Surimi Gels Research Articles

Effect of modified washing process on water usage, composition and gelling properties of grass carp surimi.

Washing is an essential process in surimi production, from which a large amount of wastewater is generated. Due to the increasing pressure of environmental protection, it is an urgent technical requirement for surimi manufacturers to reduce water usage while maintaining the quality of surimi. In this study, composition, structure and gelling properties of grass carp surimi prepared with a modified washing process (MWP) were investigated. Intermediate dehydration with various compression ratios were utilized between two washing cycles. Water usage and wastewater discharge were reduced significantly by 33% and 38%, respectively, when MWP was applied. As the compression ratio increased, composition of fat, cathepsins, transglutaminase and heme proteins in surimi decreased gradually. Yield, protein content and the major protein pattern of surimi were not changed, but surface hydrophobicity gradually decreased. As the compression rate increased to 1:2.0, textural values and water holding capacity of the corresponding surimi gel decreased gradually, while whiteness increased and then remained unchanged. At a higher compression ratio (>1:1.5), aggregated network and excessive free water were observed in the surimi gel. Composition and gelling properties of the MWP surimi with a compression ratio of 1:1.2-1:1.5 were equal to those of the surimi prepared under conventional three-cycle washing. Results indicated that MWP demonstrated its great potential in surimi production by dramatically reducing the usage of cold water and discharge of wastewater without scarifying surimi quality. © 2022 Society of Chemical Industry.

Effects of deheading and rinsing pretreatment on the quality of white leg shrimp (Litopenaeus vannamei) surimi based on endogenous proteases

In this study, the effects of different pretreatments on the quality of white leg shrimp surimi were investigated based on shrimp endogenous proteases. The results showed that removing the head and rinsing significantly (P < 0.05) improved the gel strength, texture, whiteness, water distribution, and microstructure of the shrimp surimi gels. Headless shrimp surimi (HSS) had higher salt-soluble protein and lower water-soluble protein than whole shrimp surimi (WSS). The shrimp heads had high cathepsin B, L, D, and serine protease activities. Electrophoretic analysis revealed significant degradation of the myofibrillar proteins in the WSS during cold storage and thermal gelation. Moreover, the myosin heavy chains almost disappeared after thermal gelation, and new bands appeared at about 270 kDa and 100 kDa. However, rinsing reduced the endogenous proteases, water-soluble proteins, and concentrated salt-soluble proteins in the shrimp surimi; thus, the quality of the shrimp surimi gel improved after rinsing. These results suggest that the quality of the surimi gel was damaged by the endogenous proteases, and that removal of the shrimp heads and rinsing significantly (P < 0.05) improved the quality of the shrimp surimi gel. The gel properties of WSS were similar after the second rinse to those of unrinsed HSS. The choice of headless shrimp or whole shrimp as the raw material for production needs to be comprehensively considered according to the planned cost and the quality required for the shrimp surimi product. The recommended number of rinses is 1–2.

Preparation, characterization, and potential application of shark derived single domain antibody against myofibrillar binding serine protease in Silver carp

Myofibrillar binding serine protease (MBSP) existing in fish muscle is the leading cause of gel deterioration, which adversely affects the quality of surimi produces. Screening and preparation of protease inhibitors with high efficiency and specificity is an important approach to address the reduction of surimi quality. In this study, shark derived single domain antibody specific to MBSP was expressed and its properties were investigated systematically. The results showed that single domain antibody specific to MBSP could be expressed in soluble using SUMO fusion tagged Escherichia coli expression system with good thermal and pH stability. The enzyme activity inhibition effect in vitro could reach 62.9% at the concentration of 0.1 mg/ml of single domain antibody. When added in silver carp surimi, it could significantly inhibit the deterioration of surimi gel. The results of this study implied that shark derived single domain antibody could be developed as a new inhibitor of MBSP used for the control of gel degradation in surimi produces. Novelty impact statement Shark derived single domain antibody specific to MBSP was expressed in soluble with high yield and stability; the expressed antibody could significantly inhibit the activity of MBSP both in vitro and in surimi; this good characteristic makes it to be an inhibitor for the deterioration of surimi gel.

UV irradiation improved gel properties and chill‐stored stability of surimi gel

SummaryThe study investigated the properties and storage stability of Japanese Spanish mackerel (Scomberomorus niphonius) surimi gel exposed to ultraviolet irradiation for 0.5, 1, 2 and 3 h (UV0.5, UV1, UV2, UV3) before thermal treatment. The results showed that all UV‐irradiated surimi gels exhibited compact microstructure along with increased gel strength and water‐holding capacity than control. Investigations on chemical properties of myofibrillar protein (MP) from surimi showed that tryptophan fluorescence intensity declined while bromophenol blue‐binding capability increased after UV irradiation. Sulfhydryl content in MP of UV2 and UV3 decreased while their carbonyl content increased. Electrophoresis analysis indicated that myosin heavy chain of UV2 was most attenuated. Storage test showed that UV2 maintained the highest gel strength during chilled‐storage and its total viable count was below 5 log10CFU•g−1 after 18 days. Therefore, UV irradiation might be applied to improve surimi gel properties and extend shelf life.

Effects of oil-modified crosslinked/acetylated starches on silver carp surimi gel: Texture properties, water mobility, microstructure, and related mechanisms

This study investigated the texture properties, water mobility and microstructure of surimi gel added with crosslinked tapioca starch (CTS) and acetylated tapioca starch (ATS), and their counterparts modified with oil (Oil-CTS and Oil-ATS, respectively). Both Oil-CTS and Oil-ATS could improve the breaking force, deformation and elasticity of surimi gel, especially Oil-CTS. Additionally, oil-modified starches could increase the water-holding capacity of surimi gels and prompt the transformation of free water to bound water, resulting in the decrease of water mobility. The difference between oil-modified starches and their counterparts in gel-enhancing effect is due to the swelling ability and different microstructure of surimi/starch gels. Namely, oil-modified starches prompted the formation of a more homogeneous and compact gel network, endowing the surimi/Oil-CTS gel with tiny pores due to its restricted swelling property, while others were opposite. Raman spectral results further unveiled that the addition of oil-modified starches promoted the protein conformational transition from α-helix to β-sheet and β-turn, as well as a decrease of ionic bonds and an increase of hydrogen bonds and hydrophobic interactions of surimi gel, which were beneficial to form firm and compact gel structure. The overall results indicated the new oil-modified starches (especially Oil-CTS) have great potential to improve the quality of surimi-based products.

Physicochemical properties and microstructure of composite surimi gels: The effects of ultrasonic treatment and olive oil concentration

This study was conducted to evaluate the effects of extra virgin olive (EVO) oil incorporation on the physicochemical properties and microstructure of surimi gels subjected to ultrasound-assisted water-bath heating. As the oil content was increased from 0 to 5 g/100 g, the breaking force and gel strength of the surimi gels significantly decreased, while the whiteness level exhibited the opposite tendency irrespective of the heating method. Compared with the traditional water-bath heating method, the ultrasonic heating promoted the unfolding of the α-helix structure and intensified the formation of β-sheet content and non-covalent bonds (ionic bonds, hydrogen bonds, and disulfide bonds), especially disulfide bonds, which contributed to the further crosslinking of the proteins and to gelation, thereby improving the gels’ strength. In addition, smaller cavities and compact microstructures were observed in the low-oil (≤3 g/100 g) surimi gels under ultrasonic treatment, which effectively prevented water migration in the gel network and resulted in a high water holding capacity and uniform water distribution. However, the ultrasonic treatment barely remedied the poor microstructures of the high-oil (>3 g/100 g) surimi gels owing to oil coalescence, which weakened the protein–protein interaction. In conclusion, ultrasonic treatment combined with water-bath heating significantly improved the gelation properties of the low-oil surimi gels, although it did not remarkably improve those of the high-oil gels. The choice of a suitable oil concentration could be of great importance for the production and functioning of surimi products via ultrasound-assisted treatments.

EFEKTIVITAS SUHU SETTING PADA GEL SURIMI IKAN BULAN-BULAN (Megalops cyprinoides)

Good characteristics of surimi can be seen from its ability to form a gel, one of which is the temperature setting. This study aims to determine the effectiveness of the setting temperature on the surimi gel of moonfish (Megalops cyprinoides). The study used a completely randomized design with treatments of five temperature setting with three replications. Parameters observed were gel strength, folding test, whiteness and expressible moisture content. The results showed that setting temperature had a significant effect on gel strength, folding test, whiteness degree and expressible moisture content (p&lt;0.05) at 95% confidence level. The setting temperature treatment of 40oC and without setting had the highest gel strength compared to other treatments with the max load values of 59.79 kg/cm2 and 60.63±1.44 kg/cm2, respectively, with a 5-fold test quality value, namely does not crack after being folded into quarters. The best setting temperature for the gel forming ability of fish surimi for moonfish is 40oC and without setting temperature.

Gelling properties and microstructure of the silver carp surimi treated with pomegranate (Punica granatum L.) peel extract.

Effects of ethanolic extracts of pomegranate peel (PPE) on the gelling and textural characteristics of silver carp surimi gel was investigated. The peels extracted with 100% ethanol exhibited highest total phenolics, tannin and flavonoid contents. The change of the gelling properties of surimi was explained using infrared spectroscopy, chemical interactions, and scanning electronic microscopy images. Greater number of hydrogen bonds and hydrophobic interactions were found in surimi gel fortified with 0.45% PPE. Amongst all the concentrations of PPE, 0.45% level exhibited the lowest sulfhydryl and primary amino groups and this was concurrent with the highest gel strength. The FT-IR analysis showed a gradual reduction of intensity of the amide I band with the increase of PPE concentration, and also shifting to lower value from control to surimi with PPE 0.90%. Absorption bands like C-N stretching from amide II and N-H deformation from amide III were also detected. The SEM images showed that surimi with 0.45% PPE had most ordered, finest and denser gel network, and was closely integrated with higher breaking force, hardness, and WHC. This study showed the potential of functional components of fruit wastes for improving gelling properties of surimi with additional health benefits for the consumers.

Effects of NaCl and MTGase on printability and gelling properties of extrusion-based 3D printed white croaker (Argyrosomus argentatus) surimi

Surimi has been explored as a promising 3D printed ingredient, but its rheological properties need to be identified for printing accuracy and gelling properties improvement. This study investigated the printability of white croaker surimi mixtures with NaCl and microbial transglutaminase (MTGase) in an extrusion-based 3D printing process and their gel forming characteristics after thermal treatment. The surimi mixture with different levels of NaCl (5–40 g/kg) and MTGase (0–4.0 g/kg) behaved as Herschel-Bulkley fluid. The rheological properties and printing performance screened out the appropriate amount of additive (20 g/kg NaCl and 2.0 g/kg MTGase) suitable for 3D printing. Compared the conventionally prepared surimi gels, 3D printed surimi gels with 70% infilled density had similar or even higher water holding capacity and gel strength, but lower L and whiteness values significantly (p < 0.05) because of the porous structure created by 3D printing. The addition of NaCl and MTGase had significant effect on the 3D printability of surimi, and the mechanical properties of 3D printed surimi gels were comparable to the conventionally prepared ones.

Compare with different vegetable oils on the quality of the Nemipterus virgatus surimi gel.

To enhance the quality and flavor of surimi‐based products, we investigated the effects of vegetable oils (peanut, soybean, corn, coconut, olive, and safflower seed oils) on the texture, water‐holding capacity (WHC), microstructure, and flavor of the Nemipterus virgatus surimi gel. The results showed that 6 kinds of vegetable oils could improve the whiteness and flavor of gels. However, peanut, olive, and coconut oils enriching oleic acid or lauric acid were easy to accumulate with an average diameter of more than 0.15 μm. Thus, the gel with the oil showed a loose network structures with large cavities, and the texture was deteriorated, accompanied by decreased WHC (p < .05). Compared with other vegetable oils, soybean, corn and safflower seed oils enriching linoleic acid were emulsified with protein forming a stable interfacial protein film. The gel with the oil showed an increase in the WHC and bound water content. Furthermore, the oil droplets with an average diameter of less than 0.15 μm were evenly distributed in the gel matrix, and the gel exhibited dense network structures with small cavities and smooth surface. In general, soybean and safflower seed oils can be used as a potential additive to improve the quality and flavor of surimi‐based products.

Gel &amp; three-dimensional printing properties of sheep plasma protein-surimi induced by transglutaminase

The objective of the present work was to investigate the effects of transglutaminase (TGase) on rheological property, three-dimensional (3D) printing property, textural property, water holding capacity, water distribution and secondary structures of sheep plasma protein-surimi gels. The results from 3D printing experiments showed that compared with a control group, sheep plasma protein-surimi gels added with 0.2% and 0.3% TGase presented good printing properties. During the heating process, high G′ values were achieved in the formation of sheep plasma protein-surimi gels due to the enhancement of connections between proteins by TGase. Compared with the control group, the hardness, springiness, and chewiness of the 3D printed sheep plasma protein -surimi gels reached the maximum with the addition of 0.4% TGase, which increased by 15.28%, 14.09%, 32.46% respectively. Furthermore, the concentration of the added TGase was directly proportional to the breaking force of the surimi gels. Adding 0.4% TGase increased the gel strength to a maximum value of 185.04 N × mm. The water-holding capacity of the 3D printed surimi gel was also significantly increased after the addition of TGase, as evidenced by low-field nuclear magnetic resonance. The addition of TGase restrained more residual water and increased the T 21 relaxation time. The Raman spectroscopy analysis showed that the α-helix percentage increased significantly with the addition of TGase. Taken together, the results suggest that the 3D printability and gel properties of sheep plasma protein-surimi gel can be effectively improved by TGase. • Transglutaminase (TGase) improves the gel properties of surimi containing sheep plasma protein. • TGase impacts the 3D printability of sheep plasma protein-surimi. • 3D printing technology capable of creating a surimi product.

Assessing the Gel Quality and Storage Properties of Hypophythalmalmichthys molitrix Surimi Gel Prepared with Epigallocatechin Gallate Subject to Multiple Freeze-Thaw Cycles.

Epigallocatechin gallate (EGCG) with concentrations of 0–0.03% was added to manufacture surimi gels, respectively, while effects on gel quality and storage properties indicators during freeze-thaw (F-T) cycles were investigated. The results implied that the gel quality and storage properties of surimi gels added without EGCG were seriously destroyed during F-T cycles. The addition of EGCG could inhibit the decline of texture and gel strength. Moreover, EGCG has effect on inhibiting the microbial growth and the formation of off-odor compounds such as total volatile basic nitrogen (TVB-N) and malondialdehyde (MDA). Low-field nuclear magnetic resonance (LF-NMR) and water-holding capacity (WHC) results showed that immobilized water migrated to free water with the extension of F-T cycles. The scanning electron microscope (SEM) observed denser protein networks and smaller holes from the surimi gels added with EGCG. However, excessive (0.03%) EGCG showed the loose network structure and moisture loss. Overall, EGCG in 0.01–0.02% addition was good for resisting damage of surimi gels during F-T cycles.

Effects of repeated deboning on structure, composition, and gelling properties of silver carp surimi.

Surimi is produced from the various sequences of filleting, deboning, washing, dehydrating, blending with cryprotectant, and freezing. Deboning, after which fish flesh is minced and separated from bone, skin, etc., is a vital step in the surimi production. In this study, effects of repeated deboning on yield, structure, composition, and gelling properties of silver carp surimi were investigated. Surimi yield increased rapidly from 10% to 23% as the cycle of repeated deboning was increased from one to three, and then slowly increased up to 26%. As the cycle increased, cellular structure and ultrastructure of muscle fibers progressively fractured. Contents of fat, cathepsins, heme proteins, and transglutaminase of surimi obviously increased and then decreased. Three-dimensional network of surimi gel without setting (NS gel) became more porous with the increase of cycles. It became more compact, and then turned to aggregated forms with lower homogeneity, for the surimi gel with setting (WS gel). Correspondently, the NS gel textural values gradually decreased with the cycles, while the WS gel textural values increased up to three cycles and then decreased. Regardless of setting, whiteness of surimi gels decreased and then increased with the cycles. Our results suggested that structure and compositions of surimi changed with the cycle of repeated deboning, which affected gelling properties of surimi. It is recommended to debone three or four cycles in silver carp surimi production. © 2022 Society of Chemical Industry.

Threadfin bream surimi gel containing squid fin protein hydrolysate: Textural properties, acceptability, and volatile profile.

Gel properties of threadfin bream surimi gels with squid fin protein hydrolysate (SFPH) at various concentrations (0, 1, 2, 3, and 4%; w/w) were determined. The gel without SFPH (CON) had the highest breaking force (BrF) and deformation (DeF) as compared to those with SFPH (p<0.05). Among the gel with SFPH, gel containing 1 and 2% SFPH (SFPH-1 and SFPH-2, respectively) had the highest BrF, whereas the lowest value was obtained when 4% SFPH was used (SFPH-4) (p<0.05). The whiteness of all samples was slightly decreased with an upsurging amount of SFPH. However, water holding capacity was increased with augmenting levels of SFPH (p<0.05). Sensory analysis revealed that SFPH-2 had a higher squid odor and flavor likeness score than CON (p<0.05). Textural properties, especially hardness, were decreased with increasing SFPH, except for SFPH-1 and SFPH-2 (p>0.05). In addition, the rheological properties, microstructure, and volatile profile of the selected surimi gel were also studied. The storage modulus (G') of SFPH added samples was decreased as compared to the CON sample. The CON gel had a finer and more compact network as compared to SFPH-2 and SFPH-4 samples. Volatile profiles indicated that alcohols, carboxylic acids, ketones, and ether were the major volatile compounds present in both gel samples. Furthermore, thiophene, 3-methyl-, contributing to squid flavor, was found in the SFPH-2 sample. Overall, SFPH at 2% could act as a flavorant in the threadfin bream surimi gel without markedly negative impact on gelling and textural properties, while providing squid odor and flavor to the resulting gel. PRACTICAL APPLICATION: The various low-valued byproducts generated from the squid processing industry could result in various environmental problems. Those byproducts are rich in various biomolecules such as proteins, fats, enzymes, and so forth, which could be utilized to produce value-added products. Among them, protein hydrolysate (PH) rich in amino acids with excellent antioxidant properties could serve as an alternative flavorant. Therefore, PH from squid byproducts, especially fins, could be applied in foods such as fish balls, surimi gels, and so forth to enhance the nutritional and flavoring profile of a finished product. Moreover, bioactive peptides in PH with antioxidant potential could retard the oxidation of proteins and lipids.

Effect of oil modification on the multiscale structure and gelatinization properties of crosslinked starch and their relationship with the texture and microstructure of surimi/starch composite gels

This work investigated the multiscale structure and gelatinization properties of different oil-modified crosslinked starches and their relationship with the texture and microstructure of surimi/starch composite gels. The results showed clusters were formed by the agglomeration of starch, with oil on the surface of granules. Oil modification did not damage the long-range crystalline structure but impaired the short-range ordered structure. A high oil modification degree was shown to weaken starch structure, in contrast to an adverse effect for a high crosslinking level. Furthermore, compared with crosslinked starches, Oil-CTS had lower pasting temperature and gelatinization enthalpy, a higher viscosity, and better gel-reinforcing effect. Correlation analysis revealed the texture of surimi/starch composite gels was negatively correlated with the helical structure and pasting temperature of starch, and positively correlated with final and setback viscosity of starch and the swollen size of starch granules in surimi gel.

Mechanism of low-salt surimi gelation induced by microwave heating combined with l-arginine and transglutaminase: On the basis of molecular docking between l-arginine and myosin heavy chain

The reduction of the salt content of foods is of interest for health reasons. The present study showed that low-salt surimi gels could be produced using a combination of l-arginine (Arg) and transglutaminase (TGase) under microwave (MW) irradiation. The low-salt surimi gels produced by MW had similar physicochemical properties as regular-salt surimi gels produced by conventional two-stage water bath heating. Compared to low-salt surimi gels containing TGase alone, Arg increased the water holding capacity and gel strength (P < 0.05) and promoted the formation of a more homogeneous and compact three-dimensional gel network. As a result, there was a significant increase in the proportion of immobilized water and decrease in the proportion of free water (P < 0.05). The nature of the binding sites between Arg and myosin heavy chain was predicted using the molecular docking simulations analysis. These results may be useful for the development of low-salt surimi products.

Characteristics of silver carp surimi gel under high temperature (≥100 °C): quality changes, water distribution and protein pattern

AbstractThe effects of high‐temperature treatments (100–125 °C) on the properties of silver carp surimi gel were studied. The results showed that the gel strength and water holding capacity (WHC) of surimi gel decreased significantly (P &lt; 0.05), with the increase of heating temperature and the prolongation of heating time, and the higher the temperature, the greater the decrease trend. Hydrophobic interaction and disulphide bonds decreased significantly, while ionic bonds increased significantly (P &lt; 0.05), as well as β‐sheet increased while β‐turn and coil decreased significantly, which confirmed the changes of protein secondary structure caused by high‐temperature treatments. Myosin heavy chain (MHC) and actin bands gradually narrowed, and the production of new bands larger than 250 kDa by SDS‐PAGE showed the aggregation and cross‐linking reaction of proteins. However, the increased band intensity of 50–75 kDa and the increase of trichloroacetic acid (TCA) soluble peptides showed the degradation of proteins. The decrease of PT22 and the increase of PT23 indicated the conversion of immobilised water to free water in the gel matrix. In conclusion, high‐temperature heating caused the changes of protein secondary structure as well as chemical forces and water conversion, resulting in protein denaturation, aggregation, cross‐linking and degradation, forming a loosen and irregular gel network.

Influence of histidine on gelation properties of low sodium surimi from tilapia (Oreochromis niloticus)

SummaryThe aim of this study was to reduce the salt content of tilapia surimi using histidine without affecting gelation properties. The addition of histidine (T‐1) to low salt surimi gels increased the breaking force and deformation and resulted in the highest gel strength (458 g.cm). Expressible moisture was less in the T‐1 sample and proteolytic degradation was higher in the control sample indicating that autolysis did not occur in histidine added sample during gel setting. Protein patterns revealed cross‐linking of myosin heavy chain in gels with added histidine. Fourier transformed infrared spectra implied that histidine‐induced unfolding of proteins occurred after heating. T‐1 samples exhibited a dense and compact microstructure, whereas the control gel was loose. The results of this study show that the addition of histidine could yield high‐quality gels from tilapia surimi in low salt conditions.

Ultrasonic pretreatment improves the gelation properties of low-salt Penaeus vannamei (Litopenaeus vannamei) surimi

The effects of different ultrasonic pretreatments (120–600 W, 20 min; 360 W, 10–30 min) on the gel properties of shrimp surimi were investigated. Gel properties and protein functional properties were analysed to clarify the mechanism of action of ultrasound. The gel strength, water holding capacity and surface hydrophobicity of shrimp surimi gel increased initially and then decreased with the increase in ultrasound power or time, but the change in total sulfhydryl content showed the opposite trend, which indicated that proper ultrasound pretreatment could improve the gel properties of shrimp surimi, expand the protein to a greater extent and expose more SH groups and hydrophobic groups. According to scanning electron microscopy observation, ultrasound made shrimp surimi gel form a denser gel network. Fourier transform infrared analysis indicated that the α-helix content in shrimp surimi gel decreased initially and then increased with the increase of in ultrasound power or time, whereas the change in β-sheet content showed the opposite trend. And the protein was the most stable in 360 W/20 min pretreatment. SDS-PAGE patterns showed that proper ultrasound inhibited the degradation of actin and troponin C. In addition, dynamic rheology illustrated that the G′ values of the ultrasonic pretreatment group were higher than that of the control group, indicating that ultrasound could improve the elasticity and stability of shrimp surimi gel. The results suggested that the shrimp surimi gel pretreated by 360 W/20 min ultrasound showed the best gel properties. Furthermore, the correlation between the indexes affecting the properties of the gel was analyzed. This study provides a new technical means to improve the gel properties of shrimp surimi.

Insight into the mechanism of optimal low-level pressure coupled with heat treatment to improve the gel properties of Nemipterus virgatus surimi combined with water migration

The effect of optimal low-level pressure coupled with heat treatment (OPH treatment) on the gel properties and water migration of Nemipterus virgatus surimi was studied and compared with optimal high-pressure processing treatment (OP treatment) and traditional two-stage heat treatment (H treatment). Furthermore, the mechanism of OPH treatment in improving the gel properties were explored based on myosin. OPH treatment was found to be more conducive in improving the gel strength and water-holding capacity (WHC) of surimi gel than H or OP treatments. Moreover, OPH treatment induced an increase in the proportion of myosin β-sheets and exposed more intramolecular Tyr residues as compared to the other two treatments, which promoted myosin to form large protein clusters through disulfide bonds and hydrophobic interactions, and a honeycomb three-dimensional network structure with larger fractal dimension, lower porosity, smaller water hole diameter, and a greater number of water holes, was obtained. These helped the OPH-induced surimi gel lock in more unfrozen bound water and immobile water, and ultimately rendered better gel properties.