Diacylglycerol pre-emulsion prepared through ultrasound improves the gel properties of golden thread surimi

Enhancing surimi gel properties in silver carp with innovative ultra-micro crayfish shell powder

This study investigated the preparation and application of ultra-micro crayfish shell powder to enhance the quality of surimi gels. A combination of ball milling and irradiation techniques produced an innovative powder (MID) with reduced particle size and enhanced zeta potential, dispersibility, Ca2+ release, and hydrogen bonding energy (p < 0.05), while maintaining its composition. Adding 0.50 % MID to surimi gels resulted in optimal improvements, enhancing gel strength and texture as well as elasticity. MID also increased the water holding capacity (WHC), decreased water mobility, and resulted in a dense and ordered microstructure. Fourier transform infrared spectroscopy indicated improvements were due to increased intermolecular non-covalent bonding interactions. Electronic nose analysis showed MID reduced aromatic compounds and organosulphides, preserving flavor and reducing the fishy taste. Electronic tongue analysis revealed an increase in fresh flavor response. The preparation method significantly enhanced the quality and sensory properties of surimi gels.

Improving the gel properties of Nemipterus virgatus myosin gel using soy protein isolate-stabilized Pickering emulsion

The study investigated the effects of incorporating varying doses (0 %-10 %) of soy protein isolate-stabilized Pickering emulsion (SPE) on the rheological behavior, gel properties, intermolecular interactions, microstructure, and digestive properties of Nemipterus virgatus myosin gels. Adding 2.5 %-7.5 % SPE significantly improved the rheological behavior of the myosin sols and the strength of the myosin gel (p < 0.05). This improvement in gel strength was attributable to covalent interactions between SPE and myosin, which resulted in the formation of a denser network structure. According to Raman spectroscopy, SPE promoted alterations in myosin's secondary structure and facilitated the transition of disulfide bonds from intramolecular to intermolecular. Additionally, SPE elevated the content of small molecular active peptides in digested gel products, thus enhancing their antioxidant activity. In summary, SPE is a promising food processing aid for enhancing myosin gel properties and developing emulsion surimi gel products of improved quality.

Effects of cold plasma and sodium bicarbonate on the rheological, foaming, digestibility, and gelation properties of duck myofibrillar protein

This study investigated the effects of sodium bicarbonate (SB) on the rheological properties, foaming ability, digestibility, and gelation behavior of duck myofibrillar protein (MP) during cold plasma (CP) treatment. Duck MP solutions containing 0 %, 0.2 %, 0.4 %, and 0.6 % SB were treated with CP (50 V, 3 min), and their functional characteristics were analyzed. CP treatment alone induced significant protein oxidation and aggregation, leading to reduced rheological properties, digestibility, foaming ability, and gel quality. However, SB addition effectively alleviated these adverse effects. Compared to the CP treatment alone group, the CP-SB0.6 group showed increases in gel strength (2.61-fold), digestibility (1.02-fold), and total sulfhydryl content (40.57 %), along with reductions in carbonyl and dityrosine contents by 62.58 % and 46.95 %, respectively. SB also improved foaming ability (51.42 %), water-holding capacity (34.57 %), and Ca2+-ATPase activity (87.50 %). Microstructural and low-field NMR analyses further confirmed the formation of a denser gel matrix and enhanced water retention. These findings demonstrate that SB effectively mitigates CP-induced oxidative damage and offers a promising strategy to enhance the functional properties of duck MP in meat processing.

Multicriteria decision analysis: the potential of compounded plant-based gels for egg protein substitute

This study systematically evaluated the gel-related properties of composite gels prepared from soy protein isolate (SPI), mung protein isolate (MPI), and chickpea protein isolate (CPI) using a multi-criteria decision analysis (MCDA) approach, aiming to explore their potential as alternatives to whole egg gel (EG). The results demonstrated that with increasing SPI concentration, the rheological properties of the plant-based gels became highly comparable to those of EG. Additionally, the texture properties, water-holding capacity (WHC), and gel strength of the composite gels were significantly improved, exhibiting functional characteristics similar to those of EG. The EG-like microstructure it forms may be a key factor in the superior gel properties observed in composite gels. Furthermore, multi-criteria decision analysis revealed that the SMC-852 exhibited the highest closeness coefficient (C value), indicating its optimal overall performance among all experimental groups and its strong potential as a natural egg product alternative. The results of this study demonstrated that the similarity of plant-based egg alternatives to natural egg products can be effectively enhanced through the complementary nature of different plant proteins in terms of their functional properties. This provides important theoretical support for the development of new plant-based food products in line with the concept of sustainable development.

Elevating the critical gelling concentration of soy protein by disulfide bond cleavage during preheating treatment

There has been a growing demand for the development of high protein beverages in the food industry. However, during thermal processing, high-protein beverages undergo protein aggregation and gelation. In this study, thermostable soy protein was prepared by disulfide bond cleavage combined with preheating treatment. Thermostable soy protein had a higher denature extent than the control sample, which prevented the formation of larger aggregates upon reheating. Thermostable soy protein possessed lower viscosity (nearly 0 Pa·s) and an excellent fluidity index (around 0.8) after reheating at a concentration of 10 % (w/v), whereas the control sample had gelled. Moreover, rheology and dynamic light scattering collectively demonstrated that a minimum of 2.5 mM sodium metabisulfite (Na2S2O5) was required to prepare thermostable protein solutions. The present study shows an innovative method to produce thermostable soy protein.

Enhancing gel and 3D printing performance of lipid-enhanced skipjack tuna (Katsuwonus pelamis) surimi via Pickering high internal phase emulsion

This study explored the effect of lactoferrin (LF)-stabilized fish oil Pickering high internal phase emulsions (HIPPEs) on the gel property and 3D printing performance of skipjack tuna surimi compared with directly added fish oil. Based on the various environmental stress stability, HIPPEs could remain relatively stable when added to surimi gels. The luminance and whiteness of skipjack tuna surimi gel were significantly (p < 0.05) elevated after adding HIPPEs. Compared with directly added fish oil, the texture properties, gel strength and water holding capacity of surimi gels were notably (p < 0.05) increased after adding HIPPEs, and more free water changed into bound water and non-fluidizable water. Moreover, more α-helix turned into β-sheet, and the disulfide bond content was increased. The microstructure indicated that the tiny oil droplets of HIPPEs were more evenly distributed in the surimi gel network, while directly added fish oil caused the larger droplets aggregation and damaged the gel network structure. Higher viscoelastic modulus and apparent viscosity endowed surimi with better 3D printing accuracy and stability. Consequently, HIPPEs improved the quality of skipjack tuna surimi gel, which could provide a direction for developing of new skipjack tuna products.

Ovalbumin/sodium alginate Pickering emulsion: Structural characteristics and its contribution to enhancing the gel properties of Hairtail (Trichiurus haumela) surimi

In this study, ovalbumin (OV) and sodium alginate (SA), two macromolecular complexes, were coagulated into the emulsifier (OV/SA), which stabilized soybean oil by electrostatic interaction, hydrophobic interactions, and hydrogen bonding. The structure of OV/SA and properties of OV/SA Pickering emulsion were investigated. Additionally, the effect of emulsions on the gel and protein properties of hairtail surimi was studied. The results revealed that with the increasing concentration of OV/SA, the particle size and zeta potential value (negative value) of the emulsion initially decreased and then increased, while the rheological properties gradually improved. Compared with the surimi gel directly supplemented with soybean oil, the addition of emulsion enhanced gel strength, whiteness, water holding capacity, and hydrophobic interactions, resulting in a more stable gel network structure. In summary, incorporating emulsion into surimi at the same lipid content not only maintained its gel properties but also improved its color and compensated for lipid loss.

Rice bran oil-in-water emulsion stabilized by Amur catfish myofibrillar protein: Characteristics and its application in surimi gels

The objective of this investigation was to isolate amur catfish myofibrillar protein (AMP), emulsify it with rice bran oil, and assess its application in the silver carp surimi gel. The proportion and addition of AMP/rice bran oil emulsion on the gel properties were compared. The emulsion stabilized by 3 % AMP was stable when an oil/water ratio of 0.70 and 0.75 was employed, as evidenced by its appearance, microstructure, and rheological characteristics. The L*, a* and whiteness values of gels observably elevated when the emulsion blended (p < 0.05). The mechanical capacities (texture and rheology indicators) of surimi gels were dramatically improved with 5 % emulsion added (p < 0.05). However, the addition of excessive emulsion (up to 15 %) impeded the formation of surimi protein network and lowered water retention ability of surimi gels. Moreover, 5 % emulsion was distributed uniformly throughout the gel matrix, giving rise to the development of a dense and uniform network with high water binding capacity. Furthermore, the study on protein solubility expressed that the addition of the emulsion facilitated protein-protein interactions in surimi gels. In summary, the addition of 5 % AMP stabilized rice bran oil emulsion could yield a stronger surimi gel with increased whiteness. The resulting gels could serve as healthy fat-rich surimi-based products.

Evaluation of the texture characteristics and taste of shrimp surimi with partial replacement of NaCl by non‑sodium metal salts

Ionic strength plays a significant role in the aggregation behavior of myofibrillar proteins. The study investigated the effects of KCl or CaCl2 as substitutes for NaCl on the gel properties and taste of shrimp surimi at a constant ionic strength (IS = 0.51). Increased KCl substitution ratio resulted in a reduction in α-helix content and an increase in β-sheet content of myofibrillar proteins, thereby enhancing water holding capacity. Optimal KCl substitutions (1.5% NaCl +1.94% KCl) contributed to maintaining the desired taste and improving gel properties. CaCl2 facilitates the extraction and dissolution of myofibrillar proteins, resulting in an organized and dense gel network with significant water-holding capacity. However, excessive additions (>1.27%) resulted in a notable decrease in taste and gel strength due to excessive aggregation and precipitation of myofibrillar proteins. These findings provide a solid theoretical foundation for production of high-quality, low-salt shrimp surimi.

A comparative study of different soybean oil forms on the physicochemical properties of surimi myofibrillar protein gel: The role of soybean protein isolate and κ-carrageenan

Natural soybean oil, Pickering emulsion, high-internal-phase emulsion (HIPE), and emulsion gel were prepared to investigate their effects on the physicochemical properties of surimi myofibrillar protein gels. Their effects on gel strength ranked as: emulsion gel > Pickering emulsion > HIPE > soybean oil. At the same oil content, the emulsion gel exhibited higher G' than the other forms whereas natural oil exhibited the lowest G', and T22 was smaller in the emulsion gel group, indicating that the emulsion gel enhanced the interaction between water molecules and protein macromolecules. FT-IR testified that 9 % natural oil reduced the β-sheet content to 26.34 %, whereas Pickering emulsion, HIPE, and emulsion gel recovered the β-sheet content to 31.30 %, 36.17 %, and 32.69 %, respectively. Emulsion gel led to fewer voids, and the oil droplets in emulsion gel were more regularly spherical and homogeneously dispersed in the gel matrix, which might be attributed to the filling effects as well as "bridging action" of soybean protein isolate and κ-carrageenan within surimi proteins. In conclusion, we demonstrated emulsion gel as a good replacer to mitigate the negative effect of oil on the texture and structure of surimi gels, which would be a promising approach for oil supplementation in surimi production.

Preparation of cod protein composite gels for dysphagia by high-pressure homogenization: Egg white microgels-based high-phase emulsion as a texture modifier

The rising prevalence of dysphagia among the aging population presents significant challenges in developing specialized diets that combine soft textures with high nutritional value. This study investigates the formulation of cod protein composite gels (CPCGs) using egg white based microgels-high internal phase emulsions (HIPEs, 5-25 %). The CPCGs were prepared via high-pressure homogenization at 400 bar for 10 min. The texture, water retention, rheological properties, and network structure of the CPCGs were analyzed. Results demonstrated that incorporating HIPEs increased the hardness and whiteness of CPCGs. The water holding capacity peaked at 98.52 % with 15 % HIPEs. Additionally, as the concentration of HIPEs increased, the apparent viscosity, support properties, and thermal stability of CPCGs improved, although the critical strain point decreased from 475.33 % (control) to 199.33 % (25 % HIPEs). The network structure of CPCGs became denser and more uniform with higher HIPE concentrations, with noticeable changes in the gel skeleton when HIPEs exceeded 15 %. According to the International Dysphagia Diet Standardization Initiative (IDDSI) tests, all CPCG formulations met Level 6 - soft and bite-sized criteria. This study offers valuable insights into the development of fish protein-based dysphagia diets that are both nutritious and safe for swallowing.

Influence of flaxseed-derived diglyceride-based high internal phase Pickering emulsions on the rheological and physicochemical properties of myofibrillar protein gels

The study aimed to investigate the influence of flaxseed-derived diglyceride-based high internal phase Pickering emulsions (HIPPE) at different levels (0%, 10%, 20%, 30%, 40%, and 50%) on the rheological and physicochemical properties of myofibrillar protein (MPs) gels. The study indicated that with increasing HIPPE levels, there was a significant increase in whiteness while a decrease in water-holding capacity. The gels with 10% HIPPE levels had higher ionic bonds, while those with 40% and 50% HIPPE levels showed higher hydrogen bonds. By increasing HIPPE levels in the formation of MP gels, the T2 relaxation time was found to decrease. Additionally, in all MP gels, G' values were significantly higher than G" values over time. Adding lower contents of HIPPE levels resulted in a more compact microstructure. These findings indicate that flaxseed-derived diglyceride-based HIPPEs could be utilized as fat substitutes in meat products to enhance their nutritional quality.

Improved gel properties of Nemipterus virgatus myofibrillar protein emulsion gel by Konjac glucomannan incorporation: Insight into the modification of protein conformation

This study aimed to improve the gel properties of emulsion gels prepared by physical complex of fish protein and polysaccharide. The effects of Konjac glucomannan (KGM) on the structure, emulsibility of Nemipterus virgatus myofibrillar protein (MP), and the gel properties of heat-induced MP emulsion gel were investigated. The results indicated KGM modification facilitated the unfolding of MP, exposing more tryptophan and hydrophobic groups, thereby improving the wettability and emulsifying activity of MP/KGM mixtures. The interactions between MP and KGM molecules were mainly non-covalent hydrogen bonding and hydrophobic interaction. The MP/KGM mixtures exhibited superior adsorption properties at the oil-water interface, particularly with 0.5 % KGM addition, thus forming small and evenly distributed oil droplets. Besides, the curves of viscosity, G' and G" of MP/KGM emulsions climbed continuously with the increased KGM concentration. The presence of KGM, especially the medium amount (0.5 %), was conducive to the translation of α-helix into β-sheet and the formation of more dense and ordered gel network structure, thereby enhancing the gel properties of MP/KGM emulsion gels.

Effect of modified cellulose-based emulsion on gel properties and protein conformation of Nemipterus virgatus surimi

Microcrystalline cellulose was modified by TEMPO oxidation combined with ultrasound to prepare modified cellulose-based emulsion. The effect of different emulsion concentration on gel properties and protein conformation of surimi was investigated. The results showed the length and width of microcrystalline cellulose were reduced, and a large amount of -COOH was introduced into modified cellulose. Direct addition of flaxseed oil decreased the gel strength and WHC from 3640.49 g·mm and 76.94% to 2702.95 g·mm and 75.89%, respectively, while 5% modified cellulose-based emulsion could improve the gel properties of surimi. Surimi gel containing 5% emulsion had the highest hydrophobic interaction, disulfide bond and β-sheet content. Moreover, protein network structure was the densest in 5% emulsion group. Therefore, modified cellulose-based emulsion could be used to compensating for the negative impact of direct addition of flaxseed oil on surimi, which provided a new idea for the development of healthy and new emulsified surimi products.

Effects of Soy Protein Isolate and Inulin Conjugate on Gel Properties and Molecular Conformation of Spanish Mackerel Myofibrillar Protein

The gel properties and molecular conformation of Spanish mackerel myofibrillar protein (MP) induced by soy protein isolate-inulin conjugates (SPI-inulin conjugates) were investigated. The addition of SPI-inulin conjugates significantly enhanced the quality of the protein gel. An analysis of different additives was conducted to assess their impact on the gel strength, texture, water-holding capacity (WHC), water distribution, intermolecular force, dynamic rheology, Raman spectrum, fluorescence spectrum, and microstructure of MP. The results demonstrated a substantial improvement in the strength and water retention of the MP gel with the addition of the conjugate. Compared with the control group (MP), the gel strength increased from 35.18 g·cm to 41.90 g·cm, and WHC increased from 36.80% to 52.67% with the inclusion of SPI-inulin conjugates. The hydrogen bond content was notably higher than that of other groups, and hydrophobic interaction increased from 29.30% to 36.85% with the addition of SPI-inulin conjugates. Furthermore, the addition of the conjugate altered the secondary structure of the myofibrillar gel, with a decrease in α-helix content from 62.91% to 48.42% and an increase in β-sheet content from 13.40% to 24.65%. Additionally, the SPI-inulin conjugates led to a significant reduction in the endogenous fluorescence intensity of MP. Atomic force microscopy (AFM) results revealed a substantial increase in the Rq value from 8.21 nm to 20.21 nm. Adding SPI and inulin in the form of conjugates is an effective method to improve the gel properties of proteins, which provides important guidance for the study of adding conjugates to surimi products. It has potential application prospects in commercial surimi products.

Effects of sturgeon oil and its Pickering emulsion on the quality of sturgeon surimi gel

This study aimed to extract sturgeon oil (SO) from the sturgeon head and apply it to sturgeon meat to produce surimi gel. The effects of SO and its Pickering emulsion on the qualities of surimi gel were investigated. The results demonstrated that Pickering emulsions improved the quality deterioration of the gel caused by the direct addition of SO, especially the soy isolate protein (SPI) emulsion and the pea isolate protein (PPI) emulsion. Pickering emulsions contributed to a more uniform and compact network structure of the gel, improved the texture properties, enhanced the freeze-thaw stability, and reduced lipid oxidation. Additionally, compared to the addition of exogenous lipids such as peanut oil and linseed oil, SO and its Pickering emulsion better maintained the characteristic flavor of sturgeon surimi gel. This study provides valuable data and feasible ideas for expanding the utilization of sturgeon by-products and developing new types of surimi gel products.

Understanding the Role of Filamentous Actin in Food Quality: From Structure to Application

Actin, a multifunctional protein highly expressed in eukaryotes, is widely distributed throughout cells and serves as a crucial component of the cytoskeleton. Its presence is integral to maintaining cell morphology and participating in various biological processes. As an irreplaceable component of myofibrillar proteins, actin, including G-actin and F-actin, is highly related to food quality. Up to now, purification of actin at a moderate level remains to be overcome. In this paper, we have reviewed the structures and functions of actin, the methods to obtain actin, and the relationships between actin and food texture, color, and flavor. Moreover, actin finds applications in diverse fields such as food safety, bioengineering, and nanomaterials. Developing an actin preparation method at the industrial level will help promote its further applications in food science, nutrition, and safety.

Effect of starch and peanut oil on physicochemical and gel properties of myofibrillar protein: Amylose content and addition form

Starch and peanut oil (PO) were widely used to improve the gel properties of surimi, however, the impact mechanism of addition forms on the denaturation and aggregation behavior of myofibrillar protein (MP) is not clear. Therefore, the effect of starch, PO, starch/PO mixture, and starch-based emulsion on the physicochemical and gel properties of MP was investigated. The results showed that amylose could accelerate the aggregation of MP, while amylopectin was conducive to the improvement of gel properties. The addition of PO, starch/PO mixture, or starch-based emulsion increased the turbidity, solubility, sulfhydryl content of MP, and improved the gel strength, whiteness, and texture of MP gel. However, compared with starch/PO mixture group, the gel strength of MP with waxy, normal and high amylose corn starch-based emulsion increased by 22.68 %, 10.27 %, and 32.89 %, respectively. The MP containing emulsion had higher storage modulus than MP with starch/PO mixture under the same amylose content. CLSM results indicated that the oil droplets aggregated in PO or starch/PO mixture group, while emulsified oil droplets filled the protein gel network more homogeneously. Therefore, the addition of starch and PO in the form of emulsion could effectively play the filling role to improve the gel properties of MP.

Characteristics of hairtail surimi gels treated with myofibrillar protein-stabilized Pickering emulsions

BACKGROUND

Hairtail (Trichiurus haumela) surimi exhibits poor gelation properties and a dark gray appearance, which hinder its utilization in high-quality surimi gel products. The effect of Pickering emulsions stabilized by myofibrillar proteins (MPE) on the gel properties of hairtail surimi has been unclear. In particular, the impact of MPE under NaCl and KCl treatments on the quality of hairtail surimi gels requires further elucidation.

RESULTS

Pickering emulsions stabilized by myofibrillar proteins and treated with NaCl or KCl (Na-MPE, K-MPE) were added to hairtail surimi in amounts of 10-70 g kg-1. The addition of 50 g kg-1 Na-MPE and K-MPE improved the gel strength, textural properties, whiteness, and water-holding capacity (WHC) of hairtail surimi. The relative content of β-turn and β-sheet in the surimi gels increased and the relative content of random coils and α-helix decreased with the addition of oil. The addition of Na-MPE and K-MPE did not affect the secondary structure of surimi gels but stimulated the gelation of hairtail surimi gels. Hairtail surimi containing K-MPE demonstrated similar performance in terms of hardness, microstructure, and WHC compared with the addition of Na-MPE.

CONCLUSION

The quality of hairtail surimi gels can be improved by the addition of Na-MPE or K-MPE. The K-MPE proved to be an effective option for enhancing the properties of hairtail surimi gels at 50 g kg-1 to replace Na-MPE. © 2024 Society of Chemical Industry.

Quality properties of fish ball with abalone and its relationship with sensory properties

In this work, whiteness, water-holding capacity, gel strength, textural profile analysis were performed to examine the quality of fish balls with abalone (FBA). In addition, a correlation between quality and sensory properties was established. The addition of abalone significantly increased the water holding capacity, gel strength and textural properties of FBA, and decreased their whiteness, the best overall quality was achieved at 9 % w/w abalone addition. The E-nose and E-tongue results revealed that the addition of abalone changed the flavour of FBA. HS-SPME-GC-MS identified 65 volatile organic compounds (VOCs) and proved to be effective in reducing fishy flavour. E-nose can distinguish between the VOCs in FBA. Moreover, Umami and 1-octen-3-ol can serve as important indicators to observe changes in the quality of FBA, as they were positively connected with WHC, gumminess, chewiness, resilience, a*, hexanal, etc. The results provided a theoretical basis for the development of abalone and surimi products.

Diacylglycerol emulsion with different droplet size improves the gelation properties of Nemipterus virgatus myofibrillar protein

Effects of diacylglycerol (DAG) emulsions with different particle sizes on gel properties, microstructures and chemical forces of myofibrillar protein (MP) gels were investigated. DAG emulsions addition significantly improved the whiteness of MP gels. With the decrease of emulsion droplet size, G', G" and immovable water content of MP gels gradually increased, and cooking loss decreased, in which, emulsion prepared under 200 W reduced the cooking loss to the minimum value of 2.57 %. Furthermore, the gel strength and texture properties of MP gels were enhanced as the decreasing emulsion droplet size, and significant improvement (P < 0.05) appeared in gel strength and hardness when ultrasonic power reached 200 W, and then texture indexes tended to be stable as power continued to increase. Reducing the emulsion particle size facilitated the uniform distribution of DAG in the gel network and enhanced the chemical forces of composite gel, forming the more compact network structure.

Effect of starch-based emulsion with different amylose content on the gel properties of Nemipterus virgatus surimi

The emulsion was prepared with peanut oil and corn starch with different amylose content using high-speed homogenization assisted high-pressure homogenization, and the effect of starch-based emulsion on the gel properties, whiteness, microstructure, protein secondary structure, chemical forces, texture and sensory properties of Nemipterus virgatus surimi was investigated. The results showed that high amylose corn starch was more beneficial to the stability of emulsion than normal and waxy starch. The gel strength, water holding capacity and texture properties of surimi were significantly improved by adding 10 % waxy corn starch-based emulsion or 15 % high amylose or normal corn starch-based emulsion. Moreover, the whiteness of surimi gel containing starch-based emulsion was higher, and the microstructure was more compact and delicate than that of surimi without emulsion. The addition of starch-based emulsion could increase the hydrophobic interaction and disulfide bond content, and promote the transformation of protein secondary structure to irregular direction. The sensory properties such as color, texture, taste and overall acceptability could be improved to varying degrees. Therefore, starch-based emulsion could be used to enhance the gel properties and nutritional value of surimi products.

Influence of varying oil phase volume fractions on the characteristics of flaxseed-derived diglyceride-based Pickering emulsions stabilized by modified soy protein isolate

This research aimed to create Pickering emulsions using modified soy protein isolate (SPI) as a stabilizer and flaxseed-derived diglyceride (DAG) as an oil phase. The SPI was modified through a process involving both heating and ultrasound treatment. The result indicated that the droplet size of emulsions increased with the increase in oil content (p < 0.05). For instance, the largest droplet size (23 µm) was observed at an oil-to-SPI dispersion ratio of 4:1 ratio (φ = 80), whereas the smallest droplet size (6.39 µm) was noticed at the 1:4 ratio. During the 7-day storage period, the emulsions with a 4:1 ratio (φ = 80) showed the lowest droplet size increase (from 23 µm to 25.58 µm). In contrast, the emulsions with a 1:1 ratio displayed the highest increase (from 19.39 µm to 74.29 µm). Creaming index results revealed that emulsions with a 4:1 ratio (φ = 80) showed no signs of creaming and phase separation than all other treatments (p < 0.05). Backscattering fluctuations (ΔBS) and turbiscan stability index (TSI) showed that emulsions with 4:1, 2:1, and 1:1 oil-to-SPI dispersion ratios had consistent ΔBS curves with higher and TSI curves with lower values. Optical microscopy, confocal laser scanning, and cryo-scanning electron microscopy revealed that emulsions with oil-to-SPI dispersion ratios of 4:1 and 2:1 had well-organized structures with no visible coalescence. Macromorphological and microrheological investigations demonstrated that emulsions with 80% oil content had the highest viscosity, both moduli, elasticity index, macroscopic viscosity index, and the lowest fluidity index and solid-liquid balance values. Moreover, these emulsions were more resistant to centrifugation and storage environments. In conclusion, the study determined that flaxseed-derived DAG-based high internal phase Pickering emulsions (φ = 80) had superior stability, improved viscoelasticity, and better rheological properties.

The combined effects of ultrasound and plasma-activated water on microbial inactivation and quality attributes of crayfish during refrigerated storage

In this study, a decontamination technology combining ultrasound (US) and plasma-activated water (PAW) was developed to better preserve crayfish. First, the decontamination efficacy of US, PAW and their combinations (UP) on crayfish was quantified after 0, 20, 40, or 60 min of treatments. The total viable count (TVC) was reduced by 0.27-0.77 Log CFU/g after individual US or PAW treatments, while a TVC reduction of 1.17 Log CFU/g was achieved after 40 min of UP treatment. Besides, the changes in psychrotrophic bacteria, lactic acid bacteria, yeasts and molds followed a similar trend to TVC. UP treatments normally resulted in more significant reductions in the natural microbiota of crayfish than US or PAW treatments. Furthermore, the microbial quality, physicochemical properties and sensory properties of crayfish after different treatments were assessed during storage at 4 °C for 12 days. According to TVC and total volatile basic nitrogen (TVB-N) values, the control group became unacceptable from 4 days, US or PAW groups became unacceptable from 6 days, while UP group extended the storage time to 8-10 days. During storage, thiobarbituric acid reactive substances (TBARS) values of all the groups were maintained below 0.5 mg/kg, among which the control group exhibited the highest value (0.39 mg/kg). Moreover, UP treatment effectively retarded the deterioration in color and texture properties of crayfish. Fourier transform infrared (FTIR) spectroscopy analysis indicated that UP treatment decreased the α-helix contents and increased the β-sheet contents of crayfish proteins, while the structural changes were not evident at the end of storage. Low-field nuclear magnetic resonance (LF-NMR) analysis revealed that UP treatment reduced the water migration and enhanced the stability of bond water in crayfish. In addition, E-nose analysis revealed the protection of UP treatment on the sensory properties of crayfish during storage. This study demonstrated that the combinations of US and PAW treatments effectively accelerated the decontamination of crayfish and contributed to better storage quality.

Unrinsed Nemipterus virgatus surimi provides more nutrients than rinsed surimi and helps recover immunosuppressed mice treated with cyclophosphamide

BACKGROUND

The rinsing process in the production of surimi can cause the loss of some important nutrients. To investigate the differences in nutritional properties between rinsed surimi (RS) and unrinsed surimi (US), this study compared the elemental composition, amino acid composition, fatty acid composition, proteomics, and an immunosuppression mouse model of surimi before and after rinsing, and analyzed the nutritional and immunological properties of RS and US.

RESULTS

The results showed that the protein, fat, and ash contents of RS were decreased compared with those of US; specifically, the contents of essential amino acids, semi-essential amino acids, non-essential amino acids, saturated fatty acids, monounsaturated fatty acids, and polyunsaturated fatty acids were decreased. In the non-labeled quantitative proteomics analysis, three high-abundance quantifiable protein contents and 68 low-abundance quantifiable protein contents were found in RS (P-values < 0.05, ratio > 2). Immune function experiments in mice revealed that both RS and US contributed to the recovery of immunity in immunocompromised mice. The effect of US was better than that of RS.

CONCLUSION

The rinsing process in surimi processing leads to the loss of nutrients in surimi. US promotes the recovery of immunity in immunocompromised mice more effectively than RS. © 2023 Society of Chemical Industry.

Antarctic krill (Euphausia superba) oil high internal phase emulsions improved the lipid quality and gel properties of surimi gel

In the study, high internal phase emulsions (HIPEs) prepared from Antarctic krill oil (AKO) were added into surimi and the effects on gel properties, lipid quality and stability were investigated. It is found that HIPEs-added groups exhibited higher gel strength and lower cooking loss than Oil-added counterparts. HIPEs-added groups had higher proportion of capillary water, and microstructure of HIPEs-added gels showed fewer large voids and small size droplets. HIPEs-added groups also showed less pronounced myosin heavy chain band. HIPEs- and Oil-added gels showed > 3500 mg/kg EPA + DHA and 0.4-0.8 mg/kg astaxanthin, and most HIPEs-added groups had higher levels of them but lower TBARS values. Results suggest AKO-HIPEs could reduce the intervention by lipids on myosin crosslinking during gelation, and protect fatty acids and asxtanthin from oxidation due to oxygen-isolation led by their high accumulation. Thus, AKO-HIPEs can be applied to fortify ω-3 PUFA and maintain good gel properties in surimi product.

Improvement of the emulsifying properties of mixed emulsifiers by optimizing ultrasonic-assisted processing

Optimizing ultrasound (ULD)-assisted flavonoid modification is an important component of enhancing its application potential. In this work, diverse flavonoids, such as quercetin (Que), apigenin (Api), and morin (Mor), were used to modify protein in myofibrillar protein (MP)/cellulose nanocrystal (CN) complexes using ULD-assisted method. Compared with the MP/CNs group, the triiodide contents of MP-Que/CNs, MP-Api/CNs, and MP-Mor/CNs increased by 1175.84%, 479.05%, and 2281.50% respectively. The findings revealed that the actual intensity of ULD was drastically reduced by the molecular weight decrease of these flavonoids. For olive oil emulsions prepared with mixed emulsifiers, the low interfacial diffusion rates (0.03 mN·m·s-1/2) and weak emulsifying activity (8.33 m2/g) of the MP/CN complexes were significantly improved by the flavonoids after ULD-assisted treatment. Notably, the emulsions prepared using MP-Api/CNs contained smaller oil droplets and exhibited better emulsifying properties, compared to emulsions prepared with MP-Mor/CNs or MP-Que/CNs. This study is essential for ULD-assisted treatment since the processing impact may be increased by choosing the most suitable flavonoid.

Effects of chickpea protein-stabilized Pickering emulsion on the structure and gelling properties of hairtail fish myosin gel

The effects of different amount (0-12%) of chickpea protein-stabilized Pickering emulsion (CPE) on the gelling properties, intermolecular interactions, microstructure, and physicochemical stability of hairtail fish myosin gels were investigated. The myosin gel with 6%-9% CPE demonstrated significantly higher viscoelasticity, gel strength, hardness, water-holding capacity and whiteness, compared to the control (P < 0.05). In addition, Raman spectroscopy showed that CPE changed the microenvironment of the myosin, which promoted the changes in protein secondary structures, disulfide bond conformation and the local environments of the composite gels. The addition of 6%-9% CPE also enhanced the disulfide bond and hydrophobic interaction of myosin gels which induced more compact gel network structures. Furthermore, CPE improved the lipid oxidative stability and freeze-thaw stability of myosin gel. The results indicated that CPE could improve the gelling properties of myosin, making it a potential new additive and lipid substitute for the development of new emulsion gel products.

Assessment of flavor characteristics in snakehead (Ophiocephalus argus Cantor) surimi gels affected by atmospheric cold plasma treatment using GC-IMS

The gel formation ability of freshwater surimi is weak, resulting in its poor flavor and quality. Atmospheric cold plasma (ACP), a widely developed non-thermal processing technology in the food industry, is considered to have potential applications in maintaining and improving the flavor characteristics of surimi gels. In this study, the effect of ACP on snakehead surimi gels flavor at different treatment times was investigated by sensory evaluation and gas chromatography-ion mobility spectrometry (GC-IMS) analysis. The results showed that ACP could better maintain and improve the original appearance and tissue state characteristics of surimi gels, scoring about 1-2 points higher than the ACP-untreated group. GC-IMS analysis demonstrated the obvious difference in the volatile organic compounds (VOCs) among the treatment groups. Specifically, the samples treated for 120 s with ACP exhibited the most unique aroma characteristics, which probably related to the highest thiobarbituric acid reactive substances values (73.28 μmol MDA/kg sample). Meanwhile, the reduced TCA-soluble peptides content indicated that ACP could inhibit protein degradation to maintaining the tissue state and flavor characteristics of the surimi gels. In conclusion, the advantages of ACP treatment, such as little damage to nutrients, and maximum retention of original sensory properties, provide new ideas for its application in the flavor characteristics of the snakehead surimi gels.

Ultrasound-assisted processing: Changes in gel properties, water-holding capacity, and protein aggregation of low-salt Hypophthalmichthys molitrix surimi by soy protein isolate

The effects of ultrasound combined (25 kHz, 400 ± 20 W/L, ultrasonic time of 5, 10 and 15 min) with soy protein isolate processing on gelling properties of low-salt silver carp surimi, aggregation and conformation of myofibrillar protein were investigated. The results revealed that, compared with only adding soy protein isolate components, ultrasound-assisted soy protein isolate had a more obvious effect on the protein structure in low-salt surimi, leading to the decrease in α-helix and total sulfhydryl contents, and the increase in β-sheet content and protein solubility. As a result, more proteins participated in the formation of the gel network, and significant improvements in hardness, gel strength and water-holding capacity of the low-salt surimi gel were observed, while the myosin heavy chain in SDS-PAGE was weakened. The low-field NMR results showed that the initial relaxation time of T₂ was apparently shorter, the free water content decreased and the bound water content increased under the action of ultrasound. Scanning electron microscope observation found that the surimi gel treated by ultrasound exhibited smaller holes, and had a more stable and denser network structure. In conclusion, the results of our work demonstrated that ultrasound combined with soy protein isolate can significantly improve the gel quality properties of low-salt silver carp.

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.

Role of Food Hydrocolloids as Antioxidants along with Modern Processing Techniques on the Surimi Protein Gel Textural Properties, Developments, Limitation and Future Perspectives

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.