The impact of quick-freezing methods on the quality,moisture distribution and microstructure of prepared ground pork during storage duration

The aim of present study was to investigate the influences of ultrasound-assisted immersion freezing (UIF), immersion freezing (IF) and air freezing (AF) on the quality, moisture distribution and microstructure properties of the prepared ground pork (PGP) during storage duration (0, 15, 30, 45, 60, 75 and 90 days). UIF treatment significantly reduced the freezing time by 60.32% and 39.02%, respectively, compared to IF and AF (P < 0.05). The experimental results of quality evaluation revealed that the L* and b* values, juice loss, cooking loss, TBARS values and carbonyl contents were decreased in the UIF treated samples, while the a* value, peak temperatures (T_m), enthalpy (ΔH) and sulfhydryl contents were significantly higher than those of IF and AF treated samples (P < 0.05). In addition, low-field nuclear magnetic resonance (LF-NMR) and differential scanning calorimetry (DSC) analysis demonstrated that UIF inhibited the mobility of immobilized water and reduced the loss of immobilized and free water, and then a high water holding capacity (WHC) was achieved. Compared to the IF and AF treatments, the UIF treated PGP samples possessed better microstructure. Therefore, UIF could induce the formation of ice crystals with smaller size and more even distribution during freezing process, which contributed to less damage to the muscle tissue and more satisfied product quality.     

Effect of ultrasound-assisted freezing on the physico-chemical properties and volatile compounds of red radish

Power ultrasound, which can enhance nucleation rate and crystal growth rate, can also affect the physico-chemical properties of immersion frozen products. In this study, the influence of slow freezing (SF), immersion freezing (IF) and ultrasound-assisted freezing (UAF) on physico-chemical properties and volatile compounds of red radish was investigated. Results showed that ultrasound application significantly improved the freezing rate; the freezing time of ultrasound application at 0.26 W/cm² was shorten by 14% and 90%, compared to IF and SF, respectively. UAF products showed significant (p < 0.05) reduction in drip loss and phytonutrients (anthocyanins, vitamin C and phenolics) loss. Compared to SF products, IF and UAF products showed better textural preservation and higher calcium content. The radish tissues exhibited better cellular structures under ultrasonic power intensities of 0.17 and 0.26 W/cm² with less cell separation and disruption. Volatile compound data revealed that radish aromatic profile was also affected in the freezing process.     

Effects of ultrasonic–microwave combination treatment on the physicochemical,structure and gel properties of myofibrillar protein in Penaeus vannamei (Litopenaeus vannamei) surimi

The objective of this study was to evaluate the effects of single ultrasound (360 W, 20 min), single microwave (10 W/g, 120 s) and ultrasonic–microwave combination treatment on shrimp surimi gel properties. The structure and physicochemical properties of myofibrillar protein (MP) were also determined. Low-field nuclear magnetic resonance showed that the fluidity of water molecules and the moisture content decreased, the stability and water holding capacity (WHC) increased after single ultrasound, single microwave and ultrasonic–microwave combination treatment. Compared with the traditional water bath treatment, ultrasound and microwave treatment reduced the total sulfhydryl content and promoted the formation of intermolecular disulfide bonds and hydrophobic interactions, which improved the compactness of the network structure of shrimp surimi gel. Moreover, Fourier transform infrared spectroscopy and sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis revealed that these treatments not only inhibited the degradation of MP, but also decreased the α-helix content and increased the β-sheet content. The three treatments also significantly reduced the particle size and decreased the solubility of MP. Overall, the effect of ultrasonic–microwave combination treatment was superior to that of either single treatment.     

Enhanced gelling properties of myofibrillar protein by ultrasound-assisted thermal-induced gelation process: Give an insight into the mechanism

Effects of the incorporation of ultrasound with varied intensities (0–800 W) into the thermal-induced gelation process on the gelling properties of myofibrillar protein (MP) were explored. In comparison with single heating, ultrasound-assisted heating (<600 W) led to significant increases in gel strength (up to 17.9%) and water holding capacity (up to 32.7%). Moreover, moderate ultrasound treatment was conducive to the fabrication of compact and homogenous gel networks with small pores, which could effectively impair the fluidity of water and allow redundant water to be entrapped within the gel network. Electrophoresis revealed that the incorporation of ultrasound into the gelation process facilitated more proteins to get involved in the development of gel network. With the intensified ultrasound power, α-helix in the gels lowered pronouncedly with a simultaneous increment of β-sheet, β-turn, and random coil. Furthermore, hydrophobic interactions and disulfide bonds were reinforced by the ultrasound treatment, which was in support of the construction of preeminent MP gels.     

Effect of ultrasound-assisted resting on the quality of surimi-wheat dough and noodles

In this study, the influence of ultrasound-assisted resting at different power on the rheological properties, water distribution and structural characteristics of dough with 50 % surimi as well as the texture, cooking and microstructure characteristics of the surimi-wheat noodles were investigated. Compared with the fermentation control (FC) noodles, the microstructure, cooking and texture characteristics of noodles (≤24.00 W/L) were significantly (p < 0.05) improved after ultrasonic treating. As the increasing of ultrasonic power, compared to FC, the creep strain, recovery strain, semi-bound water, and free sulfhydryl (SH) contents of surimi-wheat dough decreased at first and then increased significantly (p < 0.05). The α-helix and β-turn content of dough increased at first and then decreased after ultrasonic treatment, while the β-sheet was reversed. The surimi-wheat dough network structure was improved by ultrasonic treatment, with the densest and continuous pore size in 21.33 W/L, but the dough structure was broken and loose (>21.33 W/L), which consisted of the hardness, elasticity, chewiness, resistant and cooked quality of surimi-wheat noodles. This work elucidated the effect of ultrasonic power on the performance of surimi-wheat dough, and the optimal ultrasound power was obtained, thereby improving the nutritional properties and the quality of surimi-wheat noodles.     

Ultrasonic assisted synthesis,characterization and influence factors of monodispersed dumbbell-like YF3 nanostructures

In the present paper, we reported the successful synthesis of dumbbell-like YF₃ nanostructures with a high yield in a mixed system of water/N,N-dimethylformamide (DMF) under the assistance of ultrasound waves of 40 kHz with the ultrasonic power of 100% (200 W) at 65 °C for 2 h, employing Y₂O₃ (99.99%) and NH₄F as the starting reactants. The product was characterized by means of powder X-ray diffraction (XRD), energy dispersive spectrometry (EDS), transmission electron microscopy (TEM), selected area electron diffraction (SAED) pattern and field-emission scanning electron microscopy (SEM). Some factors influencing the morphology of YF₃ nanostructures, including the ultrasonic time and power, the amount of NH₄F, and the ratio of water/DMF, were systematically investigated. Research showed that the morphology of YF₃ could be tuned by the volume ratio of water/DMF. The roles of DMF and the ultrasonic wave in the formation of YF₃ nanostructures were discussed.     

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 ultrasound thawing,vacuum thawing,and microwave thawing on gelling properties of protein from porcine longissimus dorsi

Effect of new thawing methods (ultrasound thawing (UT), vacuum thawing, (VT), microwave thawing (MT)) on gelling properties of myofibrillar protein (MP) from porcine longissimus dorsi was investigated, compared with traditional thawing methods (water immersion thawing, (WT)) and fresh meat (FM). The results showed that a decrease in MP gelling properties of all thawing samples was observed. The increase in roughness of MP gel from all thawing samples explained that the flatter, smoother, and denser surface morphology of that from FM samples was destroyed based on the observation by atomic force microscopy. There was significant difference (P < 0.05) in all gel indicators (particle size, turbidity, whiteness, water-holding capacity (WHC), moisture distribution, rheological characteristics, surface morphology) of MP from MT samples and there was insignificant difference (P > 0.05) in turbidity, whiteness, WHC of MP from VT samples compared with that from FM samples. There was insignificant difference (P > 0.05) in gel properties between UT and VT. The effect of UT and VT (new thawing methods) on MP gelling properties was significantly lower (P < 0.05) than that of WT (traditional thawing methods), and the effect of that from MT was obviously compared with other thawing methods.     

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.     

Solubilization and stable dispersion of myofibrillar proteins in water through the destruction and inhibition of the assembly of filaments using high-intensity ultrasound

The insolubility and poor dispersion of myofibrillar proteins (MPs) in water have always been the primary factors limiting the development of novel meat-based products. This study aimed to explore the mechanisms by which high-intensity ultrasound (HIU) at various power settings (0, 150, 300, 450 and 600 W) improved the solubility and dispersion stability of MPs in water. According to the solubility analysis, HIU significantly increased the water solubility of MPs (p < 0.05). The MPs treated with 450 W exhibited the best dispersion stability in water, which corresponded to the highest zeta-potential, smallest particle size and most uniform distribution (p < 0.05). Based on the circular dichroism and fluorescence spectroscopy and surface hydrophobicity analysis, the loss of the MP superhelix and subsequent random dissociation of the filamentous myosin structure appeared to be the main mechanism of MP solubilization. In addition, according to the zeta-potential, SDS-PAGE and Nano LC-ESI-MS/MS analyses, the increase in surface charge and the formation of soluble oligomers may provide additional forces to inhibit filament assembly, thereby improving the stability of the aqueous MP suspension. Atomic force microscopy (AFM) observations further confirmed these results. In conclusion, an HIU treatment effectively improves the solubility and dispersion stability of MP in water.     

Improving the gel properties of salted egg white/cooked soybean protein isolate composite gels by ultrasound treatment: Study on the gelling properties and structure

In this study, the effects of ultrasound treatment on the texture, physicochemical properties and protein structure of composite gels prepared by salted egg white (SEW) and cooked soybean protein isolate (CSPI) at different ratios were investigated. With the increased SEW addition, the ζ-potential absolute values, soluble protein content, surface hydrophobicity and swelling ratio of composite gels showed overall declining trends (P < 0.05), while the free sulfhydryl (SH) contents and hardness of exhibited overall increasing trends (P < 0.05). Microstructural results revealed that composite gels exhibited denser structure with the increased SEW addition. After ultrasound treatment, the particle size of composite protein solutions significantly decreased (P < 0.05), and the free SH contents of ultrasound-treated composite gels were lower than that of untreated composite gels. Moreover, ultrasound treatment enhanced the hardness of composite gels, and promoted the conversion of free water into non-flowable water. However, when ultrasonic power exceeded 150 W, the hardness of composite gels could not be further enhanced. FTIR results indicated that ultrasound treatment facilitated the composite protein aggregates to form a more stable gel structure. The improvement of ultrasound treatment on the properties of composite gels was mainly by promoting the dissociation of protein aggregates, and the dissociated protein particles further interacted to form denser aggregates through disulfide bond, thus facilitating the crosslinking and reaggregation of protein aggregates to form denser gel structure. Overall, ultrasound treatment is an effective approach to improve the properties of SEW-CSPI composite gels, which can improve the potential utilization of SEW and SPI in food processing.     

Effects of ultrasound on the degradation kinetics,physicochemical properties and prebiotic activity of Flammulina velutipes polysaccharide

The controllable ultrasonic modification was hindered due to the uncertainty of the relationship between ultrasonic parameters and polysaccharide quality. In this study, the ultrasonic degradation process was established with kinetics. The physicochemical properties and prebiotic activity of ultrasonic degraded Flammulina velutipes polysaccharides (U-FVPs) were investigated. The results showed that the ultrasonic degradation kinetic models were fitted to 1/M_t-1/M₀ = kt. When the ultrasonic intensity increased from 531 to 3185 W/cm², the degradation proceeded faster. The decrease of polysaccharide concentration contributed to the degradation of FVP, and the fastest degradation rate was at 60 °C. Ultrasound changed the solution conformation of FVP, and partially destroyed the stability of the triple helix structure of FVP. Additionally, the viscosity and gel strength of FVP decreased, but its thermal stability was improved by ultrasound. Higher ultrasonic intensity led to larger variations in physicochemical properties. Compared with FVP, U-FVPs could be more easily utilized by gut microbiota. U-FVPs displayed better prebiotic activity by promoting the growth of Bifidobacterium and Brautella and inhibiting the growth of harmful bacteria. Ultrasound could be effectively applied to the degradation of FVP to improve its physicochemical properties and bioactivities.     

Ultrasonic structural modification of myofibrillar proteins from Coregonus peled improves emulsification properties

This study evaluated the effects of high intensity ultrasonication (HIU, 100, 150, 200, and 250 W) and treatment time (0, 3, 6, 9, and 12 min) on the structure and emulsification properties of myofibrillar proteins (MPs) from Coregonus peled. These investigations were conducted using an ultrasonic generator at a frequency of 20 kHz (ultrasonic probe). Analysis of the carbonyl content and total number of sulfhydryl groups showed that HIU significantly improved the oxidative modification of MPs (P < 0.05). SDS-PAGE profiling showed significant degradation of the myosin heavy chain (P < 0.05). In addition, Fourier transformed infrared spectroscopy (FTIR) revealed that HIU altered these treated MP secondary structures, this was due to molecular unfolding and stretching, exposing interior hydrophobic groups. Particle size analysis showed that HIU treatment reduced particle sizes. Solubility, emulsification capacity, and emulsion stability were improved significantly, and each decreased with an increase in treatment time (up to 12 min), indicating aggregation with prolonged sonication. These results indicate that HIU could improve the emulsification properties of MPs from C. peled, demonstrating a promising method for fish protein processing.     

An efficient enzymatic modification of cordycepin in ionic liquids under ultrasonic irradiation

A comparative study of the immobilized Candida antarctica lipase B (Novozym 435)-catalyzed acylation of cordycepin with vinyl acetate in ionic liquids (ILs) under ultrasonic irradiation and shaking was conducted. The application of ultrasonic irradiation instead of shaking during acylation resulted in an enhanced reaction rate and a higher level of substrate conversion. Among the various ILs examined, 1-butyl-3-methylimidazolium tetrafluorobrate ([C₄MIm][BF₄]) was the best medium for the reaction because it produced the highest substrate conversion. In [C₄MIm][BF₄], the optimal ultrasonic power, water activity, and reaction temperature were 120 W, 0.33, and 50 °C, respectively. The acylation of cordycepin in [C₄MIm][BF₄] proved to be regioselective under both conditions: the C5′-OH was acylated. Novozym 435 exhibited a much higher operational stability in [C₄MIm][BF₄], and 58.0% of its original activity was maintained after ten reuse cycles under ultrasonic irradiation. Compared with the cordycepin, the rate of adenosine deaminase-catalyzed deamination was greatly reduced when the 5′-OH was substituted by acetyl group. These results demonstrated that the combined application of ultrasonic irradiation and IL as a medium was an efficient approach for the enzymatic modification of cordycepin.     

Magnetostriction and magnetization measurements on a DyNi2B2C single crystal in a magnetic field

In order to investigate the interactions between lattice properties, magnetic ordering and superconductivity of DyNi₂B₂C, thermal expansion, magnetostriction and magnetization measurements were performed for T=2–15 K and for μ₀H=0–3 T on a single crystal in the crystallographic [1 1 0] direction. A magnetic phase diagram is derived that shows two phases (AF1 and AF2) in the narrow region between the zero-field antiferromagnetic AF and the induced ferromagnetic state FM. Moreover, it is characterized by a large-field hysteresis. This behaviour can be described by a two domain magnetic state. The metamagnetic structure AF1 with about a quarter of the saturated magnetization is responsible for suppressing the superconductivity in DyNi₂B₂C because of its ferromagnetic component.     

Ultrasonic-assisted ultra-rapid synthesis of monodisperse meso-SiO2@Fe3O4 microspheres with enhanced mesoporous structure

A core–shell-type of meso-SiO₂@Fe₃O₄ microsphere was synthesized via an ultrasonic-assisted surfactant-templating process using solvothermal synthesized Fe₃O₄ as core, tetraethoxysilane (TEOS) as silica source, and cetyltrimethyl ammonium bromide (CTAB) as templates. The samples were characterized by FT-IR, XRD, TEM, N₂ adsorption–desorption technology, and vibrating sample magnetometer (VSM). The results show that as-prepared meso-SiO₂@Fe₃O₄(E) and meso-SiO₂@Fe₃O₄(C) microspheres, treated by acetone extraction and high temperature calcination, respectively, still maintain uniform core–shell structure with desirable mesoporous silica shell. Therein, the meso-SiO₂@Fe₃O₄(E) microspheres possess a distinct pore size distribution in 1.8–3.0 nm with large specific surface area (468.6 m²/g) and pore volume (0.35 cm³/g). Noteworthily, the coating period of this ultrasonic-assisted method (40 min) is much shorter than that of the conventional method (12–24 h). The morphology of microspheres and the mesoporous structure of silica shell are significantly influenced by initial concentration of CTAB (C_CTAB), ultrasonic irradiation power (P) and ultrasonic irradiation time (t). The acceleration roles of ultrasonic irradiation take effect during the whole coating process of mesoporous silica shell, including hydrolysis-condensation process of TEOS, co-assembly of hydrolyzed precursors and CTAB, and deposition of silica oligomers. In addition, the use of ultrasonic irradiation is favorable for improving the homogeneity of silica shell and the monodispersity of meso-SiO₂@Fe₃O₄ microspheres.     

Analysis of ultrasonic pre-treatment for the ozonation of humic acids

This paper presents an intensification study of an ozonation process through an ultrasonic pre-treatment for the elimination of humic substances in water and thus, improve the quality of water treatment systems for human consumption. Humic acids were used as representative of natural organic matter in real waters which present low biodegradability and a high potential for trihalomethane formation. Ultrasonic frequency (98 kHz, 300 kHz and 1 MHz), power (10–40 W) and sonicated volume (150–400 mL) was varied to assess the efficiency of the ultrasonic pre-treatment in the subsequent ozonation process. A direct link between hydroxyl radical (HO) formation and fluorescence reduction was observed during sonication pre-treatment, peaking at 300 kHz and maximum power density. Ultrasound, however, did not reduce total organic carbon (TOC). Injected ozone (O₃) dose and reaction time were also evaluated during the ozonation treatment. With 300 kHz and 40 W ultrasonic pre-treatment and the subsequent ozonation step (7.4 mg O₃/L_gas), TOC was reduced from 21 mg/L to 13.5 mg/L (36% reduction). HO attack seems to be the main degradation mechanism during ozonation. A strong reduction in colour (85%) and SUVA₂₅₄ (70%) was also measured. Moreover, changes in the chemical structure of the macromolecule were observed that led to the formation of oxidation by-products of lower molecular weight.     

Sonochemical degradation of 3-methylpyridine (3MP) intensified using combination with various oxidants

3-Methyl pyridine (3MP) is a toxic and hazardous organic compound having considerable negative impact on environment and living organisms. The objective of this work to report a novel treatment strategy based on sonochemical degradation of 3MP, in combination with oxidants such as hydrogen peroxide, Fenton’s reagent, peroxymonosulphate (PMS), and potassium persulphate (KPS) as well as solar irradiations. A bath sonicator operating at 25 kHz frequency and rated power dissipation of 100 W was applied in the work to study different approaches with an objective to enhance the removal of 3MP in lesser time. Effect of operating parameters such as pH (over the range of 2–10), treatment time, temperature (25–55 °C) and ultrasonic power (25 W to 150 W) on the degradation has been studied and the best conditions were used in subsequent combination approaches. It was demonstrated that ultrasound in combination with PMS, ferrous sulphate (FeSO₄) and solar irradiations (approach of US/PMS/FeSO₄/solar irradiation) is the best treatment strategy yielding maximum degradation as 97.4% with highest cavitational yield as 1.920 × 10⁻⁴ mg/J and highest synergetic Index as 2.70. Kinetic analysis revealed that first order mechanism fitted well to all the approaches involving different combinations of ultrasound, oxidising agents and solar irradiation. Degradation products were also analysed that established the degradation mechanism as C₂ and C₃ ring cleavages forming 1, 4-dihydro3-methylpyridine followed by Levulinic acid as non -toxic main by-product. Overall the work clearly demonstrated an effective treatment approach involving combined sonication with oxidants for remediation of 3MP also providing insights on kinetics and mechanism of degradation.     

In-situ analysis of the water distribution and protein structure of dough during ultrasonic-assisted freezing based on miniature Raman spectroscopy

The effect of ultrasonic-assisted freezing (UAF) on the water distribution of dough and molecular structure of gluten was in-situ monitored by low field nuclear magnetic resonance (LF-NMR) and micro-miniature Raman spectroscopy in this research. The results showed that UAF treatment increased the bound water content between 5 min and 30 min, and weakened the signal intensity of hydrogen protons due to the ultrasound enhanced heat and mass transfer during the freezing process. In-situ Raman spectra analysis indicated that UAF delayed the transition from embedded to exposure of tyrosine and tryptophan residues during the freezing process. Meanwhile, UAF reduced the number of hydrogen bonds, gauche-gauche-gauche (g-g-g) conformation breakage, the degree of α-helix to random coil conversion and damage to the gluten network during the freezing process. UAF treatment reduced the water mobility and breakage of non-covalent bonds, which prevented a dramatic shift in the protein advanced conformation during the freezing process, thereby improving the quality of frozen dough.     

Does power ultrasound affect hydrocarbon Ionomers?

The effect of low-frequency high-power ultrasound on hydrocarbon-based ionomers, cation exchange sulfonated phenylated polyphenylene (sPPB-H⁺) and anion exchange hexamethyl-p-terphenyl poly(benzimidazolium) (HMT-PMBI), was studied. Ionomer solutions were subjected to ultrasonication at fixed ultrasonic frequencies (f = 26 and 42 kHz) and acoustic power (P_acous = 2.1 – 10.6 W) in a laboratory-grade ultrasonication bath, and a probe ultrasonicator; both commonly employed in catalyst ink preparation in research laboratory scale. Power ultrasound reduced the polymer solution viscosity of both hydrocarbon-based ionomers. The molecular weight of sPPB-H⁺ decreased with irradiation time. Changes in viscosity and molecular weight were exacerbated when ultrasonicated in an ice bath; but reduced when the solutions contained carbon black, as typically used in Pt/C-based catalyst inks. Spectroscopic analyses revealed no measurable changes in polymer structure upon ultrasonication, except for very high doses, where evidence for free-radical induced degradation was observed. Ionomers subjected to ultrasound were used to prepare catalyst layers and membrane electrode assemblies (MEA)s. Despite the changes in the ionomer described above, no significant differences in electrochemical performance were found between MEAs prepared with ionomers pre-subjected to ultrasound and those that were not, suggesting that fuel cell performance is tolerant to ionomers subjected to ultrasound.