Influence of cooking methods on physicochemical characteristics and in vitro protein digestibility of restructured pork steak hydrolyzed by bromelain and reformed by κ-carrageenan

Abstract

This study systematically investigated the effects of cooking methods (sous vide, baking, and frying), enzymatic treatment with bromelain, and hydrocolloid stabilization using κ-carrageenan on the physicochemical properties and in vitro protein digestibility (IVPD) of restructured pork steaks. Sous vide cooking retained 36 % more moisture (27 % Water holding capacity; WHC) and had 84 % lower cooking loss (4 %) than fried samples, resulting in a more tender texture (hardness reduced by 30 % compared to baked samples) and the highest IVPD (9 % higher than baked and 10 % higher than fried samples). Baked samples exhibited the highest WHC (42 %), while fried samples showed the highest cooking loss (25 %). Microstructure analysis revealed that sous vide samples maintained a more uniform and intact protein matrix, while fried samples exhibited greater structural disruption and porosity. Bromelain hydrolyzed muscle proteins into smaller peptides, improving tenderness and digestibility, while κ-carrageenan formed a stabilizing protein-polysaccharide network, counteracting bromelain's over-hydrolysis and preserving textural integrity. Additionally, κ-carrageenan significantly enhanced WHC and contributed to a uniform appearance across all cooking methods. This indicates that bromelain and κ-carrageenan work synergistically to enhance moisture retention, texture, and digestibility. Results demonstrate the potential of sous vide, combined with enzymatic and hydrocolloid treatments, to produce innovative, high-quality restructured meat products that align with modern consumer preferences for convenience, nutrition, and functionality. This research offers a promising framework for optimizing restructured meat production to meet evolving industry and consumer demands.