Determining protein denaturation of sardine (Sardina pilchardus) marinates before and after the maturation

Abstract

In this study, sardine fish (Sardina pilchardus) was subjected to marination at different degrees of acidity (2.5%–5%). On the basis of the duration of maturation (22 days) and postmaturation period (three months after maturation), protein denaturation and quality changes of marinades were determined. Quality parameters, such as pH, acidity, salinity, and lipid oxidation, were examined for both periods. As a result of the study carried out for 22 days at different acidity levels, the change in the amount of TVB‐N was found to be insignificant (p > 0.05), but the differences in pH, TBARS, acidity, and salinity levels were found to be significant (p < 0.05). In the postmaturation period, the change in the TBARS amount was insignificant (p > 0.05), and the other parameters were found to be significant (p < 0.05). SDS‐PAGE analysis showed that fish muscle and brine proteins showed different profiles and a decrease in densities of MHC, actin, and TM bands during the maturation period was observed. Practical applications Protein denaturation is important in fisheries products, so multiple verification tests should be performed to monitor this process. It was suggested that DSC and SDS‐PAGE techniques are easier and quicker analyses for determining protein denaturation in seafood products compared with traditional techniques.

A solution for fillet quality: Slaughter age's effect on protein mechanism and oxidation

“…In accordance with the previously presented results regarding the thermal stability of miyofibrillar protein, the energy required for the proteins denaturation gradually increased in an age-related manner, and then decreased at a similar rate. These increases may indicate inhibition of proteolytic enzymes in denaturation, reduction in enthalpy and lower peaks at higher temperatures, denaturation of fillet proteins [ 13 ].…”

“…Heating was applied from 20 °C to 90 °C with a heating rate of 5 °C/min using an empty container placed in the sample device and sealed in the same way as a reference. The thermal changes of the analyzed samples were acquired on thermogram [ 13 ].…”

“…The expectation from these analyzes is to provide fast and accurate results in the relevant product in a short time. They are important and pioneering analyses that usually include microbial load, aroma, some chemical (pH, TVB-N and TBARS) and physical (aw, WHC, color and texture) analyses [ 13 ]. High water activity (aw), high pH and the presence of autolytic enzymes are important factors in the high sensitivity of seafood products.…”

“…Lipid oxidation in meat and meat products is most commonly measured by Thiobarbituric acid reactive substances (TBARS) analysis. Although lipid peroxidation is the inspiration for a multitude of studies, latest findings claimed that protein oxidation is of equal importance, and is even triggered by the reactive lipid oxidation products [ 13 , [15] , [16] , [17] , [18] ].…”

The effect of multiple freeze–thaw cycles on protein oxidation and quality of Trachurus murphyi

“…Several studies have reported the changes in the structure and physicochemical properties of myofibrillar protein during storage, suggesting that protein denaturation is a major contributor of shelf-life decline, nutrient loss, and structural changes in fish (Alak et al, 2021;Isık et al, 2020). Protein oxidation is a complicated phenomenon that involves amino acid residues, buried hydrophobic exposure, and protein unfolding upon heating (Dericioglu at al., 2019). This process leads to further chemical modifications in amino acid side chains, triggers polymerisation, disruption of peptide backbones, and following aggregation, it involves intermolecular protein…”