Effect of ultrasound-assisted dough fermentation on the quality of dough and steamed bread with 50% sweet potato pulp

Ultrasound at an intensity of 17.5, 20.0, 22.5, 25.0 and 27.5 W/L was used to assist dough fermentation to prepare steamed bread with 50% sweet potato pulp (SB-50% SPP), which was compared with SB-50% SPP without ultrasonic treatment. The dough rheology, starch–gluten network, texture characteristics and sensory quality of steamed bread with different ultrasonic power densities (UPDs) were investigated. Dough samples at UPD of 22.5 W/L showed optimal viscoelasticity. The microstructure images exhibited that the content of starch particles wrapped in the gluten network increased significantly after sonication. In addition, the reduction in free sulfhydryl (SH) content and increase in wet gluten content after ultrasonic treatment led to significantly improved dough extensibility (p < 0.05). Results exhibited that the specific volume of SB-50% SPP increased by 13.93% and the hardness decreased by 21.96% compared with the control under UPD of 22.5 W/L. This study suggested that the application of ultrasound as a green technology to dough fermentation could lead to SB-50% SPP with good quality and sensory characteristics.     

Effects of multi-frequency ultrasound on physicochemical properties,structural characteristics of gluten protein and the quality of noodle

In this study, the influence of multi-frequency ultrasound irradiation on the functional properties and structural characteristics of gluten, as well as the textural and cooking characteristics of the noodles were investigated. Results showed that the textural and cooking characteristics of noodles that contain less gluten pretreated by multi-frequency ultrasonic were ultrasonic frequency dependent. Moreover, the noodles that contain a smaller amount of sonicated gluten could achieve the textural and cooking quality of commercial noodles. There was no significant difference in the cooking and texture characteristics between commercial noodles and noodles with 12%, 11%, and 10% gluten pretreated by single-frequency (40 kHz), dual-frequency (28/40 kHz), and triple-frequency sonication (28/40/80 kHz), respectively. Furthermore, the cavitation efficiency of triple-frequency ultrasound was greater than that of dual-frequency and single-frequency. As the number of ultrasonic frequencies increased, the solubility, water holding capacity and oil holding capacity of gluten increased significantly (p < 0.05), and the particle size was reduced from 197.93 ± 5.28 nm to 110.15 ± 2.61 nm. Furthermore, compared to the control group (untreated), the UV absorption and fluorescence intensity of the gluten treated by multi-frequency ultrasonication increased. The surface hydrophobicity of gluten increased from 8159.1 ± 195.87 (untreated) to 11621.5 ± 379.72 (28/40/80 kHz). Raman spectroscopy showed that the α-helix content of all sonicated gluten protein samples decreased after sonication, while the β-sheet and β-turn content increased, and tryptophan and tyrosine residues were exposed. Through scanning electron microscope (SEM) analysis, the gluten protein network structure after ultrasonic treatment was loose, and the pore size of the gluten protein network increased from about 10 μm (untreated) to about 26 μm (28/40/80 kHz). This work elucidated the effect of ultrasonic frequency on the performance of gluten, indicating that with increasing frequency combination increases, the ultrasound effect became more pronounced and protein unfolding increased, thereby impacting the functional properties and the quality of the final product. This study provided a theoretical basis for the application of multi-frequency ultrasound technology in the modification of gluten protein and noodle processing.     

Study of ultrasonic treatment on the structural characteristics of gluten protein and the quality of steamed bread with potato pulp

Physicochemical properties and microstructure of gluten protein, and the structural characteristics of steamed bread with 30 % potato pulp (SBPP) were investigated by ultrasonic treatments. Results showed that 400 W ultrasonic treatment significantly (P < 0.05) increased the combination of water and substrate in the dough with 30 % potato pulp (DPP). The contents of wet gluten, free sulfhydryl (SH), and disulfide bond (SS) were influenced by ultrasonic treatment. Moreover, UV-visible and fluorescence spectroscopy demonstrated that the conformation of gluten protein was changed by ultrasonic treatment (400 W). Fourier transform infrared (FT-IR) illustrated that the β-sheet content was significantly (P < 0.05) increased (42 %) after 400 W ultrasonic treatment, and the surface hydrophobicity of gluten protein in SBPP increased from 1225.37 (0 W ultrasonic treatment) to 4588.74 (400 W ultrasonic treatment). Ultrasonic treatment facilitated the generation of a continuous gluten network and stabilized crumb structure, further increased the specific volume and springiness of SBPP to 18.9 % and 6.9 %, respectively. Those findings suggested that ultrasonic treatment would be an efficient method to modify gluten protein and improve the quality of SBPP.     

Ultrasound-assisted thawing of frozen white yak meat: Effects on thawing rate,meat quality,nutrients, and microstructure

The objective of this study was to assess the effects of ultrasound-assisted thawing (UAT) on the quality of longissimus dorsi muscles from white yak meat (WYM). Ultrasonic power levels of 0, 200, 400, and 600 W (frequency of 20 kHz) were used to assist thawing. The thawing rate, meat quality, nutrient substances, volatile compounds, and microstructure of the WYM were determined. The results showed that ultrasonic thawing treatment reduced thawing times by 30.95–64.28% compared to control. The meat quality results revealed that the thawing loss, cooking loss, L* and b* values, and pH values decreased significantly while the a* value and cutting force increased significantly (P < 0.05) at the lower 400 W power level compared with the control. In addition, the free amino acid (FAA), mineral, and vitamin (especially water-soluble vitamins) contents were significantly (P < 0.05) increased with the ultrasound treatment. UAT significantly (P < 0.05) increased the content of volatile compounds, an effect that was highest in the UAT-400 W group. Partial least squares discrimination analysis (PLS-DA) showed that 2,4-heptadienal was critical in distinguishing the UAT groups from the control. When the ultrasonic power was lower than 400 W, the muscle cell area was significantly (P < 0.05) increased but decreased when higher power was used. Therefore, UAT improves the thawing efficiency and quality of frozen WYM, particularly at a power level of 400 W, and these findings have potential applications in the meat industry.     

Effects of ultrasound pretreatment on the quality,nutrients and volatile compounds of dry-cured yak meat

The objective of the present study was to assess the effects of ultrasound pretreatment on the quality of dry-cured yak meat. The ultrasonic power with 0, 200, 300 and 400 W (ultrasonic frequency of 20 kHz) were used to assist processing of dry-cured yak meat. The meat quality, nutrient substances, sensory quality, electronic nose, electronic tongue and volatile compounds of dry-cured yak meat were determined. The results indicated that the moisture content and hardness value of ultrasonic treatment group was significantly lower compared to the control group (P < 0.05). Ultrasonic treatment increased the value of b*, and decreased the value of L*, a*, pH, chewiness, melting temperature and enthalpy. Springiness value significantly increased from control group to 300 W of ultrasonic power group. Shear force significantly decreased with the increase of ultrasonic power (P < 0.05). Ultrasonic treatment had no effect on the TVB-N content, but it could increase the TBARS content. Ultrasonic treatment could significantly increase the essential FAA (EFAA) and total FAA (P < 0.05). In addition, the saturated fatty acid (SFA) content significantly increased with the increase of ultrasonic power (P < 0.05). Ultrasound treatment negatively affected the meat’s color, smell, and taste but increased its tenderness and the overall acceptability. It also significantly increased alcohols and aldehydes contents (P < 0.05), which were consistent with the measurement of electronic nose and electronic tongue. The results demonstrated that the the appropriate ultrasonic power assisted in the processing improves quality of dry-cured yak meat, particularly for the power of 300 W.     

Application of simultaneous ultrasonic curing on pork (Longissimus dorsi): Mass transport of NaCl,physical characteristics,and microstructure

This study aimed to investigate the effect of ultrasound curing with various working modes and frequency combinations, including mono-, dual- and tri-frequency, on the content of NaCl and tenderness of pork loins (Longissimus dorsi). The physical qualities, myoglobin, moisture migration, distribution, and microstructure of pork were also evaluated. The results displayed that the NaCl content of samples cured by simultaneous ultrasound (100 W/L) working mode with a frequency combination of 20, 40, and 60 kHz was higher than that of other ultrasound working modes. The effect of ultrasonic brining was significantly better than the static curing when the saline solution was >35 mL. In addition, the samples cured by simultaneous ultrasound had better physical qualities, including more pickling absorptivity, less cooking loss, and lower hardness, tenderness, and chewiness value. The intensity of lightness was reduced, although redness and yellowness remained unaltered compared to static curing. The myoglobin content decreased drastically without changing the oxygenation level, and the relaxation time of T_2b and T₂₁ was delayed. The microstructure indicated that the ultrasonic treatment could promote changes in meat texture. Overall, the simultaneous ultrasound at various frequencies could efficiently accelerate NaCl penetration and improve pork quality.     

Impact of applied ultrasonic power on the low temperature drying of apple

Low temperature drying (LTD) allows high-quality dried products to be obtained, preserving the nutritional properties of fresh foods better than conventional drying, but it is a time-consuming operation. Power ultrasound (US) could be used to intensify LTD, but it should be taken into account that process variables, such as the level of applied power, have an influence on the magnitude and extension of the ultrasonic effects. Therefore, the aim of this work was to assess the influence of the level of applied ultrasonic power on the LTD of apple, analyzing the drying kinetics and the quality of the dried product. For that purpose, apple (Malus domestica cv. Granny Smith) cubes (8.8 mm side) were dried (2 m/s) at two different temperatures (10 and −10 °C), without and with (25, 50 and 75 W) US application. In the dried apple, the rehydration kinetics, hardness, total phenolic content, antioxidant capacity and microstructure were analyzed to evaluate the impact of the level of applied ultrasonic power.At both temperatures, 10 and −10 °C, the higher the ultrasonic power level, the shorter the drying time; the maximum shortening of the drying time achieved was 80.3% (at −10 °C and 75 W). The ultrasonic power level did not significantly (p < 0.05) affect the quality parameters analyzed. Therefore, US could be considered a non-thermal method of intensifying the LTD of fruits, like apple, with only a mild impact on the quality of the dried product.     

Effects of dual-frequency slit ultrasound on the enzymolysis of high-concentration hydrolyzed feather meal: Biological activities and structural characteristics of hydrolysates

Ultrasound-assisted enzymolysis has been applied to improve conventional enzymolysis, while there are rare reports on the application of ultrasound to high-concentration feather protein enzymolysis. Therefore, the feasibility of dual-frequency slit ultrasound (DFSU) for enzymolysis of high-concentration hydrolyzed feather meal (HFM), as well as the biological activities and structural characteristics of hydrolysates were investigated. The single-factor test was used to optimize the ultrasonic processing parameters: substrate concentration, frequency mode, intermittent ratio, power density, and time. The results showed that protein recovery rate and conversion rate increased by 6.08% and 18.63% under the optimal conditions (200 g/L, 28/80 kHz, 5:2 s/s, 600 W/L, and 3 h) compared with conventional enzymolysis, respectively. The macromolecular proteins in hydrolysates were converted into micromolecular peptides (< 500 Da) when treated by DFSU, and antioxidant activity and angiotensin-I-converting enzyme (ACE) inhibitory activity of hydrolysates were increased. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) images illustrated the microstructure changes of feather protein particles in the ultrasound-assisted enzymatic hydrolysates of HFM (UEH), including more porous, smaller, and more uniform. Additionally, the conformation of protein molecules was significantly affected (P < 0.05), including the increase in free sulfhydryl (SH), the decrease in disulfide bond (SS) and surface hydrophobicity (H₀). Fourier transform infrared (FTIR) spectra analysis further showed that the secondary structure of feather proteins was modified with a reduction in α-helix, β-turn, and β-sheet, while an increase in random coil content was observed. These results indicated that DFSU could be a promising method to enhance high-concentration HFM for preparing peptide-rich hydrolysates with high antioxidant activity and ACE inhibitory activity.     

Green ultrasound-assisted extraction of chlorogenic acids from sweet potato peels and sonochemical hydrolysis of caffeoylquinic acids derivatives

Sweet potato peels are rich in chlorogenic acids. In this work, we applied ultrasound technology to extract the main compounds from sweet potato peel and used multivariate analysis and principal component analysis (PCA) to evaluate the effects of different extraction conditions on the extraction of chlorogenic acids. The extraction was studied varying ultrasonic power density (20, 35 and 50 W/L) and processing time (5, 10, 20 and 40 min) using an ultrasonic bath operating at 25 kHz. The chemical analysis was carried out by UPLC-qTOF-MS, and the results were evaluated by PCA and PLS-DA chemometric analysis. Results show that both ultrasonic power density and processing time influences in the extraction of different chlorogenic acid, and that different extraction conditions can be used to selectively extract specific caffeoylquinic acids and feruloylquinic acids in higher amounts. Ultrasound promoted the hydrolysis of tricaffeoylquinic acid when subjected to ultrasonic waves (20–50 W/L), and of 3,4-caffeyolquinic acid at high ultrasonic power density (50 W/L).     

Effects of low-frequency ultrasonic pre-treatment in water/oil medium simulated system on the improved processing efficiency and quality of microwave-assisted vacuum fried potato chips

The effects of low-frequency ultrasonic pre-treatment in water/oil medium simulated system on the improved processing efficiency and quality of microwave-assisted vacuum fried potato chips were investigated. The water medium system (distilled water and 5% NaCl osmotic solution) and oil medium system (90 °C) were designed with different power levels of ultrasound to simulate the ultrasonic conditions. Results showed that the changes of moisture content, water loss, solid gain and dielectric properties of potato slices were facilitated by the ultrasonic treatment. LF-NMR analysis showed the binding force between the moisture and structure in the material was significantly (p < 0.05) weakened. The changes become greater with the increase of ultrasonic power levels. Microscopic channels and disruptions were induced on the microstructure by the ultrasonic treatment. The effective moisture diffusivity of vacuum fried (VF) potato chips was increased by about 56.2%-67.0% and 53.9% with the combination of microwave energy and the ultrasonic pre-treatment in water and oil medium simulated system, respectively. The oil uptake, hardness, shrinkage, total color change and water activity of vacuum fried samples were significantly (p < 0.05) decreased by the assist of microwave energy combined ultrasonic pre-treatment.     

Effect of ultrasonic treatment on the structure and functional properties of mantle proteins from scallops (Patinopecten yessoensis)

In this study, scallop mantle protein was treated by ultrasound at different powers, and then analyzed by ANS fluorescent probes, circular dichroism spectroscopy, endogenous fluorescence spectrum, DNTB colorimetry and in-vitro digestion model to elucidate the structure–function relationship. The results indicated that ultrasound can significantly affect the secondary structure of scallop mantle protein like enhancing hydrophobicity, lowering the particle size, increasing the relative contents of α-helix and decreasing contents of β-pleated sheet, β-turn and random coil, as well as altering intrinsic fluorescence intensity with blue shift of maximum fluorescence peak. But ultrasound had no effect on its primary structure. Moreover, the functions of scallop mantle protein were regulated by modifying its structures by ultrasound. Specifically, the protein had the highest performance in foaming property and in-vitro digestibility under ultrasonic power of 100 W, oil binding capacity under 100 W, water binding capacity under 300 W, solubility and emulsification capacity under 400 W, and emulsion stability under 600 W. These results prove ultrasonic treatment has the potential to effectively improve functional properties and quality of scallop mantle protein, benefiting in comprehensive utilization of scallop mantles.     

Improvement in enzymolysis efficiency and changes in conformational attributes of corn gluten meal by dual-frequency slit ultrasonication action

The influences of dual-frequency slit ultrasound (DFSU) pretreatment with various working parameters on the enzymolysis efficiency and conformational characteristics of corn gluten meal (CGM) were studied. Results indicated that under the conditions of ultrasonic power density of 80 W/L, time of 30 min, ultrasonic intermittent ratio of 5:2 s/s, temperature of 30 °C, and substrate concentration of 50 g/L, the relative enzymolysis efficiency (REE) of CGM reached a maximum of 21.05%, and the protein dissolution rate was 68.50%. In addition, ultrasonication had considerable impact on the conformation of CGM and consequently improved the susceptibility to alcalase proteolysis. Changes in free sulfhydryl (SH_F) and disulfide bonds (SS) groups indicated spatial conformation of CGM was altered following sonication (sonochemical) treatment. Fourier Transform Infrared Spectrum (FITR) analysis showed a reduction in α-helix and β-turn content; and an increase in β-sheet and random coil content of CGM. Alterations in the particle size, particle size distribution, microstructure and surface roughness (R_a, R_q) indicated generation of smaller and more uniform protein fragments of CGM by sonochemical pretreatment. The proposed mechanism of sonicated CGM was elaborated. Our findings suggest that using DFSU in pretreating CGM may be an efficacious approach to enhance proteolysis.     

Influence of ultrasound treatment on the physicochemical and antioxidant properties of mung bean protein hydrolysate

This study aimed to investigate influence of ultrasonic treatment on physicochemical and antioxidant properties of mung bean protein hydrolysate (MPH). Physicochemical properties of MPH were evaluated by Tricine-SDS-PAGE, particle size distribution, fourier transform infrared spectroscopy (FTIR) and fluorescence spectroscopy, among others. Radicals scavenging activities of ABTS, hydroxyl, superoxide anion, Fe²⁺ chelating ability and reducing power characterized antioxidant activities of MPH. MPH contained four bands of 25.6, 12.8, 10.6 and 4.9 kDa, in which 4.9 kDa was the most abundant. Ultrasonic treatment increased the contents of aromatic and hydrophobic amino acids in MPH. Ultrasonic treatment decreased the content of α-helix of MPH and increased β-sheet and β-turn compared to MPH. MPH-546 W (ultrasonic treatment 546 W, 20 min) had the lowest average particle size (290.13 nm), zeta potential (-36.37 mV) and surface hydrophobicity (367.95 A.U.). Antioxidant activities of ultrasonicated-MPH increased with the ultrasonic power, achieving the lowest IC₅₀ (mg/mL) of 0.1087 (ABTS), 1.796 (hydroxyl), 1.003 (superoxide anion) and 0.185 (Fe²⁺ chelating ability) in 546 W power. These results indicated ultrasonic treatment would be a promising method to improve the antioxidant properties of MPH, which would broaden the application scope of MPH as bioactive components in the food industry.     

Effects of ultrasonic treatment on color,carotenoid content,enzyme activity,rheological properties,and microstructure of pumpkin juice during storage

Freshly squeezed pumpkin juice (Cucurbita moschata D.) was sonicated at various power levels at a constant frequency of 25 kHz and a treatment time of 10 min. Samples were stored in the dark for 0, 4, 8, and 12 days at 4 °C and were subsequently analyzed. The combined effects of power level and storage period on color parameters, carotenoid content, particle size distribution, cloud value, rheological characteristics, and microstructure were investigated. The results showed ultrasonic-treated samples had little effect on carotenoid content, cloud value, particle size distribution, and polydispersity during storage compared to those of the untreated samples. The L^⁎, a^⁎, b^⁎, and C* values decreased significantly during 8–12 days of storage, resulting in a significant increase in ΔE, especially 400 W/10 min-treated samples. Meanwhile, the enzyme activity and rheological properties increased significantly on storage days 8–12. However, the microstructure of all samples did not change significantly during storage. Based on these results, during the storage period, the physical and chemical properties of 400 W/10 min-ultrasonic treated pumpkin juice were retained more than those in the untreated pumpkin juice. Therefore, ultrasonic treatment has broad application prospects in preserving bioactive substances and physicochemical properties and improving the storage life of fresh pumpkin juice.     

Optimization of ultrasonic-assisted ultrafiltration process for removing bacterial endotoxin from diammonium glycyrrhizinate using response surface methodology

Ultrasonic-assisted ultrafiltration (UAU) removing bacterial endotoxin from diammonium glycyrrhizinate, was firstly applied to surfactant separation. Separation efficiency was related with four variables, including ultrafiltration molecular weight cut off (MWCO), ultrasonic power, concentration and pH. The SCQ-9200E ultrasonic system was provided for the study with adjustable ultrasonic power 80 W to 800 W, and the ultrasonic frequency was 40 KHz. On the basis of response surface methodology (RSM), the optimal separation conditions were determined to be the ultrafiltration MWCO as 10 kDa, the ultrasonic power as 570 W, diammonium glycyrrhizinate concentration as 150.00 μg/mL and the pH as 4.70. The experimental rejection of bacterial endotoxin was 94.08%, meanwhile the transmittance of diammonium glycyrrhizinate was 93.65%. Based on the ultrasonic power, solution volume, and ultrasonic container size, the experiments with UAU at different power intensities showed that ultrasonic at a power intensity of 57 W/L and the power density of 0.32 W/cm² could solve the separation contradiction between diammonium glycyrrhizinate and bacterial endotoxin. This study indicated that UAU could be an innovation in ultrasonic separation fields, and had a vast range of prospects for making use in pharmaceutical preparation area.     

Effect of high intensity ultrasound on the fermentation profile of Lactobacillus sakei in a meat model system

The objective of this study was to investigate the efficacy of high intensity ultrasound on the fermentation profile of Lactobacillus sakei in a meat model system. Ultrasound power level (0–68.5 W) and sonication time (0–9 min) at 20 °C were assessed against the growth of L. sakei using a Microplate reader over a period of 24 h. The L. sakei growth data showed a good fit with the Gompertz model (R² > 0.90; SE < 0.042). Second order polynomial models demonstrated the effect of ultrasonic power and sonication time on the specific growth rate (SGR, μ, h⁻¹) and lag phase (λ, h). A higher SGR and a shorter lag phase were observed at low power (2.99 W for 5 min) compared to control. Conversely, a decrease (p < 0.05) in SGR with an increase in lag phase was observed with an increase in ultrasonic power level. Cell-free extracts obtained after 24 h fermentation of ultrasound treated samples showed antimicrobial activity against Staphylococcus aureus, Listeria monocytogenes, Escherichia coli and Salmonella typhimurium at lower concentrations compared to control. No significant difference (p < 0.05) among treatments was observed for lactic acid content after a 24 h fermentation period. This study showed that both stimulation and retardation of L. sakei is possible, depending on the ultrasonic power and sonication time employed. Hence, fermentation process involving probiotics to develop functional food products can be tailored by selection of ultrasound processing parameters.     

Effect of multiple-frequency ultrasound-assisted transglutaminase dual modification on the structural,functional characteristics and application of Qingke protein

Qingke protein rich in restricted amino acids such as lysine, while the uncoordination of ratio of glutenin and gliadin in Qingke protein has a negative impact on its processing properties. In this study, the effect of multiple-frequency ultrasound combined with transglutaminase treatment on the functional and structural properties of Qingke protein and its application in noodle manufacture were investigated. The results showed that compared with the control, ultrasound-assisted transglutaminase dual modification significantly increased the water and oil holding capacity, apparent viscosity, foaming ability, and emulsifying activity index of Qingke protein, which exhibited a higher storage modulus G' (P < 0.05). Meanwhile, ultrasound combined with transglutaminase treatment enhanced the cross-linking degree of Qingke protein (P < 0.05), as shown by decreased free amino group and free sulfhydryl group contents, and increased disulfide bond content. Moreover, after the ultrasound-assisted transglutaminase dual modification treatment, the fluorescence intensity, the contents of α-helix and random coil in the secondary structure of Qingke protein significantly decreased, while the β-sheet content increased (P < 0.05) compared with control. SDS-PAGE results showed that the bands of Qingke protein treated by ultrasound combined with transglutaminase became unclear. Furthermore, the quality of Qingke noodles made with Qingke powder (140 g/kg dual modified Qingke protein mixed with 860 g/kg extracted Qingke starch) and wheat gluten 60–70 g/kg was similar to that of wheat noodles. In summary, multiple-frequency ultrasound combined with transglutaminase dual modification can significantly improve the physicochemical properties of Qingke protein and the modified Qingke proteins can be used as novel ingredients for Qingke noodles.     

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

The present research aimed to investigate the effects of high-intensity ultrasound (HIU, 20 kHz, 0 W, 100 W, 300 W and 500 W)-assisted vacuum tumbling (UVT) for 60 min and 120 min on the oxidation and physicochemical properties of the pork myofibrillar proteins (MPs). Compared with the vacuum tumbling (VT) groups without the HIU assistance, the carbonyl content increased, while the total sulfhydryl (SH) content was reduced with the increase of HIU power and treatment time (P < 0.05). The reactive SH content was increased significantly after treated by UVT with 300 W compared with the VT group (P < 0.05) regardless of the treatment time. Similarly, the surface hydrophobicity (S₀), the intrinsic tryptophan intensity, and the solubility in the UVT group (300 W) were remarkably higher than those of the VT group (P < 0.05). In contrast, the α-helix content and the particle size of MPs significantly decreased when the HIU power was at 100 W and 300 W (P < 0.05). The results suggest that UVT treatment could change the structure and physicochemical properties of MPs accompanied by protein oxidation.