Cryoprotective characteristics of different sugar alcohols on peeled Pacific white shrimp (Litopenaeus vannamei) during frozen storage and their possible mechanisms of action

Combining soy protein isolate and sorbitol as cryoprotectants for portuguese oysters (Crassostrea angulata) and investigating the effect on ice crystal damage

Freezing and thawing often cause significant damage to the muscle tissue of seafood products, reducing their quality and shelf life. This study investigated the combined effects of soy protein isolate (SPI) and sorbitol (So) to mitigate freezing damage in portuguese oysters. A single-factor analysis was performed to determine the optimal concentrations of SPI (1 %-9 %), So (1 %-9 %), and soaking times (30-90 min) based on the steaming loss. An orthogonal experimental design further assessed the combined effects of these factors. The results demonstrated that the combination of 6.0 % SPI and 4.0 % So reduced steaming loss by 10 % and oxidative damage by 0.17 mg MDA/kg. It minimized ice crystal formation in oyster muscle tissue, reduced Ca2+-ATPase inactivation, and decreased total sulfhydryl group loss. These findings indicate that the SPI-So composite effectively preserves the structural and functional properties of frozen oysters, offering a promising natural cryoprotectant for the seafood industry.

Cryoprotective effect of soluble soybean polysaccharides and enzymatic hydrolysates on the myofibrillar protein of Nemipterus virgatus surimi

Cryoprotective effect and potential mechanism of soluble soybean polysaccharides (SSPS) and enzymatic hydrolysates on surimi was investigated. After hydrolysis, the molecular weight of SSPS significantly decreased, and the hydrolysates prepared by endo-polygalacturonase (EPG-SSPS) was the lowest (154 kDa). Infrared spectrum analysis revealed that enzymatic hydrolysis didn't alter the functional groups of SSPS, but it did augment the exposure to hydroxyl groups. Surimi containing 5 % EPG-SSPS had the lowest freezable water after 20 days of frozen storage. Furthermore, the 5 % EPG-SSPS group manifested the highest metrics in total sulfhydryl (8.0 × 10-5 mol/g), active sulfhydryl content (6.7 × 10-5 mol/g), Ca2+-ATPase activity, and exhibited the lowest level in carbonyl content, surface hydrophobicity (153 μg). Notably, the 5 % EPG-SSPS maintained the stability of protein structure. Conclusively, SSPS enzymatic hydrolysate using endo-polygalacturonase imparted superior cryoprotective effect on the myofibrillar protein of surimi, and the mechanism might be a decrease in molecular weight and exposure of hydroxyl groups.

The influence of γ-PGA on the quality of cooked frozen crayfish during temperature fluctuations

The purpose of this study was to compare the influences of gamma-poly glutamic acid (γ-PGA) (1, 2, 3, and 4 %) to see which could outperform conventional cryoprotectant mixture (4 % sorbitol + 4 % sucrose) on cooked crayfish properties, such as physicochemical, textural qualities, oxidation reaction, water distributions, and microstructure integrity, during different freeze-thaw cycles. Crayfish quality characteristics improved significantly as γ-PGA concentration increased compared to control samples.Adding γ-PGA 4 % reduced the carbonyl content from 4.20 to 3.00 nmol/ mg protein during fluctuation-1 (F1), and from 4.15 to 2.80 nmol/ mg protein during fluctuation-2 (F2) compared to control samples. Furthermore, it increased the total sulfhydryl content from 4.15 and 4.76 to 6.19 and 6.47 mol/105 g protein during F1 and F2 and after five freeze-thaw cycles (FTC). This suggests that this concentration was more effective at controlling protein changes than other concentrations. γ-PGA generally enhanced the water-holding capacity by preventing protein denaturation and limiting ice crystal recrystallization. As a result, microstructure stability was evident, texture degradation was avoided, and the crayfish's color was preserved.

Exploring xylitol as a low-salt alternative for effective inhibition of gelation in frozen egg yolks

Xylitol and NaCl were studied as alternative inhibitors of gelation in frozen egg yolks, considering the current dietary preference for low salt and low sucrose intake. The effects of different ratios of xylitol and NaCl on gelation were investigated. Compared to the control group, all treatment groups showed decreased egg yolk particle size and turbidity, increased solubility, surface hydrophobicity, λmax, and fluorescence intensity, reduced loss of free water, and enhanced yolk fluidity. The addition of xylitol and NaCl effectively prevented ice crystal growth, minimized protein denaturation caused by water loss, and formed complexes with proteins and water lost during freezing, thereby inhibiting the aggregation of protein molecules and the formation of gels. This study presents a novel and healthier strategy for inhibiting gelation of frozen egg yolk using xylitol and NaCl.

Effects of cold atmospheric plasma pre-treatment on maintaining the quality of ready-to-eat drunken red shrimp (Solenocera crassicornis) stored at chilled conditions

This present study investigated the effect of cold atmospheric plasma (CAP) pre-treatment on the quality of ready-to-eat drunken red shrimp (Solenocera crassicornis) during chilled storage. The shrimp were pre-treated with the CAP at 40 kV and 36 kH for 100 s in a plasma generating equipment before the drunken treatment and compared with an untreated control sample. The results showed that the CAP pre-treatment significantly inhibited the total viable count (TVC) values, total volatile basic nitrogen (TVB-N) content, and polyphenol oxidase (PPO) activity of the drunken shrimp compared to the control treatment. Furthermore, the CAP pre-treatment also significantly maintained the myofibrillar protein (MP) content, texture properties, and a more stable histological structure of muscle fibers compared to the control. High-throughput sequencing results confirmed that the CAP pre-treatment significantly reduced the diversity and abundance of several bacteria in the shrimp. Gas chromatography-ion mobility spectrometry (GC-IMS) analysis detected that the CAP pre-treatment effectively maintained the stability of volatile organic compounds (VOCs). These findings provide valuable theoretical support for the processing and storage of drunken shrimp.

Effects of immersing treatment of curcumin and piperine combined with vacuum packaging on the quality of salmon (Salmo salar) during cold chain logistics

In order to study the effects of the compound preservatives (curcumin and piperine (CP)) and vacuum packaging (VP) on the quality of salmon during cold chain logistics suffered from temperature abuse, the physiochemical indexes (texture, water holding capacity (WHC), total volatile basic nitrogen (TVB-N), thiobarbituric acid reactive substances (TBARS), free amino acids (FAA) contents), microbial indicators (total mesophilic bacteria count (MBC), total psychrotrophic bacteria count (PBC), H2S-producing bacteria count (HSBC)) were determined, and the moisture changes were explored by near-infrared (NIR) spectroscopy and low-field nuclear magnetic resonance (LF-NMR). The results showed that the treatment of curcumin and piperine in combination with vacuum packaging could maintain the quality of salmon suffered from temperature abuse most effectively. At the end of storage, the MBC of VP+CP was only 4.95 log CFU/g, which was about 1 log CFU/g lower than the control sample stored at the same condition. The combined treatment also retarded the increase of TVB-N, TBARS, and the decrease of hardness, springiness, and a* value, as well as water migration in salmon, contributing to higher water holding capacity and better appearance. Besides, VP+CP retarded the decrease of free glutamate, which contributed to umami taste. Due to the biological activity and safety of the preserves, the combined treatment could be a promising method for preservation of seafood.

Phosphorylated Trehalose Suppresses the Denaturation of Myofibrillar Proteins in Peeled Shrimp (Litopenaeus vannamei) during Long-Term Frozen Storage

The protective effects of phosphorylated trehalose on the quality and characteristics of peeled shrimp (Litopenaeus vannamei) were determined. Quality changes in treated samples were evaluated by assessing the physicochemical properties of myofibrillar proteins (MP) and compared to fresh water-, sodium tripolyphosphate-, and trehalose-treated samples during 12 weeks of frozen storage. The sensitivity of MP to oxidation and denaturation was increased during frozen storage. Phosphorylated trehalose significantly improved the quality of shrimp by increasing water-holding capacity. Further analysis showed that the addition of phosphorylated trehalose reduced the decrease in soluble MP content, Ca²⁺-ATPase activity, and total sulfhydryl contents and also effectively inhibited the increase in the surface hydrophobicity of MP. In addition, atomic force microscopy and hematoxylin and eosin staining revealed that phosphorylated trehalose preserved the integrity of the myofibril microstructure. Thermal stability results further confirmed that the denaturation temperature and denaturation enthalpy of MP were improved by phosphorylated trehalose. Overall, phosphorylated trehalose suppresses the denaturation of MP in peeled shrimp during long-term frozen storage.

Effect of NaCl on the Rheological, Structural, and Gelling Properties of Walnut Protein Isolate-κ-Carrageenan Composite Gels

In this study, we discovered that a certain concentration of Na⁺ (15 mM) significantly improved the bond strength (12.94 ± 0.93 MPa), thermal stability (72.68 °C), rheological properties, and textural attributes of walnut protein isolate (WNPI)-κ-carrageenan (KC) composite gel. Electrostatic force, hydrophobic interaction, hydrogen bond, and disulfide bond were also significantly strengthened; the α-helix decreased, and the β-sheet increased in the secondary structure, indicating that the protein molecules in the gel system aggregated in an orderly manner, which led to a much denser and more uniform gel network as well as improved water-holding capacity. In this experimental research, we developed a new type of walnut protein gel that could provide technical support for the high-value utilization and quality control of walnut protein.

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.

The quality properties of frozen large yellow croaker fillets during temperature fluctuation cycles: improvement by cellobiose and carboxylated cellulose nanofibers

Frozen aquatic products undergo unavoidable quality changes owing to temperature fluctuations during frozen storage and distribution. This study investigated the effects of 1% cellobiose (CB), and 0.5 and 1% carboxylated cellulose nanofibers (CNF) on ice crystal growth and recrystallization of frozen large yellow croaker fillets exposed to temperature fluctuations. Denser and more uniformly distributed ice crystals were observed in the CB- and CNF-treated samples than in the water-treated samples. Furthermore, the addition of CB and CNF suppressed the conversion of bound water to frozen water in the samples during temperature fluctuation cycles, played a positive role in fixing the ionic and hydrogen bonds that stabilize the protein structure, limited the conformational transition from α-helix to β-sheet, and improved protein thermal stability. Based on turbidity, zeta potential, and confocal laser scanning microscopy (CLSM) analyses, the presence of CB and CNF restricted the protein aggregation. Compared with CB, CNF molecules with abundant carboxyl functional groups and longer morphology exhibited better cryoprotective effects. Moreover, the fillets were more improved protected from mechanical damage induced by large ice crystals at a higher CNF concentration. This study reveals the potential of CB and CNF as novel cryoprotectants.

Improving the Quality of Frozen Fillets of Semi-Dried Gourami Fish (Trichogaster pectoralis) by Using Sorbitol and Citric Acid

Semi-dried gourami fish (Trichogaster pectoralis) is popularly consumed domestically and exported as a frozen product. This study was conducted to prevent deterioration quality in frozen fish fillets during storage. This research aims to investigate the effects of sorbitol and citric acid at concentrations of 2.5% and 5% (w/w) of frozen gourami fish fillets compared to the fillets soaked in distilled water on physicochemical properties, such as cooking loss, cooking yield, drip loss, pH, TBARS, color, and texture profile analyses (TPA) during storage at -18 ± 2 °C for a period of 0, 20, and 40 days. The fish soaked in sorbitol and citric acid solutions had significantly (p < 0.05) higher protein and fat contents than the control sample. Sorbitol was able to retain moisture in the product; therefore, the drip loss and cooking loss were the lowest, and cooking yield was the highest among other samples (p < 0.05). The addition of 5% (w/v) citric acid in frozen fish fillets can significantly retard the thiobarbituric acid reactive substance (TBARS) (p < 0.05) during storage when compared to fish soaked in sorbitol solution kept for the same period. However, the addition of citric acid resulted in low quality in texture and color of frozen fish fillets. The use of sorbitol was the best alternative in frozen fish fillet product due to reducing the negative effects of freezing quality of the products and generating a cryoprotective effect compared to the fillets soaked in distilled water.

Insights into the similarities and differences of whiteleg shrimp pre-soaked with sodium tripolyphosphate and sodium trimetaphosphate during frozen storage

In this study, similarities and differences of sodium tripolyphosphate (STPP) and sodium trimetaphosphate (STMP) pre-soaking on the stability of muscle proteins in shrimp were investigated during 12 weeks of frozen storage (-30 °C). The physicochemical analysis indicated significant improvements in the WHC, springiness, chewiness, and thermal stability of STPP and STMP pre-soaked samples when compared to the control. Interestingly, STMP pre-soaking showed better cryoprotective effects than the STPP treatment when the storage period reached the end of the 12 weeks. Furthermore, the label-free based proteomics results indicated that 62 upregulated differentially abundant proteins (DAPs) were detected in STMP when compared to STPP. These identified DAPs specifically included 40S ribosomal proteins, actin-related proteins, heat shock proteins, myosin heavy chain, and tubulin beta chain. Additionally, the gene ontology (GO) and eukaryotic clusters of orthologous group (KOG) analyses verified that the incorporation of STMP molecules enhanced the resistance of cytoskeleton proteins to cold-temperature stress.

Kappa-carrageenan and its oligosaccharides maintain the physicochemical properties of myofibrillar proteins in shrimp mud (Xia-Hua) during frozen storage

As a popular hot-pot ingredient, Chinese-style shrimp mud (Xia-Hua) is usually transported and stored frozen. However, frozen storage leads to decreased quality of Xia-Hua products caused by the variations in physicochemical and functional properties of myofibrillar proteins (MPs). Κ-carrageenan and its oligosaccharides are reported as antioxidants and antifreeze and can stabilize proteins in whole shrimp, but their effects on MPs in Xia-Hua remain poorly understood. Compared to the control and Na₄ P₂ O₇ treatments, the physicochemical properties of MPs in κ-carrageenan and its oligosaccharides-incorporated Xia-Hua were evaluated during 120 days of frozen storage. The results showed that cold stress increased the susceptibility of MPs to denaturation and oxidation during frozen storage. Carrageenan oligosaccharides maintained the turbidity, emulsifying activity, stability, and foaming capacity of MPs. Oxidation analysis showed that the incorporation of carrageenan oligosaccharides significantly retarded the rapid decrease of Ca²⁺ -ATPase activity, total sulphydryl and active sulphydryl contents, and also effectively inhibited the increases of carbonyl content and surface hydrophobicity of MPs. Thermal stability results confirmed that the oligosaccharides improved the denaturation temperature and enthalpy of MPs compared to the control, Na₄ P₂ O₇ , and carrageenan treatments. This study suggests that κ-carrageenan and its oligosaccharides maintain the properties of MPs in Xia-Hua during frozen storage. PRACTICAL APPLICATION: The cryoprotection and antioxidant effects of carrageenan oligosaccharides on the stability of MPs in frozen shrimp mud can be used to extend the shelf-life and maintain the quality of frozen Xia-Hua products. Furthermore, it can drive the development of aquatic product health industry, improve the quality and safety of aquatic products, reduce the occurrence of public food safety incidents, and maintain social stability.

Label-free based proteomics analysis of protein changes in frozen whiteleg shrimp (Litopenaeus vannamei) pre-soaked with sodium trimetaphosphate

Muscle proteins in peeled shrimp (Litopenaeus vannamei) are known to be unstable and prone to denaturation affected by freezing and frozen storage. In this study, label-free proteomics were performed to explore the stabilization of frozen (30 days at -18 °C) shrimp muscle proteins when a pre-soaking treatment with distilled water (DW)- or sodium trimetaphosphate (ST) was applied; comparison to fresh samples (FS) was carried out. In total, 163 differentially abundant proteins (DAPs) were down-regulated in DW batch when compared to FS, these including ribosomal proteins, actins, myosin, paramyosin, myosin heavy chains, and tropomyosin; interestingly, most of these DAPs (181 proteins) were up-regulated in ST batch when compared to DW shrimp, mainly due to the incorporation of ST into muscle tissues. The results revealed the decreased protein degradation resulting from the reduced damage from ice-crystal growth. Gene ontology (GO) analysis suggested that these DAPs were mainly involved in catalytic activity, binding, and metabolic processes. Kyoto encyclopedia of genes and genomes (KEGG) results indicated that many pathways, including phototransduction, metabolic, and ribosomal pathways that interacted with phosphoglycerate mutase, actins, and ribosomal proteins were altered. Additionally, Eukaryotic clusters of orthologous group (KOG) results confirmed that incorporated ST maintained the stability of these DAPs in shrimp muscle, especially for cytoskeleton proteins, and retarded the degradation of muscle proteins during frozen storage.