# Potato Protein Suppresses Proteolytic Activity and Improves Textural Property of Tropical and Cold-Water Fish Surimi

## TL;DR

Potato protein can replace egg white protein to improve fish surimi texture and reduce proteolytic degradation in both tropical and cold-water fish.

## Contribution

Potato protein is shown as an effective alternative to egg white protein for proteolytic inhibition and texture improvement in fish surimi.

## Key findings

- Potato protein at 0.3% inhibited autolysis in Alaska pollock surimi by 72.24%.
- Potato protein improved breaking force in tropical surimi gels by 4.13–5.38-fold.
- Potato protein reduced whiteness in lizardfish and Alaska pollock surimi gels.

## Abstract

Potato protein (PP) at concentrations of 0.025–0.3% was added to tropical fish surimi, including lizardfish (LZ) and threadfin bream (TB), and cold-water fish, namely Alaska pollock (AP) and Pacific whiting (PW), to examine its effect on proteolytic inhibition and surimi gel texture. Tropical fish surimi, particularly LZ, exhibited the highest degree of autolysis induced by endogenous proteases (p < 0.05), as evidenced by degradation of myosin heavy chain and tropomyosin. PP demonstrated a broad range of proteolytic inhibition activities against chymotrypsin, trypsin, papain, and cathepsin L, with chymotrypsin being the most susceptible. At a PP concentration of 0.3%, the highest autolytic inhibition was obtained in AP (72.24%), followed by LZ surimi (60.44%, p < 0.05). Egg white protein (EW) showed autolytic inhibitory activity at 14.50–50.52% in all species at 0.3%. Surimi gels with only 0.025% PP exhibited breaking forces and distance comparable to those with added 0.3% EW, regardless of the cooking regimes. In tropical surimi, PP at 0.3% increased the breaking force by 4.13–5.38-fold under a setting condition (as the best heating regime) compared with the control. At this concentration, PP decreased the whiteness of LZ and AP in the set surimi gels by 7.03% and 6.42% (p < 0.05), respectively, whereas its effect on TB and PW surimi was negligible. The study demonstrates that PP can be a promising alternative to EW to control proteolytic degradation and improve textural properties of cold-water and tropical surimi.