Effects of ultrasound-assisted vacuum tumbling on the oxidation and physicochemical properties of pork myofibrillar proteins

Insights into the impact mechanism of tumbling-curing on the edible quality of beef salted ham through analysis of myofibrillar protein gel properties

This study aimed to investigate the effects of vacuum tumbling curing (VTC), pulsating vacuum tumbling curing (PVTC), tumbling curing (TC), and static curing (SC) on the myofibrillar protein (MP) gel properties of beef as well as the underlying mechanisms contributing to the enhancement of edible quality in beef salted ham. The results revealed that VTC significantly improved the texture characteristics and sensory evaluation scores of beef salted ham, and the yield increased by 11.85 % compared with SC (P < 0.05). VTC increased the gel strength and water-holding capacity (WHC) of MP gels and improved their rheological behavior. The MP gel of the VTC group exhibited strong hydrophobic interactions and disulfide bonds, leading to self-assembly of the α-helix into β-sheet structures, thereby forming a stable and organized gel network. This enhancement in structural stability ultimately contributes to the improved texture characteristics of beef salted ham, thereby improving its edible quality. Compared with alternative curing techniques, VTC demonstrated its effectiveness in the development of high-end reconstituted beef products.

Mechanism of Toona sinensis seed polyphenols inhibiting oxidation and modifying physicochemical and gel properties of pork myofibrillar protein under oxidation system

This research aimed to elucidate how Toona sinensis seed polyphenols (TSSs) inhibited pork myofibrillar protein (MP) oxidation and modified physicochemical and gel properties in the Fenton oxidation system. Our result displayed that TSSs had a lower carbonyl (from 1.38 to 0.59 nmol/mg) and dityrosine contents (from 47.22 to 25.07), and higher free amino content (from 386.99 to 485.00 nmol/mg), followed by ellagic acid (EA) and quercetin-3-O-rhamnoside (QC). Meanwhile, the incorporation of phenolic compounds changed secondary and tertiary structure of proteins and then increased solubility and absolute value of zeta potential, as well as decreased turbidity and average particle size. Molecular docking indicated that MP interacted with EA primarily via hydrogen bonds and hydrophobic interaction, and with QC mostly through hydrogen bonds and electrostatic interaction. Otherwise, the incorporation of EA promoted MP gel to form a honeycomb-like microstructure after oxidation. Therefore, TSSs, EA, and QC could significantly inhibit MP oxidation as well as modify its physicochemical properties, but only EA enhanced its gel properties after oxidation. The results could be useful to improve the comprehensive utilization of plant by-products and provide theoretical references for the role of TSSs in the improvement of meat products.

Enhancing salt-induced gelation of egg yolk granules through pH-ultrasound combined treatment: A physicochemical and microstructural analysis

Salted duck eggs are a popular food product, but their high salt content and uneven salt distribution can reduce acceptability. This study investigated the effects of pH-high-intensity ultrasound combined treatment on the salt-induced gelation properties of egg yolk granules. The results showed that the pH5 + 150 W treatment group exhibited the best physical and gelation properties, with the smallest particle size (1597.33 nm), optimal dispersibility (PDI 0.29), and good stability. The gelation properties of this group also demonstrated excellent springiness (0.30 mm), cohesiveness (0.56), and gumminess (0.05 N). Furthermore, the pH5 + 150 W group had the highest water holding capacity of 97.42 % and relatively high hydrophobicity (173.39 μg). Notably, it also showed high oil exudation (2.83 %) and good sandiness (62.07 %). The pH5 + 150 W led to a significant redshift of the fluorescence peak at 335 nm and an enhancement of the peak intensity at 562 nm compared to the control group. Structural characterization revealed a more ordered protein structure and a uniform gel structure with enhanced electrostatic repulsion between oil droplets. Secondary structure analysis of the proteins showed a significant reduction in α-helix and β-sheet, while β-turn and random coil increased. In summary, the pH5 + 150 W treatment displayed the best gelation properties, providing theoretical guidance for enhancing the processing performance of yolk and expanding their application in the food industry.

Insight into the effects of ultrasound-assisted intermittent tumbling on the gelation properties of myofibrillar proteins: Conformational modifications, intermolecular interactions, rheological properties and microstructure

The aim of the present study was to evaluate the effects of ultrasound-assisted intermittent tumbling (UT) at 300 W, 20 kHz and 40 min on the conformation, intermolecular interactions and aggregation of myofibrillar proteins (MPs) and its induced gelation properties at various tumbling times (4 and 6 h). Raman results showed that all tumbling treatments led the helical structure of MPs to unfold. In comparison to the single intermittent tumbling treatment (ST), UT treatment exerted more pronounced effects on strengthening the intermolecular hydrogen bonds and facilitating the formation of an ordered β-sheet structure. When the tumbling time was the same, UT treatment caused higher surface hydrophobicity, fluorescence intensity and disulfide bond content in the MPs, inducing the occurrence of hydrophobic interaction and disulfide cross-linking between MPs molecules, thus forming the MPs aggregates. Additionally, results from the solubility, particle size, atomic force microscopy and SDS-PAGE further indicated that, relative to the ST treatment, UT treatment was more potent in promoting the polymerization of myosin heavy chain. The MPs aggregates in the UT group were more uniform than those in the ST group. During the gelation process, the pre-formed MPs aggregates in the UT treatment increased the thermal stability of myosin, rendering it more resistant to heat-induced unfolding of the myosin rod region. Furthermore, they improved the protein tail-tail interaction, resulting in the formation of a well-structured gel network with higher gel strength and cooking yield compared to the ST treatment.

The Effect of Ultrasound Treatment on the Structural and Functional Properties of Tenebrio molitor Myofibrillar Protein

The objective of this study was to explore the impacts of various ultrasonic powers (0, 300, 500, 700, and 900 W) on the structure and functional attributes of the myofibrillar protein (MP) of Tenebrio molitor. As the ultrasonic intensity escalated, the extraction efficiency and yield of the MP rose, while the particle size and turbidity decreased correspondingly. The reduction in sulfhydryl group content and the increase in carbonyl group content both suggested that ultrasonic treatment promoted the oxidation of the MP to a certain extent, which was conducive to the formation of a denser and more stable gel network structure. This was also affirmed by SEM images. Additionally, the findings of intrinsic fluorescence and FTIR indicated that high-intensity ultrasound significantly altered the secondary structure of the protein. The unfolding of the MP exposed more amino acid residues, the α-helix decreased, and the β-helix improved, thereby resulting in a looser and more flexible conformation. Along with the structural alteration, the surface hydrophobicity and emulsification properties were also significantly enhanced. Besides that, SDS-PAGE demonstrated that the MP of T. molitor was primarily composed of myosin heavy chain (MHC), actin, myosin light chain (MLC), paramyosin, and tropomyosin. The aforementioned results confirmed that ultrasonic treatment could, to a certain extent, enhance the structure and function of mealworm MP, thereby providing a theoretical reference for the utilization of edible insect proteins in the future, deep-processing proteins produced by T. molitor, and the development of new technologies.

Effects of brining, ultrasound, and ultrasound-assisted brining on quality characteristics of snakehead (Channa argus) fillets

The change of quality characteristics in snakehead fillets were investigated during brining, ultrasound, and ultrasound-assisted brining processing. Results showed that ultrasound and brine had significantly impact on the tissue microstructure and the color parameter of fillets. Compared to 60-min marination in deionized water, the shear force was reduced by 17.67 g by ultrasound, compared to 80-min marination in deionized water, the shear force was reduced by 28.68 g by brine. Brine significantly increased the water-holding capacity of fish fillets. Ultrasound resulted in increased random coils, β-turn and hydrophobic interaction, while brine significantly promoted the formation of the α-helix structure. The increase of the thermal stability of the myosin head was due to the synergistic effect of ultrasound and brine, but the decrease of the thermal stability of actin only associated with brine. The study provides the reference for the application of ultrasound-assisted brining technology to aquatic industry.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01506-8.

Integrated ultra-high pressure and salt addition to improve the in vitro digestibility of myofibrillar proteins from scallop mantle (Patinopecten yessoensis)

Myofibrillar protein (MP) is susceptible to the effect of ionic strength and ultra-high pressure (UHP) treatment, respectively. However, the impact of UHP combined with ionic strength on the structure and in vitro digestibility of MP from scallop mantle (Patinopecten yessoensis) is not yet clear. Therefore, it is particularly important to analyze the structural properties and enhance the in vitro digestibility of MP by NaCl and UHP treatment. The findings demonstrated that as ionic strength increased, the α-helix and β-sheet gradually transformed into β-turn and random coil. The decrease of endogenous fluorescence intensity indicated the formation of a more stable tertiary structure. Additionally, the exposure of internal sulfhydryl groups increased the amount of total sulfhydryl content, and reactive sulfhydryl groups gradually transformed into disulfide bonds. Moreover, it reduces aggregation through increased solubility, decreased turbidity, particle sizes, and a relatively dense and uniform microstructure. When MP from the scallop mantle was treated with 0.5 mol/L ionic strength and 200 MPa UHP treatment, it had the highest solubility (90.75 ± 0.13%) and the lowest turbidity (0.41 ± 0.03). The scallop mantle MP with NaCl of 0.3 mol/L and UHP treatment had optimal in vitro digestibility (95.14 ± 2.01%). The findings may offer a fresh perspectives for developing functional foods for patients with dyspepsia and a theoretical foundation for the comprehensive utilization of scallop mantle by-products with low concentrations of NaCl.

Transcriptomic and Physiological Analysis Reveals the Possible Mechanism of Inhibiting Strawberry Aroma Changes by Ultrasound after Harvest

The volatile compounds in strawberries play a significant role in the formation of strawberry aroma. However, these compounds undergo continual changes during storage, resulting in a decline in quality. In this study, a total of 67 volatile organic compounds (VOCs) were identified in strawberries through quantitative analysis. At the end of the storage period, the VOC content in the ultrasonic group was 119.02 µg/kg higher than that in the control group. The results demonstrated that the ultrasonic treatment increased the contents of terpenes and esters at the end of storage. Among these, linalool increased from 67.09 to 91.41 µg/kg, while ethyl cinnamate increased from 92.22 to 106.79 µg/kg. Additionally, the expression of the key metabolic genes closely related to these substances was significantly up-regulated. The expression of the FaNES gene, related to terpene metabolism, was up-regulated by 2.8 times in the second day, while the expression of the FaAAT gene, related to ester metabolism, was up-regulated by 1.5 times. In summary, this study provides a theoretical basis for exploring the mechanism of ultrasonic effect on strawberry flavor and quality after harvest.

Effect of ultrasound-assisted L-lysine treatment on pork meat quality and myofibrillar protein properties during postmortem aging

This paper aimed to investigate the effects of ultrasound-assisted L-lysine treatment on meat quality and myofibrillar proteins (MPs) properties of pork longissimus dorsi during postmortem aging. The results revealed that the L-lysine (Lys) and/or ultrasound treatment significantly increased (p < 0.05) the water-holding capacity and tenderness of the pork during postmortem aging, while the ultrasound-assisted Lys treatment had the lowest cooking loss, pressurization loss, Warner-Bratzler shear force, and hardness. In addition, L-lysine and/or ultrasound treatment increased (p < 0.05) pH value, T21, and myofibrillar fragmentation index, while the ultrasound-assisted Lys treatment had the highest value. Meanwhile, the protein solubility was increased with Lys and/or ultrasound treatment during postmortem aging, and ultrasound-assisted Lys treatment had the highest solubility, reaching 88.19%, 92.98%, and 91.73% at 0, 1, and 3 days, respectively. The result of protein conformational characteristics showed that Lys and/or ultrasound treatment caused the unfolding of the α-helix structure, resulting in the exposure of more hydrophobic amino acids and buried sulfhydryl groups, ultimately enhancing MPs solubility. In summary, ultrasound-assisted Lys treatment altered the structure of MPs, resulting in the enhancement of the water-holding capacity and tenderness of the pork. PRACTICAL APPLICATION: This study showed that ultrasound-assisted L-lysine (Lys) treatment could enhance the water-holding capacity and tenderness of pork during postmortem aging. The results might provide a reference for the application of ultrasound-assisted Lys treatment on the improvement of pork meat quality. To facilitate practical applications in production, the development of medium and large-sized ultrasound equipment for conducting small-scale and pilot experiments is crucial for future research.

Recent advancements in the utilization of ultrasonic technology for the curing of processed meat products: A comprehensive review

Curation meat products involves multiple stages, including pre-curing processing (thawing, cleaning, and cutting), curing itself, and post-curing processing (freezing, and packaging). Ultrasound are nonthermal processing technology widely used in food industry. This technology is preferred because it reduces the damages caused by traditional processing techniques on food, while simultaneously improving the nutritional properties and processing characteristics of food. The utilization of ultrasonic-assisted curing technology has attracted significant attention within the realm of meat product curing, encouraging extensive research efforts. In terms of curing meat products, ultrasonic-assisted curing technology has been widely studied due to its advantages of accelerating the curing speed, reducing nutrient loss, and improving the tenderness of cured meats. Therefore, this article aims to comprehensively review the application and mechanism of ultrasound technology in various stages of meat product curing. Furthermore, it also elaborates the effects of ultrasonic-assisted curing on the tenderness, water retention, and flavor substances of the meat products during the curing process. Besides, the implication of the ultrasound in the processing of meat curation plays a potent role together with other technologies or methods. The use of ultrasound technology in the process of meat curation was analyzed, which might be a theoretical insight for the industrialization prospects of the meat product.

Effects of ultrasound-assisted cooking on the physicochemical properties and microstructure of pork meatballs

This research aims to investigate the effect of different ultrasonic powers cooking on the quality of pork meatballs. Pork meatballs treated with ultrasound-assisted cooking at 450 W had the most uniform and smooth structures displayed by scanning electron microscopy. Furthermore, with increasing ultrasonic powers, the water retention capacity of pork meatballs first increased and then decreased, compared with the non-ultrasound group, when the ultrasonic power was 450 W, the cooking yield of pork meatballs increased from 82.55% to 92.87%, and the centrifugal loss decreased from 25.35% to 11.52%. Additionally, ultrasound-assisted cooking had a positive effect on the moisture migration, tenderness, and sensory property of pork meatballs, and 450 W sample exhibited the highest overall acceptability score (P < 0.05). In conclusion, the physicochemical properties and microstructure of pork meatballs could be improved by appropriate ultrasonic power, and ultrasonic technology was considered as an effective processing method for improving the quality of meat products.

Effects of ultrasound-assisted intermittent tumbling on the quality of cooked ham through modifying muscle structure and protein extraction

BACKGROUND

Tumbling treatment is widely used in the production of cooked ham. However, traditional intermittent tumbling (IT) treatment is time-consuming. To enhance the tumbling efficiency, high-intensity ultrasound was used to assist IT treatment (UIT).

RESULTS

UIT treatment reduced the tumbling time and significantly improved the water holding capacity, tenderness, sliceability and texture of cooked ham compared to IT treatment. Furthermore, more violent destruction of meat tissue was exhibited in the UIT treatment. This change facilitated extraction of more salt-soluble protein, which in turn welded meat pieces tightly and improved the quality of the cooked ham.

CONCLUSION

UIT treatment could accelerate the tumbling process and enhance the quality of cooked ham. These results may provide guidance on effective strategies for a high-quality meat production process. © 2023 Society of Chemical Industry.

Novel NaCl reduction technologies for dry-cured meat products and their mechanisms: A comprehensive review

Sodium chloride (NaCl) confers a unique flavor and quality in meat products, however, due to growing concerns about the adverse effects of excessive NaCl consumption, how to reduce NaCl content while ensuring quality and safety has become a research hotspot in this field. This review mainly discusses the role of NaCl in dry-cured meat, as well as novel salt-reducing substances that can substitute for the effects of NaCl to achieve sodium reduction objectives. New technologies, such as vacuum curing, ultrahigh pressure curing, ultrasonic curing, pulsed electric field curing, and gamma irradiation, to facilitate the development of low-sodium products are also introduced. The majority of current salt reduction technologies function to enhance salt diffusion and decrease curing time, resulting in a decrease in NaCl content. Notably, future studies should focus on implementing multiple strategies to compensate for the deficiencies in flavor and safety caused by NaCl reduction.

Evaluation of ultrasound-assisted process as an approach for improving the overall quality of unsmoked bacon

Our previous study has found that ultrasonic application on raw meat could improve the flavor of unsmoked bacon. For comprehensively evaluating the impacts of ultrasonic pretreatment (0, 250, 500 or 750 W, 20 kHz) on the overall quality of unsmoked bacon during processing, the following indicators were determined including salt and water content, pH, shear force, color, water distribution, texture and myofibril microstructure. Results manifest that ultrasonic pretreatment could significantly improve the salt and water content, pH and redness of unsmoked bacon. The water retention capacity was obviously enhanced by ultrasonic pretreatment proved by increased immobile water and decreased free water. Meanwhile, the shear force, the hardness and the chewiness were notably ameliorated after ultrasonic pretreatment, suggesting a better tenderness verified by the observation results of transmission electron microscope. However, no significant differences were found on the brightness, yellowness, springiness, cohesiveness and resilience of unsmoked bacon after ultrasonic pretreatment. Consequently, ultrasound could be considered as a potential tool for the overall-quality improvement of unsmoked bacon.

Physicochemical and structural changes of myofibrillar proteins in muscle foods during thawing: Occurrence, consequences, evidence, and implications

Myofibrillar protein (MP) endows muscle foods with texture and important functional properties, such as water-holding capacity (WHC) and emulsifying and gel-forming abilities. However, thawing deteriorates the physicochemical and structural properties of MPs, significantly affecting the WHC, texture, flavor, and nutritional value of muscle foods. Thawing-induced physicochemical and structural changes in MPs need further investigation and consideration in the scientific development of muscle foods. In this study, we reviewed the literature for the thawing effects on the physicochemical and structural characters of MPs to identify potential associations between MPs and the quality of muscle-based foods. Physicochemical and structural changes of MPs in muscle foods occur because of physical changes during thawing and microenvironmental changes, including heat transfer and phase transformation, moisture activation and migration, microbial activation, and alterations in pH and ionic strength. These changes are not only essential inducements for changes in spatial conformation, surface hydrophobicity, solubility, Ca2+ -ATPase activity, intermolecular interaction, gel properties, and emulsifying properties of MPs but also factors causing MP oxidation, characterized by thiols, carbonyl compounds, free amino groups, dityrosine content, cross-linking, and MP aggregates. Additionally, the WHC, texture, flavor, and nutritional value of muscle foods are closely related to MPs. This review encourages additional work to explore the potential of tempering techniques, as well as the synergistic effects of traditional and innovative thawing technologies, in reducing the oxidation and denaturation of MPs and maintaining the quality of muscle foods.

Effects of ultrasound on the oxidation and structures of the myofibrillar protein in the presence or absence of soybean oil

BACKGROUND

Ultrasound is widely used as a novel non-thermal processing technique to improve protein properties. In recent decades, applying ultrasound-assisted emulsification (UAE) to produce protein-stabilized emulsion has attracted people's attention. Instead of applying ultrasound to treat a single protein solution, UAE treatment refers to the use of sonication to a mixture of protein and oil. The purpose of this study was to compare the different effects of ultrasound treatment on the properties of the myofibrillar protein (MP) in the presence or absence of soybean oil. A suitable sonication power was selected based on the change in emulsion properties.

RESULTS

The 300W sonication power was selected due to its most effectively decreased emulsion droplet size and increased absolute zeta potential. Sonication more significantly increased the protein carbonyl content and disulfide bonds of the MP-soybean oil sample than MP sample. Due to the existence of oil, ultrasound could unfold more protein molecules illustrated by a lower α-helix content and intrinsic fluorescence intensity, and a higher surface hydrophobicity. LC-MS/MS results illustrated that sonication enhanced the myosin heavy chain and actin content at the soybean oil interface as well as accelerated the myosin light chain to separate from myosin in the MP-soybean oil system.

CONCLUSION

In summary, ultrasound treatment could lead to a higher level of protein oxidation and more protein molecule exposure in the MP with the presence of oil system than in the oil-free MP system. This article is protected by copyright. All rights reserved.

Study on film forming characteristic of ε-polylysine grafted chitosan through TEMPO oxidation system and its preservation effects for pork fillet

The present study synthesized a new type of ε-polylysine (PL) modified chitosan film (TO-CH-PL) through TEMPO (2,2,6,6-Tetramethylpiperidine) oxidation system. Firstly, the physicochemical properties of the TO-CH-PL were characterized using Fourier transform infrared spectroscopy, scanning electron microscopy, and energy dispersive spectrometer analysis. Results proved that PL was successfully grafted onto chitosan molecules. Based on the water vapor, oxygen permeability, and mechanical analysis, the TO-CH-PL film demonstrated higher physical properties than chitosan and PE films. Secondly, the TO-CH-PL film's preservation effect on pork fillets was evaluated. Due to the significant retardation of growth of the aerobic plate count (APC), total volatile basic nitrogen (TVBN), and thiobarbituric acid reactive substances (TBARS), as well as the changes of pH and color in packaged pork, TO-CH-PL film exhibited better preservation effects for the pork samples. According to the criteria of TVBN values (<15 mg/100 g), compared with CH and PE films, TO-CH-PL film can prolong the shelf life of pork for 2 to 3 days. Therefore, PL-modified chitosan films could be introduced as an alternative method to maintain the quality indices and extend the shelf life of pork during refrigerated storage.

Effect of Nitric Oxide and Its Induced Protein S-Nitrosylation on the Structures and In Vitro Digestion Properties of Beef Myofibrillar Protein

This study aimed to investigate the effects of nitric oxide (NO) and its induced protein S-nitrosylation on the structures and digestion properties of beef myofibrillar protein (MP). The MP was treated with 0, 50, 250, 500, and 1000 μM concentrations of NO-donor S-nitrosoglutathione (GSNO) for 30 min at 37 °C. The results indicated that GSNO treatment significantly decreased the sulfhydryl contents whereas the carbonyl contents increased. Meanwhile, compared with the control group, the surface hydrophobicity, the intrinsic fluorescence intensity, and the α-helix content of proteins were decreased significantly with the enhancement of GSNO concentrations. In addition, 250 μM GSNO treatment increased the gastric digestibility of MP, while the gastrointestinal digestibility and the release of peptides were both inhibited by 500 and 1000 μM GSNO treatments. These data demonstrate that protein S-nitrosylation can affect the in vitro digestion properties of proteins by altering the physicochemical properties and structure of MP.

Effect of Ultrasound Combined with Glycerol-Mediated Low-Sodium Curing on the Quality and Protein Structure of Pork Tenderloin

Considering the hazards of high salt intake and the current status of research on low-sodium meat products, this study was to analyze the effect of ultrasound combined with glycerol-mediated low-sodium salt curing on the quality of pork tenderloin by analyzing the salt content, water activity (aw), cooking loss, and texture. The results of scanning electron microscope (SEM) analysis, Raman spectroscopy, ultraviolet fluorescence, and surface hydrophobicity were proposed to reveal the mechanism of the effect of combined ultrasound and glycerol-mediated low sodium salt curing on the quality characteristics of pork tenderloin. The results showed that the co-mediated curing could reduce salt content, aw, and cooking loss (p < 0.05), improve texture and enhance product quality. Compared with the control group, the co-mediated curing increased the solubility of the myofibrillar protein, improved the surface hydrophobicity of the protein, increased the content of reactive sulfhydryl groups (p < 0.05), and changed the protein structure. The SEM results showed that the products treated using a co-mediated curing process had a more detailed and uniform pore distribution. These findings provide new insights into the quality of ultrasonic-treated and glycerol-mediated low-salt cured meat products.

A comparative study of vacuum tumbling and immersion marination on quality, microstructure, and protein changes of Xueshan chicken

Marination is a common technology in meat processing with advantages of enhancing tenderness, water retention, and overall quality. This study was conducted to investigate the effect of vacuum tumbling and immersion marination on meat quality, microstructure, water mobility, protein changes, and denaturation of Xueshan chicken. Results showed that vacuum tumbling significantly increased the marinating rate of chicken, tenderness, meat texture, and water retention. Meanwhile, vacuum tumbling decreased total sulfhydryl content alongside an increased protein surface hydrophobicity and free sulfhydryl content, indicating that vacuum tumbling elevated the degree of protein denaturation. Further, the peak area corresponding to the relaxation time T22 after vacuum tumbling was significantly higher than that of immersion marination, suggesting that the stability of the immobilized water of chicken was reduced by vacuum tumbling. Compared to immersion marination, vacuum tumbling improved myofibril fragmentation index (MFI) presenting fewer myofibrillar protein bands in sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) gel and more damaged muscular cells. Overall, vacuum tumbling could improve the marination absorptivity, protein degradation, and denaturation, resulting in changes in myofibril structure and meat quality of Xueshan chicken.

Strategies to optimize the structural and functional properties of myofibrillar proteins: Physical and biochemical perspectives

Myofibrillar protein (MP), as the main meat protein, have high nutritional value. However, the relatively poor solubility of MP at low ionic strength sometimes limits the utilization of MP to produce products rich in meat protein. Accordingly, appropriate modification of MP is needed to improve their functional properties. In general, MP modification strategies are categorized into biochemical and physical approaches. Different from other available reviews, the review focuses on summarizing the principles and applications of several techniques of physical modification, briefly depicting biochemical modification as a comparison. Modification of MP with a certain intensity of direct current magnetic field, ultrasound, high pressure, microwave, or radio frequency can improve solubility, emulsification, stability, and gel formation. Of these, magnetic field and microwave-modified MP have shown some potential in reducing salt in meat. These physical techniques can also have synergistic effects with other conditions (temperature, pH, physical or chemical techniques) to compensate for the deficiencies of individual treatment techniques. However, these strategies still need further research for practical applications.HIGHLIGHTSThe current status and findings of research on direct current magnetic field in meat processing are presented.Several physical strategies to modify the microstructure and functional properties of MPs.The synergistic effects of these techniques in combination with other methods to modify MPs are discussed.

Effects of ultrasound on the structural and emulsifying properties and interfacial properties of oxidized soybean protein aggregates

Oxidative attack leads to the oxidative aggregation and structural and functional feature weakening of soybean protein. We aimed to investigate the impact of ultrasonic treatment (UT) with different intensities on the structure, emulsifying features and interfacial features of oxidized soybean protein aggregates (OSPI). The results showed that oxidative treatment could disrupt the native soy protein (SPI) structure by promoting the formation of oxidized aggregates with β1-sheet structures through hydrophobic interactions. These changes led to a decrease in the solubility, emulsification ability and interfacial activity of soybean protein. After low-power ultrasound (100 W, 200 W) treatment, the relative contents of β1-sheets, β2-sheets, random coils, and disulfide bonds of the OSPI increased while the surface hydrophobicity, absolute ζ-potential value and free sulfhydryl content decreased. Moreover, protein aggregates with larger particle sizes and poor solubility were formed. The emulsions prepared using the OSPI showed bridging flocculation and decreased protein adsorption and interfacial tension. After applying medium-power ultrasound (300 W, 400 W, and 500 W) treatments, the OSPI solubility increased and particle size decreased. The α-helix and β-turn contents, surface hydrophobicity and absolute ζ-potential value increased, the structure unfolded, and the disulfide bond content decreased. These changes improved the emulsification activity and emulsion state of the OSPI and increased the protein adsorption capacity and interfacial tension of the emulsion. However, after a high-power ultrasound (600 W) treatment, the OSPI showed a tendency to reaggregate, which had a certain negative effect on the emulsification activity and interfacial activity. The results showed that UT at an appropriate power could depolymerize OSPI and improve the emulsification and interfacial activity of soybean protein.

Study on the Flavor Compounds of Fo Tiao Qiang under Different Thawing Methods Based on GC–IMS and Electronic Tongue Technology

“Fo Tiao Qiang” is a famous dish with Chinese characteristics. It is delicious, rich in materials, and high in nutritional value. Through physical and chemical analysis, electronic tongue, gas chromatography–ion mobility spectroscopy, and other technologies, the present study explored the quality characteristics and flavor differences of Fo Tiao Qiang by using different thawing methods (natural thawing, ultrasonic thawing, microwave thawing, and water bath thawing). The results show that the protein content was slightly higher in Fo Tiao Qiang with ultrasonic thawing than others. The fat content of the microwave-thawed Fo Tiao Qiang was significantly lower than the other three kinds of samples. After ultrasonic thawing, the number of free amino acids in the samples were the highest and the umami taste was the best. Compared with natural thawing, most of the flavor substances decreased in ultrasonic thawing, microwave thawing, and water bath thawing. However, several substances increased, such as alpha-terpineol, beta-phenylethyl alcohol, phenylacetaldehyde, cis-rose oxide, isobutyl acetate, and 2–3-pentanedione. This study revealed the changing laws of different thawing methods on the quality characteristics and flavor characteristics of Fo Tiao Qiang. It provides theoretical guidance for the industrial production and quality control of Fo Tiao Qiang.

Effects of different curing methods on edible quality and myofibrillar protein characteristics of pork

This study aimed to investigate the effects of standing curing (SC), tumbling curing (TC), vacuum tumbling curing (VTC) and ultrasonic-assisted curing (UAC) on the edible quality of black pork and property of myofibrillar proteins (MPs) extracted from black pork. The results showed that all curing methods could improve the marinating absorptivity and the gel water retention of black pork, the solubility and surface hydrophobicity of myofibrillar proteins, and reduce the cooking loss and shear force of black pork, the hydrogen bond content of myofibrillar proteins and the gel whiteness compared with the control group (SC). The result of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that the concentration of protein bands by VTC treatment was decreased obviously. In addition, the result of the scanning electron microscope (SEM) presented that tumbling and ultrasound treatment would destroy the structure of muscle fibers and make them loose and disordered.

Microencapsulated procyanidins by extruding starch improved physicochemical properties, inhibited the protein and lipid oxidant of chicken sausages

Microencapsulated procyanidins by extruding starch (MPS) were used in meat and meat products as an antioxidant for their simple production process and high stability. This study investigated the controlled released properties of MPS and their effect on antioxidant capacity, physicochemical properties, and sensory qualities of chicken sausages during 4°C storage within 28 days. Antioxidant capacity, particle size analysis, and simulated digestion in vitro demonstrated that microencapsulation by extruding starch delayed the procyanidins release. The reduced crystal structure of MPS was determined by the morphology observation (SEM) and the decrease of the typical diffraction peak at 2θ of 20.9° (XRD). The MPS-added sausage had a higher (p < 0.05) ABTS and DPPH radical scavenging ratio (97.6% and 67.3%) and sulfhydryl contents (114.69 nmol/g protein) than other groups. Moreover, lower (p < 0.05) thiobarbituric acid reactive substances (TBARS) (0.67 mg MDA/kg sausage) and carbonyl values (3.24 nmol/mg protein) were detected in MPS-added sausages than others at the end of storage. The MPS addition increased redness (a* value) and decreased the lightness (L* value). The sensory analysis suggested that the sausage with the increased redness was favorable. These results denominated that MPS was an alternative antioxidant in chicken sausages. Practical Application: In this study, microencapsulated procyanidins were prepared by extrusion technology, and the effect on the quality of chicken sausages was investigated, which provides an alternative natural antioxidant for meat and meat products.

Comparison of oil-in-water emulsions prepared by ultrasound, high-pressure homogenization and high-speed homogenization

This study was designed to compare the properties of myofibrillar protein (MP) stabilized soybean oil-in-water emulsions fabricated by ultrasound-assisted emulsification (UAE), high-pressure homogenization (HPH) and high-speed homogenization (HSH). The emulsion properties, droplet characteristics, interfacial proteins, protein exposure extent, microrheological properties, multiple light scattering results, and 7 d storage stabilities of the three emulsions were specifically investigated. Our results indicate that UAE and HPH were better emulsification methods than HSH to obtain high-quality emulsions with higher emulsifying activity index (UAE 20.73 m²·g^-1, HPH 11.76 m²·g^-1 and HSH 6.80 m²·g^-1), whiteness (UAE 81.05, HPH 80.67 and HSH 74.09), viscosity coefficient (UAE 0.44 Pa·sⁿ, HPH 0.49 Pa·sⁿ and HSH 0.22 Pa·sⁿ), macroscopic viscosity index (UAE 2.31 nm^-2·s, HPH 0.38 nm^-2·s and HSH 0.34 nm^-2·s), and storage stability, especially for the UAE. Furthermore, UAE was a more efficient emulsification method than HPH to prepare the fine MP-soybean oil emulsion. The protein-coated oil droplets were observed in the three emulsions. The emulsion droplet size of the UAE-fabricated emulsion was the lowest (0.15 μm) while the interfacial protein concentration (93.37%) and the protein exposure extent were the highest among the three emulsions. During the 7 d storage, no separation was observed for the UAE-fabricated emulsion, while the emulsions fabricated by HPH and HSH were separated after storage for 5 d and 2 h. Therefore, this work suggests that UAE could be a better method than HPH and HSH to fabricate MP-soybean oil emulsion.

Influence of ultrasound-assisted tumbling on NaCl transport and the quality of pork

The present study aimed to investigate the impact of ultrasound-assisted tumbling (UAT; 20 kHz, 100, 300, 500 and 700 W) with different treatment time (30, 60, 90 and 120 min) on the diffusion and distribution of NaCl as well as the change of pork texture properties during curing. Results showed that in comparison with the single tumbling (ST), the NaCl content and the NaCl diffusion coefficient were increased along with UAT treatment (P < 0.05). The scanning electron microscopy and the energy dispersive X-ray analysis showed that UAT treatment changed the microstructure of pork which may facilitate the NaCl dispersion homogeneously. In addition, the moderate UAT treatment of 300 W with 60 min could significantly improve the tumbling yield, water-holding capacity and textural properties of pork compared with the ST treatment (P < 0.05). Meanwhile, in comparison with the ST group, protein extraction was considerably increased after UAT (300 and 500 W) treated for 120 min (P < 0.05). Our study demonstrated that UAT treatment could effectively promote the penetration and distribution of NaCl and improve pork meat quality via facilitating the extraction of meat protein.

Effect of ultrasonic on the structure and quality characteristics of quinoa protein oxidation aggregates

Protein oxidation leads to covalent modification of structure and deterioration of functional properties of quinoa protein. The objective of this study was to investigate the effects of ultrasonic treatment on the functional and physicochemical properties of quinoa protein oxidation aggregates. In this concern, 2,2'-azobis (2-amidinopropane) dihydrochloride (AAPH) was selected as oxidative modification of quinoa protein. The microstructure of quinoa protein displayed by scanning electron microscope (SEM) indicated that oxidation induced extensive aggregation, leading to carbonylation and degradation of sulfhydryl groups. Aggregation induced by oxidation had a negative effect on the solubility, turbidity, emulsifying stability. However, according to the analysis of physicochemical properties, ultrasonic significantly improved the water solubility of quinoa protein. The quinoa protein treated by ultrasonic for 30 min exhibited the best dispersion stability in water, which corresponded to the highest ζ-potential, smallest particle size and most uniform distribution. Based on the FT-IR, SDS-PAGE and surface hydrophobicity analysis, the increase of α-helix, β-turn and surface hydrophobicity caused by cavitation effect appeared to be the main mechanism of quinoa protein solubilization. In addition, the hydrophobic region of the protein was re-buried by excessive ultrasonic treatment, and the protein molecules were reaggregated by disulfide bonds. Microstructural observations further confirmed that ultrasonic treatment effectively inhibited protein aggregation and improved the functional properties of quinoa protein.