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

Cryoprotective effect of trehalose on myofibrillar protein of snakehead fish (Channa argus) during freeze-thaw cycles

This study investigated the cryoprotective effect of trehalose on myofibrillar protein (MP) of snakehead fish (Channa argus) during freeze-thaw (F-T) cycles. After 7 F-T cycles, trehalose reduced solubility loss by 9.8 % compared to control group. Turbidity and surface hydrophobicity increased significantly with repeated F-T cycles. However, trehalose, particularly at 1.5 %, effectively inhibited these changes by stabilizing the structure and reducing aggregation. Sulfhydryl content decreased by 10.8 % less in the trehalose group than in the control group, indicating reduced oxidative damage and maintaining sulfhydryl groups. Differential scanning calorimetry (DSC) and scanning electron microscope (SEM) showed that trehalose reduced freezable water content and minimized structural damage caused by ice crystals, with 1.5 % trehalose exhibiting the most pronounced effect. Trehalose's polyhydroxylated structure forms hydrogen bonds with polar residues, reducing hydrophobic interactions and maintaining protein stability. Additionally, trehalose reduced secondary structure degradation, offering optimal protection against oxidation, aggregation, and structural damage during F-T cycles.

Cyclodextrin induces synergistic cryoprotection with carrageenan oligosaccharide against myofibrillar protein denaturation during fluctuated frozen storage

High-performance saccharide-based cryoprotectants are gaining increasing attention for their application in frozen meat products. While various physiochemical and/or enzymatic approaches have been employed to enhance the cryoprotective efficacy of saccharides, potential synergistic effects between different saccharide candidates remain largely unexplored. This study, for the first time, demonstrates that the combinational use of β-cyclodextrin (CD) and carrageenan oligosaccharide (CGO) exhibit significant synergistic cryoprotective effects on surimi myofibrillar proteins (MP) during freeze-thaw cycles. At 1 wt% concentration, the CD-CGO complex exhibited significantly greater cryoprotective efficiency than the commercial surimi cryoprotectant (4 % sucrose with 4 % sorbitol). Specifically, the CD-CGO co-treatment mitigated surimi MP denaturation over six freeze-thaw cycles, as evidenced by increased solubility (2.17 times), Ca2+-ATPase activity (3.91 times), and sulfhydryl content (2.55 times), along with reduction in surface hydrophobicity (0.42 times). In addition, freezing-induced MP aggregation and conformational changes, e.g., α-helix loss and disulfide bond destabilization, were effectively inhibited. Consequently, MP treated with CD-CGO complex demonstrated more ordered microstructures, uniform water distribution, and significantly improved viscoelasticity and mechanical strengths. This study provides a novel synergistic paradigm to boost saccharide cryoprotection performance, which also exhibits the potentials to elevate the FT stability of MP gel products.

Investigating the cryoprotective mechanism of phosphorylated nano-chitin in shrimp (Litopenaeus vannamei) during frozen storage

This study aims to explore the cryoprotective effects of phosphorylated surface deacetylated chitin nanofibers (PS-ChNFs) on shrimp. Compared to the control- and those treated with surface deacetylated chitin nanofibers (S-ChNFs) or sodium tripolyphosphate (STPP), the PS-ChNFs-treated group showed lower thawing losses and cooking losses, alongside higher myofibrillar protein concentrations and Ca2+-ATPase activity in frozen shrimp. Additional, PS-ChNFs-treated significantly delayed protein aggregation and the deterioration of the secondary structure in shrimp during frozen storage (p < 0.05). Furthermore, microscopy analysis revealed PS-ChNFs effectively inhibited ice crystal growth and slowed the damage to muscle tissue structures. Molecular simulations suggested that the cryoprotective effect of PS-ChNFs were primarily achieved through the "water substitution" and "glassy state" hypotheses, wherein PS-ChNFs formed hydrogen bonds with water and reduced the number of water molecules around myosin. These findings indicate that PS-ChNFs hold significant potential as cryoprotectants for freeze-stored aquatic products.

Crosslinking ability of hydrolyzed distarch phosphate and its stabilizing effect on rehydrated sea cucumber

Effective crosslinking among food constituents has the potential to enhance their overall quality. Distarch phosphate (DSP), a common food additive employed as a thickening agent, bears a pre-crosslinked oligosaccharide (PCO) moiety within its molecular structure. Once this moiety is released, its double reducing end has the potential to undergo crosslinking with amino-rich macromolecules through Maillard reaction. In this study, hydrolyzed distarch phosphate (HDSP) was synthesized, and spectroscopic analysis verified the presence of PCO within HDSP. Preliminary validation experiment showed that HDSP could crosslink chitosan to form a hydrogel and significant browning was also observed during the process. Furthermore, rehydrated sea cucumber (RSC) crosslinked with HDSP exhibited a more intact appearance, higher mechanical strength, better color profile, and increased water-holding capacity. This series of results have confirmed that HDSP is capable to crosslink amino-rich macromolecules and form more stable three-dimensional network.

Study of the structural characterization, physicochemical properties and antioxidant activities of phosphorylated long-chain inulin with different degrees of substitution

In this study, phosphorylated derivatives of long-chain inulin with different substitution degrees were prepared. The synthesized samples were named PFXL-1, PFXL-2, PFXL-3, and PFXL-4 according to their degree of substitution (from low to high). The structures of FXL and PFXL were characterized by infrared spectroscopy and nuclear magnetic resonance spectroscopy, and the results indicated the successful introduction of phosphate groups. FXL and PFXL were composed of two types of sugar, fructose and glucose, with a molar ratio of 0.977:0.023. The SEM results showed that phosphorylation changed the morphology of FXL from an irregular mass to small spherical aggregates. The XRD pattern showed that the crystallinity was reduced by the introduction of phosphate groups. The Mw of FXL was 2649 g/mol, and the Mw of PFXL-4 increased the most (2965 g/mol). Additionally, PFXL was more stable and uniform, and the absolute value of the PFXL potential reached 7.83 mV. Phosphorylation decreased the weight loss rate of FXL and improved the viscoelastic properties and antioxidant activity of FXL. This study presents a method for the modification of FXL, demonstrating that phosphorylation can enhance its physicochemical properties and physiological activity and suggesting its potential as a functional food and quality modifier.