Extraction of plant protein from green leaves: Biomass composition and processing considerations

There is an increasing need to explore alternative sources of proteins for food applications. Green leaves contain high levels of the enzyme RuBisCO, representing a source of protein with good functional and nutritional properties. However, the optimal conditions for extraction and purification of RuBisCO at a large scale have not yet been defined. This review discusses the main factors affecting the extraction of proteins from green leaves, from plant composition in terms of protein content and other compounds that affect the yield and quality of extractable protein, to the essential steps and challenges faced during extraction and purification, including considerations for achieving food-grade ingredient status. There are some key factors to consider when developing a protein concentrate for human consumption. The first step is the selection of an optimal raw material; plant tissues are complex matrices that require thorough characterization, including non-protein nitrogen and other undesirable compounds. The effect of the extraction and purification process on functionality, oxidation and proteolytic stability should also be considered. Moreover, the appropriate removal of undesired compounds must be considered to obtain plant protein concentrates suitable for food products.