Effect of kelp powder on gel properties and microstructure of shrimp (Litopenaeus vannamei) surimi

Abstract

This study systematically investigated the effects of kelp powder (KP) (0%, 1%, 3%, 6%, 9%) on the gelation behavior, physicochemical properties, and protein structural changes in shrimp (Litopenaeus vannamei) surimi gel (SSG). Notably, it enhanced gel strength by 156% and increased hardness from 80.05 N to 231.87 N, while appropriately reducing springiness to form a firmer texture. KP addition also improved water retention by facilitating the conversion of free water into immobilized and bound water, leading to a water holding capacity of 86.6% and a cooking loss as low as 1.6%. Rheological analysis revealed that KP fortification increased the storage modulus (G’) and viscosity, indicating enhanced gel network elasticity. At the molecular level, Fourier-transform infrared spectroscopy revealed that KP promoted the transition of protein secondary structures from random coils and α-helices to β-sheets. This structural rearrangement was accompanied by strengthened hydrophobic interactions and disulfide bonding, as confirmed by chemical interaction analysis. Scanning electron microscopy further validated that KP facilitated the formation of a denser and more homogeneous gel microstructure. Collectively, KP acts as an effective functional modifier to enhance SSG quality, providing a theoretical basis for the development of high-quality shrimp surimi-based products with natural additives.