Structure-function guided production of oat and chickpea protein isolates in comparison to pea protein isolate following mild extraction conditions

As the global plant protein consumption continues to rise, legumes remain the dominant protein source on the market. Additional plant protein sources with desirable functionality must be identified to meet the growing protein demand. To achieve desirable functionality of these rather challenging plant proteins, it is essential to preserve the structural integrity of the protein during the extraction process by employing mild conditions. Accordingly, a mild process involving alkaline extraction coupled with isoelectric precipitation (AE-IEP) to produce protein isolates from two legumes (chickpea and pea) and a cereal source (oat) was evaluated at a bench and pilot scale. Scaling the process was essential to demonstrate its potential commercial adaptation. Oat, chickpea, and pea protein isolates (OPI, ChPI, and PPI) were produced at benchtop and their production was scaled-up (SU) in the pilot plant to obtain SUOPI, SUChPI, and SUPPI. The adapted AE-IEP process effectively maintained structural integrity with limited denaturation and polymerization. Such structural integrity contributed to superior or comparable solubility of both SUPPI and SUChPI relative to commercial pea and soy protein isolates (cPPI and cSPI), and superior gel strength of SUOPI compared to SUChPI and SUPPI, and to cPPI. These functional performances were linked to unique surface properties, presence of soluble aggregates, and to the characteristics of the indigenous globulin proteins. These findings uniquely highlighted the potential of the underutilized oat and chickpea proteins, along with pea protein as functional contenders in the plant protein market, when produced following a mild yet scalable extraction process.