Effect of ice structuring protein on the microstructure and myofibrillar protein structure of mirror carp (Cyprinus carpio L.) induced by freeze-thaw processes

Effect of different freezing conditions on ice crystal formation behavior and ice-growth inhibition by cryoprotectants

BACKGROUND

The formation of ice crystals will have adverse effects on aquatic products, and the key to ensure the long-term preservation and better quality preservations of the product is to evaluate the intercellular ice crystal formation to find suitable refrigeration conditions and cryoprotectants.

RESULTS

The ice crystal formation was successfully captured by using an inverted microscope cryomicroscopic system equipped with a low-temperature stage, the ice crystals formed under different freezing methods between tuna muscle cells were observed directly, the deformation degree of muscle tissue pores during crystallization was evaluated, and the effect of freeze-thaw times on tuna samples was analyzed. The effects of the use of cryoprotectant such as cellobiose and carboxylated cellulose nanofibers on ice-growth inhibition were investigated, and the reliability of the ice crystal observation results was further verified by the determination of physical properties. The results showed that carboxylated cellulose nanofibers had the best ice-growth inhibition effect, they prevented about 50% cell deformation compared with the control group, and also reduced the minimum size of ice crystal formation. In addition, the addition of cellobiose and sodium tripolyphosphate gave the ice crystals a more uniform size and roundness.

CONCLUSION

The experiment proposed a stable and clear observation method for the process of intercellular ice crystal formation, and the accuracy of the observation method was further verified by some physical indicators. This may help in the selection of suitable measurement methods to directly observe ice crystal formation behavior and screen cryoprotectants. © 2024 Society of Chemical Industry.

Multi-layered structure and physicochemical properties of reconstituted meat-based products from minced fish by physical extrusion: Impact of extrusion strength

Multi-layered structure of reconstituted meat-based products from minced fish was formed by physical extrusion, followed by an investigation into the impact of extrusion strength on structural and physicochemical properties before and after frying. Under an appropriate pressure (3-9 kPa), the air within minced fish underwent enrichment and rearrangement to form a stratified phase, promoting the formation of multi-layered structure during frying. Conversely, the lower pressure (≤1.5 kPa) was insufficient for phase separation and directional rearrangement, while the higher pressure (≥15 kPa) would cause the stratified phase to flow out of food system. Moreover, by directly increasing water mobility and meat compactness, physical extrusion indirectly caused more water loss and stronger ionic bonds during frying, which was positively correlated with multi-layered structure. However, an excessive pressure caused an increase in random coil and hydrophobic interactions during frying, which was negatively correlated with multi-layered structure. In conclusion, appropriate physical extrusion strength promoted the formation of multi-layered structure.

Inhibitive effect of trehalose and sodium pyrophosphate on oxidation and structural changes of myofibrillar proteins in silver carp surimi during frozen storage

This work investigated the cryoprotective effect of trehalose (TH) and sodium pyrophosphate (SPP) alone and in combination on myofibrillar protein (MP) oxidation and structural changes in silver carp surimi during 90 days of frozen storage (-20 °C). TH combined with SPP was significantly more effective than single TH or SPP in preventing MP oxidation (P < 0.05), showing a higher SH content (6.05 nmol/mg protein), and a lower carbonyl (4.24 nmol/mg protein) and dityrosine content (1280 A.U.). SDS-PAGE results indicated that TH combined with SPP did not differ significantly from TH and SPP in inhibiting protein degradation but was more effective in inhibiting protein crosslinking. Moreover, all cryoprotectants could stabilise the secondary and tertiary structures and inhibit unfolded and aggregation of MP, with the combination of TH and SPP being the best. It's worth noting that TH combined with SPP had a synergistic effect on inhibiting the decrease in α-helix content and gel-forming ability, and the increase in surface hydrophobicity. Overall, TH combined with SPP could significantly inhibited MP oxidation and structural changes in surimi during frozen storage and improve the gel-forming ability, which was significantly better than single TH or SPP.

Near-Infrared Spectroscopy for Rapid Differentiation of Fresh and Frozen-Thawed Common Carp (Cyprinus carpio)

This study aimed to investigate near-infrared spectroscopy (NIRS) in combination with classification methods for the discrimination of fresh and once- or twice-freeze-thawed fish. An experiment was carried out with common carp (Cyprinus carpio). From each fish, test pieces were cut from the dorsal and ventral regions and measured from the skin side as fresh, after single freezing at minus 18 °C for 15 ÷ 28 days and 15 ÷ 21 days for the second freezing after the freeze-thawing cycle. NIRS measurements were performed via a NIRQuest 512 spectrometer at the region of 900-1700 nm in Reflection mode. The Pirouette 4.5 software was used for data processing. SIMCA and PLS-DA models were developed for classification, and their performance was estimated using the F1 score and total accuracy. The predictive power of each model was evaluated for fish samples in the fresh, single-freezing, and second-freezing classes. Additionally, aquagrams were calculated. Differences in the spectra between fresh and frozen samples were observed. They might be assigned mainly to the O-H and N-H bands. The aquagrams confirmed changes in water organization in the fish samples due to freezing-thawing. The total accuracy of the SIMCA models for the dorsal samples was 98.23% for the calibration set and 90.55% for the validation set. For the ventral samples, respective values were 99.28 and 79.70%. Similar accuracy was found for the PLS-PA models. The NIR spectroscopy and tested classification methods have a potential for nondestructively discriminating fresh from frozen-thawed fish in as methods to protect against fish meat food fraud.

Low-voltage electrostatic field enhances the frozen force of -12 ℃ to suppress oxidative denaturation of the lamb protein during the subsequent frozen storage process after finishing initial freezing

The effect of low-voltage electrostatic field (LVEF) assisted -9 °C (LVEF-9) and -12 °C (LVEF-12) frozen, non-LVEF-assisted -9 °C (NLVEF-9) and -12 °C (NLVEF-12) frozen, and conventional frozen (CF-18, -18 °C) storage on the muscle microstructure and the oxidative denaturation of the lamb protein during the subsequent frozen storage process after finishing initial freezing was investigated. Compared with NLVEF-9, LVEF-9, and NLVEF-12, LVEF-12 maintained the better integrity of muscle microstructure, demonstrated by smaller holes, more complete Z-line and M-line, and no significant difference with CF-18 (P > 0.05). Furthermore, LVEF-12 effectively inhibited protein oxidative denaturation as shown by the lower carbonyl content, surface hydrophobicity, and higher total/active sulfhydryl groups and Ca2+-ATPase activity. Moreover, LVEF-12 effectively maintained the integrity of the secondary and tertiary structure of proteins, reduced cross-linking aggregation of proteins, and sustained better functional properties, as shown by higher α-helix content, fluorescence intensity, protein solubility, and lower R-value, disulfide bonds.

The Protection of Quinoa Protein on the Quality of Pork Patties during Freeze-Thaw Cycles: Physicochemical Properties, Sensory Quality and Protein Oxidative

The present study investigated the impact of quinoa protein (QP) on the physicochemical properties, sensory quality, and oxidative stability of myofibrillar protein (MP) in pork patties during five freeze-thaw (F-T) cycles. It was observed that repeated F-T cycles resulted in a deterioration of pork patty quality; however, the incorporation of QP effectively mitigated these changes. Throughout the F-T cycles, the sensory quality of the QP-treated group consistently surpassed that of the control group. After five F-T cycles, the thiobarbituric acid reactive substance (TBARS) content in the control group was measured at 0.423 mg/kg, whereas it significantly decreased to 0.347 mg/kg in the QP-treated group (p < 0.05). Furthermore, QP inclusion led to a decrease in pH and an increase in water-holding capacity (WHC) within pork patties. Following five F-T cycles, Ca2+-ATPase activity exhibited a significant increase of 11.10% in the QP-treated group compared to controls (p < 0.05). Additionally, supplementation with QP resulted in elevated total sulfhydryl content and reduced carbonyl content, Schiff base content, and dityrosine content within myofibrillar proteins (MPs), indicating its inhibitory effect on MP oxidation. In particular, after five F-T cycles, total sulfhydryl content reached 58.66 nmol/mL for the QP-treated group significantly higher than that observed for controls at 43.65 nmol/mL (p < 0.05). While carbonyl content increased from 2.37 nmol/mL to 4.63 nmol/mL between the first and fifth F-T cycle for controls; it only rose from 2.15 nmol/mL to 3.47 nmol/mL in the QP-treated group. The endogenous fluorescence levels were significantly higher (p < 0.05) in the QP-treated group compared to controls. In conclusion, the addition of QP enhanced the quality of pork patties and effectively inhibited the oxidative denaturation of MP during F-T cycles.

Effect of sodium alginate ice glazing on the quality of the freeze-thawed fish balls

The effect of 1.0 % (w/v) sodium alginate (SA) glazing on surface frost formation and the quality of frozen fish balls in repeated freeze-thaw (F-T) cycles was studied. The optimal glazing property of 1.0 % SA solution was manifested by high transmittance, excellent water resistance, and high ice glazing rate. After seven F-T cycles, compared with the control, the ice production, thawing loss, and total volatile base nitrogen (TVB-N) value of samples with 1.0 % ice glazing decreased by 28.30 %, 21.02 %, and 27.35 %, while the chewiness and whiteness were increased by 15.02 % and 10.40 %, respectively. Moreover, compared to the control, the microstructure of fish balls glazed with 1.0 % SA was smoother and more uniform, and the ice crystal diameter was smaller. Therefore, 1.0 % SA glazing effectively inhibits the formation of ice crystals, reducing water migration and loss while minimizing damage to the meat structure, thus enhancing the quality of meat products.

Observation and Measurement of Ice Morphology in Foods: A Review

Freezing is an effective technology with which to maintain food quality. However, the formation of ice crystals during this process can cause damage to the cellular structure, leading to food deterioration. A good understanding of the relationship between food microstructure and ice morphology, as well as the ability to effectively measure and control ice crystals, is very useful to achieve high-quality frozen foods. Hence, a brief discussion is presented on the fundamentals/principles of optical microscopic techniques (light microscopy), electronic microscopic techniques (transmission electron microscopy (TEM) and scanning electron microscopy (SEM)), as well as other non-invasive techniques (X-rays, spectroscopy, and magnetic resonance) and their application to measuring ice formation rates and characterizing ice crystals, providing insight into the freezing mechanisms as well as direct monitoring of the entire process. And, in addition, this review compares (the negative and positive aspects of) the use of simple and cheap but destructive technologies (optical microscopy) with detailed microscopic technologies at the micro/nanometer scale but with pretreatments that alter the original sample (SEM and TEM), and non-destructive technologies that do not require sample preparation but which have high acquisition and operational costs. Also included are images and examples which demonstrate how useful an analysis using these techniques can be.

Cryoprotective Effect of NADES on Frozen-Thawed Mirror Carp Surimi in Terms of Oxidative Denaturation, Structural Properties, and Thermal Stability of Myofibrillar Proteins

Quality degradation due to the formation and growth of ice crystals caused by temperature fluctuations during storage, transportation, or retailing is a common problem in frozen surimi. While commercial antifreeze is used as an ingredient in frozen surimi, its high sweetness does not meet the contemporary consumer demand for low sugar and low calories. Therefore, the development of new green antifreeze agents to achieve an enhanced frozen-thawed stability of surimi has received more attention. The aim of this study was to develop a cryoprotectant (a mixture of citric acid and trehalose) to enhance the frozen-thawed stability of surimi by inhibiting the oxidative denaturation and structural changes of frozen-thawed mirror carp (Cyprinus carpio L.) surimi myofibrillar protein (MP). The results showed that the amounts of free amine, sulfhydryl, α-helix, intrinsic fluorescence intensity, and thermal stability in the control significantly decreased after five F-T cycles, while the Schiff base fluorescence intensity, amounts of disulfide bonds and surface hydrophobicity significantly increased (p < 0.05). Compared to sucrose + sorbitol (SS), the natural deep eutectic solvents (NADES) effectively inhibited protein oxidation. After five F-T cycles, the α-helix content and Ca2+-ATPase activity of the NADES samples were 4.32% and 80.0%, respectively, higher, and the carbonyl content was 17.4% lower than those of the control. These observations indicate that NADES could inhibit oxidative denaturation and enhance the structural stability of MP.

Mechanism of low-voltage electrostatic fields on the water-holding capacity in frozen beef steak: Insights from myofilament lattice arrays

This study investigated the impact of low-voltage electrostatic field-assisted freezing on the water-holding capacity of beef steaks. The enhances mechanism of water-holding capacity by electrostatic field was elucidated through the detection of dynamic changes in the myofilament lattice and the construction of an in vitro myosin filaments model. The findings demonstrated that the disorder of the myofilament array, resulted from the aggregation of myosin filaments during freezing, is a crucial factor responsible for the water loss. The intervention of the electrostatic field can effectively reduce the myofibril density by 18.7%, while maintaining a regular lattice array by modulating electrostatic and hydrophobic interactions between myofibrils. Moreover, the electrostatic field significantly inhibited the migration of immobilized water to free water, thus resulting in an increase in the water-holding capacity of myofibrils by 36%. This work provides insights into the underlying mechanisms of water loss in frozen steaks and its regulation.

Cryoprotective effect of water-tailored trehalose-based natural deep eutectic solvents on frozen-thawed mirror carp (Cyprinus carpio L.) surimi

The inhibitory effect of water-tailored natural deep eutectic solvents (NADES) constructed from citric acid and trehalose with different amounts on the quality deterioration and oxidation of frozen-thawed (F-T) mirror carp (Cyprinus carpio L.) surimi was studied. NADES was obtained by citric acid to trehalose and the effect of moisture addition (v/v) on the structure, physicochemical, and anti-freezing capacity of NADES was assessed. NADES + 10 % H₂O has relatively low viscosity (25 %) and strong freezing resistance. However, a 50 % H₂O addition leads to the disappearance of the hydrogen bond. The addition of NADES effectively inhibits water loss, migration, and mechanical damage on F-T surimi. An inhibitory effect of 4 % (w/w) NADES on oxidation was verified by a decrease in carbonyl contents (17.4 %, 8.63 %) and TBARS (37.9 %, 15.2 %) of surimi compared with control (P < 0.05) and sucrose + sorbitol after 5F-T cycles, suggesting the potential of NADES as a cryoprotectant for the food industry.

Quinoa protein Pickering emulsion: A promising cryoprotectant to enhance the freeze-thaw stability of fish myofibril gels

In this work, the effects of different QPE addition on the freeze-thaw (F-T) stability of fish myofibrillar protein (MP) gels were revealed. During freezing process, QPE decreased the freezing point of MP gels and shortened the time to pass through the maximum-ice-crystal-formation zone. The occurrence of thermal hysteresis effect led to the formation of small ice crystals and alleviated the damage to MP gel network. The incorporation of 7.5% QPE also reduced the free water amount to 19.23% and improved the water holding capacity of MP gels. Furthermore, the incorporation of QPE decreased the carbonyl content of MP gels after F-T cycles and delayed the protein oxidation. Meanwhile, QPE addition maintained the stability of the tertiary structure of MP gels via stabilizing the microenvironment of tyrosine and tryptophan. Overall, QPE shows the potential as a new cryoprotectant to improve the F-T stability of MP gel products.

Analysis of the water state and microfractal dimension of tilapia fillets during freezing and thawing

To study the effects of freezing and thawing times and freezing temperatures on the water state and microstructure of tilapia fillets, experiments on tilapia fillets were carried out at -4 and -18°C with one to four freezing and thawing cycles (FTCs). Low-field nuclear magnetic resonance (LF-NMR) and nuclear magnetic resonance imaging were used to observe the water state after different treatments, and scanning electron microscopy (SEM) and frozen sections were used to observe the microstructure changes. Fractal dimension (FD) was used to quantitatively characterize the microstructure of the fish tissue, and the correlation between FD and fish fillet quality parameters was studied by principal component analysis (PCA). The findings showed that with the increase of FTCs, the thawing loss increased, and the water holding capacity (WHC) fell. FTCs cause a decrease in immobilized water and an increase in free water in the fillet. This indicates the migration of immobilized water to free water. SEM and frozen slice images showed that the growth of ice crystals led to the destruction of myogenic fibers. A decrease in freezing temperature inhibited ice crystal growth. The FD value dropped in accordance with an increase in FTCs. PCA demonstrated that the WHC, NMR data, and FD value had a strong correlation with the quality changes in the tilapia fillets. Therefore, FD and water state can reflect the quality characteristics of tilapia fillets. PRACTICAL APPLICATION: The water migration in tilapia fillets is detected with LF-NMR, and the microscopic image may be quantified using the FD value. Both approaches can offer fresh perspectives on how to assess the quality of tilapia fillets and reflect changes in their quality.

Research progress on quality deterioration mechanism and control technology of frozen muscle foods

Freezing can prolong the shelf life of muscle foods and is widely used in their preservation. However, inevitable quality deterioration can occur during freezing, frozen storage, and thawing. This review explores the eating quality deterioration characteristics (color, water holding capacity, tenderness, and flavor) and mechanisms (irregular ice crystals, oxidation, and hydrolysis of lipids and proteins) of frozen muscle foods. It also summarizes and classifies the novel physical-field-assisted-freezing technologies (high-pressure, ultrasound, and electromagnetic) and bioactive antifreeze (ice nucleation proteins, antifreeze proteins, natural deep eutectic solvents, carbohydrate, polyphenol, phosphate, and protein hydrolysates), regulating the dynamic process from water to ice. Moreover, some novel thermal and nonthermal thawing technologies to resolve the loss of water and nutrients caused by traditional thawing methods were also reviewed. We concluded that the physical damage caused by ice crystals was the primary reason for the deterioration in eating quality, and these novel techniques promoted the eating quality of frozen muscle foods under proper conditions, including appropriate parameters (power, time, and intermittent mode mentioned in ultrasound-assisted techniques; pressure involved in high-pressure-assisted techniques; and field strength involved in electromagnetic-assisted techniques) and the amounts of bioactive antifreeze. To obtain better quality frozen muscle foods, more efficient technologies and substances must be developed. The synergy of novel freezing/thawing technology may be more effective than individual applications. This knowledge may help improve the eating quality of frozen muscle foods.

Changes in Quality and Collagen Properties of Cattle Rumen Smooth Muscle Subjected to Repeated Freeze-Thaw Cycles

This study revealed changes in the quality, structural and functional collagen properties of cattle rumen smooth muscle (CSM) during F-T cycles. The results showed that thawing loss, pressing loss, β-galactosidase, β-glucuronidase activity, β-sheet content, emulsifying activity index (EAI), emulsion stability index (ESI), surface hydrophobicity, and turbidity of samples were significantly (p < 0.05) increased by 108.12%, 78.33%, 66.57%, 76.60%, 118.63%, 119.57%, 57.37%, 99.14%, and 82.35%, respectively, with increasing F-T cycles. Meanwhile, the shear force, pH, collagen content, α-helix content, thermal denaturation temperature (Tmax), and enthalpy value were significantly (p < 0.05) decreased by 30.88%, 3.19%, 33.23%, 35.92%, 10.34% and 46.51%, respectively. Scanning electron microscopy (SEM) and SDS-PAGE results indicated that F-T cycles induced an increase in disruption of CSM muscle microstructure and degradation of collagen. Thus, repeated F-T cycles promoted collagen degradation and structural disorder in CSM, while reducing the quality of CSM, but improving the functional collagen properties of CSM. These findings provide new data support for the development, processing, and quality control of CSM.

Effect of antifreeze proteins on the freeze-thaw cycle of foods: fundamentals, mechanisms of action, current challenges and recommendations for future work

Freezing is widely used in food preservation, but if not carried out properly, ice crystals can multiply (nucleation) or grow (recrystallization) rapidly. This also affects thawing, causing structural damage and affecting overall quality. The objective of this review is to comprehensively study the cryoprotective effect of antifreeze proteins (AFPs), highlighting their role in the freeze-thaw process of food. The properties of AFPs are based on their thermal hysteresis capacity (THC), on the modification of crystal morphology and on the inhibition of ice recrystallization. The mechanism of action of AFPs is based on the adsorption-inhibition theory, but the specific role of hydrogen and hydrophobic bonds/residues and structural characteristics is also detailed. Because of the properties of AFPs, they have been successfully used to preserve the quality of a wide variety of refrigerated and frozen foods. Among the limitations of the use of AFPs, the high cost of production stands out, but currently there are solutions such as the use the production of recombinant proteins, cloning and chemical synthesis. Although in vitro, in vivo and human studies have shown that AFPs are non-toxic, their safety remains a matter of debate. Further studies are recommended to expand knowledge about AFPs, to reduce costs in their large-scale production, to understand their interaction with other food compounds and their possible effects on the consumer.

Freezing-induced denaturation of myofibrillar proteins in frozen meat

Freezing is commonly used to extend the shelf life of meat and meat products but may impact the overall quality of those products by inducing structural changes in myofibrillar proteins (MPs) through denaturation, chemical modification, and encouraging protein aggregation. This review covers the effect of freezing on the denaturation of MPs in terms of the effects of ice crystallization on solute concentrations, cold denaturation, and protein oxidation. Freezing-induced denaturation of MPs begins with ice crystallization in extracellular spaces and changes in solute concentrations in the unfrozen water fraction. At typical temperatures for freezing meat (lower than -18 °C), cold denaturation of proteins occurs, accompanied by an alteration in their secondary and tertiary structure. Moreover, the disruption of muscle cells triggers the release of cellular enzymes, accelerating protein degradation and oxidation. To minimize severe deterioration during the freezing and frozen storage of meat, there is a vital need to use an appropriate freezing temperature below the glass transition temperature and to avoid temperature fluctuations during storage to prevent recrystallization. Such an understanding of MP denaturation can be applied to determine the optimum freezing conditions for meat products with highly retained sensory, nutritional, and functional qualities.

Inhibitory Effect of Guava Leaf Polyphenols on Advanced Glycation End Products of Frozen Chicken Meatballs (-18 °C) and Its Mechanism Analysis

The inhibitory effect of guava leaf polyphenols (GLP) on advanced glycation end products (AGEs) of frozen chicken meatballs (−18 °C) and its possible inhibitory mechanism was investigated. Compared with control samples after freezing for 6 months, acidic value (AV), lipid peroxides, thiobarbituric acid reactive substance (TBARS), A294, A420, glyoxal (GO), Nε-carboxymethyl-lysine (CML), pentosidine, and fluorescent AGEs of chicken meatballs with GLP decreased by 11.1%, 22.3%, 19.5%, 4.30%, 8.66%, 8.27%, 4.80%, 20.5%, and 7.68%, respectively; while free sulfhydryl groups the content increased by 4.90%. Meanwhile, there was no significant difference between meatballs with GLP and TP in AV, A294, GO, and CML (p > 0.05). Correlation analysis indicated that GO, CML, pentosidine, and fluorescent AGEs positively correlated with AV, TBARS, A294, and A420, while GO, CML, pentosidine, and fluorescent AGEs negatively correlated with free sulfhydryl groups. These results manifested GLP could inhibit AGEs formation by inhibiting lipid oxidation, protein oxidation, and Maillard reaction. The possible inhibitory mechanism of GLP on the AGEs included scavenging free radicals, capturing dicarbonyl compounds, forming polyphenol−protein compounds, and reducing the formation of glucose. Therefore, the work demonstrated that the addition of plant polyphenols may be a promising method to inhibit AGEs formation in food.

The drip loss inhibitory mechanism of nanowarming in jumbo squid (Dosidicus gigas) mantles: protein structure and molecular dynamics simulation

BACKGROUND

The magnetic nanoparticles plus microwave thawing (MNPMT), a new rewarming technology entitled 'nanowarming', can serve as an effective method to achieve rapid and uniform thawing, thus reducing drip loss. The purpose of this study was to decipher the drip loss inhibitory mechanism of MNPMT in jumbo squid (Dosidicus gigas) from the perspectives of protein structure and ice crystal recrystallization. A number of different techniques such as dynamic rheology, Raman spectra, intrinsic fluorescence measurement, and ultraviolet (UV) absorption spectra were conducted to analyze myofibrillar protein conformation and stability of jumbo squid. Scanning electron microscopy (SEM) and myofibrillar fragmentation index (MFI) were used to observe the growth of ice crystals. The interaction between magnetic nanoparticles (MNPs) and ice crystals was studied by using molecular dynamic (MD) simulation.

RESULTS

MNPMT exhibited the highest storage modulus (G') value at 90 °C, suggesting the protein conformation was more stable. The increase in α-helices, fluorescence intensity and characteristic absorption peak of MNPMT illustrated that MNPMT can effectively maintain the secondary and tertiary structure of the protein. Compared with cold storage thawing (CST) and microwave thawing (MT), the MFI value of MNPMT was significantly decreased (P < 0.01). The result of MD simulation showed that MNPs displayed a tendency to gradually approach the surface of ice crystals, and induced a certain degree of damage to the ice crystal surface, thereby markedly inhibiting ice crystal recrystallization.

CONCLUSION

MNPMT can reduce the drip loss by keeping the protein conformation stable and inhibiting the recrystallization of ice crystals during the thawing process. © 2022 Society of Chemical Industry.

Comparison of Effects from Ultrasound Thawing, Vacuum Thawing and Microwave Thawing on the Quality Properties and Oxidation of Porcine Longissimus Lumborum

The effects of vacuum thawing (VT), ultrasound thawing (UT) and microwave thawing (MT) on the quality, protein and lipid oxidation, internal temperature distribution and microstructure of porcine longissimus lumborum were compared. The results showed that a significant decrease (p < 0.05) in quality compared with those of fresh meat (FM) occurred for all of the thawing samples, especially for the MT samples. Changes in quality of the VT and UT samples were less significant than those of the MT samples. The increases in carbonyl content and TBARS value indicated that proteins and lipids in the thawing samples were oxidized. The decreases in uniform degrees of internal temperature distributions of muscles from the thawing samples were analysed by infrared thermography. Scanning electron microscopy images showed that the myofibril arrangements of thawing samples were looser than those of the FM samples with compact and ordered structure, which was proven by the obvious increase in the myofibril gap value of the thawing samples.

Effects of Ultrasound-Assisted Vacuum Impregnation Antifreeze Protein on the Water-Holding Capacity and Texture Properties of the Yesso Scallop Adductor Muscle during Freeze-Thaw Cycles

The effect of antifreeze protein (AFP) on the water-holding capacity (WHC) and texture properties of the Patinopecten yessoensis adductor muscles during freeze–thaw cycles (FTCs) were evaluated based on three impregnation methods: general impregnation (GI), vacuum impregnation (VI), and ultrasound-assisted VI (US-VI). The WHC, texture properties, and tissue microstructure were all evaluated. Results showed that the WHC and texture properties of adductor muscle were significantly improved in the VI and US-VI groups during FTCs (p < 0.05). The WHC of the adductor muscle in the US-VI group was maximally enhanced in terms of yield (6.63%), centrifugal loss, cooking loss, and T₂₂. The US-VI group of the adductor muscle had the optimal chewiness and springiness compared to others, and the shear force and hardness were most effectively enhanced by VI. The growth and recrystallization of ice crystals in the frozen adductor muscle were significantly inhibited by VI and US-VI. The average cross-sectional area and roundness of ice crystals in the US-VI group were decreased by 61.89% and increased by 22.22% compared with those of the control, respectively. The partial least squares regression (PLSR) model further confirmed that the WHC and texture properties of the adductor muscle were correlated appreciably with the degree of modification of ice crystal morphology through the AFP.

Recent development in evaluation methods, influencing factors and control measures for freeze denaturation of food protein

Frozen storage is most widely adopted preservation method to maintain food freshness and nutritional attributes. However, at low temperature, food is prone to chemical changes such as protein denaturation and lipid oxidation. In this review, we discussed the reasons and influencing factors that cause protein denaturation during freezing, such as freezing rate, freezing temperature, freezing method, etc. From the previous literatures, it was found that frozen storage is commonly used to prevent freeze induced protein denaturation by adding cryoprotectants to food. Some widely used cryoprotectants (for example, sucrose and sorbitol) have been reported with higher sweetness and weaker cryoprotective abilities. Therefore, this article comprehensively discusses the new cryopreservation methods and providing comparative study to the conventional frozen storage. Meanwhile, this article sheds light on the freeze induced alterations, such as change in functional and gelling properties. In addition, this article could be helpful for the prolonged frozen storage of food with minimum quality related changes. Meanwhile, it could also improve the commercial values and consumer satisfaction of frozen food as well.