Threadfin bream surimi gel containing squid fin protein hydrolysate: Textural properties, acceptability, and volatile...

Gel properties of threadfin bream surimi gels with squid fin protein hydrolysate (SFPH) at various concentrations (0, 1, 2, 3, and 4%; w/w) were determined. The gel without SFPH (CON) had the highest breaking force (BrF) and deformation (DeF) as compared to those with SFPH (p < 0.05). Among the gel with SFPH, gel containing 1 and 2% SFPH (SFPH-1 and SFPH-2, respectively) had the highest BrF, whereas the lowest value was obtained when 4% SFPH was used (SFPH-4) (p < 0.05). The whiteness of all samples was slightly decreased with an upsurging amount of SFPH. However, water holding capacity was increased with augmenting levels of SFPH (p < 0.05). Sensory analysis revealed that SFPH-2 had a higher squid odor and flavor likeness score than CON (p < 0.05). Textural properties, especially hardness, were decreased with increasing SFPH, except for SFPH-1 and SFPH-2 (p > 0.05). In addition, the rheological properties, microstructure, and volatile profile of the selected surimi gel were also studied. The storage modulus (G') of SFPH added samples was decreased as compared to the CON sample. The CON gel had a finer and more compact network as compared to SFPH-2 and SFPH-4 samples. Volatile profiles indicated that alcohols, carboxylic acids, ketones, and ether were the major volatile compounds present in both gel samples. Furthermore, thiophene, 3-methyl-, contributing to squid flavor, was found in the SFPH-2 sample. Overall, SFPH at 2% could act as a flavorant in the threadfin bream surimi gel without markedly negative impact on gelling and textural properties, while providing squid odor and flavor to the resulting gel. PRACTICAL APPLICATION: The various low-valued byproducts generated from the squid processing industry could result in various environmental problems. Those byproducts are rich in various biomolecules such as proteins, fats, enzymes, and so forth, which could be utilized to produce value-added products. Among them, protein hydrolysate (PH) rich in amino acids with excellent antioxidant properties could serve as an alternative flavorant. Therefore, PH from squid byproducts, especially fins, could be applied in foods such as fish balls, surimi gels, and so forth to enhance the nutritional and flavoring profile of a finished product. Moreover, bioactive peptides in PH with antioxidant potential could retard the oxidation of proteins and lipids.