A review of alternative plant protein sources, their extraction, functional characterisation, application, nutritional value and pinch points to being the solution to sustainable food production

Proteins from animal sources have for many centuries been used as the conventional food proteins in the food industry to produce a variety of food products. This is mainly attributed to their functional properties that range from foaming ability and stability to emulsification and gelation. However, animal husbandry has a greater impact on the environment compared to crop production. Thus, research on the potential use of plant-based proteins, which could be more sustainable, cheaper and environmentally friendly has continued to be the focus of many academics and the food industry. Even though studies have been carried out to investigate the functional properties of plant-based protein sources, there is still a need to understand the challenges that exist in the extraction and the functional characteristics of proteins from plant sources, which could be used as a more feasible exchange for animal-based proteins. Therefore, this review aims to contribute to the existing knowledge on the extraction, characterisation and functional properties of plant-based proteins. To this end, relevant literature was searched on several databases such as EBSCO HOST and Science Direct. Google Scholar was also used as a complementary search engine. Research that has addressed the extraction and functional characterisation of proteins from plant sources was critically evaluated and the findings are discussed herein. Additionally, the pinch points that exist in the use of plant-based proteins as alternatives to animal proteins in food processing are highlighted in this review.