Simultaneous combination of subcritical water extraction and enzyme-assisted extraction for protein recovery from lime peels. Characterization of protein hydrolysates

Lime peels are citrus industry residues constituting a great source of bioactive compounds. Reusing these residues contributes to sustainability and reduces the negative environmental impact of food waste removal. In this work, environmentally friendly strategies based on green techniques were developed for the efficient extraction of proteins from lime peels. Two techniques, non-employed before with this aim, were employed: subcritical water extraction (SWE) and enzyme-assisted extraction (EAE), as well as their simultaneous combination. SWE with Viscozyme Wheat HT as polysaccharide enzyme enabled a high extraction yield (95 %) in a short analysis time. Proteases Thermolysin and Alcalase were evaluated to release peptides with antioxidant, antihypertensive, and antimicrobial activities from protein extracts. Most active hydrolysates were analysed by UHPLC-Q-TOF-MS/MS enabling to identify 30 peptides along with 44 phenolics, and other bioactive compounds. Some of these compounds are associated to the observed bioactivities, highlighting the potential contribution of the ACE-related antihypertensive peptide FDAVGVK.