Elucidating the role of compositional and processing variables in tailoring the technological functionalities of plant protein ingredients

Although various plant protein (PP) ingredients are available on the market, their application in foods is not trivial, and food companies are struggling to identify PP ingredients fitting the intended use. To fill this gap, abundant literature has appeared but data are hardly comparable due to the absence of a recognized classification of PP ingredients accounting not only for protein purity but also for the process history, and of standardised protocols for technological functionality assessment. In this review, a comprehensive analysis of comparable literature data was thus carried out to elucidate the effect of composition and processing variables on PP technological functionalities. The review presents four sections describing: (i) the approach followed for the construction of a database of PP ingredient functionalities; (ii) the composition and processing factors relevant to PP ingredients; (iii) PP ingredient functional properties and methods used for their determination; (iv) the effect of composition and processing factors on PP ingredient functionalities. This analysis showed legume proteins to present the highest solubility and interfacial properties while pseudocereal ones the highest water-holding capacity. Although pure ingredients show higher functionalities, non-protein components could contribute to interfacial properties. Alkaline extraction, isoelectric precipitation and freeze-drying is the process mostly used in academic research to obtain PP ingredients. However, other extraction, purification, and drying methods can be properly combined, resulting in specific PP ingredient functionalities. Overall, this review highlights that, besides protein purity and source, knowledge of the processing history is required to select PP ingredients with desired functionalities.