Effect of pH shift and high pressure homogenization on the structure and techno-functional properties of protein extracts from substandard peas

This study aimed to elucidate the mechanisms involved in the modification of structure and techno-functional properties of pea proteins upon pH-shift (PS), high-pressure homogenization (HPH) and their combination (PS + HPH). Unlike many previous studies on dried commercial isolates, treatments were applied directly to wet extracts to increase sustainability. Wet protein extracts obtained from substandard peas by alkaline extraction and isoelectric precipitation were subjected to PS, HPH and PS + HPH before drying. Differential scanning calorimetry showed that proteins were extensively denatured already upon extraction. None of the treatments impacted protein primary and secondary structure, as detected by SDS-PAGE and FTIR. Single treatments promoted protein aggregate detachment, exposing hydrophilic and hydrophobic groups, and particle size decrease, while PS + HPH favored intramolecular bonding of the small particles formed upon PS. These structural changes increased extract solubility, interfacial properties, water/oil holding capacity and antioxidant activity. PCA highlighted structural changes induced by PS and HPH on pea proteins to be associated with improved functionalities, opening new possibilities for pea waste upcycling into protein-rich ingredients.