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BACKGROUND: The cryoprotective effect of xylooligosaccharide (XO) and kappa‐carrageenan (KC) mixture on silver carp proteins in fluctuated frozen storage from 4 to −18 °C was analyzed. Positive control as a conventional cryoprotectant mixture of sucrose (4%) and sorbitol (4%), KC (3%) and XO/KC (3%) treatments were incorporated in silver carp surimi and myofibrillar proteins to analyze the water mobility and its influence on structural attributes. RESULTS: The temperature fluctuation significantly increased the structural alteration in samples with no treatments due to oxidative changes, protein denaturation and recrystallization. Meanwhile, the mixture of XO and KC (XO/KC 3%) significantly reduced the tertiary and secondary structural alterations by preventing the oxidative changes in α‐helix and tryptophan (Trp) residues. Moreover, XO/KC (3%) inhibited water mobility, hindering the T22 relaxation time, as compared to the samples added with KC (3%) and the positive control. Interestingly, the XO/KC (3%) mixture significantly reduced the formation of extracellular spaces and recrystallization by restricting the partial dehydration of muscles and extracellular solution concentration. CONCLUSION: From the current results, it can be concluded that the XO/KC mixture could be efficient in protecting aquatic food proteins during fluctuating frozen storage by preventing the exposure of Trp residues and α‐helix contents. Moreover, XO/KC restricted the water mobility by establishing a bond and making water unavailable for crystallization and recrystallization. Therefore, XO/KC could be used as an effective mixture to prevent fluctuated and frozen storage changes in aquatic foods. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Summary: The effect of egg white protein (EWP) and β‐cyclodextrin (β‐CD) mixture was analysed on the myofibrillar proteins (MP) of Culter alburnus during a frozen storage at −18 °C for 60 days. Different proportions of EWP:β‐CD mixture (0%, 2%, 4% and 6%) were added into MP to analyse their effect against oxidative changes. During the study, sulphydryl contents and Ca‐ATPase activity (0.297 to 0.136 mmol g−1) decreased. Moreover, protein denaturation also prompted the surface hydrophobicity (11.47 to 32.06 μg) and carbonyls (26.36 to 49 mg.28 nmol mg−1) of control MP. A significant decline was observed in emulsifying properties. Besides, EWP:β‐CD showed remarkable stability against oxidative changes, by significantly reducing the carbonyls (26.26 to 37.69 nmol mg−1) and surface hydrophobicity (11.51 to 20.31 μg) and also the decline of Ca‐ATPase activity (0.29 to 0.19 mmol g−1). It can be concluded that EWP:β‐CD (6%) is an efficient approach against oxidative changes in MP from Culter alburnus. [ABSTRACT FROM AUTHOR]

Texture is an important parameter in determining the quality characteristics and consumer acceptability of seafood and fish protein-based products. The addition of food-based additives as antioxidants (monosaccharides, oilgosaccharides, polysaccharides and protein hydrolysates) in surimi and other seafood products has become a promising trend at an industrial scale. Improvement in gelling, textural and structural attributes of surimi gel could be attained by inhibiting the oxidative changes, protein denaturation and aggregation with these additives along with new emerging processing techniques. Moreover, the intermolecular crosslinking of surimi gel can be improved with the addition of different food hydrocolloid-based antioxidants in combination with modern processing techniques. The high-pressure processing (HPP) technique with polysaccharides can develop surimi gel with better physicochemical, antioxidative, textural attributes and increase the gel matrix than conventional processing methods. The increase in protein oxidation, denaturation, decline in water holding capacity, gel strength and viscoelastic properties of surimi gel can be substantially improved by microwave (MW) processing. The MW, ultrasonication and ultraviolet (UV) treatments can significantly increase the textural properties (hardness, gumminess and cohesiveness) and improve the antioxidative properties of surimi gel produced by different additives. This study will review potential opportunities and primary areas of future exploration for high-quality surimi gel products. Moreover, it also focuses on the influence of different antioxidants as additives and some new production strategies, such as HPP, ultrasonication, UV and MW and ohmic processing. The effects of additives in combination with different modern processing technologies on surimi gel texture are also compared. [ABSTRACT FROM AUTHOR]

This study was done to analyze the cryoprotective influence of ovalbumin (OVA) with kappa-carrageenan (KC) in grass carp myofibrillar proteins during frozen storage. Ca2+-ATPase activity of MP was significantly reduced due to protein denaturation and showed a direct association with decreased sulphydryl (SH) contents and tertiary structural properties. Besides that, an increase in carbonyl, surface hydrophobicity, and dityrosine contents was observed. The addition of OVA-KC significantly restricted the decline in Ca2+-ATPase and SH groups, which were further confirmed by the retarded increase in carbonyls. Furthermore, the addition of OVA-KC increased the stability of α-helix contents. Moreover, MP treated with 6% OVA-KC also improved intermolecular interaction forces linked with gelling and water holding properties of MP. Therefore, it can be concluded that OVA-KC could be used as an effective cryoprotectant in fish and related products for preservation and commercialization. [ABSTRACT FROM AUTHOR]

The meat industry routinely utilizes commercial cryoprotectants to preserve silver carp myofibrillar proteins (MFP) quality. Unfortunately, current commercial additives have low cryoprotective abilities against freeze-induced crystallization, recrystallization, and structural changes. Therefore, we evaluated the cryoprotective role of tea polysaccharides (TPC) on secondary and tertiary structural attributes of MFP during multiple fluctuated frozen storage (FSF) conditions. The study used untreated (CG), treated with TPC (1 and 3%) and an industrial cryoprotective mixture (PCG) as a positive control. Throughout the multiple FSF conditions, all samples showed oxidative induced structural changes. The CG samples showed a major decline in total sulfhydryl contents (TSH) (from 50.63 to 25.06 mmol/kg) and an increase in surface hydrophobicity (S o) (from 14.48 to 32.51 μg) due to oxidative changes in MFP than TPC (1 and 3%) and PCG. Meanwhile, structural attributes were also reduced due to their association with TSH and S o, unfolding of MFP, oxidation of myosin and protein denaturation. The addition of PCG and TPC (1 and 3%) inhibited the freeze-induced modifications in MFP during 6-FSF. Overall, the addition of TPC (3%) in MFP substantially prevented the loss in secondary structure by stabilizing the α-helix degradation (from 57 to 46%) and tertiary structure by inhibiting the oxidation of tryptophan indole residues compared to PCG and TPC (1%). Meanwhile, TPC (3%) reduced the decline in band intensities of the CH bond, SH groups and amide II region. Therefore, it was concluded that TPC as an effective cryoprotectant and could be used for seafood on an industrial scale. [Display omitted] • Tea polysaccharides (TPC) was used a cryoprotectant in silver carp surimi protein. • TPC (3%) prevented the conversion of sulfhydryl contents into disulfides. • TPC (3%) inhibited the freeze-induced degradation of α-helix in myosin. • TPC (3%) constrained the decline in tryptophan and tyrosine residue. • Overall, the TPC (3%) could be used a potential substitute of commercial additives. [ABSTRACT FROM AUTHOR]

The aim of this study was to analyze the effect of Kanjoc oligo-glucomannan (KOG) on functional and structural changes in silver carp surimi during fluctuated (FLUC) frozen storage. During this study, KOG was prepared and added 1 and 3% in surimi and myofibrillar protein (MP) and compared with a positive control (PC) of sucrose and sorbitol mixture added samples. The results showed that the water holding capacity (WHC), textural and structural properties decreased during FLUC-I and FLUC-II, indicating that it could be due to protein denaturation induced by the formation of irregular crystallizations and recrystallization. Moreover, it was noted that the addition of KOG (3%) enhanced the stability of α-helix content (58–47%) during FLUC-I and (60–50%) during FLUC-II by inhibiting the hydrophobic residue exposure and change in aromatic amino acids. Meanwhile, KOG (3%) enhanced the textural properties by inhibiting the freeze induced protein denaturation. During FLUC frozen storage, the KOG (3%) was found to be a more effective concentration than conventional cryoprotectant mixture (PC). At industrial level, KOG (3%) could be used as a potential alternative to conventional cryoprotectants to attain prolonged commercial and economic values of silver carp. • Kanjoc oligo-saccharides (KOG) analyzed as cryoprotectant in silver carp surimi. • KOG significantly reduced the protein changes during fluctuated frozen storage. • Dense and compact gel was formed after incorporating KOG (3%). • KOG (3%) improved the physicochemical and structural properties of surimi gel. • KOG (3%) proved to be as a potential alternative to conventional cryoprotectants. [ABSTRACT FROM AUTHOR]

• Mulberry anthocyanins actually aided the digestion of energy balls after storage. • Mulberry anthocyanins partially unfolded the secondary structure of whey proteins. • Non and covalent binding were occurred between mulberry anthocyanin and whey-protein. The effects of mulberry anthocyanins (MAs) on the digestibility of whey proteins (WP) in freshly-prepared and stored energy balls were studied. Results showed that MAs increased digestibility of the energy balls by increasing their hydrolysis-degree, soluble peptides-fractions, and decreasing their particle's size and agglomeration. To understand the mechanism of the promoting and/or inhibiting digestive effects of MAs, secondary structure alterations and binding of WP-MAs-mixtures were therefore measured. Results revealed that MAs could noncovalently/covalently interact with WP and form WP-MAs-adducts. This interaction seemed to be responsible for the alterations in the secondary structure of WP which could promote the digestibility of the energy balls subsequently. MAs also partially unfolded the structure of digested-WP through fluctuating their α-helix and β-sheet. It was concluded that the unfolding in WP-structure induced by MAs-interactions might increase accessibility of the peptide bonds to the digestive enzymes and consequentially facilitate the protein's digestibility in the energy balls. [ABSTRACT FROM AUTHOR]

The purpose of this research was to investigate the cryoprotective role of EWP-XO in the prevention of oxidative and structural changes in the myofibrillar proteins (MPs). Different concentrations of egg white protein and xylooligosaccharide (EWP-XO) mixture (0, 2, 4 and 6%) were added to the MPs of Culter alburnus fish during frozen storage (−18 °C) of 60 days. During the study, it was observed that EWP-XO significantly (P <.05) reduced the Ca-ATPase activity, which is greatly related with tertiary structural changes. Meanwhile, carbonyl contents of MPs increased in line with frozen storage (control samples). Meanwhile, samples treated with 6% EWP-XO showed less increase in carbonyl content indicating the decreased protein oxidation. The addition of EWP-XO efficiently inhibited the decline in the sulfhydryl contents. Furthermore, through circular dichroism analysis it was confirmed that the addition of EWP-XO increased the secondary structural stability by preventing the reduction in α-helix content. Microstructural analysis confirmed the preservation of a well-structured protein network that reduced the porosity and protein aggregation of MPs gel. It was concluded that 6% EWP-XO was an effective cryoprotectant mixture, which preserved the functional and structural properties of Culter alburnus during 60 days of frozen storage period. [Display omitted] • Cryoprotective effect of EWP-XO was checked on myofibrillar proteins during frozen storage • EWP-XO significantly (P <.05) reduced the oxidative changes during frozen storage • 6% EWP-XO effectively inhibited protein denaturation and aggregation in frozen storage • 6% EWP-XO improved myofibrillar proteins gelling and structural properties • 6% EWP-XO is an effective concentration to exhibit cryoprotective role on MP [ABSTRACT FROM AUTHOR]

The cryoprotective effect of konjac oligosaccharide (KOG) on the silver carp surimi proteins during frozen storage was analyzed. Meanwhile, molecular dynamic simulation (MD) was carried out to examine the insight interaction of KOG with myosin. The Ca2+ - ATPase and gel strength decreased in all samples, despite the treatment with a sucrose (4%) + sorbitol (4%) mixture as PC and KOG (1 and 3%). The samples added with no cryoprotectants (C) showed a remarkable decline in Ca2+-ATPase activity and gel strength. The decline in these properties could be due to oxidative changes in myosin, ice crystallization, and protein denaturation. Most interestingly, KOG (3%) incorporated samples that presented significant constancy in Ca2+-ATPase and gel strength properties, this stability was further proved with a MD computational study. Our findings of homology and MD analysis affirmed that KOG could substitute water molecules and form hydrogen bonds with amino acid residues, thereby leading to protein stability. Overall, the KOG water substitution action played an efficient cryoprotective effect on frozen silver carp protein. Furthermore, this application could extend the role of KOG at the industrial level as an effective cryoprotectant. • The cryoprotective mechanism of konjac oligosaccharide was analyzed on myosin. • The addition of konjac oligosaccharide reduced the decline in Ca2+ATPase activity. • Konjac oligosaccharide could substitute water molecules and form hydrogen bonds. • Multiple noncovalent connections help stabilize proteins. [ABSTRACT FROM AUTHOR]

This study focused on the effects of egg white protein (EWP) and β-cyclodextrin (βCD) mixture (3:1, EWP/βCD) at 0, 2, 4 and 6% concentrations on fish (Culter alburnus) myofibrillar proteins (MP) during 60 days of frozen storage (−18 °C) by analyzing functional, rheological and structural changes in MP and MP gels. After 60 days of storage, circular dichroism (CD) and Fourier transform infrared (FTIR) spectroscopy revealed a decrease in the MP α-helix content, and EWP/βCD addition improved the MP secondary structural properties by inhibiting protein aggregation induced by exposure of hydrophobic residues. Particularly, the 6% EWP/βCD treatment significantly decreased (P < 0.05) the pores and spaces of MP gels formed during frozen storage, resulting in a denser network. Moreover, compared with the control (0%), EWP/βCD addition significantly increased (P < 0.05) the gel hardness, springiness, gumminess and cohesiveness as well as whiteness and water holding properties. Dynamic rheological analysis showed that 6% EWP/βCD also increased the MP storage modulus (G') and loss modulus (G"). This research provides useful information for increasing the commercial life of fish products by frozen storage and contributes to the potential application of EWP/βCD as a low-sweetness cryoprotectant for Culter alburnus fish. Image 1 • Effect of EWP/βCD was analyzed in myofibrillar protein of culter alburnus during 60 days of frozen storage. • EWP/βCD decreased the protein denaturation and aggregation during frozen storage. • Well-established and interconnected MP gel network was formed with addition of 6% EWP/βCD. • Over all EWP/βCD improved the functional, rheological and structural properties of MP. [ABSTRACT FROM AUTHOR]