Insight into the Effect of Ice Addition on the Gel Properties of Nemipterus virgatus Surimi Gel Combined with Water Migration

Elucidating the molecular mechanism of water migration in myosin gels of Nemipterus virgatus during low pressure coupled with heat treatment

The relationship between myosin denaturation, aggregation and water migration in Nemipterus virgatus myosin gels with different treatment processes under optimal low pressure coupled with heat treatment was investigated to clarify the molecular mechanism of water migration. With the different treatment processes, the proportion of bound water of the myosin gels increased significantly (P < 0.05). Denaturation of myosin S1 sub-fragments and α-helical unfolding during different treatment processes led to an increase in β-sheets content. These promote increased exposure of Try residues and hydrophobic groups of myosin, formation of clathrate hydrates, and reduced mobility of bound water. Furthermore, hydrophobic interactions and disulfide bonds caused the head-head and head-hinge to coalesce into a 3D honeycomb network with greater fractal dimension, less lacunarity, smaller water hole diameter and more water holes. This increased the capillary pressure experienced by the bound water, causing immobile water to migrate towards the bound water. The present study may be necessary to improve the mechanism of water migration in protein gel systems and to promote the industrial application of high pressure processing technology in surimi-based foods.

Investigation of the changes in gelation properties of hydroxypropyl distarch phosphate-surimi gel under different gelation-freezing treatments

BACKGROUND

Frozen storage often leads to quality deterioration of surimi-based products. At present, most of the research focuses on improving the quality of surimi products by adding cryoprotectants, and there are few studies available on preparation technology. Therefore, the effects of different gelation-freezing treatments, high temperature heating-freezing treatment (HF), low temperature heating-high temperature heating-freezing treatment (LHF) and low temperature heating-freezing-high temperature heating treatment (LFH) on the quality changes of surimi gels containing hydroxypropyl distarch phosphate (HPDSP) during frozen storage were investigated.

RESULTS

With the extension of frozen storage time, the quality of surimi gel in all groups decreased, but the quality of surimi gel with HPDSP was better than that of surimi gel without HPDSP. Compared with HF and LHF, the change range of breaking force, hardness, gumminess, whiteness and disulfide bond content of HPDSP-surimi gel treated with LFH was the least during the frozen storage. In the reheating process of LFH, HPDSP could absorb the water lost during freezing. Therefore, the change in the transverse relaxation time of HPDSP-surimi gels treated with LFH was smaller, with more immobile water and less free water and P22 of 96.81% and P23 of 0% at 16 weeks. In addition, the breaking deformation, cohesiveness, resilience, springiness and protein composition of surimi gels with and without HPDSP treated with HF, LHF and LFH did not change significantly during frozen storage.

CONCLUSION

The combination of LFH and HPDSP could effectively reduce the quality change of surimi gel during frozen storage. © 2023 Society of Chemical Industry.

Discovery of Potential Protein Markers Associated with Quality Characteristics of Antarctic Krill (Euphausia superba) Surimi Gel

Antarctic krill are a consumption resource with great exploitation potential. However, the poor gel properties of Antarctic krill meat seriously limit its high-value application. In the present study, the quality characteristics and proteome changes of the κ-/ι-carrageenan-Antarctic krill surimi gel were systematically analyzed and compared. In addition, the transcriptome sequencing of Antarctic krill was carried out, which filled the gap in the Antarctic krill database. Higher molecular forces (disulfide bond and hydrophobic interaction) and the degree of network cross-linking significantly promoted the formation of κ/ι-carrageenan-Antarctic krill surimi compared to that of Antarctic krill surimi. This is the first study to investigate and map potential protein markers for quality characteristics of Antarctic krill surimi based on mass spectrometry-based label-free quantitative proteomics. The results could provide a theoretical reference for the quality control of Antarctic krill during application.

Correlation between Water Characteristics and Gel Strength in the Gel Formation of Golden Pompano Surimi Induced by Dense Phase Carbon Dioxide

The relationship between the gel quality of golden pompano surimi treated with dense phase carbon dioxide (DPCD) and changes in water characteristics was evaluated. Low-field nuclear magnetic resonance (LF-NMR) and nuclear magnetic resonance imaging were used to monitor changes in the water status of surimi gel under different treatment conditions. Whiteness, water-holding capacity and gel strength were used as the quality indicators of the surimi gel. The results showed that DPCD treatment could significantly increase the whiteness of surimi and the strength of the gel, while the water-holding capacity decreased significantly. LF-NMR analysis showed that, as the DPCD treatment intensity increased, the relaxation component T₂₂ shifted to the right, T₂₃ shifted to the left, the proportion of A₂₂ decreased significantly (p < 0.05) and the proportion of A₂₃ increased significantly (p < 0.05). A correlation analysis of water characteristics and gel strength showed that the water-holding capacity of surimi induced by DPCD was strongly positively correlated with gel strength, while A₂₂ and T₂₃ were strongly negatively correlated with gel strength. This study provides helpful insights into the quality control of DPCD in surimi processing and also provides an approach for the quality evaluation and detection of surimi products.

Insight into the Gel Properties of Antarctic Krill and Pacific White Shrimp Surimi Gels and the Feasibility of Polysaccharides as Texture Enhancers of Antarctic Krill Surimi Gels

Antarctic krill is a potential and attractive resource for consumption. However, most Antarctic krill meat is used to produce primary products with low commercial value, with few highly processed products. This study aimed to evaluate and improve the gelling properties of Antarctic krill surimi, with Pacific white shrimp surimi as control. Compared with Pacific white shrimp surimi, the lower β-sheet content and protein aggregation degree had a severe impact on the formation of the gel network of Antarctic krill surimi, which resulted in weaker breaking force, gel strength, and viscoelasticity (p < 0.05). Moreover, water retention capacity and molecular forces had a positive effect on the stability of the gel matrix of shrimp surimi. Thus, the high α-helix/β-sheet ratio, weak intermolecular interactions, and low level of protein network cross-linkage were the main reasons for the poor quality of Antarctic krill surimi. On this basis, the effects of six polysaccharides on the texture properties of Antarctic krill surimi were studied. Chitosan, konjac glucomannan, sodium carboxyl methyl cellulose, and waxy maize starch resulted in no significant improvement in the texture properties of Antarctic krill surimi (p > 0.05). However, the addition of ι-carrageenan (2%) or κ-carrageenan (1~2%) is an effective way to improve the texture properties of Antarctic krill surimi (p < 0.05). These findings will contribute to the development of reconstituted Antarctic krill surimi products with high nutritional quality and the promotion of deep-processing products of Antarctic krill meat.

Low-Content Pre-Emulsified Safflower Seed Oil Enhances the Quality and Flavor of the Nemipterus Virgatus Surimi Gel

Surimi-based products occupy an important position in the aquatic product processing industry. To enhance the quality and flavor of surimi-based products, the effects of pre-emulsified safflower seed oil on the texture, water-holding capacity (WHC), microstructure, and flavor of Nemipterus virgatus surimi gel was evaluated. The texture and whiteness of the gel were improved, and the WHC increased (p < 0.05) as the content of safflower seed oil increased up to 2 mL per 100 g surimi. Furthermore, the drops of pre-emulsified safflower seed oils with an average diameter of less than 0.10 μm were evenly distributed in gel matrix. Microstructure and infrared spectroscopy analyses indicated that low-content pre-emulsified safflower seed oil acted as filler particles to occupy void spaces, resulting in gel exhibiting a dense network structure. Volatile analysis showed the gel containing pre-emulsified oil enriched volatile compounds, mainly resulting from the oxidation and decomposition of oils by the activation of lipoxygenase, which synergistically contributes to unique flavors of gel. Consequently, low-content pre-emulsified safflower seed oil can used to enhance the quality and flavor of N. virgatus surimi-based products. These findings are especially relevant to the current growing interest in low-fat and high-protein diets.

Cryoprotective Roles of Carboxymethyl Chitosan during the Frozen Storage of Surimi: Protein Structures, Gel Behaviors and Edible Qualities

Carboxymethyl chitosan (CMCh) is an ampholytic chitosan derivative that manifests versatile applications in food industry, such as antibacterial ingredients and nutritional additives. However, its use as a cryoprotectant remains under-researched. In this study, the cryoprotective effect of CMCh oligosaccharide (CMCO) on frozen surimi (silver carp) was systematically investigated in terms of protein structures, gelling behaviors, and sensory qualities. CMCO (0.6%) was incorporated in the surimi before frozen storage (-18 °C for 60 days) while the commercial cryoprotectant (4% sucrose, 4% sorbitol) was used as a positive control. Results indicated that CMCO could inhibit the freezing-induced denaturation of myofibrillar protein, whose values of solubility, Ca²⁺-ATPase and sulfhydryl content were 24.8%, 64.7%, and 17.1% higher than the nonprotected sample, respectively, while the surface hydrophobicity was 21.6% lower. Accordingly, CMCO stabilized microstructure of the surimi gels associated with improved gel strength, viscoelasticity, water-holding capacities, and whiteness. Moreover, the cryoprotective effect of CMCO with higher degree of carboxymethyl substitution (DS: 1.2) was more pronounced than that of low-DS-CMCO (DS: 0.8). Frozen surimi treated with high-DS-CMCO achieved competitive gelling properties and sensory acceptability to those with the commercial counterpart. This study provided scientific insights into the development of ampholytic oligosaccharides as food cryoprotectants.

Different Thermal Treatment Methods and TGase Addition Affect Gel Quality and Flavour Characteristics of Decapterus maruadsi Surimi Products

Decapterus maruadsi surimi products were prepared using the thermal treatment methods of boiling (BOI), steaming (STE), back-pressure sterilization (BAC), roasting (ROA), microwaving (MIC), and frying (FRI), respectively. The effect of glutamine transaminase (TGase) addition was also investigated. The moisture distribution, water retention, microstructure, color, fracture constant, protein secondary structure, chemical forces, and flavor components of each sample were determined. The differences in gel and favor characteristics between D. maruadsi surimi products caused by thermal treatment methods were analyzed. The results showed that BOI, STE, and FRI had the largest protein secondary structure transitions and formed dense gel structures with high fracture constant. The kinds of flavour components in BOI and STE were completer and more balanced. The high temperature treatment available at BAC and FRI (110 °C and 150 °C) accelerated the chemical reaction involved in flavor formation, which highlighted the flavor profiles dominated by furans or esters. The open thermal treatment environments of ROA, MIC, and FRI gave them a low moisture content and water loss. This allowed the MIC to underheat during the heat treatment, which formed a loose gel structure with a low fracture coefficient. The addition of TGase enhances the gel quality, most noticeably in the ROA. The aldehyde content of the FRI was enhanced in the flavor characteristic. The effect of adding TGase to enhance the quality of the gel is most evident in ROA. It also substantially increased the content of aldehydes in FRI. In conclusion, different heat treatments could change the gel characteristics of surimi products and provide different flavor profiles. The gel quality of BOI and STE was consistently better in all aspects.

Changes in Gel Structure and Chemical Interactions of Hypophthalmichthys molitrix Surimi Gels: Effect of Setting Process and Different Starch Addition

The modifications of histological properties and chemical forces on heated surimi gels with starch addition (0-12 g/100 g surimi) were investigated. Two types of heating processes (direct heating and two-step heating) were carried out on surimi gels in order to reveal the effect of setting on mixed matrices. The results of transverse relaxation time showed less immobile water and free water converted into bound water in a matrix subjected to the setting process. Scanning electron microscope and light microscopy images revealed inefficient starch-swelling in two-step heated gels. Chemical interactions and forces in direct cooking gels were more vulnerable to starch addition, resulting in significant decreases in hydrophobic interaction and sulfhydryl content (p < 0.05). With the increment of starch, the disulfide stretching vibrations of the gauche-gauche-gauche conformation were reduced in both gel matrices. The structural variations of different components collectively resulted in changes in texture profile analysis and water holding capacity. Overall, the results demonstrated that starch addition had a great and positive effect on the weak gel matrix by direct heating.