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

## TL;DR

This study shows how pH shift and high pressure homogenization can improve the properties of proteins from low-quality peas, making them useful for food products.

## Contribution

The study applies pH shift and HPH directly to wet pea protein extracts, offering a sustainable way to upcycle pea waste.

## Key findings

- Proteins were extensively denatured during extraction from substandard peas.
- PS and HPH treatments reduced protein aggregation and improved solubility and functionality.
- Combined PS+HPH enhanced interfacial properties and antioxidant activity of pea proteins.

## Abstract

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.

Image 1

•Proteins were extracted from substandard peas wasted by canning industry.•pH shift-PS and high pressure homogenization-HPH were applied to wet protein extracts.•Extraction caused extensive denaturation and aggregation of pea proteins.•PS and HPH application resulted in protein aggregate detachment.•PS and HPH lead to proteins with improved techno-functionalities from wasted peas.

Proteins were extracted from substandard peas wasted by canning industry.

pH shift-PS and high pressure homogenization-HPH were applied to wet protein extracts.

Extraction caused extensive denaturation and aggregation of pea proteins.

PS and HPH application resulted in protein aggregate detachment.

PS and HPH lead to proteins with improved techno-functionalities from wasted peas.