Raman analysis of surimi gelation by addition of wheat dietary fibre

Effect of cellulose on gel properties of heat-induced low-salt surimi gels: Physicochemical characteristics, water distribution and microstructure

The processing of surimi products requires the addition of high levels of salt, which makes it a high-salt food that poses a risk to human health. The search for exogenous additives to reduce the salt content of surimi products while ensuring their quality characteristics is crucial. Therefore, the effect of different species of cellulose on enhancing the quality characteristics of low-salt surimi gels was investigated and the best-modified cellulose was identified. Carboxymethyl cellulose (CMC), hydroxypropyl methylcellulose (HPMC), and microcrystalline cellulose (MCC) were selected for this study to compare with high-salt control and low-salt control. The results showed that cellulose could induce conformational transitions of proteins and promote the formation of an ordered and dense surimi gel network and the minimum porosity of 15.935% was obtained in the MCC-treated group. The cellulose-treated group conferred good textural properties to the surimi gels, significantly improved gel strength and water retention capacity (p < 0.05), and reduced the amount of water lost after cooking treatment (p < 0.05). Low-field NMR results showed that cellulose reduced the release of water, converting more free water to immobile water, thus increasing the water proton density. The higher energy storage modulus G' in the presence of cellulose indicated a more stable surimi gel system dominated by springiness. In summary, cellulose could confer better quality characteristics to low-salt surimi gels and MCC performance was superior to other cellulose species. This study helps the understanding of the mechanism of cellulose-surimi action on the development of high-quality low-salt surimi gels.

Using Potassium Bicarbonate to Improve the Water-Holding Capacity, Gel and Rheology Characteristics of Reduced-Phosphate Silver Carp Batters

To study the use of partial or total potassium bicarbonate (PBC) to replace sodium tripolyphosphate (STPP) on reduced-phosphate silver carp batters, all the batters were composed of silver carp surimi, pork back fat, ice water, spices, sugar, and sodium chloride. Therein, the sample of T1 contained 4 g/kg STPP; T2 contained 1 g/kg PBC, 3 g/kg STPP; T3 contained 2 g/kg PBC, 2 g/kg STPP; T4 contained 3 g/kg PBC, 1 g/kg STPP; T5 contained 4 g/kg PBC, and they were all produced using a bowl chopper. The changes in pH, whiteness, water- and oil-holding capacity, gel and rheological properties, as well as protein conformation were investigated. The pH, cooking yield, water- and oil-holding capacity, texture properties, and the G' values at 90 °C of the reduced-phosphate silver carp batters with PBC significantly increased (p < 0.05) compared to the sample without PBC. Due to the increasing pH and enhanced ion strength, more β-sheet and β-turns structures were formed. Furthermore, by increasing PBC, the pH significantly increased (p < 0.05) and the cooked silver carp batters became darkened. Meanwhile, more CO₂ was generated, which destroyed the gel structure, leading the water- and oil-holding capacity, texture properties, and G' values at 90 °C to be increased and then decreased. Overall, using PBC partial as a substitute of STPP enables reduced-phosphate silver carp batter to have better gel characteristics and water-holding capacity by increasing its pH and changing its rheology characteristic and protein conformation.

Effect of Chickpea Dietary Fiber on the Emulsion Gel Properties of Pork Myofibrillar Protein

In this study, the effect of chickpea dietary fiber (CDF) concentration (0%, 0.4%, 0.8%, 1.2%, 1.6%, and 2.0%) on emulsion gel properties of myofibrillar protein (MP) was investigated. It was found that the emulsifying activity index (EAI) and emulsifying stability index (ESI) of MP increased with the increasing content of CDF. Moreover, the water- and fat-binding capacity (WFB), gel strength, storage modulus (G'), and loss modulus (G") of MP emulsion gel also increased with increasing content of CDF. When the concentration of CDF was 2%, the most significant improvement was observed for EAI, breaking force, and WFB (p < 0.05); the three-dimensional gel network structure of the MP emulsion gel was denser and the pore diameter was smaller. The T₂₁ relaxation time of emulsion gel decreased while the PT₂₁ increased significantly with the increasing content of CDF, suggesting that the emulsion gel with CDF had a better three-dimension network. The addition of CDF led to an increased content of β-sheet and reactive sulfhydryl and increased surface hydrophobicity of MP, thus improving the gel properties of the MP emulsion gel. In conclusion, the addition of CDF improved the functional properties and facilitated the gelation of the MP emulsion, indicating that CDF has the potential to improve the quality of emulsified meat products.

Impact of Insoluble Dietary Fiber and CaCl2 on Structural Properties of Soybean Protein Isolate-Wheat Gluten Composite Gel

The effect and mechanism of soybean insoluble dietary fiber (SIDF) (0~4%) and CaCl₂ (0~0.005 M) on the properties of soybean protein isolate (SPI)-wheat gluten (WG) composite gel were studied. It was revealed that the addition of insoluble dietary fiber (1~2%) increased the strength and water-holding capacity (WHC) of the composite gel (p < 0.05) and enhanced the gel network structure compared with the control. WHC and LF-NMR showed that the water-binding ability of the gel system with only 2% SIDF was the strongest. The addition of excessive SIDF increased the distance between protein molecules, impeded the cross-linking of protein, and formed a three-dimensional network with low gel strength. The infrared spectrum and intermolecular force indicated that the interaction between SIDF and SPI were mainly physical, and the hydrophobic interaction and disulfide bond were the main forces in the gel system. The addition of CaCl₂ can increase the critical content of gel texture destruction caused by SIDF, and the gel strength attained its peak at 3% SIDF, indicating that appropriate CaCl₂ improved gel structure weakening caused by excessive SIDF. This study provides insights in enhancing the production of multi-component composite gel systems.

Insight into the Mechanism of Porcine Myofibrillar Protein Gel Properties Modulated by κ-Carrageenan

The purpose of this study is to explain the mechanism of porcine myofibrillar protein gel properties modulated by κ-carrageenan. The textural properties results showed that the stress at fracture of the composite gel with 0.4% κ-carrageenan had the highest value (91.33 g), which suggested that the 0.4% κ-carrageenan addition was the limitation. The strain at fracture was significantly reduced with κ-carrageenan addition. The composite gel with 0.4% κ-carrageenan had the lowest proportion of T22 (7.85%) and the shortest T21 relaxation time (252.81 ms). The paraffin section showed that the phase separation behavior of the composite gel transformed from single-phase behavior to dispersed phase behavior to bi-continuous phase behavior, and the ratio of CG/MP phase area significantly increased from 0.06 to 1.73. The SEM showed that the three-dimensional network of myofibrillar protein transformed from a loose structure to a compact structure to an unaggregated structure with κ-carrageenan addition. The myofibrillar protein network of the treatment with 0.4% κ-carrageenan had the highest DF value (1.7858) and lowest lacunary value (0.452). The principal component analysis was performed on the data of microstructure and textural properties, and the results showed that the dispersed phase behavior and moisture stabilization promoted the aggregation of myofibrillar protein and the composite gel had better water holding capacity and textural properties, while bi-continuous phase behavior hindered the aggregation of myofibrillar protein and the composite gel had worse water holding capacity and textural properties.

Improvement on gel properties of myofibrillar protein from chicken patty with potato dietary fiber: Based on the change in myofibrillar protein structure and water state

Influence of potato dietary fiber (PDF) on myofibrillar protein (MP) structure, aggregation behavior, and gel properties of chicken patty was evaluated. The Raman spectroscopy results indicated that the α-helix content decreased by 21.9 %, while β-sheets content increased by 45.0 % in 3.0 % PDF sample compared with the control (P < 0.05), and aliphatic residues cross-linked. Particle size, turbidity, and the roughness of MP surface morphology increased, whereas the zeta-potential of MPs decreased with PDF increasing. The gelation process of MP with PDF proceeded at a fast rate and their elasticity and viscosity were high as determined by dynamic rheology. Gels with 3.0 % PDF exhibited significantly enhanced gel strength and a high WHC, which increased by 44.20 % and 22.5 %, respectively, compared with the control, PDF inhibited the transformation of immobilized water to free water and eliminated the water channels during heating as well as formed a more uniform and denser microstructure. Therefore, PDF can be a potential ingredient for improving the quality of processed meat products.

Effects of Citrus Fiber on the Gel Properties of Mutton Myofibrillar Protein

This work investigated the effects of different additions of water-soluble citrus fiber (SCF) and water-insoluble citrus fiber (ICF) on the gel properties of the mutton myofibrillar protein (MP). The key parameters of water-holding capacity (WHC), rheological properties, and microstructure were evaluated. The addition of 2.5-10% of SCF and ICF significantly improved (p < 0.05) the WHC and gel strength of mutton MP gel. The rheological results showed that the viscoelasticity of MP with 5% SCF was the best, and the T₂ relaxation time of the gel was significantly shortened. SEM results showed SCF reduced the number of pores in the MP gel, forming a more compact network structure. ICF stabilized the MP gel network structure as a filler after water absorption and expansion. However, the gel lost moisture under the action of strong external force (freeze-drying), which left large pores. These data confirmed that SCF and ICF could effectively improve the gel properties of meat products.

Gel properties of okara dietary fiber-fortified soy protein isolate gel with/without NaCl

BACKGROUND

Soy protein isolate (SPI) is widely used as an alternative to animal-based protein, and its gelling property is essential for producing plant protein-based foods. Insoluble dietary fiber has been used to improve the properties of protein gels.

RESULTS

Effects of partial replacement of SPI by okara dietary fiber (ODF) on the gelling properties of ODF-fortified SPI gels with and without 0.1 m NaCl were investigated. The presence of ODF hindered the SPI self-aggregation and reduced the surface hydrophobicity of SPI. The presence of ODF reduced the hydrophobic interaction and improved the proportion of disulfide bonds in the gels. In the microstructure, the swollen ODF promoted the local aggregation of SPI at 0.1 m NaCl. Texture profile analysis showed that 5% and 10% ODF improved the SPI gel hardness in the absence of NaCl, whereas only 5% ODF improved the gel hardness at 0.1 m NaCl. The results of low-field nuclear magnetic resonance imaging revealed that ODF shortened the T₂ relaxation time of the free water in the gel. The gel of ODF-10 had the highest storage modulus.

CONCLUSION

Using an appropriate amount of ODF to replace SPI could improve the quality of SPI gel and increase the dietary fiber content in the product. In addition, the appropriate ratio of ODF/SPI varied in different solution environments. © 2022 Society of Chemical Industry.

Water-insoluble dietary fibers from oats enhance gel properties of duck myofibrillar proteins

The effects of different particle sizes (90-µm and 200-µm) and contents (1.5% and 3%) of water-insoluble dietary fibers (IDF) on the gelation properties of duck myofibrillar protein (MP) were explored. The results showed that the addition of IDF improved the gel strength and water holding capacity of MP compared with the control (P < 0.05). IDF reinforced the formation of network structure and the viscoelasticity of gel; 1.5% 200-µm IDF reached the maximum among these treatments. PT₂₁ of the gel with IDF was higher than that of the control (P < 0.05), revealing that the addition of IDF accelerated the transformation of free water into immobilized water within the gel matrix. An ordered flaky gel network with small water holes was responsible for the increase of fractal dimension of the gel with IDF. Water distribution and viscoelasticity are the critical factors that IDF affects the gel properties of duck MP.

Influence of okara with varying particle sizes on the gelling, rheological, and microstructural properties of glucono-δ-lactone-induced tofu

Influence of lyophilized okara with varying particle sizes (250-380, 150-180, 120-150, and < 75 μm) on the quality of glucono-δ-lactone-induced tofu was investigated. Adding okara significantly (p < 0.05) improved the yield, water-holding capacity, cooking loss, and nutritional value of the conventional tofu. The gel strength and sensory score of the okara-added tofu (OAT) increased with the decreasing of the particle size of okara, and these quality attributes of the OAT were better than those of the conventional tofu, except for the OAT with 250-380 μm okara. The microstructural profile of the OAT with reduced okara particle size was similar to that of the conventional tofu. Theoretically, the addition of okara mainly impacted the interactions among denatured proteins via disulfide bonding and hydrophobic interactions and the sizes of insoluble solid and oil droplet in soymilk, thereby affecting the formation of the gel network and finally the edible quality of tofu. In conclusion, the addition of okara with appropriate particle sizes can remarkably improve the processing quality and nutritional value of tofu, which is beneficial to the reasonable exploration of okara for the producers of soybean products.

Effects of Oil Droplet Size and Interfacial Protein Film on the Properties of Fish Myofibrillar Protein-Oil Composite Gels

The effects of oil droplet size and the formation of an interfacial protein film (IPF) on silver carp myofibrillar protein (MP)-oil composite gels were studied. MP- or Tween 80-stabilized camellia seed oil emulsions with different droplet sizes were prepared and added to MPs to prepare composite gels. The oil droplet size of the Tween 80-stabilized emulsion was significantly smaller (p < 0.05) than that of the MP-stabilized emulsion with the same homogenization speed. However, polymerization of Tween 80-stabilized emulsions during the preparation of the composite gels was found. Composite gels with the MP-stabilized emulsions of a small droplet size showed significantly improved water-holding capacity, texture, and dynamic rheological properties. Interfacial shear rheology studies revealed that the storage modulus (G') of the MP-stabilized emulsion composite gels was higher than that of the Tween 80-stabilized gels, and the tan δ of the MP-stabilized oil emulsion composite gels was smaller than that of the Tween 80-stabilized gels, indicating that stronger elastic gel structures were formed. These results suggested that the IPF formed in the MP-stabilized emulsion helped stabilize the oil droplets embedded in the protein gel network, and the smaller the droplet size, the more stable the composite gel. This work provides a better understanding of how oil emulsions interact with protein and affect the properties of MP-oil composite gels.

Effects of oxidative modification on textural properties and gel structure of pork myofibrillar proteins

Isolated myofibrillar protein (MP) was treated by the oxidation system of FeCl₃ (0.01 mM) at four different H₂O₂ concentrations (0, 1, 10, 20 mM). The oxidation degree was determined by measuring the carbonyl and total sulphydryl values. The structure and physicochemical properties of MP gels were investigated by water holding capacity (WHC) evaluation, sodium dodecyl sulfate-polyacryl amide gel electrophoresis (SDS-PAGE), texture profile analysis (TPA), Raman spectroscopy, and NMR transverse relaxation (T₂). The results of carbonyls and total sulphydryls indicated that oxidation degree of MP increased with increasing H₂O₂ concentration. TPA showed that moderate oxidation (10 mM H₂O₂) could improve the hardness, springiness, gumminess and cohesiveness of MP gels, but not contribute to the maintenance of their WHC, probably due to severe depolymerization of MPs, unfolding of α-helix, exposure of the hydrophobic groups and the migration of protein-associated water (T_2b) and intra-myofibrillar water (T₂₁) to the longer relaxation time.

Effects of microwave heating on the gelation properties of heat-induced Alaska Pollock (Theragra chalcogramma) surimi

In the present study, we examined the properties of Alaska Pollock ( Theragra chalcogramma) surimi gels in response microwave heating at different powers (300, 400, or 500 W) and time (10, 20, or 30 min). The surimi gels heated by a microwave at 300 W for 10 min showed the highest gel strength and water-holding capacity. Increasing the power and time resulted in decreases in both the gel strength and water-holding capacity. The gel formation rate of microwave-heated gels was significantly higher than that produced by water bath heating. In addition, differential scanning calorimetry indicated that microwave heating caused less damage to the native structures of myosin and actin than water bath heating. Microstructure studies revealed that microwave heating contributed to the formation of a denser and stronger frame of the surimi gels. Raman spectroscopy indicated that the degree of the secondary structure denaturation caused by microwave heating was less than that induced by water bath heating. Thus, the results demonstrated that microwave heating is a promising method to enhance the gelation properties of surimi.

The improvement effect and mechanism of citrus fiber on the water-binding ability of low-fat frankfurters

Water-binding ability is a major quality attribute of low-fat meat products. This study aimed to evaluate the effects of citrus fiber on the water-binding ability of low-fat frankfurters. Low-fat (10% fat) frankfurters with different contents (0, 1, 2, and 3%) of citrus fiber were prepared. Their cooking loss, water distribution, microstructure, and protein structure were assessed and compared to those of normal-fat (20% fat) frankfurters. Results demonstrated that citrus fiber could significantly reduce the cooking loss of low-fat frankfurters from 12.69 to 4.71%. Adding citrus fiber led to a faster relaxation time in low-fat frankfurters, and a significant increase in the proportion of immobilized water. Frankfurters with citrus fiber exhibited a more compact, continuous protein network structure. Furthermore, the intensity changes in the Raman bands near 760 and 2930 cm^-1 showed that citrus fiber increased hydrophobic interactions around hydrocarbon chains and tryptophan residues in myofibrillar proteins. In conclusion, citrus fiber effectively improved the water-binding ability of low-fat frankfurters by increasing the hydrophobic interactions of myofibrillar proteins and changing the frankfurter microstructure.

New Alternatives in Seafood Restructured Products

A general overview, focusing on new trends in the different techniques used in restructured seafood product processing has been described in this work. Heat-induced gelation has been more widely studied in scientific literature than cold gelation technology. This latter technology includes the use of hydrocolloids (alginates and glucomannan) or enzymes (microbial transglutaminase) for making both raw and cooked restructured products. In restructuration processes, fortification processing with some functional ingredients is studied, giving as a result extra value to the products as well as increasing the variety of new seafood products. The process of alleviating heavy metals and organic pollutants from the raw material used has also been reviewed in the present paper.

In vitro digestion of short-dough biscuits enriched in proteins and/or fibres using a multi-compartmental and dynamic system (2): Protein and starch hydrolyses

The influence of protein and/or fibre enrichment on the nutritional properties of biscuits was studied in terms of proteolysis and amylolysis. Biscuits were digested using a multi-compartmental and dynamic system that simulates the main physiological digestive functions of the upper tract of healthy adult humans: the TIM-1. A control biscuit and three biscuits enriched in proteins and/or fibres were digested under the same conditions. Samples were collected in each compartment of the TIM-1 (stomach, duodenum, jejunum and ileum) at different times of digestion and analysed in terms of proteolysis and amylolysis. Results indicate that both formulation and processing impacted the digestive fate of the biscuits. Incorporating proteins or fibres in biscuits lowered or delayed proteolysis. Moreover a protein-plus-fibre additional or synergic effect was observed. Biscuits enriched in proteins and/or fibres displayed a higher amylolysis degree than the control biscuit, probably due to lower starch amounts and higher gelatinization degrees.