Effects of high pressure freezing (HPF) on denaturation of natural actomyosin extracted from prawn (Metapenaeus ensis)

The effect of structural changes on the activity of peroxidase with different initial state under high-pressure freezing

The combined impact of initial state, pressure, and freezing on peroxidase denaturation during high-pressure freezing (HPF) processing of enzyme-containing foods remains unclear. This study investigated solid-liquid (initial low/high concentration) biphasic peroxidase using spectroscopic and computer simulation techniques to analyze structural changes affecting peroxidase (POD) activity under HPF. The results indicate that the primary factors determining POD activity during HPF treatment can be ranked as follows: concentration > physical state > pressure > freezing. Higher initial concentrations strengthen protein interactions, leading to a 1% increase in the molecular diameter and a 34% increase in molecular height of HL-POD, thereby increasing aggregation likelihood during crystallization and facilitating structural changes that activate enzymes by 6-17%. The amide I peak proves to be a reliable indicator for monitoring both POD activity and structural alterations. This study offers valuable insights for optimizing HPF technology in food processing.

Effect of ultrasonic treatment on the structure and emulsification properties of soybean isolate protein-hyaluronic acid complexes and the stability of their loaded astaxanthin emulsions

The purpose of this work was to prepare an astaxanthin emulsion stabilized by a soybean isolate protein (SPI)-hyaluronic acid (HA) complex and to investigate its protective effect on astaxanthin. In order to examine the impact of various ultrasonic energies (0 W-300 W) on the structural characteristics of the complex and the stability of the emulsion, the SPI-HA complex was created via ultrasonography. The findings demonstrated that ultrasonication may had an impact on the hydrophobic, electrostatic, and hydrogen bonding interactions between SPI and HA, which caused the protein structure to unfold and reveal the interior hydrophobic amino acid residues. Moreover, ultrasonication enhanced the emulsification qualities of SPI-HA complexes by lowering their average particle size. The rheological findings demonstrated that the emulsion's viscosity and energy storage modulus (G') were considerably decreased by the ultrasonic treatment. The appearance of the emulsions and optical microscopy results further indicated that the emulsions prepared from SPI-HA had superior storage stability, pH stability, and light stability compared to pure SPI. SPI-HA exhibited superior emulsion stability and lower particle size at 150 W ultrasonic power. The AST incorporated in the emulsion was also well protected. The emulsion effectively slows down the degradation of AST. The findings of this study may help create more robust and natural emulsion delivery systems that guarantee the continuous or regulated release of lipophilic bioactive compounds.

Effects of different power multi-frequency ultrasound-assisted thawing on the quality characteristics and protein stability of large yellow croaker (Larimichthys crocea)

This study investigated the impact of multi-frequency ultrasound-assisted (20/28/40 kHz) thawing (MUAT) at different power levels (195, 220, 245, and 270 W, respectively) on the flesh quality and protein stability of large yellow croakers. Compared with flowing water thawing (FWT) and the other MUAT sample, flesh quality results indicated that the MUAT-220 W significantly reduced (p < 0.05) thawing loss, total volatile base nitrogen (TVB-N), total free amino acids (FAAs) and thiobarbituric acid reactive substances (TBARS). Low-field nuclear magnetic resonance (LF-NMR) spectroscopy indicated that MUAT-220 W samples had higher immobilized water content and lower free water content. In addition, the MUAT-220 W sample contained higher sulfhydryl and lower carbonyl contents compared to the FWT sample. Secondary and tertiary structural results of myofibrillar proteins (MPs) showed that MUAT-220 W significantly reduced thawing damage to MPs. Therefore, MUAT-220 W improved the quality and protein stability of the large yellow croaker during the defrosting process.

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.

Effect of L-cysteine on the physicochemical properties of heat-induced sheep plasma protein gels

The effects of different l-Cysteine additions (0-2 %) on the gel properties, microstructure and physicochemical stability of sheep plasma protein gels were studied. The introduction of l-Cys significantly improved the water retention capacity and whiteness of the plasma protein gel (p < 0.05). The addition of 0.2 %-0.4 % l-Cys increased gel strength, but l-Cys had no significant effect on gel elasticity (p < 0.05). Scanning electron microscopy confirmed that the addition of l-Cys also promoted the formation of a porous three-dimensional network structure in the gel. Raman spectroscopy and SDS-PAGE revealed that the addition of l-Cys generally reduced α-helix structures in protein gels and promoted the formation of β-folds. Addition of 0.2 % l-Cys treatment leading to the greatest increase in disulfide bonds, and its surface hydrophobicity and endogenous fluorescence intensity were the largest. At this time, the comprehensive performance of sheep plasma protein gel is the best performance.

Whey Protein Hydrolysate Improved the Structure and Function of Myofibrillar Protein in Ground Pork during Repeated Freeze-Thaw Cycles

Whey protein hydrolysate (WPH) has made a breakthrough in inhibiting oxidative deterioration and improving the quality of meat products during storage. Based on our previous study of extracting the most antioxidant active fraction I (FI, the molecular weight < 1 kDa) from whey protein hydrolysates of different molecular weights, the present study continued to delve into the effects of WPH with fraction I on the structure and function of myofibrillar proteins (MP) in ground pork during the freeze-thaw (F-T) cycles. With the number of F-T cycles raised, the total sulfhydryl content, the relative contents of α-helix, Ca2+-ATPase activity, K+-ATPase activity, solubility, emulsion activity index (EAI), and emulsion stability index (ESI) of MP gradually decreased. Conversely, the carbonyl content and the relative content of random curl showed an increasing trend. In particular, the damage to the structure and the function of MP became more pronounced after three F-T cycles. But, during F-T cycles, FI stabilized the structure of MP. Compared to the control group, the 10% FI group showed a remarkable improvement (p < 0.05) in the total sulfhydryl content, Ca2+-ATPase activity, K+-ATPase activity, solubility, EAI and ESI after multiple F-T cycles, suggesting that 10% FI could effectively inhibit protein oxidation and had the influence of preserving MP function properties. In conclusion, WPH with fraction I can be used as a potential natural antioxidant peptide for maintaining the quality of frozen processed meat products.

Nano Freezing-Thawing of Atlantic Salmon Fillets: Impact on Thermodynamic and Quality Characteristics

The presence of magnetic nanoparticles (MNPs) suppresses ice nucleation and growth during freezing and thawing. In this study, the effects of MNPs-assisted cryogenic freezing integrated with MNP-combined microwave thawing (NNMT) on the thermodynamic and quality changes of salmon fillets were investigated. Results have shown that NNMT raises Tg (glass transition temperature) and Tmax (transition temperature), thus improving the storage stability of salmon fillets. MNPs-assisted freezing and thawing treatment, especially NNMT treatment, significantly improved the water holding capacity, texture, color, and other quality characteristics of salmon fillets. In addition, the lipid and protein oxidation degrees of the NNMT treatment were the lowest, while the myofibrillar protein solubility of NNMT was the highest (87.28%). This study demonstrated that NNMT has minimal impact on the freezing-thawing quality of salmon fillets, making it a more suitable option for the preservation of aquatic foods.

Physicochemical and structural changes of myofibrillar proteins in muscle foods during thawing: Occurrence, consequences, evidence, and implications

Myofibrillar protein (MP) endows muscle foods with texture and important functional properties, such as water-holding capacity (WHC) and emulsifying and gel-forming abilities. However, thawing deteriorates the physicochemical and structural properties of MPs, significantly affecting the WHC, texture, flavor, and nutritional value of muscle foods. Thawing-induced physicochemical and structural changes in MPs need further investigation and consideration in the scientific development of muscle foods. In this study, we reviewed the literature for the thawing effects on the physicochemical and structural characters of MPs to identify potential associations between MPs and the quality of muscle-based foods. Physicochemical and structural changes of MPs in muscle foods occur because of physical changes during thawing and microenvironmental changes, including heat transfer and phase transformation, moisture activation and migration, microbial activation, and alterations in pH and ionic strength. These changes are not only essential inducements for changes in spatial conformation, surface hydrophobicity, solubility, Ca2+ -ATPase activity, intermolecular interaction, gel properties, and emulsifying properties of MPs but also factors causing MP oxidation, characterized by thiols, carbonyl compounds, free amino groups, dityrosine content, cross-linking, and MP aggregates. Additionally, the WHC, texture, flavor, and nutritional value of muscle foods are closely related to MPs. This review encourages additional work to explore the potential of tempering techniques, as well as the synergistic effects of traditional and innovative thawing technologies, in reducing the oxidation and denaturation of MPs and maintaining the quality of muscle foods.

The antibacterial mechanism of compound preservatives combined with low voltage electric fields on the preservation of steamed mussels (Mytilus edulis) stored at ice-temperature

Mussels are a kind of economically valuable ocean bivalve shellfish. It has a short harvest period and is susceptible to contamination during storage and processing. Having proper preservation methods is critical to prevent quality deterioration. However, the effect of low voltage variable frequency electric field and compound preservative on the freshness of steamed mussels in ice-temperature storage are still unknown. We utilized the method of coefficient variation weighting to calculate the overall scores of steamed mussels stored under different preservation conditions. The protein physicochemical properties of samples, the growth curves of two dominant spoilage bacteria; Bacillus subtilis and Pseudomonas in the mussels as well as the Structural changes of the cell membranes were mensurated. The results show that compared with the preservative group and the low voltage variable frequency electric field group, the compound preservatives combined with the electric field group had the highest overall score and thus the best preservation effect. Compared with the blank group, the total sulfhydryl content and myogenic fibrin content of the combined group decreased at the slowest rate, 19.46%, and 44.92%, respectively. The hydrophobicity of the protein surface increased by only 5.67%, with the best water retention, indicating that the samples of the combined group had the least protein deterioration in the combined group. The inhibition mechanism of the combined group inhibited the growth of two dominant spoilage bacteria: Bacillus subtilis and Pseudomonas, in the mussels, destroying the integrity of the cell membrane structure and changing the cell morphology. Overall, we found that the combination of the composite preservatives and the low voltage variable frequency electric field can maintain the best quality of steamed mussels during ice-temperature storage and slow down the rate of protein deterioration during storage. This study proposed a new method of mussel preservation, which provides a new idea for the application of low voltage variable frequency electric field and compound preservative in the preservation of aquatic products.

Ultrasound combined with slightly acidic electrolyzed water thawing of mutton: Effects on physicochemical properties, oxidation and structure of myofibrillar protein

The effects of air thawing (AT), water immersion thawing (WT), microwave thawing (MT) and ultrasound combined with slightly acidic electrolyzed water thawing (UST) on the myofibrillar protein (MP) properties (surface hydrophobicity, solubility, turbidity, particle size and zeta potential), protein oxidation (carbonyl content and sulfhydryl content) and structure (primary, secondary and tertiary) of frozen mutton were investigated in comparison with fresh mutton (FM). The solubility and turbidity results showed that the MP properties were significantly improved in the UST treatment. UST treatment could effectively reduce the MP aggregation and enhance the stability, which was similar to the FM. In addition, UST treatment could effectively inhibit protein oxidation during thawing as well. The primary structure of MP was not damaged by the thawing methods. UST treatment could reduce the damage to MP secondary and tertiary structure during the thawing process compared to other thawing methods. Overall, the UST treatment had a positive influence in maintaining the MP properties by inhibiting protein oxidation and protecting protein structure.

Changing the IgE Binding Capacity of Tropomyosin in Shrimp through Structural Modification Induced by Cold Plasma and Glycation Treatment

Tropomyosin (TM) is the major allergen of shrimp (Penaeus chinensis). Previous studies showed that separate cold plasma or glycation have their drawback in reducing allergenicity of TM, including effectiveness and reliability. In the current study, a new processing combining cold plasma (CP) and glycation was proposed and its effect on changing IgE binding capacity of TM from shrimp was investigated. Obtained results showed the IgE binding capacity of TM was reduced by up to 40% after CP (dielectric barrier discharge, 60 kV, 1.0 A) combined with glycation treatment (4 h, 80 °C), compared with the less than 5% reduction after single CP or glycation treatment. Notably, in contrast to the general way of CP prompting glycation, this study devised a new mode of glycation with ribose after CP pretreatment. The structural changes of TM were explored to explain the decreased IgE binding reactivity. The results of multi-spectroscopies showed that the secondary and tertiary structures of TM were further destroyed after combined treatment, including the transformation of 50% α-helix to β-sheet and random coils, the modification and exposure of aromatic amino acids, and the increase of surface hydrophobicity. The morphology analysis using atomic force microscope revealed that the combined processing made the distribution of TM particles tend to disperse circularly, while it would aggregate after either processing treatment alone. These findings confirmed the unfolding and reaggregation of TM during combined processing treatment, which may result in the remarkable reduction of IgE binding ability. Therefore, the processing of CP pretreatment combined with glycation has the potential to reduce or even eliminate the allergenicity of seafood.

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.

Regulatory mechanisms governing collagen peptides and their 3D printing application for frozen surimi

Myofibrillar proteins (MPs) are important to the gel formation that occurs in frozen surimi. Importantly, their unique gel-forming ability indicates that surimi may be a promising material for use in 3D printing. The objective of the present study was to investigate the effects of collagen peptides on the cryoprotection of MPs during freeze-thaw (FT) cycles and the subsequent printability of surimi. The results showed that the collagen peptide had both protective and destructive actions during the tested FT cycles. The addition of 1.0% collagen peptide provided significant cryoprotection to the MPs. This addition effectively maintained the structural stability of MPs while also weakening FT effects on bound water and its mobility. We also assessed the rheological and 3D-printing characteristics of surimi with 1.0% collagen peptide. The rheological results indicated that the surimi with collagen peptides had better characteristics, including shear-thinning behavior, better recovery, and improved mechanical properties. Combined with the actual printing effect, materials with good shear-thinning behavior, high apparent viscosity, and high recovery might be more suitable for 3D printing. Moreover, the high G' contributed to good structural maintenance after printing. Collectively, these results indicated that collagen peptide may serve as a new, low-sugar cryoprotectant for use in surimi. Moreover, that its use would result in a healthier system that has increased stability, precision, and formability with applications in extrusion-based 3D printing. The results of this study provide theoretical reference for the development of new surimi materials with freezing stability and good 3D printing performance. PRACTICAL APPLICATION: This study confirmed the protective action of 1.0% collagen peptides for surimi and the contribution of it to well printing precision and structure maintenance for 3D printing, providing a firm foundation for the use of collagen peptide as a low-sugar cryoprotectant and developed a new type of surimi as a food material for 3D printing.

The rise of thawing drip: Freezing rate effects on ice crystallization and myowater dynamics changes

To better reveal the formation of thawing drip, this study investigated the ice crystallization and myowater dynamics changes in frozen bovine Longissimus dorsi muscle. In ultra-fast freezing a narrow distribution of ice crystals size was observed together with higher solubility, lower surface hydrophobicity and stable second structure of myofibrillar protein. Accordingly, ultra-fast freezing samples exhibited significantly lower thaw loss (4.35 %) than slow freezing (8.22 %) after 48 h of freezing. Upon thawing, 2D T₁-T₂ relaxation spectra indicated a myowater redistribution, in which slow freezing led to major migration of water from immobile water to free water. Besides, T₁ and T₂ relaxation times showed an increasing trend with freezing process. The proton density images displayed major free water seep from myofibrils to the surface of muscle. Consequently, the water from the "reservoir" (free water) flowed into the "channel" (the widened spaces between muscle fibres), and formed into the thawing drip.

Seafood Processing, Preservation, and Analytical Techniques in the Age of Industry 4.0

Fish and other seafood products are essential dietary components that are highly appreciated and consumed worldwide. However, the high perishability of these products has driven the development of a wide range of processing, preservation, and analytical techniques. This development has been accelerated in recent years with the advent of the fourth industrial revolution (Industry 4.0) technologies, digitally transforming almost every industry, including the food and seafood industry. The purpose of this review paper is to provide an updated overview of recent thermal and nonthermal processing and preservation technologies, as well as advanced analytical techniques used in the seafood industry. A special focus will be given to the role of different Industry 4.0 technologies to achieve smart seafood manufacturing, with high automation and digitalization. The literature discussed in this work showed that emerging technologies (e.g., ohmic heating, pulsed electric field, high pressure processing, nanotechnology, advanced mass spectrometry and spectroscopic techniques, and hyperspectral imaging sensors) are key elements in industrial revolutions not only in the seafood industry but also in all food industry sectors. More research is still needed to explore how to harness the Industry 4.0 innovations in order to achieve a green transition toward more profitable and sustainable food production systems.

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.

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.

Finite Element Method for Freezing and Thawing Industrial Food Processes

Freezing is a well-established preservation method used to maintain the freshness of perishable food products during storage, transportation and retail distribution; however, food freezing is a complex process involving simultaneous heat and mass transfer and a progression of physical and chemical changes. This could affect the quality of the frozen product and increase the percentage of drip loss (loss in flavor and sensory properties) during thawing. Numerical modeling can be used to monitor and control quality changes during the freezing and thawing processes. This technique provides accurate predictions and visual information that could greatly improve quality control and be used to develop advanced cold storage and transport technologies. Finite element modeling (FEM) has become a widely applied numerical tool in industrial food applications, particularly in freezing and thawing processes. We review the recent studies on applying FEM in the food industry, emphasizing the freezing and thawing processes. Challenges and problems in these two main parts of the food industry are also discussed. To control ice crystallization and avoid cellular structure damage during freezing, including physicochemical and microbiological changes occurring during thawing, both traditional and novel technologies applied to freezing and thawing need to be optimized. Mere experimental designs cannot elucidate the optimum freezing, frozen storage, and thawing conditions. Moreover, these experimental procedures can be expensive and time-consuming. This review demonstrates that the FEM technique helps solve mass and heat transfer equations for any geometry and boundary conditions. This study offers promising insight into the use of FEM for the accurate prediction of key information pertaining to food processes.

The Formation and Control of Ice Crystal and Its Impact on the Quality of Frozen Aquatic Products: A Review

Although freezing has been used to delay the deterioration of product quality and extend its shelf life, the formation of ice crystals inevitably destroys product quality. This comprehensive review describes detailed information on the effects of ice crystals on aquatic products during freezing storage. The affecting factors (including nucleation temperature, freezing point, freezing rate, and temperature fluctuation) on the size, number, distribution, and shape of ice crystals are also elaborated in detail. Meanwhile, the corresponding technologies to control ice crystals have been developed based on these affecting factors to control the formation of ice crystals by inhibiting or inducing ice crystallization. In addition, the effects of ice crystals on the water, texture, and protein of aquatic products are comprehensively discussed, and the paper tries to describe their underlying mechanisms. This review can provide an understanding of ice crystallization in the aquatic products during freezing and contribute more clues for maintaining frozen food quality.

Impacts of high pressure assisted freezing on the denaturation of polyphenol oxidase

The mechanism of enzyme protein denaturation induced by high pressure freezing is complicated and unclear as this process involves Pressure-Factors (pressure and time) and Freezing-Factors (temperature, phase transition, recrystallization, and ice crystal types). In this study, the thermodynamics and conformation changes of mushroom polyphenol oxidase (PPO) under high pressure freezing treatments (HPF, ^{100,150,200,300,400,500MPa}P_-20°C/30min) and high pressure processes (HPP) followed with normal pressure immersion freezing (HPP-IF, ^100-500MPaP_25°C/30min - ^0.1MPaP_-20°C/30min) are investigated as compared with that processed under high pressure processes (HPP, ^100-500MPaP_25°C/30min) and normal pressure immersion freezing process (IF, ^0.1MPaP_-20°C/30min). The results suggested that the treated PPO with the same enzyme activity may have various thermodynamic characteristics and conformations; Pressure-Factors play the main roles in the denaturation of the PPO during the HPF treatment, and Freezing-Factors can weak the effect of Pressure-Factors on PPO denaturation; The treated PPO may be transferred into a partially fold intermediate state.

Terahertz spectroscopy technology as an innovative technique for food: Current state-of-the-Art research advances

With the dramatic development of source and detector components, terahertz (THz) spectroscopy technology has recently shown a renaissance in various fields such as medical, material, biosensing and pharmaceutical industry. As a rapid and noninvasive technology, it has been extensively exploited to evaluate food quality and ensure food safety. In this review, the principles and processes of THz spectroscopy are first discussed. The current state-of-the-art applications of THz and imaging technologies focused on foodstuffs are then discussed. The advantages and challenges are also covered. This review offers detailed information for recent efforts dedicated to THz for monitoring the quality and safety of various food commodities and the feasibility of its widespread application. THz technology, as an emerging and unique method, is potentially applied for detecting food processing and maintaining quality and safety.

Effects of T-2 toxin on the muscle proteins of shrimp (Litopenaeus vannamei) - a proteomics study

BACKGROUND

T-2 toxin (T-2) is a potent mycotoxin and a common contaminant of aquatic animal feed, posing a serious risk to health and aquatic animals. We investigated the effect of T-2 on shrimp muscle proteins using proteomics and conventional biochemical methods. Shrimp were fed a diet containing T-2 at 0-12.2 mg kg^-1 for 20 days, and changes to the muscle protein composition, ATPase activities, and the sulfhydryl (SH) content and hydrophobicity of actomyosin (AM) were determined. A proteomics study of the proteins was conducted with sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), two-dimensional (2D) electrophoresis, and matrix-assisted laser desorption/ionization - time of flight mass spectrometry (MALDI-TOF/TOF MS).

RESULTS

Exposure to T-2 markedly affected the muscle protein composition of shrimp in a concentration-responsive manner that displayed a diphasic effect. At a low T-2 concentration (1.2 mg kg^-1 ), the levels of three major muscle proteins (myofibrillar, sarcoplasmic, and stroma) increased but at higher concentrations they declined progressively. T-2 exposure also led to a breakdown of muscle proteins as evidenced by increases in alkali-soluble protein and the surface hydrophobicity (SoANS) of AM. Thirty differentially expressed proteins were detected, 12 of which showed a concentration-response relationship with T-2 exposure. Among them, 11 homologous proteins were identified by mass spectrometry (MS), with several being key enzymes in energy metabolism.

CONCLUSION

This study demonstrated that T-2 exposure at medium to high concentrations could significantly affect the protein composition and quality of shrimp muscle, and potentially some of its key metabolisms. One of the arginine kinases (spot 27) was particularly responsive to T-2 and could potentially be used as a biomarker protein for T-2 intoxication by shrimp. © 2019 Society of Chemical Industry.

Effects of high hydrostatic pressure-assisted thawing on the physicohemical characteristics of silver pomfret (Pampus argenteus)

Effects of high hydrostatic pressure-assisted thawing (HPAT, 100, 150, and 200 MPa) on the physicochemical characteristics of silver pomfret were evaluated in comparison with conventional (water immersion thawing, WIT) thawed samples. HPAT significantly decreased the thawing time, as well as the cooking and total losses. The maximum water holding capacity was observed at 100 MPa. Color changed obviously at ≥150 MPa, resulting in a cooked appearance. Samples thawed with HPAT showed better texture quality and lower lipid oxidation. The levels of myofibrillar protein oxidation and surface hydrophobicity increased, while Ca2+-ATPase activities decreased as the pressure increased. The oxidation of myofibrillar protein was significantly decreased at 100 MPa; total sulfhydryl content was 30.85% higher than that of WIT. Overall, 100 MPa is the optimum treatment condition for silver pomfret thawing without negative effects on quality of the product. HPAT can be a potential alternative to produce high-quality thawed fish.

Effects of Mild Oxidative and Structural Modifications Induced by Argon Plasma on Physicochemical Properties of Actomyosin from King Prawn ( Litopenaeus vannamei)

In the present work, the structure and physicochemical properties of natural actomyosin (NAM) extracted from king prawn ( Litopenaeus vannamei) and subjected to atmospheric pressure plasma jet (APPJ) generated in argon gas as a function of the treatment time were examined. The results revealed that prawn NAM exhibited a correlating decrease in pH from 7.06 ± 0.03 to 6.92 ± 0.02 and a slight increase ( p > 0.05) in solubility from 91.89 ± 1.57 to 96.86 ± 1.19 within the first few minutes of plasma exposure as a result of the formation of soluble aggregates. A rise in turbidity was also noted, confirming the occurrence of protein aggregation. These changes were also accompanied by a rise in emulsifying activity from 48.96 ± 1.66 to 67.31 ± 1.39 m²/g ( p < 0.05) and a nearly 50% increase in foaming capacity after 5 min of APPJ exposure. The modulation of these properties occurred as a result of conformational changes in NAM evident by various complementary structural analyses conducted. Overall, these findings show that mild oxidation from argon plasma can be used for modification of protein functionality and emphasize the need for optimal selection of plasma processing conditions.