Effects of chitosan grafted phenolic acid coating on microbiological, physicochemical and protein changes of sea bass (Lateolabrax japonicus) during refrigerated storage

Abstract

This project aimed to evaluate the effects of gallic acid (GA) and protocatechuic acid (PA) grafted onto chitosan (CS) on the improved quality of sea bass (Lateolabrax japonicus) during refrigerated storage. The incorporation of GA and PA onto CS (CS‐g‐GA and CS‐g‐PA) were achieved by the carbodiimide‐mediated grafting procedure. Samples were treated with different solutions (deionized water [CK], 1% CS [m/v], 1% CS‐g‐GA [m/v], and 1% CS‐g‐PA [m/v]) for 10 min, which were then stored at 4 °C. Microbiological quality, including total viable counts (TVC), psychrophilic bacterial counts (PBC), Pseudomonas bacterial counts, and H2S‐producing bacterial counts were measured. Physicochemical parameters, including pH, total volatile basic nitrogen (TVB‐N), thiobarbituric acid (TBA) value, water holding capacity (WHC), and K value, were measured. The changes in protein characteristics, including sulfhydryl groups (SH), Ca2+‐ATPase activity, sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE), and tertiary structure of protein were analyzed periodically, along with texture profile analysis (TPA). The results demonstrated that the CS copolymers treatment exhibited better preservation effects. The CS‐g‐GA and CS‐g‐PA treatments could significantly inhibit the growth of microorganisms and retard the increase of pH, TVB‐N, TBA, WHC, and K‐value during refrigerated storage compared with the CK and CS groups. Additionally, the CS‐g‐GA and CS‐g‐PA treatments could delay the protein oxidation by keeping a higher SH level and Ca2+‐ATPase activity. The CS copolymers treatment could also extend the shelf life for another 6 days compared with that of CK. As a result, CS copolymers can be employed in a promising method for the preservation of sea bass. Practical Application The incorporation of gallic acid and protocatechuic acid onto chitosan (CS‐g‐GA and CS‐g‐PA) showed superior antioxidant and antimicrobial activities when applied on sea bass. The CS‐g‐GA and CS‐g‐PA coatings could maintain the quality and freshness of refrigerated sea bass. Additionally, this research could provide a theoretical basis for the application of graft copolymers on the preservation of aquatic products.

Preparation of chitosan grafted caffeic acid coating and its effect on pompano (Trachinotus ovatus) preservation

“…The content of CA in CS-g-phenolic acid products was determined by the Folin-Ciocalteu method. 11 The standard compound was CA (Maclin Biochemical Co. Ltd Shanghai, China). The content of CA was expressed by the phenolic acid standard curve.…”

Combining slightly acidic electrolyzed water and slurry ice to prolong the shelf‐life of mackerel ( Pneumatophorus japonicus )

“…The TVCs and the counts of psychrophilic bacteria, pseudomonas bacteria, H 2 S-producing bacteria were measured by the plate diffusion method according to the method of Liu et al (2020).…”

“…Moreover, the SAEW-SI sample had the highest hardness value compared to the control and SI sample. After an external force is applied, the ability of samples to return to their original state is called springiness and chewiness is related to the number of chews required to swallow food (Liu et al, 2020). It was observed that neither springiness nor chewiness followed a clear trend in all samples during storage.…”

“…Therefore, changes in protein conformation could be reflected by changes in the endogenous fluorescence. And tryptophan (Trp) could be used to determine the degree of MP expansion (Liu et al, 2020). The fluorescence intensity in control, SI, and SAEW-SI during storage is shown in Figure 7.…”

Effects of Melissa officinalis L. Essential Oil in Comparison with Anaesthetics on Gill Tissue Damage, Liver Metabolism and Immune Parameters in Sea Bass (Lateolabrax maculatus) during Simulated Live Transport

“…Sea bass ( Lateolabrax maculatus ) is rich in protein and is the main marine commercial fish in China. Live sea bass are sold at a high price compared to refrigerated and frozen products [ 1 ]. However, the edible value of aquatic products falls sharply during storage.…”