Water status evolution of pork blocks at different cooking procedures: A two-dimensional LF-NMR T1-T2 relaxation study

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.

Effects of Processing Methods on the Physical Properties of Aquafaba Powder: Time-Domain Nuclear Magnetic Resonance Analysis

Aquafaba, the water remaining after cooking chickpeas, has been a promising emulsifier and stabilizer in food products. Despite its potential, the variability in its composition and dry matter content poses challenges for its consistent use. This study aimed to enhance the dry matter content of aquafaba through different processing methods-microwave heating, microwave-infrared heating, and conventional boiling-and to evaluate how these methods affect the physical properties of the resulting powders. The experiment also explored the effect of overnight soaking of chickpeas on the dry matter yield. The powders produced were characterized using time-domain nuclear magnetic resonance (TD-NMR) to investigate their water absorption, hydration behavior, and emulsification properties. Results showed that microwave and microwave-infrared heating significantly increased the dry matter content compared to conventional boiling. Furthermore, overnight soaking of chickpeas led to a notable increase in dry matter yield across all processing methods. TD-NMR analysis revealed that microwave-infrared samples exhibited improved hydration rates and more stable emulsions over time compared to those processed with other methods. These findings suggest that alternative processing techniques, especially microwave-infrared heating, can improve the consistency and functionality of aquafaba as an ingredient in food products. By increasing the dry matter content and enhancing hydration properties, these methods may provide a more reliable plant-based emulsifier. This study contributes to the development of novel, sustainable approaches in food processing that can enhance the quality and performance of plant-based ingredients across various applications.

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.

The Effects of Different Reheating Methods on the Quality of Pre-Cooked Braised Chicken

This study investigated the effects of microwave (MW) reheating, water boiling (WB) reheating, and steaming (ST) reheating on the quality attributes (including reheating loss, moisture content, centrifugal loss, water distribution, color, texture, microstructure, flavor, and taste) of pre-cooked braised chicken (PBC), using a non-reheated group as a control (C). The results showed that the ST group demonstrated the lowest reheating loss, and that ST reheating had the least influence on textural characteristics among all the reheating methods. In addition, the results of the scanning electron microscope (SEM) showed that the integrity of the muscle fibers in the ST group was most comparable to the C group. Meanwhile, the aroma of the ST group was similar to that of the other reheating groups, and it exhibited a greater taste intensity. The ST treatment emerges as a viable reheating method for preserving the quality characteristics of PBC.

Physicochemical and conformational changes of krill myofibrillar protein induced by two-stage thermal treatment and their relationship with muscle texture

To preserve the juiciness of Krill muscle, a simple but robust strategy of two-stage thermal treatment (40-70 °C followed by 90 °C) was explored while the alterations in muscles, physicochemical and conformational changes of myofibrillar proteins were investigated. Conventional one-stage boiling treatment was considered as the control. The results revealed that the actomyosin dissociation was most pronounced preheated by 50 °C, supported by higher content of actin and increased surface hydrophobicity with a substantial drop in α-helix. The disulfide bonding for the control and 70 °C group was significantly higher, indicating a pronounced oxidation. The most robust affinity for water of krill was observed when subjected to preheating at 50 °C, exhibiting the wildest separations between muscle bundles and well-preserved fibers, while severe contraction of muscle bundles was observed with fracturing and minor gaps. The findings provide direct proof to support the feasibility of implementing a preheating thermal processing method for krill.

Spirulina platensis protein-based emulsion gel as fat substitute in meat analogs: Evaluation performance across post-processing

In this paper, Spirulina platensis protein-based emulsion gels were investigated as fat substitutes in meat analogs and compared with conventional fat sources like palm oil, oleogel, and soybean oil. Evaluating parameters such as cooking loss, shrinkage, texture, appearance, and moisture distribution across various cooking methods. Emulsion gels imparted superior juiciness to meat analogs whereas palm oil and oleogel led to drier meat textures. Besides they also resulted in comparable cooking loss and shrinkage to traditional fats, indicating preferred fat options for incorporation of emulsion gels. The novel emulsion gel-filled meat analogs exhibited robust tolerance across three distinct cooking methods, boiling, steaming, and deep-frying. Steamed meat analogs exhibited brighter MRI signals, while fried counterparts displayed peripheral hollowing, attributed to steam's energy transfer and humidity-induced water migration, respectively. Overall, the study underscores the efficacy of these fat analogs in meat analogs, offering insights into their potential as viable alternatives in food formulations.

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.

How thawing and salting affects the post-cooked quality of frozen beef: New insights into the mechanism of fiber morphology evolution and water migration

To get insight into the thawing and salting in recovery and protection mechanisms on quality in frozen meat after subsequent cooking. The myofiber morphological-water evolution and quality changes in beef during freezing-thawing-cooking and freezing-cooking treatments were investigated. The cooking losses of fresh-cooked, frozen-cooked, and frozen-thawed-cooked samples were 27.14, 30.42, and 29.10 %, respectively. Compared to fresh-cooked samples, the moisture contents of frozen-cooked and frozen-thawed-cooked beef were reduced by 3.29 % and 1.03 %, respectively. Inter and intra-myofibril ice crystallization during freezing destroyed the myofibril structure and interacted with the heat-induced constriction due to cooking, driving myowater to migrate from intrafibrous to interfibrous space, which induced higher cooking loss in the frozen samples. Thawing contributed to the renaturation of myofiber and decreased the cooking loss. Salt regulated ice formation and melting, enhanced the resistance of myofiber and promoted free water reabsorption during thawing, which reduced the freezing-induced damage of muscle and improved the final quality of cooked beef. This study provides new insights into the mechanism of freezing-heating loss of beef based on myofiber morphology and water distribution visual analysis, which could help reduce the quality deterioration along the frozen processing supply chain.

Evaluation of the water state and protein characteristics of Tibetan pork under the storage conditions of modified atmosphere packaging: Effect of oxygen concentration

To explore the changes in water status and protein characteristics of Tibetan pork (TP) under modified atmosphere packaging (MAP) with different oxygen concentrations compared to Duroc×Landrace×Yorkshire pork (DLY), the water holding capacity (WHC), water distribution, protein oxidation, and conformation of both types were determined. Results indicate that under MAP, TP pork and DLY pork exhibited higher water retention and lower protein oxidation compared to air packaging. However, with increased oxygen concentration in the MAP, protein oxidation intensified, leading to reduced WHC in the pork. Compared to DLY pork, TP pork in different packaging conditions maintained the integrity of protein secondary and tertiary structures, reducing protein cross-linking aggregation. The lower content of P 3 in the two-dimensional relaxation spectra, shorter T 1 and T 2 relaxation times, and higher proton density suggest better water retention properties in Tibetan pork. These findings support the development of long-distance preservation and transportation technologies for TP pork.

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.

Influence of beeswax-based fish oil oleogels on the mechanism of water and oil retention in Pacific white shrimp (Litopenaeus vannamei) meat emulsion gels: Filling, emulsification and phase transition

Oleogels have been used in the gelled surimi products to replace animal fats due to its structure characteristics. The effect of structure characteristics in fish oil oleogels on the mechanism of oil/water retention was investigated in meat emulsions. Beeswax assembly improved the oil and water retention. The unsaturation degree of fatty acids lowered the mobility of bound water, immobilized water as well as bound fat in the fish oil oleogel, but enhanced the mobility of free water and protons of unsaturated fatty acids. Beeswax addition and oil phase characteristics could enhance β-sheets, disulfide bonds and hydrophobic force to improve the viscoelasticity, gel strength and oil/water retention. Beeswax assembly facilitated the tight micro-sol network and filling effect, and high unsaturation degree promoted the emulsification effect, thus reducing phase transition temperature and juice loss. The study could lay the foundation for development of gelled shrimp meat products with EPA and DHA.

Exploring the role of static magnetic field in supercooling storage from the viewpoint of meat quality and microbial community

In order to explore the application prospects of static magnetic field (SMF) combined with supercooling in meat preservation, this study proposed a novel method of supercooling assisted by a stationary magnetic field (SMF + supercooling) for the preservation of chilled pork, evaluating its cooling rate and quality changes (e.g., water holding capacity, color, pH, and TVB-N), as well as the evolution trend of the microbiota. The results showed that SMF + supercooling significantly (P < 0.05) improved the cooling rate of pork. Compared to chilling and supercooling, SMF + supercooling significantly delayed the increase of TVB-N and TVC on the 12th day of storage (P < 0.05). SMF + supercooling treatment achieves the maintenance of pork water-holding capacity by inhibiting water migration, reducing drip loss, cooking loss, and centrifugal loss of pork. The 16S rDNA bacteria flora analysis demonstrated that SMF + supercooling treatment reduced the relative abundance of spoilage bacteria such as Acinetobacter, Streptococcus, and Pseudomonas, delaying the deterioration of pork quality caused by microbial growth. The SMF + supercooling treatment can be considered a novel refrigeration preservation method that delays the deterioration of pork quality and extends its shelf life.

Research Progress on the Mechanism of the Impact of Myofibrillar Protein Oxidation on the Flavor of Meat Products

Myofibrillar proteins primarily consist of myosin, actin, myogenin, and actomyosin. These proteins form complex networks within muscle fibers and are crucial to the physical and chemical properties of meat. Additionally, myofibrillar proteins serve as significant substrates for the adsorption of volatile flavor compounds, including aldehydes, alcohols, ketones, and sulfur and nitrogen compounds, which contribute to the overall flavor profile of meat products. A series of chemical reactions occur during the processing, storage, and transportation of meat products. Oxidation is one of the most significant reactions. Oxidative modification can alter the physical and chemical properties of proteins, ultimately impacting the sensory quality of meat products, including flavor, taste, and color. In recent years, considerable attention has been focused on the effects of protein oxidation on meat quality and its regulation. This study investigates the impact of myofibrillar protein oxidation on the sensory attributes of meat products by analyzing the oxidation processes and the factors that initiate myofibrillar protein oxidation. Additionally, it explores the control of myofibrillar protein oxidation and its implications on the sensory properties of meat products, providing theoretical insights relevant to meat processing methods and quality control procedures.

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.

Crucial textural properties of braised pork to evaluate the oral mastication behavior and its water distribution to influence tenderness

The complex composition of braised pork, including lean meat, pigskin, and fat, makes it difficult for sensory evaluation of its texture properties. This study investigated the correlation between sensory texture attributes and physicochemical properties to achieve an objective and comprehensive evaluation of the texture of braised pork. Sensory analysis demonstrated that the overall texture acceptability of braised pork was significantly and negatively influenced by sensory texture attributes (including sensory hardness, chewiness, and toughness), while it was positively impacted by sensory adhesiveness, softness, and juiciness. Shear force and texture profile analysis (TPA) variables, reflecting mastication behavior, were used to characterize the textural properties of braised pork. They were closely related to water distribution, with a higher proportion of immobilized water (P21), indicating a higher water holding capacity and a more tender texture. Correlation analysis between sensory texture attributes and physicochemical properties through partial least squares regression further revealed significant associations between shear force, TPA variables, and sensory texture attributes. Moreover, the proportion of immobilized water (P21) significantly and negatively affected sensory hardness and chewiness, whereas the proportion of free water (P22) significantly influenced sensory toughness. Sensory texture attributes could be well predicted by the physicochemical properties by projecting test samples onto calibration models established by known samples. Therefore, a combination of sensory and instrumental measures can reliably reflect the texture properties of braised pork. PRACTICAL APPLICATION: The combination of sensory and instrumental methods is an effective strategy to accurately and objectively evaluate the texture properties of braised pork, which overcomes the limitations caused by the complexity of the composition and texture traits of braised pork. The accurate evaluation and standardization of texture properties is an important premise for the repeatable and stable cooking of traditional braised pork. Furthermore, this research method and findings can also be applied to guide the procedural optimization of smart appliances (e.g., induction cookers) for cooking braised pork.

Impact of Packaging Methods Coupled with High Barrier Packaging Loaded with TiO2 on the Preservation of Chilled Pork

This study investigated the impact of packaging methods coupled with high barrier packaging loaded with titanium dioxide (TiO2) on the quality of chilled pork. The experiment consisted of three treatment groups: air packaging (AP), vacuum packaging (VP), and vacuum antibacterial packaging (VAP). Changes in total viable count (TVC), pH value, total volatile basic nitrogen (TVB-N) value, sensory attributes, and water holding capacity of pork were analyzed at 0, 3, 6, 9, and 12 d. TVC of the VAP group was 5.85 Log CFU/g at 12 d, which was lower than that of AP (6.95 Log CFU/g) and VP (5.93 Log CFU/g). The antibacterial film incorporating TiO2 effectively inhibited microorganism growth. The VAP group exhibited the lowest pH value and TVB-N value among all the treatment groups at this time. The findings demonstrated that the application of VAP effectively preserved the sensory attributes of pork, the hardness, cohesiveness and adhesiveness of pork in VAP group were significantly superior than those in AP group (p<0.05), but not significantly compared with VP group. On the 12 d, the CIE a* value of pork in VAP group was significantly higher (p<0.05). This exhibited that VAP could effectively maintain the freshness of chilled pork and extend the shelf life for 3 d compared to the AP group. These findings provide empirical evidence to support the practical implementation of TiO2-loaded packaging film in the food industry.

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.

Effects of Different Roasting Methods on the Quality of Roasted Large Yellow Croaker (Larimichthys crocea)

This study investigated the effects of different roasting methods (45% light wave and 55% microwave roasting, 70% light wave and 30% microwave roasting, 100% light wave roasting, far-infrared roasting, and oven roasting) on the quality of roasted large yellow croaker. The quality was evaluated using sensory evaluation, texture characteristics, color differences, moisture content, and volatile flavor substances. In this context, different roasting methods can affect the color, taste, and flavor of large yellow croaker fish, significantly improving the overall acceptance of roasted fish. The results showed that after 45% light wave and 55% microwave roasting, the elasticity of fish meat was maintained, the hardness of fish meat was reduced, the moisture content and distribution were changed, and the taste was the best. Far-infrared roasting and 45% light wave and 55% microwave roasting had a significant effect on the color of large yellow croaker samples and improved the sensory evaluation score. Forty-six volatile compounds were detected using gas chromatography-mass spectrometry. After roasting, the oxidation and Maillard reactions of lipids and proteins were increased, with the 45% light wave and 55% microwave roasting giving the highest variety of volatile flavor substance products.

Constructing gellan gum/konjac glucomannan/wheat fiber composite hydrogel to simulate edible cartilage by ionic cross-link and moisture regulation

The utilization of non-animal-derived materials to imitate cartilage is critical for the advancement of plant-based simulated meat. In this study, gellan gum (GG), konjac glucomannan (KGM), and wheat fiber (WF) were used to construct hydrogel, and the mechanical strength, water properties, and microstructure were regulated by constructing Ca2+ cross-links and moisture control. The hardness, chewiness, resilience, shear force, and shear energy of the Ca2+ cross-linked samples were significantly improved. Extrusion dehydration further changes the related mechanical properties of the hydrogel and results in a tighter microstructure. The findings suggest that the establishment of Ca2+ cross-links and water regulation are efficacious techniques for modifying the texture of the GG/KGM/WF composite hydrogel. Correlation analysis and sensory evaluation showed that the test indexes and sensory scores of the samples with Ca2+ crosslinking and 80 % moisture content were similar to chicken breast cartilage, and the samples with Ca2+ crosslinking and 70 % moisture content were similar to pig crescent bone. This study presents a framework for designing edible cartilage simulators using polysaccharide hydrogels, with implications for enhancing the resemblance of plant-based meat products to real meat and expanding the range of vegetarian offerings available.

Characterization and discrimination of lamb with different breeds and muscle types using precursors and volatile compounds

The unique aromas of mutton stem from the chemical reactions between the characteristic precursors during cooking. This study aimed to establish the relationship of volatile compounds and aroma precursors (protein, fat, free amino acids and fatty acids) in lamb from different breeds and muscle types. Hong lamb was characterized by greater tenderness and water holding capacity, higher polyunsaturated fatty acids and higher essential/non-essential amino acids in comparison with Hu lamb. Aldehydes, such as heptanal, hexanal, octanal and nonanal were higher in Hong-ST compared with Hu-ST. Principal component analysis (PCA) showed that aroma precursors were closely related to volatile components of cooked lamb. Discriminant analysis results showed that precursors and volatile compounds could be used to identify the breeds and muscle types of lamb. These findings revealed the contributors of lamb aroma and might help understand the regulatory mechanism of aroma in lamb from different breeds and muscle types.

Insight into the evolution of textural properties and juiciness of ready-to-eat chicken breasts upon different thermal sterilization: From the perspective of protein degradation

Texture deterioration of meat products upon high-temperature sterilization is a pressing issue in the meat industry. This study evaluated the effect of different thermal sterilization temperatures on the textural and juiciness of ready-to-eat (RTE) chicken breast. In this study, by dynamically monitoring the texture and juiciness of chicken meat products during the process of thermal sterilization, it has been observed that excessively high sterilization temperatures (above 100°C) significantly diminish the shear force, springiness and water-holding capacity of the products. Furthermore, from the perspective of myofibrillar protein degradation, molecular mechanisms have been elucidated, unveiling that the thermal sterilization treatment at 121°C/10 min triggers the degradation of myosin heavy chains and F-actin, disrupting the lattice arrangement of myofilaments, compromising the integrity of sarcomeres, and resulting in an increase of approximately 40.66% in the myofibrillar fragmentation index, thus diminishing the quality characteristics of the products. This study unravels the underlying mechanisms governing the dynamic changes in quality of chicken meat products during the process of thermal sterilization, thereby providing theoretical guidance for the development of high-quality chicken products.

Correlations of dynamic changes in lipid and protein of salted large yellow croaker during storage

Protein and lipid are two major components that undergo significant changes during processing of aquatic products. This study focused on the protein oxidation, protein conformational states, lipid oxidation and lipid molecule profiling of salted large yellow croaker during storage, and their correlations were investigated. The degree of oxidation of protein and lipid was time-dependent, leading to an increase in carbonyl content and surface hydrophobicity, a decrease in sulfhydryl groups, and an increase in conjugated diene, peroxide value and thiobarbituric acid reactive substances value. Oxidation caused protein structure denaturation and aggregation during storage. Lipid composition and content changed dynamically, with polyunsaturated phosphatidylcholine (PC) was preferentially oxidized compared to polyunsaturated triacylglycerol. Correlation analysis showed that the degradation of polyunsaturated key differential lipids (PC 18:2_20:5, PC 16:0_22:6, PC 16:0_20:5, etc.) was closely related to the oxidation of protein and lipid. The changes in protein conformation and the peroxidation of polyunsaturated lipids mutually promote each other's oxidation process.

Effect of different thermal processing methods on sensory, nutritional, physicochemical and structural properties of Penaeus vannamei

The aim of this study was to investigate the effect of different thermal processing methods on the nutritional and physicochemical qualities of Penaeus vannamei. Three different thermal processing methods, namely, drying (DS, 120 °C/40 min), steaming (SS, 100 °C/2 min), and microwaving (MS, 600 W/2 min) were used to treat the shrimps. Low-field nuclear magnetic resonance data indicated that fixed water was the main component of Penaeus vannamei. The ratio of fatty acids in MS and DS samples was more in line with the FAO/WHO recommended health requirements; The myofibrillar protein carbonyl group increased, whereas sulfhydryl content decreased after thermal processing, indicating that the proteins were oxidized by thermal processing. The magnitude of oxidation is: MS > SS > DS. Different thermal processing methods can exert great influence on color texture and nutrition to Penaeus vannamei, which can provide a theoretical knowledge for consumers to choose the appropriate processing method.

Construction of a soybean protein isolate/polysaccharide-based whole muscle meat analog: Physical properties and freeze-thawing stability study

A growing interest has arisen in recreating real meat by mimicking its texture characteristics and muscle fiber structure. Our previous work successfully created meat analog fiber based on soybean protein isolate (SPI) and sodium alginate (SA) with the wet-spinning method. In this work, we analyzed the microstructure, texture profile, and water retainability of the assembled plant-based whole muscle meat analog (PMA) made of SPI/SA-based meat analog fiber and systematically studied the effect of different combinations and contents of transglutaminase (TG), salt, and soybean oil on the rheological behavior of the formulated adhesive. The estimated optimal condition that has the most similar texture characteristic with real chicken breast meat is: for every 1:1 mass ratio of simulated plant meat fibers to the adhesive, add 0.1 % TG enzyme addition in the adhesive and 100 mM NaCl addition. The physical behavior of PMA during cryopreservation was investigated through freeze-thaw cycles and freezing times. The addition of a small amount of oil and salt can efficiently prevent the PMA through freezing conditions which is comparable with the addition of D-Trehalose (TD). Overall, this study not only created a plant-based whole muscle meat analog product that is similar in texture to real chicken breast meat but also provided a new direction for constructing fiber-rich structure protein-based muscle meat analogs and their further commercialization.

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.

Differentiation of antioxidants in reducing oxidation and improving quality of ready-to-eat roasted shrimp after thermal sterilization

Sterilization is essential for ready-to-eat foods; however, it tends to degrade the quality of the product. To explore the role of antioxidants in regulating the edible quality of roasted Pacific white shrimp after sterilization, color changes, degree of oxidation, microstructure and quality of roasted shrimp treated with tea polyphenols, phytic acid, rosemary extract, and d-sodium erythorbate were investigated. Tea polyphenol-treated roasted shrimp had the lowest Maillard intermediate products and browning strength after sterilization; phytic acid significantly reduced carbonyl content and TBARS value; rosemary extract exhibited the lowest level of free radicals, while d-sodium erythorbate preserved a relatively intact myofibrillar structure. Correlation analysis revealed a negative correlation between the degree of oxidation and the edible quality of roasted shrimp after sterilization. Therefore, the addition of antioxidants inhibited oxidation and improved the quality of roasted shrimp, and different antioxidants had diverse effects on the quality improvement of roasted shrimp after thermal sterilization.

Effects of deep frying and baking on the quality attributes, water distribution, and flavor characteristics of duck jerky

Introduction

The nutritional value of duck meat is well acknowledged due to its low cholesterol and high protein content. Nevertheless, the impacts of deep-frying and baking on its quality characteristics are not extensively documented in literature.

Methods

The objective of this study is to examine the effects of deep-frying, pre-boilingdeep-frying, baking, and pre-boiling-baking on the quality attributes, water distribution, microstructure, and flavor characteristics of duck jerky.

Results and discussion

The findings revealed that the deep-frying group had better quality attributes than the baking, pre-boiling-deep-frying, and pre-boiling-baking groups. The deepfried duck jerky had a higher a* value (4.25) and a lower b* value (5.87), with a more appropriate texture profile, and had the highest comprehensive impression score (5.84). Moreover, the drying rate was faster, and the intensity of the free water and oil signal was significantly elevated in the deep-frying group. The microstructure results indicated that the muscle fibers in the deep-frying group were closely packed, whereas those in the baking group were relatively loose. Furthermore, the GC-IMS test revealed that the deep-fried duck jerky had a wider range of volatile flavor compounds, including 11 unique compounds that were only found in this particular product.

Improving the Edible and Nutritional Quality of Roasted Duck Breasts through Variable Pressure Salting: Implications for Protein Anabolism and Digestion in Rats

Variable pressure salting (VPS) is considered a novel salting approach to improve meat quality. This study aimed to investigate the effects of roasted duck's edible and nutritional quality after VPS through serum biochemical indicators and in vivo digestion properties in rats. The results show that roasted duck after VPS led to an increase in the total protein content (57.24 g/L) and blood glucose levels (6.87 mmol/L), as well as a decrease in the blood urea nitrogen content (11.81 mmol/L), in rats. Compared to rats fed base diets and roasted duck after static wet salting (SWS), those ingesting roasted duck after VPS exhibited higher values of apparent protein digestibility (51.24%), pepsin activity (2.40 U/mg), and trypsin activity (389.80 U/mg). Furthermore, VPS treatment improved the textural properties and microstructure of duck breasts shown by a higher immobilized water relaxation area and more ordered protein structures (α-helixes and β-sheets). These improvements enhanced the protein anabolism capacity and in vivo digestion properties in rats. Therefore, VPS represents a beneficial salting method for promoting effective digestion and absorption in rats.

Changes provoked by altitudes and cooking methods in physicochemical properties, volatile profile, and sensory characteristics of yak meat

The present study aimed to shed light on the effects of altitudes and three cooking methods (boiling, steaming, and roasting) on the physicochemical quality, volatile profile, and sensorial characteristics of yak meat. Composite meat samples were prepared to represent each cooking method and altitude level from the longissimus thoracis et lumborum (LTL) muscle of nine yaks. The techniques employed were gas chromatography-mass spectrometry (GC-MS) and electronic nose (E-nose) along with chemometrics analysis to study the changes occurring in yak volatile profile, and TBARS measurement in lipid oxidation during cooking. Among the cooking methods, boiling and steaming exhibited higher protein and fat content while lower volatile compound contents. Additionally, roasted yak meat received the highest sensory scores, along with decreased L*-values, while elevated a*- and b*-values, and tenderness. A total of 138 volatile compounds were detected, and among them, 36 odorants were identified as odor-active compounds in cooked yak meat. It is evidenced that low-altitude yak presented more complex and richer flavor profiles than high-altitude ones. Moreover, yak meat from low- and high-altitude was classified into two groups by an electronic nose (E-nose) owing to distinct flavor characteristics. Overall, roasted yak meat originating from low altitudes tends to be more popular from a sensory perspective.

Improving the quality and processing efficiency of beef jerky via drying in confined conditions of pre-stretching

Inspired by the mechanical enhancement of hydrogel via drying in confined conditions, we applied this strategy to beef jerky manufacture for improving the quality and processing efficiency. In our study, beef strips were pre-stretched and then dried in a tensile state, and the confined conditions were achieved by controlling the stretched strains from 20% to 120%. Compared with the sample dried freely, beef jerky dried in confined conditions of different pre-stretching strains exhibited improved quality based on texture and sensory analysis. Additionally, this method also enhanced processing efficiency by reducing approximately 50% drying time. The excellent sensory quality and good texture of beef jerky were obtained as the pre-stretching strain was 80%. Drying beef strips in confined conditions made muscle fibers tense and enhanced hydrophobicity of myofibrillar proteins, leading to a compact structure with high shear force and anisotropy, and rapid water loss in beef jerky. This facile and green method provides a promising route to enrich the existing technologies of jerky processing.

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

Tenderness of lean meat in braised pork is of great importance to the consumer palatability and acceptance. The influence of water status, protein structure and histological changes on lean meat tenderness during cooking was investigated. Results indicated that lean meat began to tenderize mainly after 20 min-cooking. In the early period of cooking, the decrease of total sulfhydryl content caused the protein oxidative cross-linking, leading to the gradual unfolding of the protein structure, thus resulting in a decrease of T₂₂ and an increase of centrifugal loss, which decreased the tenderness of lean meat. However, after cooking for 20 min, the β-sheet decreased and random coil increased, thus generating conversion between P₂₁ and P₂₂. The rupture of perimysium structure was observed. Changes in protein structure, water status, and tissue histology could facilitate the initiation and development of lean meat tenderness.

Effects of ultrasound treatment on muscle structure, volatile compounds, and small molecule metabolites of salted Culter alburnus fish

This study investigated the effects of ultrasound treatment on the quality of salted Culter alburnus fish. The results showed that with the increasing ultrasound power, the structural degradation of muscle fibers was intensified, and the conformation of myofibrillar protein was significantly changed. The high-power ultrasound treatment group (300 W) had relatively higher thiobarbiturate reactive substance content (0.37 mg malondialdehyde eq/kg) and peroxidation value (0.63 mmol/kg). A total of 66 volatile compounds were identified with obvious differences among groups. The 200 W ultrasound group exhibited fewer fishy substances (Hexanal, 1-Pentene-3-ol, and 1-Octane-3-ol). Compared with control group, ultrasound groups (200, 300 W) contained more umami taste-related amino peptides such as γ-Glu-Met, γ-Glu-Ala, and Asn-pro. In the ultrasound treatment group, L-isoleucine and L-methionine, which may be used as flavor precursors, were significantly down-regulated, while carbohydrates and its metabolites were up-regulated. Amino acid, carbohydrate, and FA (fatty acyls) metabolism products in salted fish were enriched by ultrasound treatment, and those products might ultimately be related to the taste and flavor of salted fish.

Insight into the Effects of Drying Methods on Lanzhou Lily Rehydration

This study investigated the effects of drying methods (hot air drying (HAD), microwave vacuum drying (MVD), and vacuum freeze drying (VFD)) on the rehydration performance (RP) of dried Lanzhou lily scales (LLS). Rehydration rate and water migration showed that MVD had the best RP, followed by VFD, while HAD had the worst. The results of additional morphology observation using scanning electron microscopy (SEM) and micro X-ray computed tomography (CT) imaging showed that both MVD and VFD created more channels in more porous structures, which facilitated their better RP than that by HAD. The results also revealed the spatial structure diversity (including pores, channels size, and internal network) of each dried Lanzhou lily scale group. In addition, studies analyzed how drying techniques affected the physiochemical properties of lily starch, including its water solubility, pasting profiles, and starch particle morphology. The findings indicated that when MVD was in operation, partial gelatinization in lily starch was brought about by thermal effects, allowing MVDS crystals to change from B-type to V-type and causing MVDS to have better water absorption ability. Consequently, despite the fact that MVD's desiccated lilies have a lower porous structure and thinner channels than VFD's, MVD has a higher RP than VFD.

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.

Underlying formation mechanisms of ultrasound-assisted brined porcine meat: The role of physicochemical modification, myofiber fragmentation and histological organization

Ultrasound treatment has been a good hurdle technique for meat curing processing, where both physical and chemical consequences can be involved towards final quality of obtained products. However, the specific correlation between ultrasound parameters and muscle fiber fragmentation and myofibrillar microstructural changes during curing deserve further evaluation. In present study, we comparatively studied the effect of ultrasound-assisted brining (UAB) and static brining (SB) on the muscle proteolysis events and microstructural/morphological variation of porcine meat as well as the physicochemical indices and histological characteristics. The results showed that UAB (20 kHz, 315 W for 1 h) could markedly enhance the muscle proteolysis with higher free-/peptide-bound alpha-amino-nitrogen (α-NH2-N) content (P < 0.05) than SB treatment and greatly improved the fragmentation of muscle fiber tissues of cured meat. Meanwhile, UAB processing favored more opening structures of myofibrillar proteins with more hydrophobic groups being exposed. The quantitative histological analysis revealed that, compared with SB treatment, UAB could significantly increase the gap between muscle fibers and the swelling of the perimysium (P < 0.01), proving an efficient curing process with better textural and water holding properties.

Effects of conjugates of ε-polylysine-dextran created through Maillard reaction on quality and storage stability of the chicken gel

The present study mainly focused on the effects of the conjugates of PL-dextran produced through the Maillard reaction on the quality and storage stability of chicken gel for 5 days at 4 ℃. According to the results of the texture profile, water retention capacity (WRC), low-field nuclear magnetic resonance (LF NMR), aerobic plate count (APC), and total volatile basic nitrogen (TVBN), ε-polylysine (PL) could improve chicken gel storage stability while decreasing the quality of protein gels (p < 0.05). Additionally, adding dextran with high or low molecular weight could significantly increase the quality of gel during storage (p < 0.05), whereas decreased storage stability could be obtained (p < 0.05). In general, conjugates formed by PL and dextran with high molecular weight were beneficial for quality maintenance. In comparison, the polymers produced from the low molecular weight of dextran could modify the storage stability of gels. Adding conjugates of dextran and PL benefited the structure formation of protein gel, while PL would retain part of antibacterial activity when crosslinked with dextran. Therefore, it could be concluded that the quality improvement effect of PL-dextran addition on gel quality was greater than its antibacterial effect, which would impact the formulation design of novel emulsion-type meat products.

Mechanism of polyhydroxy alcohol-mediated curing on moisture migration of minced pork tenderloin: On the basis of molecular docking

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Polyhydroxy alcohols affect salt diffusion and moisture migration.

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Polyhydroxy alcohols cause the water to migrate out to reduce aw in meat.

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Polyhydroxy alcohols retard salt diffusion into the meat by forming a viscose barrier.

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Polyhydroxy alcohols can prevent meat structural damage by binding to myosin.

This study investigated the mechanism of glycerol, xylitol, and sorbitol-mediated curing of cured minced pork tenderloin. The use of polyhydroxy alcohol during mediated curing significantly reduced the salt content (p < 0.01) and water activity (aw) of the cured pork tenderloin. Low-field nuclear magnetic resonance (LFNMR) revealed that 1 % glycerol, 1 % xylitol, 1 % sorbitol, and 10 % glycerol-mediated curing decreased water mobility, and improved water holding capacity (WHC), and produced uniform dense microstructures. Raman spectroscopy and molecular docking indicated that polyhydroxy alcohols formed hydrogen bonds with myosin, as well as hydrogen bonds with free water molecules to convert free water into bound water to reduce aw, and altered the hydrophobic environment of myosin surface to reduce structural damage caused by high salt content. In conclusion, using polyhydroxy alcohol to mediate curing can effectively reduce the salt content of cured meat and provide a theoretical basis for its application in the cured meat industry.

Effect of subfreezing storage on the qualities of dough and bread containing pea protein

BACKGROUND

In this paper, -6, -9 and -12 °C were selected as subfreezing temperatures of dough containing pea protein based on the results of low-field nuclear magnetic relaxation time. The effect of storage at subfreezing temperatures on dough properties was then investigated and compared with sample storage at -18 °C.

RESULTS

The pH value, springiness, resilience, cohesiveness of dough and sensory score of bread gradually decreased and the hardness and water loss rate of dough gradually increased with the extension of storage time. However, dough hardness, viscoelasticity and fermentation volume were maintained more effectively in subfreezing storage than in -18 °C storage. The subfreezing temperature could alleviate the damage of gluten network structure in frozen dough by ice crystals and was beneficial in maintaining the elasticity of gluten proteins. The network system of pea protein, gluten protein and starch granules in dough storage at -9 and -12 °C was more tightly connected and the microstructure was similar to that at -18 °C. There was no significant difference between the quality of bread made from the dough stored at subfreezing temperature and that stored at -18 °C for 1-6 weeks, and the preservation effect at -12 °C was closer to that at -18 °C.

CONCLUSION

Subfreezing storage can keep the stability of dough containing pea protein close to traditional frozen storage (-18 °C), which provides a new method for storage and transportation of frozen dough. © 2022 Society of Chemical Industry.

Effect of different sweeteners on the quality, fatty acid and volatile flavor compounds of braised pork

This study aimed to assess how several sweeteners (white sugar, Siraitia grosvenorii fruit, mogrosides, and stevia glycoside) affected the flavor, fatty acid composition, and quality of braised pork. The findings indicated that braised meat prepared with sweeteners differed from typical braised pork. When simmered for 60 min, the typical braised pork with white granulated sugar exhibited a significant cooking loss (CL) and little water content. Significantly more than in the group containing Siraitia grosvenorii, mogroside, and stevia glycoside, the Thiobarbituric acid (TBARS) value increased by 14.39% (P < 0.05). The sample in the group that included mogroside had a low CL rate. After 40 min of stewing, the lean pork has the highest L* value, but the 60-min stew sample is nicely colored and stretchy. Mogroside can prevent protein, and lipid oxidation, is thermally stable and reduces CL during stewing. Additionally, Siraitia grosvenorii and stevia glycosides help prevent oxidation from intensifying during stewing. When Siraitia grosvenorii is added, lipid oxidation is significantly inhibited, and stevia glycosides are more beneficial for enhancing meat color. With an increase in heating time, the fatty acids in braised pork reduced; the unsaturated fatty acid (UFA) of the Siraitia grosvenorii fruit (SF) and mg group also fell somewhat, and the UFA: SFA ratio was higher than that of the white sugar (WS) group. The SFA content of the braised meat in the stevia glycoside group was higher than that of the WS group. In all, 75 volatile flavor elements in braised pork were discovered by Gas chromatography-ion mobility spectrometry (GC-IMS). The sweetener increased alcohols, esters, and acids in the braised pork. As stewing time increased, ketones decreased, but aldehydes and esters increased. The pork formed antioxidant peptides with great nutritional value after cooking. Braised pork with mogroside and stevia glycoside additions primarily have some protein color protection and antioxidant effects. This study may offer fresh perspectives on applying natural sweeteners and enhancing braised pork’s flavor.

Changes in Textural Quality and Water Retention of Spiced Beef under Ultrasound-Assisted Sous-Vide Cooking and Its Possible Mechanisms

The present study investigated the effects of ultrasound (28 kHz, 60 W at 71 °C for 37 min) combined with sous-vide cooking (at 71 °C for 40, 60, 80, 100, 120 min) on the textural quality, water distribution, and protein characteristics of spiced beef. Results showed that the spiced beef treated with conventional cooking (CT) had the highest cooking loss (41.31%), but the lowest value of shear force (8.13 N), hardness (55.66 N), springiness (3.98 mm), and chewiness (64.36 mJ) compared to ultrasound-assisted sous-vide (USV) and sous-vide cooking (SV) groups. Compared with long-time thermal treatment, USV heating within 100 min enhanced the water retention of spiced beef by maintaining the lower values of cooking loss (16.64~25.76%), T₂ relaxation time (242.79~281.19 ms), and free water content (0.16~2.56%), as evident by the intact muscle fibers. Moreover, the USV group had relatively lower carbonyl content, but higher sulfhydryl content compared to CT and SV groups. More protein bands coupled with a minor transformation from α-helixes to β-turns and random coils occurred in USV40~USV80. In conclusion, these results indicated that USV treatment within 100 min positively affected the textural quality and water retention of spiced beef by moderate protein oxidation.

Differentiation of Penaeus vannamei from different thermal processing methods in physico-chemical, flavor and sensory characteristics

Differentiation in physico-chemical, flavor and sensory characteristics of shrimps (Penaeus vannamei) after direct roasting (DR, 200 °C), boiling (100 °C/2 min) + roasting (BR), steaming (100 °C/2 min) + roasting (SR) and microwaving (280 W/2 min) + roasting (MR) was investigated. BR, SR, and MR endowed shrimps with better texture to varying degrees and significantly (P < 0.05) increased lightness when compared to DR, which closely related to their different water status. High correlations between nuclear magnetic resonance data and quality properties were found by partial-least-squares regression (PLSR). Shrimps possessed by SR significantly (P < 0.05) increased the proportion of sweet amino acids (63.89 ± 0.92%), with superior umami and richness detected by electronic tongue. Compared with DR, both SR and MR endowed shrimps with richer ester, while BR endowed shrimps with richer hydrocarbons. Roasting combined with other thermal processing would favor improving the quality of shrimp products.