Influence of stewing conditions on tenderness and protein structure in beef

Characterization of stewed beef by sensory evaluation and multiple intelligent sensory technologies combined with chemometrics methods

Though stewed beef is favored by consumers, the impact of the domestic high-pressure stewing method on beef has received little attention. This study characterized the beef cooked under varied pressures in the household pressure cooker by analytical instruments, sensory evaluation, and multiple intelligent sensory technologies. Totally, 165 volatile compounds were identified by SPME-GC-TOF-MS, with more detected in samples with higher pressure. The glutamic acid contributed significantly to the umami taste of beef (TAV > 1.25). The meaty and fatty odor, hardness, chewiness, and sweet taste contributed to the overall liking of stewed beef (P < 0.05). The multiple-target BPNN model based on fused data from multiple intelligent sensory technologies could simultaneously predict sensory perception intensities with a satisfying performance (R² > 0.9340), but could not efficiently predict subjective overall liking scores. The study guides the domestic cooking of beef stew and quantitative sensory prediction based on multiple intelligent sensory techniques.

Improved tenderness and water retention of pork pieces and its underlying molecular mechanism through the combination of low-temperature preheating and traditional cooking

The effects of two-stage heating with different preheating combinations on the shear force and water status of pork-pieces were explored. The results showed that the combined preheating at 50 ℃ for 35 min or at 60 ℃ for 5 or 20 min with traditional high temperature heating reduced the shear force and improved the water retention of meat, which was attributed to uniformly separation of myofibers and smaller myofiber space. Visible dissociation of actomyosin in heating groups of 50 ℃-35 min, and 60 ℃-5, 20 min was related to the tenderization of meat. The higher surface hydrophobicity, tryptophan fluorescence intensity, and lower α-helices of actomyosin at 60 ℃ contributed to the liberation of actin. However, severe oxidation of sulfhydryl groups at 70 ℃ and 80 ℃ promoted the aggregation of actomyosin. This study presents the advantage of two-stage heating in improving meat tenderness and juiciness and its underlying mechanisms.

Insights into peptide profiling of sturgeon myofibrillar proteins with low temperature vacuum heating

BACKGROUND

Protein oxidation during food processing causes changes in the balance of protein-molecular interactions and protein-water interactions, ultimately leading to protein denaturation, which results in the loss of a range of functional properties. Therefore, how to control the oxidative modification of proteins during processing has been the focus of research.

RESULTS

In the present study, the intrinsic fluorescence value of the myofibrillar proteins (MP) decreased and the surface hydrophobicity value increased, indicating that the heat treatment caused a significant change in the conformation of the MP. With an increase in heating temperature, protein carbonyl content increased, total sulfhydryl content decreased, and protein secondary structure changed from α-helix to β-sheet, indicating that protein oxidation and aggregation occurred. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed that heat treatment can lead to the degradation of proteins, especially myosin heavy chain, although actin had a certain thermal stability. In total, 733 proteins were identified by proteomics, and the protein oxidation caused by low temperature vacuum heating (LTVH) was determined to be mild oxidation dominated by malondialdehyde and 4-hydroxynonenal by oxidation site division.

CONCLUSION

The present study has revealed the effect of LTVH treatment on the protein oxidation modification behavior of sturgeon meat, and explored the effect mechanism of LTVH treatment on the processing quality of sturgeon meat from the perspective of protein oxidation. The results may provide a theoretical basis for the precise processing of aquatic products. © 2023 Society of Chemical Industry.

Interaction and binding mechanism of lipid oxidation products to sturgeon myofibrillar protein in low temperature vacuum heating conditions: Multispectroscopic and molecular docking approaches

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A comparative study of the effects of malondialdehyde and 4-hydroxy-2-nonenal on protein oxidation.

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Interaction mechanism between lipid oxidation production and protein at temperatures were firstly studied.

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Hydrogen bonding was the main driving force for bonding.

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Malondialdehyde had a strong ability to bind MP and accelerated protein oxidation.

In this work, the binding mechanism of myofibrillar protein (MP) with malondialdehyde and 4-hydroxy-2-nonenal under low temperature vacuum heating was investigated via multispectroscopic and molecular docking. The results showed that binding interaction and increasing temperature caused significant changes in the conformations as well as a decrease in the value of protein intrinsic fluorescence, surface hydrophobicity, and fluorescence excitation-emission matrix spectra. Furthermore, the decrease in α-helix and β-turn, increase in β-sheet and a random coil of MP, imply the MP molecules to be more unfolded. Isothermal titration calorimetry and molecular docking results showed that main driving force for binding with MP was hydrogen bond, and the binding ability of malondialdehyde was superior to that of 4-hydroxy-2-nonenal. Moreover, increasing the heating temperature was beneficial to the binding reaction and intensified the conformational transition of MP. These results will provide a reference for further studies on the lipid and protein interaction of sturgeon.

Enrichment of taste and aroma perceptions in chicken meat stewed in braised soup used repeatedly

Flavor enrichment of sauce-braised chicken creates a popular umami taste and aroma. In order to preliminarily reveal the enrichment of taste and aroma compounds of sauce-braised meat products processed with braised soup used repeatedly, the system containing only chicken and chicken soup was designed to simulate the process of repeated stewing. Free amino acids, 5-nucleotides, fatty acids, and volatile compounds in stewed chicken were determined, and taste and aroma profiles were evaluated using an electronic tongue (E-tongue) and an electronic nose (E-nose), respectively. As repeated stewing times increased, the total free amino acid content increased from 514.37 mg/100 g to 721.33 mg/100 g, and the contents of 5'-inosine monophosphate, 5'-guanosine monophosphate, and 5'-adenosine monophosphate increased by approximately 20%. Meanwhile, the relative content of saturated fatty acids increased, and the relative content of monounsaturated fatty acids decreased significantly. Oleic acid, linoleic acid, and palmitoleic acid accounted for more than 80% of the total fatty acid content. A total of 15 aroma-active compounds were identified during repeated stewing, and their concentrations increased by more than 40%, especially for monounsaturated alkenals. Within 10 times of repeated stewing, the taste and aroma compounds were enriched because of a decrease in the concentration difference of taste substances and an increase in the flavor-adsorption capacity of fat, which was also consistent with the results from the E-nose and E-tongue. The taste and aroma of stewed chicken tended to remain constant after 10 times of repeated stewing of braised soup. The obtained information can provide guidelines for regulating the aroma and taste of sauce-braised chicken. PRACTICAL APPLICATION: The fat level of stewed chicken and the difference in concentration between stewed meat and braised soup were important potential factors that could be employed to enhance the flavor of stewed meat.