at the Faculty of Agriculture and Forestry, University of Helsinki.

In her dissertation work, Arte has succeeded in releasing valuable proteins for nutritional use by employing the method of bioprocessing, that is, by utilising enzymes that break down cell walls as well as lactic acid and yeast fermentation. Through optimised bioprocessing, she has managed to substantially increase the solubility of wheat bran proteins, as well as improve their nutritional quality and technological properties.

Bioprocess-induced changes in wheat bran protein bioavailability, nutritional quality and technological functionality