Processing Technologies to Produce Plant Protein Concentrates and Isolates

Abstract

AbstractThe demand for new healthy food ingredients and products is on the rise. The global plant-based protein market is projected to grow from US$10.3 billion in 2020 to US$14.5 billion by 2025, recording a compound annual growth rate of 7.1% during the forecast period. Plant protein ingredients, namely concentrate (65–90% w/w protein dry basis) and isolate (90%+ w/w protein dry basis), are increasingly finding their way into a broad range of food products, not only due to their nutritional value but also given that such ingredients interact well with other food ingredients. However, their functional properties differ depending on the protein source and on the way the ingredients are processed and/or extracted. Key functional properties include solubility, water- and fat-adsorption capacities, emulsifying properties, foam-forming capacity and stability, and gelling properties. The main plant protein sources are oilseeds (soybean, canola, flax, etc.), pulses (pea, chickpea, bean, lentil, etc.), and cereals (wheat, corn, barley, etc.), with soybean, wheat, pea and corn being the current key players in the plant-based foods market. However, new alternative sources are finding their way into the market, including barley, bean, camelina, canola, chickpea, flax, hemp, lentil, mustard, peanut, pea, quinoa, rice, sesame, sorghum, and sunflower. Plant proteins can be extracted directly from the oilseeds, pulses and cereals moreover, several sources of plant proteins are from different agro-industrial waste materials. The redirection of by-products, which are usually used as animal feed livestock, to human consumption helps to preserve the environment, ensure food security and support the sustainability of food systems. Many technologies are involved in the production of plant protein concentrates and isolates, including milling to obtain flour, and drying to dry the protein extracts into a powder when wet extraction is carried out. However, the core of the process is protein extraction and separation. Protein extraction and separation processes can be classified into two main categories: dry fractionation and wet extraction processes. Wet extraction processes are the most common methods used to produce plant protein ingredients and include conventional processes such as alkaline extraction–isoelectric precipitation (AE-IP), salt extraction–dialysis (SED), and micellar precipitation (MP). They also include emerging processes such as enzyme-assisted extraction, ultrasound-assisted extraction, microwave-assisted extraction, and membrane technologies. The selection of the most appropriate plant protein extraction/separation process depends on many factors, such as the composition of the oilseeds, pulses, and cereals (fiber-rich content, polysaccharides, and fat), the part that is used, the targeted level of proteins in the ingredients, and so on. This chapter provides a review of the processing technologies used to produce plant protein concentrates and isolates, and discusses their impact on the main plant protein sources.