Recovery and Utilization of Plant Protein from Agricultural By-Streams

A shift toward production and consumption of foods with lower environmental impacts such as plant foods is necessary to promote sustainability in our food system. This project focus on the utilization of three different plant proteins as a novel food resource in new markets.
Rapeseed is the second-largest cultivated oilseed crop worldwide and is primarily used for edible oil. Rapeseed press cake, a by-stream from the oil production, contains around 30-40% of high quality protein. However, the press cake in mainly used as animal feed today. Hemp is today mainly grown for the textile industry and are used as sustainable building material. The seeds, a by-product, can be pressed to produce an edible oil. The hemp press cake can therefore be regarded as a secondary by-stream and contains around 40-50% protein. Oat can be used for several types of food. Oat bran, a part of the oat grain, can be separated from husk and endosperm by dehulling and dry milling. It contains around 18-26% protein that is possible to extract and purify. All three protein rich fractions are today not used at their full potential due to various reasons, one being the presence of anti-nutrients such as glucosinolates, phytic acid, polyphenols, and lectins. Extraction and concentration of plant proteins can lower the level of antinutrients. Therefore, it is important to incorporate this step before the plant proteins can be used as a novel food source. There are two protein recovery processes which are the most common ones, salt extraction and alkaline extraction. The protein extracted from the two methods usually shows different quality in functional properties and can therefore be incorporated in different applications.
The overall aim of the thesis is to evaluate different ways of extracting the protein from the three different plant protein sources, investigate functional properties and evaluate which applications the different protein fractions can be used for.