Effect of low-frequency alternating magnetic field on the rheological properties, water distribution and microstructure of low-salt pork batters

Modulation of the conformation, water distribution, and rheological properties of low-salt porcine myofibrillar protein gel influenced by modified quinoa protein

High-pressure homogenization modified quinoa protein (HQP) was added to porcine myofibrillar proteins (MP) to study its the influence on protein conformation, water distribution and dynamical rheological characteristics of low-salt porcine MP (0.3 M NaCl). Based on these results, the WHC, gel strength, and G' value of the low-salt MP gel were significantly improved with an increase in the added amount of HQP. A moderate amount of HQP (6%) increased the surface hydrophobicity and active sulfhydryl content of MP (P < 0.05). Moreover, the addition of HQP decreased particle size and endogenous fluorescence intensity. FT-IR results indicated that the conformation of α-helix gradually converted to β-sheet by HQP addition. The incorporation of HQP also shortened the T2 relaxation time and enhanced the proportion of immobile water, contributing to the formation of a compact and homogeneous gel structure. In conclusion, the moderate addition of HQP can effectively enhance the structural stability and functionality of low-salt MP.

Effects of secondary cross-linking on the physicochemical properties of sodium alginate-hydrogel and in vitro release of anthocyanins

To enhance the physicochemical properties and extend the release duration of sodium alginate (SA) hydrogels, this study explored the impact of acidifier type and the number of cross-linking on the physicochemical characteristics and in vitro anthocyanin release from SA hydrogels, utilizing calcium carbonate as the cross-linking agent. The findings revealed that the utilization of gluconolactone (GDL) as an acidifying agent in the preparation of SA hydrogels, as opposed to hydrochloric acid, resulted in a deceleration of the hydrolysis process of calcium carbonate. This deceleration led to the strengthening of hydrogen-bonding interactions and the development of a more compact network structure within the SA hydrogels. Consequently, there was a noticeable enhancement in the hardness, relaxation time, and anthocyanin encapsulation efficiency of the gels. Additionally, the release of anthocyanins in simulated intestinal fluid was delayed. Secondary cross-linking was found to facilitate ionic interactions between SA and Ca2+, further intensifying the denseness of the network structure and enhancing the physicochemical characteristics of the SA hydrogels. Overall, SA hydrogels processed with GDL as the acidifier and subjected to secondary cross-linking exhibited improved physicochemical properties, delayed release effects, and proved to be an efficient system for the delayed release of anthocyanins.

Effects of low-frequency magnetic field on solubility, structural and functional properties of soy 11S globulin

BACKGROUND

Soy 11S globulin has high thermal stability, limiting its application in the production of low-temperature gel foods. In this study, the low-frequency magnetic field (LF-MF, 5 mT) treatment (time, 30, 60, 90, and 120 min) was used to improve the solubility, conformation, physicochemical properties, surface characteristics, and gel properties of soy 11S globulin.

RESULTS

Compared with the native soy 11S globulin, the sulfhydryl content, emulsifying capacity, gel strength, water-holding capacity, and absolute zeta potential values significantly increased (P < 0.05) after LF-MF treatment. The LF-MF treatment induced the unfolding of the protein structure and the fracture of disulfide bonds. The variations in solubility, foaming properties, viscosity, surface hydrophobicity, and rheological properties were closely related to the conformational changes of soy 11S globulin, with the optimum LF-MF modification time being 90 min.

CONCLUSION

LF-MF treatment is an effective method to improve various functional properties of native soy 11S globulin, and this study provides a reference for the development of plant-based proteins in the food industry. © 2024 Society of Chemical Industry.

Low-frequency alternating magnetic field and CaCl2 influence the physicochemical, conformational and gel characteristics of low-salt myofibrillar protein

In this study, the improvement mechanism of low-frequency alternating magnetic field (LF-AMF, 5 mT, 3 h) combined with calcium chloride (CaCl2, 0-100 mM) on the gel characteristics of low-salt myofibrillar protein (MP) was investigated. LF-AMF combined with 80 mM CaCl2 treatment increased solubility (32.71%), surface hydrophobicity (40.86 μg), active sulfhydryl content (22.57%), water-holding capacity (7.15%). Besides, the combined treatment decreased turbidity, particle size and intrinsic fluorescence strength of MP. Fourier transform infrared spectroscopy (FT-IR) results indicated that the combined treatment altered the secondary structure of MP by increasing β-sheet and β-turn, and reducing α-helix and random coil. The combined treatment also induced a high G' value and shortened T2 relaxation time for forming a homogeneous and compact gel structure. These results revealed that LF-AMF combined CaCl2 treatment could as a potential approach for modifying the gel characteristics of low-salt MP.

Effect of low-frequency alternating magnetic fields on the physicochemical, conformational and rheological properties of myofibrillar protein after iterative freeze-thaw cycles

In this work, the effects of low-frequency alternating magnetic fields (LF-AMF) on the physicochemical, conformational, and functional characteristics of myofibrillar protein (MP) after iterative freeze-thaw (FT) cycles were explored. With the increasing LF-AMF treatment time, the solubility, active sulfhydryl groups, surface hydrophobicity, emulsifiability, and emulsion stability of MP after five FT cycles evidently elevated and then declined, and the peak value was obtained at 3 h. Conversely, the moderate LF-AMF treatment time can significantly reduce the average particle size, carbonyl content, and endogenous fluorescence intensity of MP. The rheology results showed that various LF-AMF treatment times would elevate the G' value of MP after iterative FT cycles. The FTIR spectroscopy results suggested that LF-AMF influenced the secondary structure of MP after multiple FT cycles, resulting in a depression in α-helix content and an increment in β-folding proportion. Moreover, LF-AMF treatment induced the gradually lighter and wider myosin heavy chain bands of MP, implying that LF-AMF accelerated the degradation of macromolecular aggregates. Therefore, the LF-AMF treatment efficaciously ameliorates the structural and functional deterioration of MP after iterative FT cycles and could be used as a potential quality-improving technology in the frozen meat industry.

Structure, properties, and resistant starch content of modified rice flour prepared using dual hydrothermal treatment

In this study, modified rice flour with high resistant starch (RS) content was prepared by dual hydrothermal treatment, which combined the heat-moisture treatment with the pressure-heat treatment method. The effects of dual hydrothermal treatment on the structure and properties of modified rice flour and their relationship with RS content were further discussed. The results showed that the RS content of modified rice flour was higher than that of rice flour (RF), and dual hydrothermal treatment was more effective than single hydrothermal treatment. Adhesion and aggregation occurred between the particles of modified rice flour. Both crystallinity and short-range ordering were increased in modified rice flour compared to RF. Moreover, the modified rice flour of dual hydrothermal treatment had higher crystallinity and a more ordered short-range structure of starch, which improved RS content to a certain extent. Compared to single hydrothermal treatment, the modified rice flour of dual hydrothermal treatment had a lower viscoelasticity and a better thermal stability. Both RF and modified rice flour gels were composed mainly of free water, with minimal amounts of bound and immobile water. The study may provide a reference for the production and application of modified rice flour.

Minced Beef Meat Paste Characteristics: Gel Properties, Water Distribution, and Microstructures Regulated by Medium Molecular Mass of γ-Poly-Glutamic Acid

The influences of various m-γ-PGA (0.08-0.20%, w/w) concentrations on the properties of minced beef meat paste in terms of rheological properties, texture, moisture distribution, and microstructures were evaluated. The results indicated that m-γ-PGA enhanced the water-holding capacity, gel strength, texture, and whiteness of the minced beef meat paste. Based on the microstructural results, m-γ-PGA helped form a more organized and compact gel, thereby limiting the migration of water through the gel matrix. In contrast to the control group, the water-holding property, gel strength, and whiteness of minced meat paste gels with m-γ-PGA content of 0.12% increased from 75.89%, 584.51 g·cm, and 61.83 to 79.91%, 780.87 g·cm, and 62.54, respectively (p < 0.05), exhibiting the highest water-holding property and gel strength. Thus, m-γ-PGA exhibits great potential for minced meat paste products as a healthy gel water retainer and enhancer in low-fat meat products.

Improvement of gelation properties of Penaeus vannamei surimi by magnetic field-assisted freezing in combination with curdlan

Traditional methods of freezing and thawing may harm the quality of meat products. In order to reduce the negative impact of freezing on surimi products, the magnetic field-assisted freezing method is combined with various curdlan ratios to enhance the gelation characteristics of Penaeus vannamei surimi in this study. The results showed that the magnetic field-assisted freezing technique significantly improved the quality of thawed surimi compared with soaking freezing (SF), whereas the addition of curdlan further improved the gelation properties, and the gel strength, water-holding capacity, textural properties, whiteness, and G' value were significantly improved when its content was increased to 0.6 %. However, excessive amounts of curdlan interfered with protein covalent cross-linking, leading to a decrease in gel quality. Additionally, the addition of magnetic field and curdlan encouraged the shift of the α-helix to the random coil and β-sheet transition, which stimulated the growth of myofibril molecules, exposed the hydrophobic groups and thiols, improved protein-molecule interactions, and promoted systematic gathering of proteins, leading to the formation of the microstructure of dense and small pores. It also resulted in a drop in water release, an increase in the proton density and a shift in the water condition from free water to more immobile water, which had higher sensory qualities. These effects together resulted in a reduction in thawing and cooking loss to 11.41 % and 13.83 %, respectively. These results also help to clarify the gelation process of shrimp surimi and help to regulate the gelation characteristics of shrimp surimi products.

Evaluating the effects of low-frequency alternating magnetic field thawing on oxidation, denaturation, and gelling properties of porcine myofibrillar proteins

The impact of low-frequency alternating magnetic field thawing (LF-MFT) on the physicochemical and gelling properties of porcine myofibrillar proteins (MP) was studied. Results showed that compared to atmosphere thawing (AT), LF-MFT helped in inhibiting the oxidation and denaturation of protein during thawing, thereby maintaining a superior MP gel (P < 0.05). In particular, LF-MFT-4 (LF-MFT at 4 mT) could decrease the oxidation of MP, which might be due to having a higher content of total sulfhydryl and less carbonyl of MP than other thawing treatments. The denaturation of MP was reduced since LF-MFT-4 led to less aggregation and degradation than AT. The gelling properties were also retained, and a compact and homogeneous network structure was formed after LF-MFT-4, resulting in excellent water retention. These findings suggested that LF-MFT-4 improved the gelling properties of MP by inhibiting its oxidation and denaturation, demonstrating a potential application of LF-MFT in meat thawing.

Unlocking the Potential of Microwave Sterilization Technology in Ready-to-Eat Imitation Crab Meat Production

Microwave sterilization is a novel potential sterilization technology to improve food quality. An industrial microwave sterilization system was used to sterilize imitation crab meat under thermal processing intensity F0 = 1, 2, 3. The characteristics of the microwave process, such as heating rate, processing time, and C100, were calculated. In addition, the quality of processed imitation crab meat was investigated. Compared with the conventional retort method, microwave sterilization significantly shortened the processing time of imitation crab meat by 63.71% to 72.45%. Under the same thermal processing intensity, microwave sterilization has demonstrated better results than retort sterilization in terms of water-holding capacity, color, and texture. Furthermore, microwave-treated imitation crab meat ingredients had a greater capacity to bind water molecules and obtained a more appropriate secondary protein structure. In addition, microwave technology can better preserve the unsaturated fatty acids (UFA) of imitation crab meat, which are 9.14%, 1.19%, and 0.32% higher than the traditional method at F0 = 1, 2, 3. The results would provide useful data for the subsequent research and development of ready-to-eat surimi products.

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.

Low-frequency alternating magnetic field thawing of frozen pork meat: Effects of intensity on quality properties and microstructure of meat and structure of myofibrillar proteins

The purpose of the study was to evaluate the changes in quality properties and microstructure of pork meat as well as structural variation in myofibrillar proteins (MPs) after low-frequency alternating magnetic field thawing (LF-MFT) with different intensities (1-5 mT). LF-MFT at 3-5 mT shortened the thawing time. LF-MFT treatment significantly influenced the quality properties of meat and notably improved the structure of MPs (P < 0.05), compared to atmosphere thawing (AT). Especially, among the thawing treatments, LF-MFT-4 (LF-MFT at 4 mT) had the lowest values of thawing loss and drip loss, and the least changes in the color and myoglobin content. Regarding the results of rheological properties and micrographs, an optimal gel structure and a more compact muscle fiber arrangement formed during LF-MFT-4. Moreover, LF-MFT-4 was beneficial for improving the conformation of MPs. Therefore, LF-MFT-4 reduced the deterioration of porcine quality by protecting MPs structure, indicating a potential use in the meat thawing industry.

Effect of Artemisia sphaerocephala krasch gum on the functional properties of pork batters

The influence of the incorporation of Artemisia sphaerocephala krasch gum (ASK gum; 0-0.18%) on the water holding capability (WHC), texture, color, rheological property, water distribution, protein conformation and microstructure of pork batters was investigated. The results showed that the cooking yield, WHC and L* value of pork batter gels significantly increased (p < .05) with the increasing incorporation of ASK gum, and the highest value were observed at 0.15%; the a* value decreased significantly (p < .05) and no significance was obtained in b* value (p > .05); the hardness, elasticity, cohesiveness and chewiness increased first and then decreased, and reached the highest value at 0.15%. The rheological results showed that the higher G' value was obtained in pork batters by the incorporation of ASK gum; the low field NMR analysis indicated that ASK gum significantly increased the proportion of P2b and P21 (p < .05) and decreased the proportion of P22 ; Fourier transform infrared spectroscopy (FTIR) indicated that the ASK gum significantly reduced the α-helix content and increased the β-sheet content (p < .05). Scanning electron microscopy results suggested that the incorporation of ASK gum could promote the formation of a more homogeneous and stable microstructure of pork batter gels. Therefore, appropriate incorporation (0.15%) of ASK gum may improve the gel properties of pork batters, and while excessive incorporation (0.18%) could weaken the gel properties.

Magnetic field-assisted cascade effects of improving the quality of gels-based meat products: A mechanism from myofibrillar protein gelation

Physics-assisted processing technologies have huge potential in the meat processing industry. By modeling two essential procedures (pickling and preheating) of gels-based meat products, this work investigated the cascade effects of a new physical technology (magnetic field) on the conformational structures and gel properties of myofibrillar proteins (MPs). Samples were subjected with four magnetic field (MF)-assisted treatments (group A, both processes without MF; group B, pickling without MF combining with preheating with 4.5 mT MF; group C, pickling with 3.0 mT MF combining with preheating without MF; group D, pickling with 3.0 mT MF combining with preheating with 4.5 mT MF). The result showed that MF-assisted treatments significantly improved water holding capacity (WHC) of MP gels compared with group A (46.9%), reaching the maximum value of 52.1% in group D.According to the low-field nuclear magnetic results, group D decreased the percentages of P₂₂ (6.97%) and increased the percentages of P₂₁ (93%), which showed that water molecules were more tightly bound to each other. Meanwhile, the unfolding of α-helix and the formation of random coil of MF-assisted treatments resulted in more exposure of internal groups, leading to the formation of a dense network. These findings would provide new insights to improve the quality of gels-based meat products via the MF.

Effect of oil-modified crosslinked starch as a new fat replacer on gel properties, water distribution, and microstructures of pork meat batter

This work investigated the effects of oil-modified crosslinked starch (Oil-CTS) as a fat replacer on the gel properties, water distribution, microstructures, and fatty acid composition of pork meat batter. Results showed that the replacement of pork back fat by Oil-CTS could improve the gel performance in terms of rheological property, texture, and water-holding capacity (WHC), and reduce the water mobility of pork meat gels, which caused by the formation of a more ordered and denser protein network structure. Additionally, when the fat was replaced by Oil-CTS partially or totally (25-100 %), the total fat content in pork meat gels decreased by 16.5-82 % and the saturated fatty acids (SFAs) content decreased from 5.87 g/100 g in untreated sample to 1.17-4.88 g/100 g in starch-replacing-fat samples, indicating Oil-CTS could be used as a fat replacer to prepare the low-fat meat products.

Inulin for surimi gel fortification: Performance and molecular weight-dependent effects

Inulin is a prebiotic carbohydrate widely used in food industry due to its health benefits and unique rheological properties. For the first time, this study explores the potential of natural inulin as a sustainable food additive to enhance surimi gel characteristics, specifically focusing on understanding its molecular weight effects. The good solubility of inulin facilitates the conversion of α-helix to other secondary conformations which are favorable for protein denaturation and aggregation during gelation. Moreover, the abundant -OH groups at the surface of inulin can boost the chemical forces within surimi proteins to reinforce the gel network. Compared to short-chain inulin, long-chain inulin can alleviate proteolysis, enhance hydrophobic interactions and intertwine with myosin molecules, thereby reinforcing the gel network. A more viscous long-chain inulin solution formed within surimi gels fills the space between aggregated proteins and facilitates the lock of water molecules, improving the water-holding capacity (WHC). Thus, an addition of 12 % long-chain inulin leads to an enhanced hardness of surimi gel from 943 to 1593 and improved WHC from 72 % to 85 %. A new inulin-myosin interaction mechanism model is also proposed to provide useful guidelines for surimi processing and expanding the application of inulin within the food industries.

Effect of Oudemansiella raphanipies Powder on Physicochemical and Textural Properties, Water Distribution and Protein Conformation of Lower-Fat Pork Meat Batter

The effects of the addition of different amounts (0%, 1%, 2%, 3% and 4%) of Oudemansiella raphanipies powder (ORP) to lower-fat pork batter on its physicochemical, textural and rheological properties, water distribution and protein conformation were evaluated. The results showed that the addition of ORP from 0% to 4% significantly decreased the pH and L* value of pork batter (p < 0.05); however, it also increased the a* value and enhanced the cooking yield of pork batter from 77% to 92%. Pork batter with 1−2% ORP added had an improved texture profile and a higher storage modulus (G’), but the addition of 3−4% ORP resulted in an inferior texture of pork batter and G’. LF-NMR showed that the addition of ORP significantly increased the peak area ratio of immobile water and reduced the peak area ratio of free water (p < 0.05). ORP significantly affected protein secondary structure of pork batter. The α-helix content of pork batter with 1−2% ORP decreased and β-sheet content increased. Overall, the addition level of 1−2% ORP effectively improved the texture and water holding capacity of lower-fat emulsified sausage and provides a new reference for developing nutritional meat products.

Whey Protein Hydrolysates Improved the Oxidative Stability and Water-Holding Capacity of Pork Patties by Reducing Protein Aggregation during Repeated Freeze-Thaw Cycles

The effects of whey protein hydrolysates (WPH) on myofibrillar protein (MP) oxidative stability and the aggregation behavior and the water-holding capacity of pork patties during freeze-thaw (F-T) cycles were investigated. During F-T cycles, the total sulfhydryl content and zeta potential of MP decreased, while peroxide value, surface hydrophobicity, particle size, pressure loss and transverse relaxation times increase. The oxidative stability and the water-holding capacity of pork patties were enhanced by the addition of WPH in a dose-dependent manner, whereas the MP aggregation decreased. The addition of 15% WPH had the most obvious effects on the pork patties, which was similar to that of the 0.02% BHA. After nine F-T cycles, the POV, surface hydrophobicity, particle size and pressure loss of the pork patties with 15% WPH were reduced by 17.20%, 30.56%, 34.67% and 13.96%, respectively, while total sulfhydryl content and absolute value of zeta potential increased by 69.62% and 146.14%, respectively. The results showed that adding 15% WPH to pork patties can be an effective method to inhibit lipid and protein oxidation, reducing protein aggregation and improving the water-holding capacity of pork patties during F-T cycles.