Ultrasound-assisted Freezing Research Articles

The Effect of Ultrasound-Assisted Freezing, Metal Plate Assisted Freezing and Conventional Freezing on the Quality Characteristics of Beef Samples

The Effect of Ultrasound-Assisted Freezing, Metal Plate Assisted Freezing and Conventional Freezing on the Quality Characteristics of Beef Samples

Effects of multi-frequency ultrasound-assisted immersion freezing processing on myofibrillar protein structure and lipid oxidation of large yellow croaker (Larimichthys crocea) during long-time frozen storage

In this study, large yellow croaker (Larimichthys crocea) was frozen using multi-frequency ultrasound-assisted freezing (MUIF) with different powers (160 W, 175 W, and 190 W, respectively) and stored at −18 °C for ten months. The effect of different ultrasound powers on the myofibrillar protein (MP) structures and lipid oxidation of large yellow croaker was investigated. The results showed that MUIF significantly slowed down the oxidation of MP by inhibiting carbonyl formation and maintaining high sulfhydryl contents. These treatments also held a high activity of Ca2+-ATPase in the MP. MUIF maintained a higher ratio of α-helix to β-sheet during frozen storage, thereby protecting the secondary structure of the tissue and stabilizing the tertiary structure. In addition, MUIF inhibited the production of thiobarbituric acid reactive substances value and the loss of unsaturated fatty acid content, indicating that MUIF could better inhibit lipid oxidation of large yellow croaker during long-time frozen storage.

The Effects of Assisted Freezing with Different Ultrasound Power Rates on the Quality and Flavor of Braised Beef.

This study investigated the effects of ultrasound-assisted immersion freezing (UIF) at different power rates (0, 200, 400, and 600 W) on the changes in beef quality and flavor after braising. The results demonstrated that UIF treatment at 400 W significantly reduced the juice loss (cooking loss decreased from 49.04% to 39.74%) and fat oxidation (TBARS value decreased from 0.32 mg/kg to 0.20 mg/kg) of braised beef. In addition, the tenderness (hardness value decreased from 5601.50 g to 2849.46 g) and color stability of braised beef were improved after UIF treatment. The flavor characteristics of braised beef were characterized using an electronic nose and an electronic tongue. The PCA analysis data showed that the cumulative contribution rates of the first and second principal components were 85% and 93.2%, respectively, with the first principal component accounting for a higher proportion. The UIF-400 W group had the highest concentration for the first principal component, and the differentiation was not significant compared to the control group. The total amino acid values of different power UIF treatment groups were improved compared to the AF treatment group, indicating that UIF can effectively reduce the losses caused by freezing. The results demonstrate that ultrasound-assisted freezing treatment is beneficial in enhancing the tenderness and flavor attributes of beef after braising, providing new insights into the processing of meat products with desirable quality characteristics.

Adenosine monophosphate boosts the cryoprotection of ultrasound-assisted freezing to frozen surimi: Insights into protein structures and gelling behaviors

Ultrasound-assisted freezing (UAF) is a clean technique for meat cryoprotections; however, its effectiveness is still limited compared to conventional cryoprotectants, e.g., sugars, polyols, especially at high dosages. To resolve this problem, a synergistic cryoprotection strategy was developed in this study. Adenosine monophosphate (AMP), an adenosine-type food additive, was introduced into frozen surimi at a considerably reduced content (0.08%), yet substantially enhanced the efficiency of UAF to comparable levels of commercial cryoprotectant (4% sucrose with 4% sorbitol). Specifically, UAF/AMP treatment retarded denaturation of surimi myofibrillar protein (MP) during 60-day frozen storage, as evidenced by its increased solubility, Ca2+-ATPase activity, sulfhydryl content, declined surface hydrophobicity, particle size, and stabilized protein conformation. Gels of UAF/AMP-treated surimi also demonstrated more stabilized microstructures, uniform water distributions, enhanced mechanical properties and water-holding capacities. This study provided a feasible approach to boost the cryoprotective performance of UAF, thus expanding its potential applications in frozen food industry.

The improvement of freezing time and functional quality of frozen mushrooms by application of probe-type power ultrasound

The study proposes a novel ultrasound-assisted freezing method for button mushrooms, which combines probe-type ultrasonication and immersion freezing. The effects of power ultrasound in both continuous and pulse modes (at five levels of 50, 100, 200, 300, and 400 W) on the freezing process and quality attributes of frozen mushrooms were investigated. Results showed that ultrasound-assisted freezing significantly reduced freezing time compared to immersion freezing, potentially due to the formation of abundant cavitation bubbles that enhanced heat and mass transfer rates. The lowest weight loss was achieved by the continuous mode of 200 W ultrasound (UC200), which may be attributed to the formation of smaller ice crystals during ultrasonication. Ultrasound also prevented acidification and resulted in the retention of the samples' pH and higher total solid solution than immersion freezing. The optimal ultrasound power and duty cycle for different freezing outcomes were determined using the TOPSIS method. UC200 was found to be the best treatment for total freezing time and minimizing weight loss, while a combination of UC200 and UC400 was optimal for gumminess and chewiness. The proposed ultrasound-assisted freezing method shows promise as an environmentally friendly and safe technique for commercial use in the future.

Effect of Ultrasound-Assisted Freezing on the Crystal Structure of Mango Sorbet

In this study, the effect of ultrasound-assisted immersion freezing (UAF) of mango sorbet in comparison to conventional freezer freezing, on freezing course and created crystal structure, was studied. The scope of work included the preparation of a sorbet mixture prepared on the basis of frozen mango fruit with the addition of locust bean gum (LBG), guar gum and a commercial mix of carrageenan without the addition of stabilizers, and freezing it using a conventional freezer and ultrasound-assisted freezing equipment, with variable operating parameters (21.5 kHz and 40 kHz—continuous or chopped mode). Then, the freezing time and the crystal structure of the frozen samples (a microscopy analysis) were examined. US-assisted freezing reduced the time of the process for stabilized samples of the sorbet. It was also proven that, proper stabilization with the combination of US treatment results in the formation of favorable crystal structure. Stabilized sorbet subjected to US action at a frequency of 21.5 kHz in chopped mode was characterized by the most uniform crystal structure, consisting of crystals with the smallest diameters among all the tested samples; the equivalent diameter was 9 µm, while for the stabilized control it was 25 µm.

Experimental Study of the Effect of Ultrasound on the Freezing Process of Bo Chinh Ginseng

The main purpose of this study was to select the appropriate ultrasound parameters that support the freezing process of Bo Chinh ginseng. This process involves placing Bo Chinh ginseng in an open-air environment and ensuring that the transducer does not come into contact with the material. The research results show that the ultrasound power, ultrasound irradiation temperature and intermittency ratio all affect the freezing time, nucleation temperature, color and microstructure of the materials. When the ultrasound continuously operated during the freezing process, at a frequency of 20 kHz, there was a 29.1% reduction in the freezing time at a power level of 100 W as compared to freezing without the help of ultrasound irradiation. The irradiation temperature and nucleation temperature have a linear relationship (y=−0.35x−0.93) which can help to control the nucleation temperature, thereby changing the ice crystal size. Ultrasound-assisted freezing at a 0.6 intermittency ratio had the shortest freezing time. The microstructure of the material changed after ultrasound-assisted freezing and many microchannels and holes were generated. When frozen at a wave rate of 0.4, the microchannels that were created in the material effectively supported the process of water drainage in the drying sublimation stage. At the same time, ultrasound irradiation did not affect the color of the post-freezing material when compared to the color of the frozen material that did not undergo ultrasound irradiation.

Effects of Different Freezing Methods on Physicochemical Properties of Sweet Corn during Storage.

Fresh sweet corn has a series of physiological and biochemical reactions after picking due to the high moisture content, leading to damaged nutritional value. Rapid freezing of sweet corn after harvest can minimize tissue damage and quality deterioration. In this study, freshly harvested sweet corn was frozen by ultrasound-assisted freezing, brine freezing, strong wind freezing, and refrigerator freezing. The effects of different freezing methods on hardness, water loss, color, epidermal structure, soluble solids content, soluble sugars content, peroxidase (POD), catalase (CAT), and ascorbate peroxidase (APX) activities of frozen sweet corn during storage were investigated. The results showed that brine freezing and strong wind freezing could effectively reduce the quality loss of sweet corn, keep the color, soluble sugars, and soluble solids content of the sweet corn, delay the decrease in antioxidant enzyme activity, and maintain the quality of sweet corn during long term storage.

Effects of ultrasound–assisted freezing on the quality of large yellow croaker (Pseudosciaena crocea) subjected to multiple freeze–thaw cycles

Repeated freezing and thawing due to temperature fluctuations irreversibly damage the muscle tissue cells of fish, thereby reducing their economic quality. In this study, the effects of ultrasound-assisted immersed freezing (UIF) technology on the changes in the quality of large yellow croaker (Pseudosciaena crocea) subjected to 0 to 5 freeze–thaw cycles were investigated. The results showed that the quality deterioration inevitably occurred after repeated freeze–thaw cycles. However, UIF significantly delayed the changes in the water holding capacity (WHC), immobilized water content, color and texture properties of fish. Compared to the control group (air freezing, AF), the thawing loss in the UIF group was reduced by 1.09 % to 4.54 % (P < 0.05), the centrifuging loss was reduced by 0.39 % to 1.86 % (P < 0.05), the migration of immobilized water content was reduced by 4 % to 5 % (P < 0.05). Moreover, SEM and LM images illustrated that the microstructures of muscle tissue in UIF group were more uniform and denser than that of the AF group after freeze–thaw cycles, and that the ice crystal size from UIF group were smaller and more regular than that of AF group. Furthermore, UIF did not caused more excessive protein oxidation of myofibrillary protein, but significantly delayed the lipid oxidation of fish muscle. The results indicated that UIF technology effectively inhibits the deterioration of fish quality affected by multiple freeze–thaw cycles, thus providing a reference for controlling the deterioration of aquatic products due to temperature fluctuations in the industry.

Ultrasound-assisted freezing retards the deterioration of functional properties of myofibrillar protein in chicken breast during long-term frozen storage

Ultrasound-assisted freezing (UF) is a novel and fast freezing technology that has attracted much attention in the food processing industry in recent years. The objective of this study was to investigate the influence of UF, immersion freezing (IF), and air freezing (AF) on the functional properties (solubility, emulsification, and gelation) of myofibrillar protein (MP) in chicken breast during frozen storage (0–180 days). Compared to AF and IF samples, UF samples showed higher solubility, absolute potential, and emulsifying activity index, and lower turbidity and particle size during frozen storage (P < 0.05). Furthermore, UF treatment could better delay the deterioration of gel structure during storage. The gel water holding capacity and gel strength of MP in UF samples were higher than those in IF and AF samples during frozen storage (P < 0.05). The results of a hierarchical cluster analysis revealed that MP in the UF, IF, and AF samples had similar functional properties at 180, 90, and 60 days, respectively. Overall, UF retarded the decrease in functional properties of MP usually seen during frozen storage.

Effect of ultrasound-assisted freezing combined with potassium alginate on the quality attributes and myofibril structure of large yellow croaker (Pseudosciaena crocea)

This research evaluated the effects of ultrasound-assisted freezing (UAF) at different power (160 W, 175 W, 190 W) combined with potassium alginate (PA, as the water-retaining agents) on the physicochemical quality, water-holding capacity (WHC), moisture migration and distribution, and myofibril structure of large yellow croaker. UAF-175 with PA as the freezing medium retained a better performance, such as color, texture, WHC, and water distribution. The pH and total volatile basic nitrogen (TVB-N) were the most desirable under the PA-UAF-175 treatment, as well as the flavor of the samples. In addition, it maintained the stability of myofibrils and reduced myofibril denaturation. Therefore, PA-UAF-175 treatment could be a possible freezing method as it maintained the quality properties and revealed better myofibril characteristics of large yellow croaker.

Effects of single-, dual-, and multi-frequency ultrasound-assisted freezing on the muscle quality and myofibrillar protein structure in large yellow croaker (Larimichthys crocea).

Ultrasound-assisted freezing (UAF) has been proved to be a new technology to improve the quality of frozen foods. Frequency is an important parameter affecting UAF result. This study was to investigate the effects of single-, dual- and multi-frequency UAF on muscle quality and myofibrillar protein structure in large yellow croaker (Larimichthys crocea), providing reference for the application of multi-frequency UAF in frozen foods. Multi-frequency UAF increased the freezing rate and had lower thawing loss, thiobarbituric acid reactive substances (TBARS) value, total volatile basic nitrogen (TVB-N) value, and higher immobilized water content. Multi-frequency UAF had lower carbonyl, higher sulfhydryl content, and more stable myofibrillar protein secondary and tertiary structures. Confocal laser scanning microscopy (CLSM) indicated that the filamentous polymer in muscle fibrin solution with multi-frequency UAF was transformed into more evenly distributed units. In general, multi-frequency UAF significantly improved the freezing rate, reduced lipid oxidation, and maintained the myofibrillar structure.

Influence of Multi-Frequency Ultrasound-Assisted Freezing on the Freezing Rate, Physicochemical Quality and Microstructure of Cultured Large Yellow Croaker (Larimichthys crocea).

The purpose of this work was to investigate the influence of multi-frequency ultrasound-assisted immersion freezing (UIF) on the freezing speed, quality attributes, and microstructure of cultured large yellow croaker (Larimichthys crocea) with different ultrasound powers. The findings revealed that UIF under multi-frequency conditions greatly enhanced the speed of food freezing. The multi-frequency UIF reduced the thawing and cooking losses, total volatile base nitrogen, K-values, and thiobarbituric acid reactive substances values, and increased the water holding capacity. The microstructure observation showed that multi-frequency UIF at 175 W reduced pore diameter and ice crystal size. Free amino acids analysis revealed that the application of multi-frequency UIF reduced the accumulation of bitter amino acids, and UIF-175 treatment increased the accumulation of umami amino acids. Therefore, multi-frequency UIF at a suitable ultrasonic power can remarkably improve the quality of large yellow croaker.

Combination strategy of CO2 pressurization and ultrasound: To improve the freezing quality of fresh-cut honeydew melon

The effects of CO2 pressurization combined with ultrasound-assisted immersion freezing (CO2USIF) on improving the freezing quality of honeydew melon were studied. The cut melon samples were first subjected to 0.2, 0.5 and 0.8 MPa CO2 pressure for 2 h respectively, and then frozen by an ultrasound-assisted freezing device. The results indicated that the CO2 pressurization affected the water state and reduced the freezable water content. Cryo-observed results showed the ice crystal area of the 0.5CO2USIF sample was 66.6% smaller than that of the SF, and 60.8% smaller than that of the IF. The drip loss of 0.5CO2USIF sample was 58.2% lower than that of SF. The indexes of vitamin C, flavor, texture and color of CO2USIF samples were kept better. The SEM results showed that the cell structures of CO2USIF samples were better maintained. These demonstrated that CO2USIF technology has application potential in improving the quality of frozen food.

Pressurized carbon dioxide combined with ultrasound-assisted immersion freezing: Effects on microstructure and nucleation of honeydew melon

To reduce freezing-induced damage, a novel freezing method based on pressurized CO2 pre-injection combined with ultrasound-assistance was developed for quick freezing of pieces of honeydew melon. The samples were first exposed to CO2 at different pressures (0.2 MPa, 0.5 MPa and 0.8 MPa) and then placed in an ultrasound-assisted freezing device. The ultrasonic intensity was 0.15 W/cm2 at 20 kHz. The results indicate that pre-injection of CO2 enhanced ultrasonic cavitation and significantly (p < 0.05) increased the nucleation temperature, thus shortening the freezing time. CO2 combined with ultrasonic assisted freezing can reduce the variation in the state of water in the sample after freezing and thawing. The results of SEM, cryo-microscopy and inverted fluorescence microscopic observations show that the cellular structure of the sample was better protected and the tissue was less damaged by ice crystals. This suggests that CO2 pre-injection combined with ultrasound assist during freezing can effectively control ice nucleation, ice crystal growth and reduce freezing-induced damage.

Influence of Multifrequency Ultrasound-Assisted Freezing on the Flavour Attributes and Myofibrillar Protein Characteristics of Cultured Large Yellow Croaker (Larimichthys crocea).

The influence of multifrequency ultrasound-assisted freezing (UAF) as compared with single- and dual-UAF on the flavour, microstructure, and myofibrillar proteins (MPs) of cultured large yellow croaker was investigated to improve food quality in a sustainable way and address the major global challenges concerning food and nutrition security in the (near) future. Multifrequency UAF-treated samples had lower total volatile basic nitrogen values during freezing than single- and dual-UAF-treated samples. Thirty-six volatile compounds were identified by solid-phase microextraction (SPME) coupled to gas chromatography–mass spectrometry (GC-MS) during freezing, and the multifrequency UAF-treated samples showed significant decreases in the relative contents of fishy flavoured compounds, including 1-penten-3-ol and 1-octen-3-ol. In addition, multifrequency UAF treatment better maintained a well-organised protein secondary structure by maintaining higher α-helical and β-sheet contents and stabilising the tertiary structure. Scanning electron microscopy images indicated that the ice crystals developed by the multifrequency UAF were fine and uniformly distributed, resulting in less damage to the frozen large yellow croaker samples. Therefore, multifrequency UAF improved the flavour attributes and MP characteristics of the large yellow croaker samples. Overall, multifrequency UAF can serve as an efficient way for improving food quality and nutritional profile in a sustainable way.

A Review on Recent Techniques for Food Preservation

Food preservation is most significant in the food industry to prevent food from the growth of bacteria and yeasts which causes spoilage of food. And also for the safety and reliability of food product, the freezing plays important role in the food industries. Modern industries has introduced many innovative food preservation freezing technologies which are explained in this review paper such freezing technologies are cryogenic freezing, air blast freezing, super-chilling, high pressure freezing and also alternate freezing processes such as ultrasound assisted freezing and electrically and magnetically assisted freezing. This freezing techniques are most commonly used to preserve the food for long period in safe manner. In this food freezing process the food is cooled from ambient temperature to chilling temperature and then stored between temperature of -18 oCand -35 oC to slow down the microbiological, physicaland chemical factorswhich are responsible for spoilage and deterioration in foods. This paper aims to accelerate the developmentand implementation of these freezing technologies by the food sector to achieve better quality and shelf life of food products.

Effects of multi-frequency ultrasound on the freezing rates, quality properties and structural characteristics of cultured large yellow croaker (Larimichthys crocea)

This research evaluated the effects of multi-frequency ultrasound assisted freezing (UAF) on the freezing rate, structural characteristics, and quality properties of cultured large yellow croaker. The freezing effects with triple ultrasound-assisted freezing (TUF) at 20, 28 and 40 kHz under 175 W was more obvious than that of single ultrasound-assisted freezing (SUF) at 20 kHz and dual ultrasound-assisted freezing (DUF) at 20 and 28 kHz. The results showed that UAF significantly increased the freezing rate and better preserved the quality of frozen large yellow croaker samples. Specifically, the quality parameters of the TUF-treated samples were closer to those of the fresh samples, with greater texture characteristics, a larger water holding capacity (lower thawing loss and cooking loss), lower K values and lower thiobarbituric acid reactive substances values. Light microscopy observation images revealed that the ice crystals formed by TUF were fine and evenly distributed, resulting in less damage to the frozen large yellow croaker samples. Therefore, multi-frequency UAF could improve the quality properties of the large yellow croaker samples.

Direct contact ultrasound assisted freezing of chicken breast samples

Nowadays, rapid freezing is sought to favor the formation of small ice crystals. Several studies have shown that the application of ultrasounds (US) accelerates the processes of energy and mass transfer when they are applied through immersion systems. However, there are hardly any studies on its application in direct systems without the use of a liquid medium for its transmission. Therefore, the objective of this work was to evaluate the potential of the application of US for improving the freezing process of chicken breast samples. First, the application of intermittent US treatments at different net sonication times of 7, 17, 37, 50 and 67% during the freezing of distilled water samples in a conventional freezer was evaluated. It was observed that net sonication times of 37, 50 and 67% reduced the phase change period by 30.0, 21.4, 27.0%, respectively. The effective freezing time was also reduced by 12.4 and 12.8% by applying net sonication times of 37 and 50%. Considering these results, an intermittent US treatment with a net sonication time of 37% was chosen for chicken breast freezing in an air-forced cooling tunnel at ambient temperatures from −13 to −22 °C. The length of all the freezing phases was reduced upon application of US, leading to an overall process time reduction of approx. 11%. On the other hand, no significant differences were found either in the Water Holding Capacity (WHC) or Cooking Loss (CL) values between control and US assisted frozen chicken breast samples. Furthermore, in vitro experiments showed that US-assisted freezing did not influence protein digestibility of chicken meat samples.This study demonstrates the potential of the application of US by direct contact to favor energy transfer processes during freezing of water and chicken breasts samples. However, its effect on the quality of the frozen products should be further studied.

Effects of nano-bubbles and constant/variable-frequency ultrasound-assisted freezing on freezing behaviour of viscous food model systems

Abstract A technique of introducing nano-bubbles (NBs) followed by constant/variable-frequency ultrasound-assisted freezing (CFUF/VFUF) was developed. Hydrolyzed gelatin-based viscous food model systems in different concentrations (G10%, G15%, G20%, G25%, and G30%) containing NBs were prepared, and their characteristics including bubble size distribution, dissolved oxygen concentration and viscosity were investigated. Freezing behaviours of the food model systems by immersion freezing (IF), CFUF and VFUF were monitored, and the elevation of freezing efficiency was analyzed using multivariate analysis of variance (MANOVA). Results indicated that NBs in G20% and G30% possessed the best size stability, showing migration distances of mean diameters less than 50 nm. Besides, MANOVA showed that the two main factors (“hydrolyzed gelatin concentration” and “freezing method”) and their interaction (“hydrolyzed gelatin concentration*freezing method”) significantly affected the freezing rate elevation and phase transition rate elevation. A tendency of VFUF > CFUF > IF in freezing promotion was observed, and the freezing process was accelerated more for G20% when performing CFUF and VFUF. VFUF could promote the freezing process better through alleviating the decline of ultrasonic efficiency induced by increases in bubble size and system viscosity. This study proved that introducing stable NBs followed by performing VFUF could remarkably improve the freezing efficiency of viscous food systems, showing great potentials for future applications in the food industry.