Effect of boiling on texture of scallop adductor muscles and its mechanism based on label-free quantitative proteomic technique.

The mechanism behind textural changes in scallop adductor muscle during boiling was investigated through proteomic analysis, determination of water holding capacity (WHC) and oxidative indices, as well as observation with scanning electron microscopy and multiphoton nonlinear optical microscopy. The hardness and shear force showed the trend of first rising and then falling in 45 min-boiling time. The results suggested that short-time boiling caused the oxidation, denaturation and aggregation of proteins, resulting in the transverse contraction of myofibers and lateral cross-linked aggregation of muscle fibers and a rise in WHC, which led to the increase in hardness and shear force. While long-time boiling caused the progressive degradation of structural proteins such as fibrillin-1, collagen alpha-2(I) chain, myosin heavy chain, basement membrane-specific heparan sulfate proteoglycan core protein, and paramyosin, resulting in a loose myofibril network and the decrease in WHC, which led to the decrease in hardness and shear force.

Differences in texture and digestive properties of different parts in boiled abalone muscles.

Differences in texture and digestive properties of different parts in 80 °C-boiled abalone muscle (adductor and transition part) after different processing time were investigated. With the extension of boiling time, the shear force and hardness of adductor increased first (6 min) and then decreased (30 min and 240 min), while the two indexes of transition part dramatically decreased after boiling for 6 min and then maintained until 240 min. Meanwhile, for adductor, the degree of protein hydrolysis, protein digestibility, and peptide transport levels declined with the extension of boiling time; While for transition part, those protein digestion and transport indexes significantly decreased first (6 min and 30 min) and then increased (240 min). By contrast, the adductor contained higher myofibrillar proteins content but lower collagen content than the transition part, which contributed to the differences in texture and digestive properties of the boiled samples.

Effects of Boiling Processing on Texture of Scallop Adductor Muscle and Its Mechanism.

The objective of this study was to reveal the effects of boiling processing on the texture of scallop adductor muscle (SAM) and its mechanism. Compared to the fresh sample, all the texture indicators, including the hardness, chewiness, springiness, resilience, cohesiveness, and shear force of 30-s- and 3-min-boiled SAMs increased time-dependently (p < 0.05). As the boiling time increased further to 15 min, the shear force and cohesiveness still increased significantly (p < 0.05), and the resilience and hardness were maintained (p > 0.05), but the springiness and chewiness decreased significantly (p < 0.05). The overall increase in the texture indicators of the boiled SAMs was due to the boiling-induced protein denaturation, aggregation, and increased hydrophobicity, resulting in the longitudinal contraction and lateral expansion of myofibrils, the longitudinal contraction and lateral cross-linked aggregation of muscle fibers, and the loss of free water. However, the decreasing springiness and chewiness of the 15-min-boiled SAMs was due to the significant degradation of proteins (especially collagen), resulting in the destruction of the connective tissue between the muscle fiber clusters. Both from a subjective sensory point of view and from the objective point of view of protein denaturation and degradation, 3-min-boiled SAMs are recommended. The quality improvement of thermally processed products by controlled, moderate cooking is of practical value from the perspective of food consumption.

Effect of boiling on texture of abalone muscles and its mechanism based on proteomic techniques.

The precise mechanism of texture changes in abalone muscles during boiling was investigated using quantitative proteomic analysis. A total 353 water-soluble proteins were identified in fresh abalone muscle. The number was decreased to 233 (6 min) and 201 (30 min), and then increased to 271 (240 min) during boiling. The undetectable protein in water-soluble fraction caused by boiling mainly belong to hemocyanins, protein kinases, dehydrogenases, phosphorylases, and transferases, while the newly identified proteins in water-soluble fraction during boiling mainly belong to collagen and myofibrillar proteins (MPs).Additionally, results also showed that boiling caused protein oxidation, denaturation, aggregation, crosslinking and degradation. Combined with the texture changes of abalone muscles during boiling, it was speculated that the oxidation, denaturation, aggregation and crosslinking of proteins led to the increase of shear force, however, the degradation of structural proteins such as MPs and collagen caused the decreases in shear force and hardness.

Effects of antioxidants of bamboo leaves on protein digestion and transport of cooked abalone muscles.

The effects of oxidation on protein digestion and transport in cooked abalone muscles were investigated using a combination of simulated digestion and everted-rat-gut-sac models for the first time. Boiling heat treatments caused protein oxidation in the abalone muscles, reflected by increases in the carbonyl group and disulfide bond contents, protein hydrophobicity and aggregation degree, as well as decreases in the free sulfhydryl group and amino acid contents. Protein oxidation significantly inhibited the degree of hydrolysis, digestion rate, and digestibility of the abalone muscles in the simulated digestion model. The results from the everted-rat-gut-sac model showed that amino acid and peptide transport levels from the digestion products of the cooked abalone muscles were lower than those of the uncooked samples. In contrast, the addition of antioxidants of bamboo leaves mitigated heat-treatment-induced protein oxidation, aggregation and increased hydrophobicity, and consequently improved abalone muscle protein digestibility and transport levels.