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.

Using Potassium Bicarbonate to Improve the Water-Holding Capacity, Gel and Rheology Characteristics of Reduced-Phosphate Silver Carp Batters.

To study the use of partial or total potassium bicarbonate (PBC) to replace sodium tripolyphosphate (STPP) on reduced-phosphate silver carp batters, all the batters were composed of silver carp surimi, pork back fat, ice water, spices, sugar, and sodium chloride. Therein, the sample of T1 contained 4 g/kg STPP; T2 contained 1 g/kg PBC, 3 g/kg STPP; T3 contained 2 g/kg PBC, 2 g/kg STPP; T4 contained 3 g/kg PBC, 1 g/kg STPP; T5 contained 4 g/kg PBC, and they were all produced using a bowl chopper. The changes in pH, whiteness, water- and oil-holding capacity, gel and rheological properties, as well as protein conformation were investigated. The pH, cooking yield, water- and oil-holding capacity, texture properties, and the G' values at 90 °C of the reduced-phosphate silver carp batters with PBC significantly increased (p < 0.05) compared to the sample without PBC. Due to the increasing pH and enhanced ion strength, more ß-sheet and ß-turns structures were formed. Furthermore, by increasing PBC, the pH significantly increased (p < 0.05) and the cooked silver carp batters became darkened. Meanwhile, more CO2 was generated, which destroyed the gel structure, leading the water- and oil-holding capacity, texture properties, and G' values at 90 °C to be increased and then decreased. Overall, using PBC partial as a substitute of STPP enables reduced-phosphate silver carp batter to have better gel characteristics and water-holding capacity by increasing its pH and changing its rheology characteristic and protein conformation.

Effect of Ultrasound-Assisted Sodium Bicarbonate Treatment on Aggregation and Conformation of Reduced-Salt Pork Myofibrillar Protein.

To study the effects of an ultrasound (0, 30, and 60 min) and sodium bicarbonate (0% and 0.2%) combination on the reduced-salt pork myofibrillar protein, the changes in pH, turbidity, aggregation, and conformation were investigated. After the ultrasound-assisted sodium bicarbonate treatment, the pH increased by 0.80 units, the absolute value of Zeta potential, hydrophobic force, and active sulfhydryl group significantly increased (p < 0.05), and the turbidity and particle size significantly decreased (p < 0.05). Meanwhile, the fluorescence intensity decreased from 894 to 623, and the fluorescence peak showed a significant redshift, which indicated that the ultrasound-assisted sodium bicarbonate treatment exposed the non-polarity of the microenvironment in which the fluorescence emission group was located, leading to the microenvironment and protein structure of myofibrillar tryptophan being changed. Overall, an ultrasound-assisted sodium bicarbonate treatment could significantly improve pork myofibrillar protein solubility and change the protein structure under a reduced-salt environment.

Changes in Gel Characteristics, Rheological Properties, and Water Migration of PSE Meat Myofibrillar Proteins with Different Amounts of Sodium Bicarbonate.

The changes in the gel and rheological properties and water-holding capacity of PSE meat myofibrillar proteins with different amounts of sodium bicarbonate (SC, 0−0.6/100 g) were studied. Compared to the PSE meat myofibrillar proteins with 0/100 g SC, the texture properties and cooking yield significantly increased (p < 0.05) with increasing SC; meanwhile, adding SC caused the gel color to darken. All samples had similar curves with three phases, and the storage modulus (G') values significantly increased with the increasing SC. The thermal stability of the PSE meat myofibrillar proteins was enhanced, and the G' value at 80 °C increased with the increasing SC. Because water was bound more tightly to the protein matrix, the initial relaxation times of T21 and T22 shortened, the peak ratio of P21 significantly increased (p < 0.05), and the P22 significantly decreased (p < 0.05), which implied that the mobility of the water was reduced. Overall, SC could improve the thermal stability of the PSE meat myofibrillar proteins and increase the water-holding capacity and textural properties of the cooked PSE meat myofibrillar protein gels.

Effects of high pressure and thermal combinations on gel properties and water distribution of pork batters.

The effects of high pressure (100-500 MPa) and heated (80 °C, 25 min) combinations on gel properties, rheological characteristic and water distribution of pork batters were investigated. Compared to the only-heat, the cooking yield, a* value, hardness, cohesiveness, and chewiness of cooked pork batters treated less than 300 MPa were significantly increased (P < 0.05), meanwhile, the b* value was significantly decreased (P < 0.05). Opposite, the color and cooking yield were not significant different (P > 0.05) when over 300 MPa, except the L* value. At 300 MPa, the cooking yield, hardness, chewiness, and G' value at 80 °C of pork batter were the highest. The initial relaxation time of T21 was decreased significantly (P < 0.05), and the peak ration of P21 was increased significantly (P < 0.05) when treated at 200 and 300 MPa, that indicated the water was bound tightly and the ratio of immobilized water was increased. Overall, 300 MPa treatment and thermal combinations could improve the gel properties of pork batters.

The effects of sodium chloride on proteins aggregation, conformation and gel properties of pork myofibrillar protein Running Head: Relationship aggregation, conformation and gel properties.

The objective of this study was to evaluate relationship with aggregation, secondary structures and gel properties of pork myofibrillar protein with different sodium chloride (1%, 2% and 3%). When the sodium chloride increased from 1 to 3%, the active sulfhydryl, surface hydrophobicity, hardness and cooking yield of myofibrillar protein were increased significantly (p < 0.05), the particle size, total sulfhydryl and Zeta potential were decreased significantly (p < 0.05), these meant the aggregations of pork myofibrillar protein were decreased. The changes of proteins aggregation induced the strongest intensity band of Amide I shifted up from 1660 cm-1 to 1661 cm-1, meanwhile, the ß-sheet structure content was increased significantly (p < 0.05) with the sodium chloride increased. From the above, the lower proteins aggregation and higher ß-sheet structure content could improve the water holding capacity and texture of pork myofibrillar protein gel.

Morphophysiological responses of detached and adhered biofilms of Pseudomonas fluorescens to acidic electrolyzed water.

Pseudomonas spp. have emerged as the main spoilage bacteria, with many strains easily forming biofilms on food-contact surfaces and causing cross-contamination. The efficacy of disinfectants against bacteria is usually tested with planktonic cells; however, the disinfection tolerance of biofilms, especially detached biofilms, remains unknown. Here, we investigated the tolerance responses of detached and adhered biofilms of Pseudomonas fluorescens to acidic electrolyzed water (AEW) by determining tolerance responses by plate counting, comparing them using a Weibull model, and verifying changes in bacterial morphology by scanning electron microscopy. The experimental data and the responses calculated using Weibull a (scale) and b (shape) parameters agreed well (R2 values: 0.974-0.999), and we found that AEW exhibited effective antimicrobial activity against P. fluorescens, with adhered biofilms were more resistant than detached biofilms and planktonic cells. Additionally, AEW increased the bacterial membrane permeability and decreased the membrane potential, intracellular ATP concentrations, and intracellular pH while also triggering the disruption of extracellular polymeric substances. These results demonstrated that the morphophysiological responses of detached and adhered biofilms differed significantly and provided information on disinfectant-resistance strategies potentially beneficial to the development of novel disinfection approaches.

Structural changes evaluation with Raman spectroscopy in meat batters prepared by different processes.

A comprehensive study was conducted to evaluate the structural changes of meat and protein of pork batters produced by chopping or beating process through the phase-contrast micrograph, laser light scattering analyzer, scanning electronic microscopy and Raman spectrometer. The results showed that the shattered myofibrilla fragments were shorter and particle-sizes were smaller in the raw batter produced by beating process than those in the chopping process. Compared with the raw and cooked batters produced by chopping process, modifications in amide I and amide III bands revealed a significant decrease of α-helix content and an increase of ß-sheet, ß-turn and random coils content in the beating process. The changes in secondary structure of protein in the batter produced by beating process was thermally stable. Moreover, more tyrosine residues were buried, and more gauche-gauche-trans disulfide bonds conformations and hydrophobic interactions were formed in the batter produced by beating process.

Effect of ultrasound treatment on functional properties of reduced-salt chicken breast meat batter.

The effect of ultrasound treatments (40 kHz, 300 W) for different times (10, 20, 30 and 40 min) combined with different salt contents (1.0 %, 1.5 % and 2.0 %) on gel properties and water holding capacity (WHC) of chicken breast meat batter were investigated. Results showed salt level significantly (p < 0.05) affected the texture, storage modulus (G'), loss modulus (G″), cooking loss and WHC. Ultrasound treatments for 10 min and 20 min improved the texture and WHC, and had higher G' values. Compared with the controls (2 % salt), ultrasound treatment for 20 min with reduced-salt (1.5 %) had not significant effect (p > 0.05) on texture, cooking loss or WHC. However, longer ultrasound (40 min) treatment resulted in a decrease in hardness, G' value and WHC. Microstructural analysis revealed that gels treated with ultrasound for 20 min had a compact structure whereas those treated for 40 min contained more protein aggregations and more cavities. Low-field nuclear magnetic resonance (LF-NMR) indicated that ultrasound treatment for 20 min lowered the values of spin-spin relaxation time (T2) and increased the proportion of myofibillar water. Overall, high power ultrasound technology is a promising process which can improve the gelation properties and thereby allowing for a partial reduction in the salt levels in chicken meat gels.

Using ultrasonic-assisted sodium bicarbonate treatment to improve the gel and rheological properties of reduced-salt pork myofibrillar protein.

To study the impact of ultrasonic duration (0, 30, and 60 min) and sodium bicarbonate concentration (0% and 0.2%) on the gel properties of reduced-salt pork myofibrillar protein, the changes in cooking yield, colour, water retention, texture properties, and dynamic rheology were investigated. The findings revealed that added sodium bicarbonate significantly increased (P < 0.05) cooking yield, hardness, springiness, and strength of myofibrillar protein while reducing centrifugal loss. Furthermore, the incorporation of sodium bicarbonate led to a significant decrease in L⁎, a⁎, b⁎, and white values of cooked myofibrillar protein; these effects were further amplified with increasing ultrasonic duration (P < 0.05). Additionally, storage modulus (G') significantly increased for myofibrillar protein treated with ultrasonic-assisted sodium bicarbonate treatment resulting in a more compact gel structure post-cooking. In summary, the results demonstrated that ultrasonic-assisted sodium bicarbonate treatment could enhance the tightness of reduced-salt myofibrillar protein gel structure while improving the water retention and texture properties.

Applying Resistant Starch to Improve the Gel and Water Retention of Reduced-Fat Pork Batter.

Emulsified meat products contain high animal fat content, and excessive intake of animal fat is not good for health, so people are paying more and more attention to reduced-fat meat products. This study investigated the impact of varying proportions of pork back-fat and/or resistant starch on the proximate composition, water and fat retention, texture properties, color, and rheology characteristic of pork batter. The results found that replacing pork back-fat with resistant starch and ice water significantly decreased the total lipid and energy contents of cooked pork batter (p < 0.05) while improving emulsion stability, cooking yield, texture, and rheology properties. Additionally, when the pork back-fat replacement ratio was no more than 50%, there was a significant increase in emulsion stability, cooking yield, hardiness, springiness, cohesiveness, chewiness, and L* and G' values (p < 0.05). Furthermore, resistant starch and ice water enhanced myosin head and tail thermal stability and increased G' value at 80 °C. However, the initial relaxation times significantly decreased (p < 0.05) and the peak ratio of P21 significantly increased from 84.62% to 94.03%, suggesting reduced fluidity of water. In conclusion, it is feasible to use resistant starch and ice water as a substitute for pork back-fat in order to produce reduced-fat pork batter with favorable gel and rheology properties.

Effects of pre-emulsified safflower oil with magnetic field modified soy 11S globulin on the gel, rheological, and sensory properties of reduced-animal fat pork batter.

In this work, the differences in macrostructure and microstructure, rheology, and storage stability of pre-emulsified safflower oil (PSO) prepared by natural and magnetic field modified soy 11S globulin were analysised. It was concluded that the PSO with magnetic field modified soy 11S globulin (MPSO) has better emulsifying activity and physical stability. The changes in gel quality, oxidational sensitivity, rheological, and sensory properties of pork batters with different substitute ratios (0%, 25%, 50%, 75%, and 100%) of pork back-fat by MPSO with magnetic field modified soy 11S globulin were studied. Compared to the sample without MPSO, pork batter with MPSO showed higher emulsion stability, apparent viscosity, L⁎ value, springiness, cohesiveness, and expressible moisture, while lower a⁎ value and cooking loss. Moreover, added MPSO could be more uniformly distributed into the meat matrix with smaller holes. With the increase in the replacement proportion of pork back-fat, the hardness, water- and fat-holding capacity, and P21 of pork batter significantly decreased (P < 0.05). As revealed by sensory evaluation and TBARS, using MPSO to substitute for pork back-fat decreased the lipid oxidational sensitivity of pork batter, and without negative effects on the appearance, juiciness and overall acceptability. Overall, it is feasible to apply MPSO as a pork-fat replacer to produce reduced-animal fat pork batter with excellent gel and sensory properties.

Effects of Potassium Bicarbonate on Gel, Antioxidant and Water Distribution of Reduced-Phosphate Silver Carp Surimi Batter under Cold Storage.

The changes in storage loss, water distribution status, gel characteristics, thiobarbituric acid reactive substances (TBARSs), total volatile basic nitrogen, and total plate count of cooked reduced-phosphate silver carp surimi batter during cold storage at 4 °C were investigated. The storage loss, content of free water, pH, hardness, TBARSs, total volatile basic nitrogen value, and total plate count of all cooked silver carp surimi batters significantly increased (p < 0.05) with an increase in cold storage time. Meanwhile, the content of immobilized water, whiteness, springiness, and cohesiveness significantly decreased (p < 0.05). At the same cold storage time, the sample of cooked reduced-phosphate silver carp surimi batter had lower water mobility, darker color, and better texture characteristics than the cooked silver carp surimi batter without potassium bicarbonate; however, the values of TBARSs, total volatile basic nitrogen, and total plate count were not significantly different (p > 0.05). This meant that there was no difference between potassium bicarbonate and sodium tripolyphosphate in antioxidant and antibacterial activity during the cold storage of silver carp surimi batter. To summarize, the use of potassium bicarbonate instead of sodium tripolyphosphate could produce cooked reduced-phosphate silver carp surimi batter with better water-holding capacity and gel characteristics during cold storage.

Combined effects of high-pressure processing and pre-emulsified sesame oil incorporation on physical, chemical, and functional properties of reduced-fat pork batters.

In this study, the changes in emulsion stability, colour, textural properties, and protein secondary structure of reduced-fat pork batters (50% pork back-fat and 50% pre-emulsified sesame oil) treated under different pressures (0.1, 200 and 400 MPa) were investigated. The emulsion stability, cooking yield, L* value, texture properties, initial relaxation times of T2b, T21, and T22, and peak ratios of P21 in the samples treated under 200 and 400 MPa significantly increased (p < 0.05) compared with those at 0.1 MPa, but the a* and b* values, and the peak ratio of P22 significantly decreased (p < 0.05). The sample treated at 200 MPa exhibited the best emulsion stability, textural properties, water-holding capacity and sensory scores among the samples. High-pressure processing induced structural changes from α-helical to ß-sheet, ß-turn, and random coil structures, enhancing protein-water incorporation and lowering water mobility. High-pressure processing and pre-emulsified sesame oil improved the techno-functional properties and emulsion stability of reduced-fat pork batters.

Effect of sodium bicarbonate on techno-functional and rheological properties of pale, soft, and exudative (PSE) meat batters.

In the study, changes in salt-soluble protein (SSP) content, gel properties, rheological characteristic, and microstructure attributes of pale, soft, and exudative (PSE) pork batters with different concentrations of added sodium bicarbonate (0-0.6%) were investigated. The pH, b⁎ value, SSP content, cooking yield, texture properties, emulsion stability, and G' values at 72 °C significantly increased with the increase in sodium bicarbonate, but the texture properties and G' values of the samples with 0.4% and 0.6% did not significantly different, while the a⁎ value significantly decreased. Moreover, a greater G' value at 72 °C was in agreement with a higher hardness value of meat batter. The microstructure of cooked PSE meat batters with 0% and 0.2% sodium bicarbonate had a dense structure, and samples with 0.4% and 0.6% had some large cavities. In conclusion, the use of sodium bicarbonate can enhance the water holding capacity, texture and rheological properties of PSE meat batters by increasing their pH, SSP content, and emulsifying stability.

Effect of ultrasound-assisted sodium bicarbonate treatment on gel characteristics and water migration of reduced-salt pork batters.

To study the potential usefulness of ultrasound (0, 30, and 60 min) and sodium bicarbonate (0 % and 0.2 %) combination on the reduced-salt pork batters, the changes in water holding capacity, gel properties, and microstructure were investigated. The pH, salt-soluble proteins solubility, cooking yield, and b* values of reduced-salt pork batters significantly increased (P < 0.05) with the increase in ultrasound time and the addition of sodium bicarbonate, leading to the hardness, springiness, cohesiveness, and chewiness significantly increased (P < 0.05). Furthermore, the use of ultrasound-assisted sodium bicarbonate treatment caused the reduced-salt pork batters to form a typical spongy structure with more evenly cavities. Due to the initial relaxation time of T21 and T22 were shorter, and the peak ratio of P21 was increased and P22 was decreased after ultrasound-assisted sodium bicarbonate treatment, implying that the mobility of water was reduced. Thus, the use of ultrasound-assisted sodium bicarbonate treatment enabled reduced-salt pork batters to have better gel characteristics and higher cooking yield.

Effects of soy protein isolate on gel properties and water holding capacity of low-salt pork myofibrillar protein under high pressure processing.

This paper studies the effects of soy protein isolate (SPI; 0, 2% and 4%; Weight/Weight) on texture, rheological property, sulfhydryl groups, and the water distribution state of low-salt (1% NaCl) pork myofibrillar protein systems under high pressure processing (HPP, 200 MPa, 10 min). The L⁎ value, cooking yield, hardness, total and reactive sulfhydryl, surface hydrophobicity, and the G' value at 80 °C of pork myofibrillar protein increased significantly (P < 0.05) when SPI was added; however, the springiness, cohesiveness, and chewiness of gels with 4% SPI were lower than of gels with 2% SPI. The rheological findings indicated that the thermal stability of the myofibrillar protein increased when SPI was added. The initial relaxation time of T2b, T21, and T22 decreased when SPI increased; meanwhile, the peak ratio of P21 increased significantly (P < 0.05), implying that water had lower mobility. Overall, the 2% SPI could enhance gel characteristics and water-holding capacity of pork myofibrillar protein under 200 MPa.

Effect of sodium bicarbonate and sodium chloride on aggregation and conformation of pork myofibrillar protein.

To investigate the effect of sodium bicarbonate instead of sodium chloride, the changes in pH, turbidity, aggregation, and conformation of myofibrillar protein solution with various amounts of sodium chloride and sodium bicarbonate were studied. When the sodium bicarbonate was increased from 0% to 0.4%, accompanied by the sodium chloride being decreased from 2.0% to 0.8%, the pH increased about 1.20 unites; the absolute values of the Zeta potential, active sulfhydryl, and surface hydrophobicity increased significantly (p < 0.05); and the turbidity, particle size, and Ca2+-ATPase activity decreased significantly (p < 0.05). In addition, the Mg2+-ATPase activity was not significantly different (p > 0.05) when increasing sodium bicarbonate, implying that sodium bicarbonate did not affect the actin. Overall, the results indicated that an increase in sodium bicarbonate could improve solubility, expose more hydrophobic residues and sulfhydryl groups, and induce Ca2+-ATPase inactivation and protein unfolding, leading the myofibrillar protein to denaturation easily.

Effects of high-pressure processing on the functional properties of pork batters containing Artemisia sphaerocephala krasch gum.

Here, the effect of high-pressure conditions (0.1-400 MPa) on the water-loss, texture, gel strength, color, dynamic rheological property, and water migration of pork batters containing 0.1% (W/W) Artemisia sphaerocephala krasch gum (PB-AG) is studied. Results indicated that the cooking yield, water-holding capacity, texture, gel strength, L* values, and G' values increased with the increase in pressure (0.1-300 MPa) (p < 0.05). Dynamic rheological results (G') revealed that the thermal gelling ability of the PB-AG gel gradually increased with pressure (0.1-300 MPa). The minimum of T22 content was observed and the proportion of immobilized water decreased at 300 MPa by low-filed nuclear magnetic resonance. However, excessive high-pressure processing treatments (400 MPa) resulted in lower gel strength, WHC, texture, and G'. The scanning electron microscopy results shown that a denser network structure with small cavities was observed at 300 MPa. Therefore, moderate pressure treatment (≤300 MPa) may improve gelation properties of PB-AG gel, while excessive pressure treatment (400 MPa) may weaken the gelation properties. PRACTICAL APPLICATION: High-pressure processing combining Artemisia sphaerocephala krasch gum could enhance the gelation properties of pork batters. To do so, establishing knowledge on gelation properties of pork batters with Artemisia sphaerocephala krasch gum at different pressure levels treatment would be of paramount importance, because this contributes furnishing engineering data pertinent to the technical progress for the processing of emulsion-type meat with high quality.

Effect of sodium alginate on physical-chemical, protein conformation and sensory of low-fat frankfurters.

In order to study the potential of replacing pork back-fat by sodium alginate solution (sodium alginate/water = 1/29, W/W), the physico-chemical, protein conformation and sensory of frankfurters made with various amounts of pork back-fat and sodium alginate were evaluated. With the increase of sodium alginate solute, the fat and energy was decreased significantly (P < .05). Compared with the control, the cooking yield, emulsion stability, L⁎ and ΔE values were not different significantly (P > .05) when pork back-fat was replaced by 25% and 50%, meanwhile, a decrease of α-helix content accompanied by an increase of ß-sheet, ß-turn and random coil content, more hydrophobic and tyrosine residues became exposed, those implied the hardness was increased. The texture, juiciness and overall acceptance scores were decreased significantly (P < .05) when pork back-fat was replaced beyond 50%. From the above, the use of sodium alginate solution instead of pork back-fat could transform protein structure and lowered fat and energy of frankfurters.