Effects of Konjac Glucomannan on Functional and Structural Properties of Antarctic Krill Surimi Gel

TL;DR

Adding konjac glucomannan improves the texture and structure of Antarctic krill surimi gels, making them more stable and better quality.

Contribution

This study demonstrates that konjac glucomannan can enhance the functional and structural properties of Antarctic krill surimi gels.

Findings

Gel strength reached a maximum of 1581.78 ± 12.86 at 10.0 mg/g KGM.

KGM increased immobilized water content and improved gel matrix homogeneity.

Non-covalent interactions dominate in Antarctic krill-KGM surimi gels.

Abstract

Antarctic krill surimi is a novel type of gel-based food that has attracted increasing attention. However, pure Antarctic krill surimi generally exhibits poor gel-forming properties. Konjac glucomannan (KGM) offers a promising approach to address this limitation due to its gel-forming ability and thermal stability. This study investigated the effect of KGM (0.0–20.0 mg/g) on the functional properties and structural characteristics of Antarctic krill-KGM surimi gels. The results demonstrated that as KGM levels increased, water-holding capacity, whiteness, hardness, chewiness, and gel strength of the composite surimi gels first increased and then decreased, while cooking loss followed the opposite trend. Texture analysis showed that gel strength was significantly enhanced at 10.0 mg/g KGM, reaching a maximum value of 1581.78 ± 12.86 (p < 0.05). Water distribution analysis confirmed that the relative content of immobilized water increased with increasing KGM levels. Fourier transform infrared spectroscopy demonstrated that the Antarctic krill-KGM surimi gels were primarily linked by non-covalent intermolecular interactions. Furthermore, microstructural analysis showed that KGM contributed to a more homogeneous and continuous gel matrix. These results indicate that KGM can modulate electrostatic repulsion, spatial potential resistance, and act as a reinforcing filler in the surimi gel matrix. Overall, the results demonstrated that KGM is a feasible candidate for enhancing the quality of Antarctic krill surimi gels.

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Full text

1. Introduction

Surimi is a product derived from the gel-forming ability of myofibrillar proteins extracted from aquatic animals [1]. Surimi gel products have gained popularity due to their nutritional value, versatility, and convenience. However, pure surimi products are susceptible to quality deterioration during storage. To mitigate this issue, various additives, such as KGM, have been widely used as quality modifiers in surimi formulations. KGM, a water-soluble, neutral polysaccharide and low-calorie dietary fiber derived from Amorphophallus konjac, is recognized as a natural and environmentally friendly food additive in many countries and regions [2]. Zhang et al. [3] reported that the complexes formed between myofibrillar proteins and KGM can help reduce protein aggregation and enhance the quality of the composite surimi gels. Rahman et al. [4] reported that modified KGM improves the gelling capability of fish protein through the hooking effect. Ran et al. [5] demonstrated that KGM can improve the textures of soy protein-based fish balls by strengthening protein cross-linking. Moreover, the European Food Safety Authority (EFSA) [6] has indicated that consuming 1 g of KGM three times per day can promote weight reduction in overweight individuals due to its satiety-enhancing properties (EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA)). Although several studies have examined the interaction of KGM with surimi from various sources, information regarding its effects on the underlying mechanisms that influence the quality of non-traditional surimi products remains limited.

Antarctic krill (Euphausia superba Dana) is a crucial marine bioresource, with an estimated biomass of 379 million tons. Antarctic krill is rich in high-quality protein (approximately 800.0 mg/g on a dry basis), phospholipids, and astaxanthin [7]. Common Antarctic krill-based products include frozen krill, krill meal, krill oil, krill protein or peptide, dried krill, canned krill, and krill sauce, among others [8]. However, the processing and deep utilization of Antarctic krill are challenging because traditional aquatic product processing methods are unsuitable for its unique biochemical characteristics. Specifically, endogenous enzymes in Antarctic krill promote autolysis, which compromises the gel-forming ability [9]. As a result, Antarctic krill has not been completely utilized as a superior-quality marine food because heat treatment and endogenous proteases lead to protein degradation and reduced product quality [10]. Wang et al. [11] reported that heat treatment of Antarctic krill protein isolates leads to poor gel formation due to proteolysis induced by endogenous enzymes. Deshelled Antarctic krill can be used to develop surimi gel products such as surimi balls, surimi cakes, and surimi slices. However, endogenous proteases in Antarctic krill degrade myofibrillar proteins, thereby affecting the structure and functional properties of Antarctic krill surimi gels [12]. Li et al. [13] further demonstrated that pure Antarctic krill surimi gels exhibit low gel strength, weak water-holding capacity, and suboptimal rheological properties. Although several studies have investigated the relationship between the functional and structural characteristics of the composite surimi gels made from Antarctic krill surimi and the alternative additives, such as KGM, it is not well elucidated.

This study aimed to evaluate the effects of KGM on the functional and structural properties of Antarctic krill surimi gels using a combination of macroscopic and microscopic analyses. The study will help promote the application of KGM in the development of Antarctic krill surimi gels.

2. Materials and Methods

2.1. Regents and Materials

Deshelled Antarctic krill was provided by Liaoyu Fishery Food Co., Ltd. (Dalian, China) and stored at −30 °C. KGM was provided by Johnson Konjac Technology Co., Ltd. (Ezhou, China). All chemicals were of analytical grade and purchased from Sinopharm Chemical Reagent Co., Ltd. (Shanghai, China).

2.2. Preparation of Antarctic Krill-KGM Surimi Gel

Frozen Antarctic krill meat was thawed at 4 °C until its core temperature reached 0 °C. The thawed surimi was chopped for 2 min using a blender (T-25, IKA, Guangzhou, China) while maintaining the temperature below 10 °C. Sodium chloride (Nacl, 25.0 mg/g) was then added, and the mixture was blended for an additional 3 min. Then, KGM was incorporated at concentrations of 0.0 mg/g, 0.5 mg/g, 1.0 mg/g, 1.5 mg/g, and 2.0 mg/g and mixed for 5 min. The moisture content of the mixtures was adjusted to 800 mg/g using ice water. The Antarctic krill-KGM surimi mixture was packed and sealed in plastic casings, then heated at 60 °C for 40 min. The composite surimi gels were immediately cooled in ice water for 15 min and stored at −20 °C for 48 h in a freezer [14].

2.3. Physical Characterization of Antarctic Krill-KGM Surimi Gel

2.3.1. Cooking Loss

Cooking loss was determined following the method described by Wang et al. [15] with slight modifications. Each sample (30 g) was sealed, heated at 95 °C for 10 min, and then rapidly cooled in ice water. The mass of the sample before heating was recorded as m_1_ (g), and the mass after heating was recorded as m_2_ (g), respectively. Cooking loss was calculated using the following Formula (1):

$$[eqn]$$

2.3.2. Water-Holding Capacity (WHC)

WHC was determined following the method described by Cao et al. [16]. Surimi gel samples (approximately 5 g) were equilibrated at 25 °C, wrapped in double-layer filter paper, and centrifuged at 6000× g for 10 min at 4 °C. After centrifugation, the samples were placed at room temperature (25 °C), and the supernatant was carefully drained. The mass of the sample before centrifugation was recorded as m_1_ (g), and the mass after centrifugation was recorded as m_2_ (g). WHC was calculated using the following Formula (2):

$$[eqn]$$

2.3.3. Texture Profile Analysis (TPA)

TPA was performed following the method described in ISO 23855:2021 [17]. The samples were cut into cubes (2 cm × 2 cm × 2 cm) and equilibrated at room temperature for 30 min. Each sample was formed into a cylinder (25 mm in diameter and 30 mm in height) and subjected to the double compression test using a texture analyzer (TA-XT2i, Stable Micro Systems Ltd., Godalming, UK) equipped with a P/5 probe. The test parameters were as follows: trigger force, 10 g; interval time between compressions, 5 s; compression ratio, 30%; pre-test and post-test speeds, 2 mm/s; and test speed, 1 mm/s. The probe deepened to a distance of 5 mm into the sample. After testing, texture attributes including hardness, springiness, cohesiveness, chewiness, and gel strength were calculated by the instrument software based on three replicates.

2.3.4. Whiteness

The whiteness of the samples was measured following the method described by Tao et al. [18] using a colorimeter (CR400, Konica Minolta, Tokyo, Japan). Each sample was cut to a thickness of 20 mm. The color parameters, including lightness (L*), redness/greenness (a*), and yellowness/blueness (b*), were recorded to determine whiteness. Whiteness was calculated using the following Formula (3):

$$[eqn]$$

2.4. Microstructure Characterization of Antarctic Krill-KGM Surimi Gel

2.4.1. Scanning Electron Microscopy (SEM)

Freeze-dried sample slices were prepared and mounted on aluminum stubs using conductive adhesive. The samples were coated with a thin layer of gold before observation, according to the method of Shi et al. [19]. The microstructure was observed using an SEM (SU8010, HITACHI, Tokyo, Japan) operated at an accelerating voltage of 10 kV and observed at magnifications of 200× and 2000×.

2.4.2. Magnetic Resonance Imaging (MRI)

MRI was performed according to the method of Ren et al. [20]. The samples (approximately 5 g) were wrapped in polyethylene film and placed in a plastic container. MRI measurements were conducted using a MesoMR23-060 V-I NMR analyzer (Suzhou Niumag Corporation, Suzhou, China). The acquisition parameters were set to an echo time of 20 ms and a repetition time of 2000 ms. Images were obtained and analyzed using an Image Evaluation software (MesoMR23-060 V-I).

2.4.3. Low-Field Nuclear Magnetic Resonance (LF-NMR)

LF-NMR measurements were performed by the method of Chen et al. [21] with minor modifications. After the excess free water of the samples was absorbed using filter paper, the sample (0.5 g) was placed in a glass tube and inserted into the NMR probe. Samples were analyzed using a MesoQMR23-060H NMR analyzer (Suzhou Niumag Corporation, Suzhou, China). The test parameters were as follows: operating frequency of 20 MHz, 8 scans, echo time of 3000 ms, and a total of 12,000 echoes. The LF-NMR relaxation curve was fitted to a multiexponential curve with the MultiExp Inv Analysis software (MesoQMR23-060H). T_21_, T_22_, and T_23_ were determined as the amplitudes of the relaxation components, respectively.

2.4.4. Fourier Transform Infrared (FT-IR) Spectroscopy

Freshly made samples were first freeze-dried, collected, and transferred into a glass humidity remover for at least 24 h. FT-IR spectra were determined for powder samples (approximately 0.5 g) with potassium bromide as the background at 25 °C. Each sample was scanned 64 times over a range of 400 to 4000 cm^−1^ at a resolution of 4 cm^−1^ and 32 scans.

2.5. Surface Hydrophobicity and Sulfhydryl Content of Antarctic Krill-KGM Surimi Gel

2.5.1. Surface Hydrophobicity

Surface hydrophobicity was measured following the method described by Dominguez-Hernandez & Ertbjerg [22]. Samples were prepared at a concentration of 5 mg/mL in 20 mmol/L phosphate buffer (pH 6.0). A 1 mL aliquot of the sample solution was mixed with 200 µL of bromophenol blue (1 mg/mL) and incubated at 25 °C for 10 min. The mixture was then centrifuged at 7000× g at 25 °C for 15 min. The supernatant was diluted 10-fold, and the absorbance of the solution was measured at 595 nm. A blank was prepared using 1 mL of 20 mmol/L phosphate buffer (pH 6.0) with 200 μL BPB. Surface hydrophobicity was calculated using the following Formula (4):

$$[eqn]$$

where A_0_ represents the absorbance of the blank solution, and A_1_ represents the absorbance of the sample solution.

2.5.2. Sulfhydryl Content

Sulfhydryl content (SH) was determined using Ellman’s method [23]. Sample solutions (4 mg/mL, 0.5 mL) were mixed with Tris-HCl buffer (0.2 M, pH 8.0, 4.5 mL) containing 8 M urea, 5 mM EDTA, and 10 mg/g SDS. The resulting mixture (5 mL) was mixed with 0.4 mL of Tris-HCl buffer (10 mM, pH 8.0) containing 10 mM DTNB and then incubated at 40 °C for 30 min. The absorbance was measured at 412 nm against a blank containing 0.6 mol/L KCl using a spectrophotometer (DU530, Beckman Coulter, Indianapolis, IN, USA). The SH was calculated using the following Formula (5):

$$[eqn]$$

where A_412_ represents the absorbance of the sample solution at 412 nm, D represents the dilution factor, c represents the protein concentration of the sample solution (mg/mL), and 73.53 was derived from 10^6^/13,600, with 13,600 representing the molar extinction coefficient of Ellman reagent.

2.6. Statistical Analysis

All experiments were conducted in triplicate, and all data were expressed as mean ± standard deviation. Statistical analysis was performed using SPSS software (version 24.0). Significant differences between means (p < 0.05) were determined using one-way analysis of variance (ANOVA).

3. Results and Discussion

3.1. Physiochemical Characterization of Antarctic Krill-KGM Surimi Gel

3.1.1. Cooking Loss

Cooking loss refers to the reduction in water and water-soluble components in food during cooking [24]. In the present study, the cooking loss rate of Antarctic krill-KGM surimi gels initially decreased and then increased as the KGM concentration increased from 0.0 to 20.0 mg/g (Figure 1A). The increase in cooking loss observed at KGM levels above 10.0 mg/g was associated with the development of a more porous gel structure. The lowest cooking loss was observed at 10.0 mg/g KGM, indicating that this level is optimal for minimizing water and water-soluble component loss. The decrease in cooking loss with an appropriate level of KGM can facilitate the formation of water-locked gel networks and improve their protein-water binding capacity. KGM undergoes physical rearrangement within the surimi gel matrix. Consequently, the composite surimi gels with suitable KGM levels can retain more water molecules, thereby reducing the cooking loss rate [19,25].

3.1.2. Water-Holding Capacity (WHC)

WHC represents the ability of surimi gels to retain water and is closely related to the spatial arrangement and three-dimensional network structure of the composite surimi gel matrix [26]. The hydrophilic groups in KGM molecules facilitate interactions with protein-protein and protein-water, promoting the formation of a water-locked gel structure with enhanced WHC. In this study, KGM significantly increased the WHC of Antarctic krill-KGM surimi gels in a dose-dependent manner (p < 0.05) (Figure 1B). Moreover, KGM was able to fill the surimi gel matrix effectively, resulting in a more compact and stable gel structure compared to the control [27]. The results were consistent with previous reports by Zhu et al. [28] and Cao et al. [16].

3.1.3. Texture Profile Analysis (TPA)

TPA is commonly used to assess the mechanical properties of materials under large-scale deformation. Texture is a key determinant of consumer perception and acceptance, making it an important indicator of food quality. In this study, the hardness (N), chewiness (N), gel strength (N), cohesiveness (%), and springiness (%) of Antarctic krill-KGM surimi gels initially increased and then decreased with increasing KGM levels compared to the control (Table 1). The highest values of hardness, chewiness, and gel strength were observed at 10.0 mg/g KGM, reaching 1666.18 ± 17.35 N, 329.94 ± 68.58 N, and 1581.78 ± 12.86 g, respectively. Gel strength of Antarctic krill-KGM surimi gels initially increased with increasing KGM concentration, reaching a maximum, and then decreased at higher levels. With the addition level of KGM exceeding 10.0 mg/g, the microstructures of the sample were weakened due to the formation of inhomogeneous network channels and the tiny pores. Furthermore, KGM significantly reduced the chewiness and hardness of the gels (p < 0.05). KGM showed no significant effect on springiness (p > 0.05). However, Li et al. [29] reported that KGM could improve surimi gel strength through its “filling effect.” These results indicated that Antarctic krill-KGM surimi gels can achieve a high-quality texture suitable for direct consumption when an optimal level of KGM is incorporated, consistent with the findings of Zhang et al. [30]. The decrease in gel strength was accompanied by the formation of a looser and more porous structure [31], likely due to interactions between the hydrophilic groups of KGM and Antarctic krill protein molecules.

3.1.4. Whiteness

Whiteness is an important quality indicator of surimi gels and is affected by the ordered structure of the surimi gel [32]. As shown in Table 2, the whiteness of Antarctic krill-KGM surimi gels initially increased and then decreased with increasing KGM levels. The maximum whiteness value (78.57) was observed at 15.0 mg/g KGM. At higher KGM concentrations, the gels developed a more porous structure, resulting in an increase in whiteness. This behavior is likely due to the hydroxyl groups in KGM forming hydrogen-bonded interactions with polar residues in the surimi gels [33]. Moreover, whiteness is mainly affected by protein denaturation, lipid oxidation, etc. The L* and a* values showed a similar trend, initially increasing and then decreasing. At lower KGM levels, the surimi gel network formed a more uniform and ordered structure, enhancing the luster and brightness of the sample. At higher KGM levels, structural changes in the composite gel increased light scattering, reducing lightness. The results showed that L* had a significant effect on the overall whiteness of the composite surimi gels [14].

3.2. Microstructure Characterization of Antarctic Krill-KGM Surimi Gel

3.2.1. Scanning Electron Microscopy (SEM)

SEM was used to assess the surface morphology of Antarctic krill-KGM surimi gels. Pure Antarctic krill surimi gel exhibited a non-uniform, porous three-dimensional network structure, which partly explained its poor gel-forming ability, often described as “curd-like” or “flake-like”. Compared with the control group, Antarctic krill-KGM surimi gels with 5.0 mg/g KGM showed a tighter microstructure with more regular and evenly distributed pores. As the KGM concentration increased, the Antarctic krill-KGM surimi gels developed a more complex network with smaller pore sizes (Figure 2A). The microstructural improvement was likely due to interactions between water molecules and KGM through hydrogen bonding and electrostatic interactions. At 15.0 mg/g KGM, the gel microstructure was more compact with fewer and smaller pores compared to the 10.0 mg/g KGM group. However, excessive KGM addition could also lead to uneven pore distribution, suboptimal water absorption, and the weakness of the gel’s structure [34]. These results indicated that an appropriate level of KGM contributes to a dense surimi gel microstructure, thereby improving WHC [19].

3.2.2. Magnetic Resonance Imaging (MRI)

Water distribution is a crucial indicator for evaluating water retention in foods [35]. In the MRI images of Antarctic krill-KGM surimi gels, colors gradually transitioning from blue to red indicated that hydrogen protons are changing from a dispersed to a dense state [36]. The proportion of red regions gradually increased with increasing KGM levels, indicating an increase in immobilized water and a corresponding decrease in free water [37]. The signal intensities significantly increased with increasing KGM level (p < 0.05). Moreover, the water distribution of the surimi gel was related to its functional properties and network structure. The 10.0 mg/g KGM group had the reddest proton density image, indicating the highest WHC among the composite gels (Figure 2B). These results demonstrated that water distribution in the composite surimi gels was consistent with their WHC.

3.2.3. Low-Field Nuclear Magnetic Resonance (LF-NMR)

LF-NMR is an essential technique for analyzing the distribution, migration, and binding capacity of water in food materials [29]. In LF-NMR, three ranges of hydrogen proton relaxation times, T_21_ (0–10 ms), T_22_ (10–100 ms), and T_23_ (100–1000 ms), represent bound water, immobilized water, and free water, respectively. In Antarctic krill surimi gels, bound water (T_21_) accounted for less than 2%, immobilized water (T_22_) was the predominant form (>95%), and free water (T_23_) comprised approximately 2%. The results showed significant shifts in the relaxation time peaks of T_22_ and T_23_ (p < 0.05) in Antarctic krill-KGM surimi gels, indicating water migration (Figure 3A). This may be due to KGM affecting the state of hydroxyl groups, network structures, and water mobility of the surimi gels. However, no significant changes were observed in the T_21_ peak, indicating that KGM does not significantly affect bound water mobility. The T_22_ peak significantly shifted to shorter relaxation times, indicating reduced mobility of immobilized water, while T_23_ decreased due to the removal of excess free water from the surimi gels. These results showed that KGM promotes the transformation of free water into immobilized water, thereby increasing the overall WHC of the composite surimi gels [38].

3.2.4. Fourier Transform Infrared (FT-IR) Spectroscopy

FT-IR is a key technique for analyzing changes in functional groups and molecular structures of materials [39]. As shown in Figure 3B, characteristic peaks corresponded to the absorption wavelengths of different functional groups. In the infrared spectra of the composite gels, the disappearance of the KGM peak at approximately 1730 cm^−1^ indicated the loss of acetyl groups (Figure 3B). Additionally, the peaks at 1646 cm^−1^ (0.0 mg/g KGM) shifted to 1636 cm^−1^ (20.0 mg/g KGM) in the infrared spectra, likely due to the aggregation of hydroxyl groups and the formation of hydrogen bonds within the gel network. The absorption peak of KGM at approximately 1730 cm^−1^ was attributed to acetyl groups. Protein secondary structures can be identified by their characteristic absorption peaks: α-helix (1651–1660 cm^−1^), β-sheet (1610–1639 cm^−1^), β-turn (1661–1700 cm^−1^), and random coil (1640–1650 cm^−1^) [40]. Furthermore, α-helix and β-sheet structures correspond to ordered protein structures, while β-turn and random coils represent unordered protein structures [41]. Previous studies have reported that poor quality of Antarctic krill surimi gels is associated with high α-helix/β-sheet ratios [13]. The most significant spectral change observed was a gradual decrease in absorbance intensity and the shift to shorter wavenumbers with increasing KGM levels.

3.3. Surface Hydrophobicity and Sulfhydryl Content of Antarctic Krill-KGM Surimi Gel

3.3.1. Surface Hydrophobicity

Surface hydrophobicity is a crucial indicator used to assess structural changes in protein molecules. The KGM (5.0 mg/g) group exhibited a significant increase in surface hydrophobicity compared to the other groups (Figure 4A). This increase in surface hydrophobicity may be attributed to the exposure of hydrophobic residues caused by protein denaturation. Similarly, Lu et al. [22] reported that the unfolding and exposure of aromatic amino acids can lead to an increase in surface hydrophobicity. Several studies have reported that hydrocolloids such as κ-carrageenan and alginate can inhibit increases in surface hydrophobicity by forming ionic and hydrogen bonding interactions [24,42]. Therefore, it was speculated that KGM could form strong ionic and hydrogen bonds with the functional sites of Antarctic krill proteins, which may help prevent protein oxidation and denaturation.

3.3.2. Sulfhydryl Content

Sulfhydryl groups are key functional groups present both on the protein surface and within the protein interior. Disulfide bonds are generated through the oxidation of sulfhydryl groups during heat treatment and can subsequently be reduced back to free sulfhydryl groups. Compared with the control group, the sulfhydryl content of Antarctic krill-KGM surimi gels decreased with increasing KGM levels. This decrease may be attributed to the formation of disulfide bonds and protein depolymerization within the samples. It is presumed that KGM can expose buried hydrophobic groups, promote the formation of disulfide bonds, and facilitate protein aggregations through hydrophobic interactions.

Interestingly, KGM-containing samples appeared to provide a protective effect against oxidative changes (Figure 4B). The observed decrease in sulfhydryl groups during storage could be due to the oxidation of cysteine thiol groups and the denaturation of myosin. Zhang et al. [43] reported that κ-carrageenan inhibited sulfhydryl group loss in shrimp proteins by improving amino acid cross-linking and radical scavenging capacity. Similarly, Walayat et al. [35] reported that the mixture of κ-carrageenan and ovalbumin inhibited disulfide formation by improving the hydrogen bonding capacity. Thus, it is shown that KGM could maintain the structural stability of Antarctic krill protein by protecting its globular head from oxidation.

3.4. Correlation Analysis

Correlation analysis was performed between the physiochemical properties and textural characteristics of Antarctic krill-KGM surimi gels (Figure 5). Texture analysis revealed that the composite surimi gels exhibited a compact and well-ordered spatial structure. Hardness, chewiness, and cohesiveness were positively correlated with KGM concentration. These findings indicated that KGM promotes the formation of an ordered gel structure by modulating protein aggregation, accompanied by a partially layered structure [44]. Therefore, the observed differences in the microstructure of Antarctic krill-KGM surimi gels may partly account for the differences in texture among the samples (Table 2) [9].

Increasing KGM levels enhanced the absolute zeta potential and negative charge of the samples, thereby strengthening electrostatic repulsion and spatial resistance [32]. Interactions between KGM and Antarctic krill proteins contributed to the transformation of free water into immobilized water within the surimi gel matrix. Moreover, due to the abundance of hydrophilic groups, KGM was capable of binding significant amounts of water. The results are consistent with those findings reported by Park et al. [45]. Therefore, the results demonstrated that hydrophobic interactions and disulfide bonds were the predominant intermolecular forces in Antarctic krill-KGM surimi gels. SEM analysis further showed that KGM promoted protein-protein and protein-water cross-linking, resulting in increased gel strength and WHC. The possible mechanism could be due to the state of the physical crosslinking or permeation network by KGM in the surimi gel. Overall, these results show that KGM facilitates interactions with Antarctic krill proteins and leads to modifications in their structure and functional properties.

4. Conclusions

KGM significantly improves the functional properties and structural characteristics of Antarctic krill-KGM surimi gels. The results showed that with increasing KGM levels, WHC, hardness, chewiness, gel strength, whiteness, and immobilized water content initially increased and then decreased. Structural analysis indicated that the interactions within the composite surimi gels were primarily governed by non-covalent intermolecular forces. These changes are attributed to the formation of a cross-linked network and the filling of matrix cavities by KGM, particularly at a 10.0 mg/g addition level. These results not only provide new insights into the quality characteristics of composite surimi gels but also offer guidance for optimizing the quality of high-value surimi products. Future research should focus on elucidating the interaction mechanisms between KGM and Antarctic krill proteins, as well as the effects of KGM with different degrees of deacetylation.