Effects of enzymatic extraction of oil and protein from almond cake on the physicochemical and functional properties of protein extracts

The effects of scaling up the aqueous (AEP) and enzyme-assisted aqueous extraction processes (EAEP) of the almond cake were evaluated in regards to oil and protein extractability, cream demulsification yield, and physicochemical and functional properties of extracted proteins. While similar oil (26.2% AEP and 29.1% EAEP) and protein (67.7% AEP and 70.2% EAEP) extraction yields were achieved at pilot-scale for both processes, under optimum extraction conditions, the use of enzyme in the EAEP generated a cream emulsion easier to be demulsified. Chemical demulsification of the EAEP cream and enzymatic demulsification of the AEP cream resulted in maximum oil recoveries of 98.7 and 62.8%, respectively. In addition, enzymatic hydrolysis resulted in important changes in the physicochemical properties and functionalities of the extracted protein. Overall, enzymatic hydrolysis increased the zeta potential and decreased the surface hydrophobicity of extracted proteins. These changes increased the solubility of the extracted protein to 95.3%, but reduced all emulsification and foaming properties evaluated compared with the aqueous extraction process. This study signifies a starting point to the valorization of the almond cake as a source of lipid and proteins for subsequent use in food, feed, and fuel applications.