Evolution of lean meat tenderness stimulated by coordinated variation of water status, protein structure and tissue histology during cooking of braised pork

High-temperature pressure cooking on the quality of Basa (Pangasius bocourti) fish maw: Gelling, in vitro digestion and proteomic analysis

This study aims to evaluate the different processing methods, soaking-high-temperature pressure cooking (SHPC) and un-soaking-high-temperature pressure cooking (USHPC), on the quality of Basa (Pangasius bocourti) fish maw (BFM). Compared to traditionally cooked BFM, SHPC and USHPC treated BFM exhibited more severe disruption of collagen fibrils and network structure, significantly decreased texture, shear force and water holding capacity of BFM with the increase of HPC time, indicating that HPC could effectively reduce soaking time of BFM. Besides, as time HPC was 30 min, USHPC almost showed similar texture results to SHPC, and the former had the higher in vitro digestibility. Microstructural and proteomic analyses confirmed that SHPC displayed more exposed fibrous structures, with collagen fibers being more prone to be fragmentation and dissolution.

Effects of combined enzyme-alkali treatment on swelling ratio and texture of bovine omasal laminae

The combined enzyme-alkali treatment (E-AO) is currently employed in the processing of salted bovine omasal laminae due to its advantages of low alkalinity and mild treatment. This study was aimed at investigating the mechanism by which the E-AO treatment improves the swelling ratio and texture of salted omasal laminae. Urea and sodium dodecyl sulfate (SDS) were used to monitor the contributions of hydrogen bonds and hydrophobic interactions in the processing of omasal laminae. The results indicated that E-AO treatment improved water migration and moisture content, resulting in an increased swelling ratio. Meanwhile, the decreased total collagen content and increased soluble collagen improved the texture of omasal laminae. The expansion and destruction of protein structure were observed through microstructure analysis. This study elucidates the mechanisms underlying quality changes in omasal laminae, providing a theoretical foundation for production of bovine omasal laminae and other by-products containing smooth muscle and connective tissue.

Effect of sous vide cooking technology on the quality, protein structure, microstructure, and flavor of yellowfin tuna (Thunnus albacares)

The study investigated the comparative effects of sous vide cooking and traditional high-temperature cooking on the quality characteristics, protein structure, microstructure, and volatile flavor compounds of yellowfin tuna (Thunnus albacares). The sous vide treatment groups (55 °C, 60 °C, 65 °C) exhibited a reduction in cooking loss, hardness, and chewiness of the fish while significantly preserving its original elasticity, cohesiveness, and color. In contrast, traditional high-temperature cooking alters the degradation of secondary and tertiary protein structures, resulting in muscle fiber contraction, damage to tissue integrity, and loss of internal moisture. Gas chromatography-mass spectrometry analysis revealed that the concentration of primary odor compounds at a sous vide temperature of 55 °C was minimized. This reduction contributes to decreased formation of undesirable odor substances while positively influencing flavor profiles. These findings suggest that sous vide cooking technology can effectively enhance both the texture and flavor profile of yellowfin tuna.

Molecular and microstructural changes of chicken breasts in preheating-freezing-reheating process: The role of ice crystal formation and growth

The molecular and microstructural evolution of meat during preheating-freezing-reheating process remained unclear, limiting the quality improvement of prepared dishes. This study revealed this evolution of chicken breasts by comparing three groups with various preheating states to fully preheated (control) and fresh samples. By ice crystal characterization, fresh samples typically form small, evenly distributed intracellular ice crystals, whereas preheating promoted the formation of irregular extracellular crystals. All samples exhibited larger ice crystals after recrystallization. Results showed that ice crystal formation primarily induced protein unfolding and aggregation, while recrystallization predominantly drove lipid oxidation and microstructural damage. Control samples displayed extreme aggregation and microstructural damage, with significantly higher turbidity and hydrophobic interaction values (p < 0.05), leading to texture deterioration. On the other hand, moderate preheating samples (CV2 [where CV is cooked value], preheated to core temperature reached 68.05°C) resulted in lower protein aggregation and water loss, with lower values in turbidity, intrinsic fluorescence intensity, covalent bonds content, and area of T2i relaxation peaks, enhancing texture quality. Scanning electron microscopy images indicated that intracellular ice crystals in fresh samples primarily caused cellular structure damage, and extracellular ice crystals in control and CV2 samples contributed to the disruption and curling of connective tissue. Overall, preheating impacted the final qualities by affecting ice crystal properties, resulting in a better maintained molecular structure and microstructure of CV2 samples compared to the control samples. PRACTICAL APPLICATION: This study revealed the molecular and microstructural change of chicken breasts during preheating-freezing-reheating process, recommending an easy way to improve prepared meat qualities: reducing the preheating state to an appropriate level rather than fully preheated. Besides, the different ice crystal properties in chicken breasts with different preheating states offered a theoretical foundation for frozen control strategy of prepared meat. These results provide critical insights into the quality control and industrial upgrade of prepared dishes.

Effect of 6-Gingerol on Oxidation and Structure of Beef Myofibrillar Protein During Heating

High-temperature cooking can induce oxidation and structural changes in myofibrillar protein (MP), harming meat product quality. 6-gingerol is a key part of ginger and a natural antioxidant. In this study, MP was mixed with 6-gingerol and cooked at different temperatures. Chemical methods, fluorescence spectroscopy, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and molecular docking were used to study the effects on protein aggregation, oxidation, molecular structure, and the microstructure of muscle fibers. The results showed that 40 μg/mL of 6-gingerol significantly optimized the indexes of beef MP. For example, 6-gingerol inhibited the decrease in MP sulfhydryl content and solubility, delayed the rise in surface hydrophobicity and carbonyl content, decreased the particle size of MP, and elevated the absolute value of Zeta potential, which, in turn, hindered oxidative denaturation and the aggregation of proteins. 6-gingerol could maintain the stability of the spatial conformational structure and microstructure of the protein. The protein secondary structure changed, and the α-helical might have been transformed into the β-folded one. The binding of 6-gingerol to MP mainly relied on hydrogen bonds, van der Waals forces, and hydrophobic interactions. Thus, 6-gingerol had a positive effect on the antioxidant properties and structural stability of beef MP during heating.

The Effects of Packaging Barrier Properties Coupled with Storage Temperatures on the Dominant Spoilage Bacteria Composition and Freshness Quality of Lamb

This study aims to establish a preservation method by coupling certain barrier packaging with storage temperatures suitable for extending the shelf of chilled lamb. Chilled lamb was packaged using three different oxygen permeability packaging materials of high-oxygen-barrier packaging (HORP), medium-oxygen-barrier packaging (MORP), and low-oxygen-barrier packaging (LORP) (1.70, 23.95, and 1631.44 cm3/(m2·24·h·0.1·MPa), respectively, then stored at temperatures of 4 °C and -1 °C for 28 days, respectively. The results of total viable count, pH, color, and volatile basic nitrogen indicate that HORP effectively inhibits the growth rate of surface microorganisms and the oxidation rate of proteins in lamb. The sulfhydryl content, carbonyl value, and electronic nose suggest that the oxidative decomposition rate of lamb during storage at -1 °C is lower compared to storage conditions at 4 °C. The microbial diversity suggests that HORP significantly hinders the growth and reproduction of Pseudomonas and Brochothrix aerobic spoilage bacteria, as well as diminishes the abundance of the dominant microbial community. Herein, utilizing high-barrier packaging with an oxygen permeability of lower than 1.70 cm3/(m2·24·h·0.1·MPa) in conjunction with ice temperature storage at -1 °C is a highly effective preservation method for prolonging the shelf life of chilled lamb to 28 days.

Precooked state based on protein denaturation kinetics impacts moisture status, protein oxidation and texture of prepared chicken breast

The quality of meat in prepared dishes deteriorates due to excessive protein denaturation resulting from precooking, freezing, and recooking. This study aimed to link the precooked state with chicken breast's recooked quality. Cooked Value (CV), based on protein denaturation kinetics, was established to indicate the doneness of meat during pre-heating. The effects of CVs after pre-heating on recooked qualities were investigated compared to fully pre-heated samples (control). Mild pre-heating reduced water migration and loss. While full pre-heating inhibited protein oxidation during freezing, intense oxidation during pre-heating led to higher oxidation levels. Surface hydrophobicity analysis revealed that mild pre-heating suppressed aggregation during recooking. These factors contributed to a better texture and microstructure of prepared meat with mild pre-heating. Finally, a potential mechanism of how pre-heating affects final qualities was depicted. This study underlines the need for finely controlling the industrial precooking process to regulate the quality of prepared meat.

Integrating multiple microstructure and water distribution visual analysis to reveal the moisture release and quality deterioration of precooked beef during freezing-thawing-reheating processes

Prepared dishes are becoming an increasingly important part of diets, while most studies focus on the flavor. In this study, the moisture loss induced by structure changes of precooked beef during freezing-thawing-reheating process was investigated. The myowater trapped and released by 'myenteric channels' and 'water reservoir' were observed by integrated multiple microstructure and water distribution visual analysis. X-ray results showed an increase in total porosity and the close porosity transfer to open porosity during freezing-thawing-reheating. The weight loss of frozen-reheated (FR) and frozen-thawed-reheated (FTR) samples was 6.34% and 7.69%, respectively. Although freezing-thawing did not significantly affect the moisture loss, magnetic resonance image (MRI) showed that the 'free water' temporarily existed in interfibrous spaces after thawing and leaked out during reheating. Directly reheating avoided the myowater redistribution and muscle extension mediated, which reduced moisture loss. These results provide a reference for quality control of prepared dishes during the industrial supply chain.

Effect of the Freeze-Drying Preservation Process on Some Quality Attributes of Pork Meat (Longissimus thoracis)

Meat preservation processes have been widely studied over time, especially those related to low temperatures (freezing and freeze-drying); however, there is very little research that directly relates the effect of these processes on the structure of meat-and the main meat proteins-and how these changes affect some attributes of the final quality. Pork loin meat (Longissimus thoracis) was used, which was frozen-thawed and freeze-dried-rehydrated to subsequently evaluate changes in its chemical composition and physicochemical parameters such as water activity (a w), pH, and water-holding capacity. Physical aspects such as color profile, surface myoglobin fraction, shear force, and histological sections were also evaluated, along with thermal analysis by modulated differential scanning calorimetry. The data obtained were analyzed through different statistical techniques. It was found that the freeze-drying process significantly modifies the interactions of water with the rest of the meat components (p < 0.05), promoting differences concerning samples that were only frozen, allowing us to establish the importance of water and its associations with each other and with proteins on their effect on meat preservation processes at low temperatures.

Influence of (ultra-)processing methods on aquatic proteins and product quality

Aquatic products are a high-quality source of protein for humans, and the changes in protein during aquatic product processing are crucial for nutritional value, product performance, and consumer health. With the advancement of science and technology, aquatic product processing methods have become increasingly diverse. In addition to traditional methods such as thermal processing (steaming, roasting, and frying) and pickling, emerging non-thermal processing technologies, such as high pressure, ultrasound, and irradiation, are also being applied. During (ultra-)processing, aquatic products undergo complex biochemical reactions, among which protein oxidation significantly affects the quality of aquatic products. Protein oxidation can alter the molecular structure of proteins, thereby changing their functional properties and ultimately impacting product quality. This paper primarily explored the effects of protein changes under different processing methods on aquatic product quality and human health, as well as techniques for controlling protein oxidation. It aims to provide a theoretical basis for selecting appropriate processing methods, improving aquatic product quality, and controlling protein oxidation in aquatic products, and to offer scientific guidance for practical production.

In situ investigation of ice fractions and water states during partial freezing of pork loins and shrimps

Ice fractions and water states in partially frozen muscle foods greatly affect their quality. In the study, a variable temperature nuclear magnetic resonance (VT-NMR) with a liquid nitrogen temperature control system was employed to in situ investigate the relationship between ice fractions and temperatures and changes in water states during partial freezing and thawing of pork and shrimp. Results indicated that changes in ice fractions ranging from -2 ∼ -20 °C could be divided into 3 stages including slow increase, random leap and remarkable leap. More serious damages to the structures related to immobile water occurred in shrimp than in pork, and partial freezing also caused deterioration in muscle fibres related to free water. Additionally, -2 ∼ -3 °C and - 3.5 °C were the appropriate partial freezing temperatures for pork and shrimp, respectively. Therefore, the VT-NMR method possessed great potential for fundamental studies and applications of partial freezing of muscle foods.

Improving the texture of braised pork by gradient-temperature heating and its molecular mechanism

A novel gradient-temperature heating regime was proposed to improve the texture of braised pork. Compared with one-stage pressure heat treatment of around 107 °C, the gradient-temperature heat regime of preheating at 60 °C, followed by a slow increase of temperature to 107 °C and simmering at 97 °C increased the retention of immobilized water and reduced the shear force of meat. In this cooking regime, preheating treatment at 50-60 °C could promote the dissociation of thin and thick myofilaments, which contributed to a weakened shrinkage of myofibrils during the subsequent high temperature heating process. Pressure-heating treatment with a slow increasing temperature and the medium-temperature simmering significantly reduced (p < 0.05) the oxidation of sulfhydryl groups and the loss of α-helical, which weakened the excessive aggregation of protein and promoted the formation of myofibril network. Both the weakened shrinkage and the formation of myofibril network during gradient-temperature heating contributed to the decreased shear force and an increased immobilized water. Hence, the reduction of the oxidation and aggregation of the proteins is the key to improve the tenderness of the braised meat.

Dynamic changes of tenderness, moisture and protein in marinated chicken: the effect of different steaming temperatures

BACKGROUND

The steam processing characteristics of chicken are a key factor in the simplicity and versatility of steamed chicken dishes. The aim of this study was to investigate in depth the changes in tenderness and water retention of marinated chicken at different slow steaming endpoint temperatures, and to further explore the effect of the evolution of protein conformations on the water status.

RESULTS

The results showed that chicken samples' shear force peaked at 80 °C and decreased rapidly at 90 °C. As the steaming endpoint temperature increased between 50 and 90 °C, T21, T22, moisture content and centrifugal loss decreased, but P21, P22 and myofibril water-holding capacity showed regular changes. The electrophoretic bands and protein conformation changes showed that protein in marinated chicken underwent different degrees of denaturation, degradation and aggregation. And at 70 °C, with an increase of hydrophobic groups and crosslinking of disulfide bonds as well as an increase in the number of denatured sarcoplasmic proteins, the intermolecular network was enhanced, thus affecting the water retention.

CONCLUSION

Water status of chicken meat heated at different steaming temperatures is closely related to the evolution of protein conformations. The present study serves as a robust theoretical foundation for enhancing the quality of steamed chicken products at an industrial scale. © 2024 Society of Chemical Industry.

Effect of different cooking conditions on the quality characteristics of chicken claws

Chicken claw products with their unique texture are loved by consumers, and cooking is a key step to affect the taste of chicken claw consumption, through the moderate hydrolysis of proteins and a series of physicochemical changes, so that the chicken claw gets tender and presents a crispy taste, but the current research on the optimal cooking conditions for chicken claw is still relatively small. In the present work, combinations of time (11, 13, 15, 17, and 19 min) and temperature (82, 86, 90, 94, and 98°C) were applied to the cooking of chicken claws. The effects of different cooking conditions on the quality characteristics of chicken claws were investigated, with special emphasis on the cooking loss rate, color, texture properties, lipid oxidation, myofibrillar fragmentation index (MFI), and total sulfhydryl content. The results showed that the cooking loss rate, lipid oxidation, and MFI value of chicken claws gradually increased, and the total color difference (∆E), puncture force, shear force, and total sulfhydryl content gradually decreased with the increase of cooking temperature and cooking time. Overall, chicken claws cooked at 86, 90, and 94°C for 15 and 17 min had better texture and flavor.

Mechanism underlying the tenderness evolution of stir-fried pork slices with heating rate revealed by infrared thermal imaging assistance

This study aimed to explore the mechanism of cooking intensity on the tenderness of stir-fried pork slices from the perspective of the changes in temperature distribution. Infrared thermal imaging was used to monitor the distribution of temperature. Results showed that the high-level heat (HH) treatment could improve tenderness. When the center temperature increased to 100 °C, the shear force of samples from the low-level heat (LH) group increased by around 3-fold, and HH reduced this upward trend. This result was mainly attributed to the shorter heating time undergone by the HH-treated samples compared to the LH treatment, which resulted in less structural shrinkage and faster passing through the protein denaturation interval of the samples. These changes alleviated temperature fluctuations caused by water loss. This explanation could be confirmed by the results of T2 relaxation time and Fourier transform-infrared spectroscopy (FT-IR). However, the LH treatment caused a slower rise in oil temperature due to more moisture migration, which required the samples to undergo longer thermal denaturation, leading to a deterioration in tenderness. Moreover, histological analysis revealed that the greater integrity of endomysium in the HH group inhibited water loss and oil absorption, which contributed to obtain low-fat meat products with higher tenderness. This study provides support for the industrialization of traditional pork cuisines using oil as the heating medium.

Cooking-Induced Oxidation and Structural Changes in Chicken Protein: Their Impact on In Vitro Gastrointestinal Digestion and Intestinal Flora Fermentation Characteristics

Meat digestion and intestinal flora fermentation characteristics are closely related to human dietary health. The present study investigated the effect of different cooking treatments, including boiling, roasting, microwaving, stir-frying, and deep-frying, on the oxidation of chicken protein as well as its structural and digestion characteristics. The results revealed that deep-fried and roasted chicken exhibited a relatively higher degree of protein oxidation, while that of boiled chicken was the lowest (p < 0.05). Both stir-frying and deep-frying led to a greater conversion of the α-helix structure of chicken protein into a β-sheet structure and resulted in lower protein gastrointestinal digestibility (p < 0.05), whereas roasted chicken exhibited moderate digestibility. Further, the impact of residual undigested chicken protein on the intestinal flora fermentation was assessed. During the fermentation process, roasted chicken generated the highest number of new intestinal flora species (49 species), exhibiting the highest Chao 1 index (356.20) and a relatively low Simpson index (0.88). Its relative abundance of Fusobacterium was the highest (33.33%), while the total production of six short-chain fatty acids was the lowest (50.76 mM). Although stir-fried and deep-fried chicken exhibited lower digestibility, their adverse impact on intestinal flora was not greater than that of roasted chicken. Therefore, roasting is the least recommended method for the daily cooking of chicken. The present work provides practical advice for choosing cooking methods for chicken in daily life, which is useful for human dietary health.

The Effect of Sodium Chloride on the Physicochemical and Textural Properties and Flavor Characteristics of Sous Vide Cooked Duck Meat

This study was conducted to evaluate the effect of salt brining process parameters (salt concentration 0-15%, brining time 4-12 h, brining temperature 4-20 °C) on the quality of sous vide cooked duck meat by a single factor combined with response surface methodology (RSM). The sensory evaluation, physicochemical indexes (color, weight loss, NaCl content, TBARS value, and texture properties), and flavor characteristics were analyzed. The sensory overall mean score was applied as the evaluation index to optimize the brining conditions by RSM, and the optimum results contained a salt concentration of 11.69%, a brining temperature of 7.35 °C, and a brining time of 8.03 h. Under these conditions, the sensory overall mean score of duck meat was 8.59, with a relatively higher a* value and moderate NaCl content. GC-MS and odor activity value (OAV) results indicated that salt brining treatment significantly promoted the formation of the major odorants in duck meat, including pentanal, heptanal, octanal, (E)-2-nonenal, cis-4-decenal, decanal, 2,4-decadienal, (E,E)-2,4-decadienal, 1-heptanol, and 2-methyl-3-octanone, but decreased the content of hexanal, (E)-2-octenal, nonanal, (E,E)-2,4-nonadienal, 1-octen-3-ol, and 1-octen-3-one. 5'-nucleotides in duck meat were significantly increased after brining treatment. Therefore, salt brining treatment could be regarded as an efficient way to improve the sensory, aroma, and taste quality of sous vide cooked meat.