Towards plant protein refinery: Review on protein extraction using alkali and potential enzymatic assistance

Abstract

The globally increasing protein demands require additional resources to those currently available. Furthermore, the optimal usage of protein fractions from both traditional and new protein resources, such as algae and leaves, is essential. Here, we present an overview on alkaline plant protein extraction including the potentials of enzyme addition in the form of proteases and/or carbohydrolases. Strategic biomass selection, combined with the appropriate process conditions can increase protein yields after extraction. Enzyme addition, especially of proteases, can be useful when alkaline protein extraction yields are low. These additions can also be used to enable processing at a pH closer to 7 to avoid the otherwise severe conditions that denature proteins. Finally, a protein biorefinery concept is presented that aims to upcycle residual biomass by separating essential amino acids to be used for food and feed, and non-essential amino acids for production of bulk chemicals.

Integration of galacturonic acid extraction with alkaline protein extraction from green tea leaf residue

“…Pectate lyase and/or pectinase can be used for hydrolysis of pectin, while galactanase, arabinanase, hemi-celllulase and cellulase are often used for the degradation of cell wall carbohydrates, including rhamnogalacturonan I pectin, hemi-cellulose and cellulose (Taherzadeh and Karimi, 2008). Using an enzyme mixture such as Viscozyme ® L, that contains several or even all enzymes mentioned above for cell wall degradation is popular for its high efficiency on hydrolysis (Sari et al, 2015) and relative low price compared to individual enzymes. Enzyme aided extraction is carried out under either weak acid or alkaline conditions, and may also be suitable for integration with protein extraction.…”

Microalgae for integrated food and fuel production

“…For protein extraction, it is of great importance to ensure that the process will not have an impact on protein functionality and quality. Protein extraction involves centrifugation, ultrafiltration, precipitation, chromatography techniques (Sari, Mulder, Sanders, & Bruins, 2015), or solvent extraction and fractionation via lyophilization (freeze drying; Brentner, Eckelman, & Zimmerman, 2011). For more complex and integrated extraction of protein and fatty acids, protein extraction should be performed before lipid extraction to avoid impairment of protein quality.…”

Valorisation of Proteins from Rubber Tree

“…Agricultural residues are important protein sources because they do not compete with protein applications for food. Processing of agricultural residues requires a biorefinery approach that enables the use of all biomass fractions for their optimal economic values [2,3].…”