Gel Textural Properties Research Articles

Structure formation mechanism of pectin-soy protein isolate gels: Unraveling the role of peach pectin fractions

This study investigated the macro & micro properties of the composite gels formed by soy protein isolate (SPI) and peach pectin fractions: water-soluble pectin (WSP), chelator-soluble pectin (CSP), and sodium carbonate soluble pectin (NSP). Specially, the interaction between pectin fractions and SPI was studied to explain the formation mechanism of the composite gels. WSP, as a high methoxyl pectin, exhibited rich branching (sugar ratio B = 3.10). CSP, as a low methoxyl pectin, depicted a high linearity. NSP, with low linearity (sugar ratio A = 6.14), contained numerous side chains. Due to the strong interaction between pectin fractions and SPI, the new composites with excellent dense network microstructures were formed, accompanied by increased apparent viscosity, higher G′ and G′′, and reduced particle size. XRD and FT-IR analysis highlighted the modifications in gel structures. SEM-dispersive X-ray spectroscopy observed elemental distribution and framework composition in pectin-SPI gels. Hydrophobic interaction was the most important chemical force in pectin-SPI binding. Molecular docking results indicated that galacturonic acid in pectin bound more strongly to 7S than to 11S, with tighter hydrogen bonds. Notably, WSP-SPI showed the lowest turbidity, indicating enhanced solubility and particle dispersion, which helped prevent aggregation. CSP-SPI demonstrated the highest G′ and G′′, ascribing to the high linearity and abundant carboxyl groups in CSP. NSP-SPI showed the highest apparent viscosity and irregular structure. Overall, the texture properties of pectin-SPI gels were driven by pectin's structure properties, which would provide new and valuable information for texture control in gel formulation.

Extraction technology determines the properties of bamboo shoots dietary fiber concentrate and its application in chicken mince gels: Systematic analysis

This study investigated how physical, chemical, and enzymatic extraction technologies affected the physicochemical properties of bamboo shoot insoluble dietary fiber (IDF). Additionally, the effects of IDF extracted by these techniques on the gel properties, water retention, microstructure, and digestibility of chicken mince gels were evaluated. Results showed that IDFs extracted by physical (P-IDF), chemical (C-IDF), and enzymatic (E-IDF) exhibited a typical cellulose polysaccharide structure and strong water and oil retention capabilities, with the highest values reaching 14.18 g/g and 6.74 g/g, respectively. Compared to P-IDF, C-IDF and E-IDF displayed a rougher porous structure and stronger adsorption capacities for glucose (409.91 mg/g and 604.95 mg/g), cholesterol (54.46 mg/g and 64.06 mg/g), sodium cholate, and nitrite. The addition of IDF improved the water retention, water stability, texture, and rheological properties of chicken mince gels, and had no negative effect on the digestion of chicken mince proteins. On the one hand, the hydrophilic groups exposed in IDF absorb water and fill the gel networks, reducing the formation of water channels in the gel and improving water stability. Furthermore, the hydrophilic groups on the glucose unit that makes up the IDF interacts with the proteins through the hydrogen bond and the transformation of protein β-structure to α-structure, promoting the formation of gel network structure and improving gel texture and rheological properties. E-IDF and C-IDF showed better overall gel performances, but E-IDF had better dry matter digestibility, protein digestibility, and gastrointestinal digestive effects. Therefore, IDF prepared by enzymatic hydrolysis is more suitable for chicken mince processing.

Exploring the effects of spontaneous and solid-state fermentation on the physicochemical, functional and structural properties of whole wheat flour (Triticum aestivum L.)

The effects of fermentation on various physicochemical and functional properties of whole wheat flour (Triticum aestivum L.) were investigated in this study. Firstly, changes in pH and total titratable acidity (TTA) were observed during spontaneous and solid-state fermentation. Spontaneous and solid-state fermentation led to a decrease in pH and a rapid increase in TTA, indicating effective acidification due to organic acid production. Both fermentation approaches significantly influenced the total starch and amylose content of wheat. The total starch content was decreased accompanied by a significant increase in apparent amylose content. This phenomenon was attributed to starch hydrolysis facilitated by microbial enzymes and organic acids, resulting in a higher amylose/amylopectin ratio. Chemical composition and mineral content of whole wheat flour were also affected. Fermentation led to reductions in moisture, crude fat, and crude protein content, while ash content increased. Furthermore, fermentation significantly impacted the soluble and total dietary fiber content of whole wheat flour, with an increase in soluble dietary fiber and a decrease in total dietary fiber. These changes were attributed to increased synthesis of non-cellulosic polysaccharides and β-glucans during fermentation. Moreover, fermentation resulted in reductions in gluten content, alterations in functional properties such as water and oil absorption capacity, changes in protein solubility, and modifications in gel texture properties. Finally, X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed minimal changes in the crystalline structure and morphology of starch granules during fermentation, with some signs of surface erosion and degradation, particularly in solid-state fermented samples. The results highlight the potential benefits of fermentation for improving the properties of whole wheat flour. This study contributes to a better understanding of the effects of fermentation on whole wheat flour, offering insights for the development of novel and improved whole wheat flour-based food products.

Soy Protein Isolate Gel Subjected to Freezing Treatment: Influence of Methylcellulose and Sodium Hexametaphosphate on Gel Stability, Texture and Structure.

Freezing affects texture and induces the loss of gel quality. This study investigated the effects of methylcellulose (MC) (0.2%, 0.4%, 0.6%) and sodium hexametaphosphate (SHMP) (0.15%, 0.3%) on the gel textural and structural properties of SPI gels before and after freezing, and explores the synergistic enhancement of gel texture and the underlying mechanisms resulting from the simultaneous addition of SHMP and MC to SPI gels. It was revealed that MC improved the strength of SPI gels through its thickening properties, but it could not inhibit the reduction of SPI gels after freezing. The 0.4% MC-SPI gel exhibited the best gel strength (193.2 ± 2.4 g). SHMP inhibited gel reduction during freezing through hydrogen bonding and ionic interactions; it enhanced the freezing stability of SPI gels. The addition of 0.15% SHMP made the water-holding capacity in SPI gels reach the highest score after freezing (58.2 ± 0.32%). The synergistic effect of MC and SHMP could improve the strength and the freezing stability of SPI gels. MC facilitated the release of ionizable groups within SPI, causing negatively charged SHMP groups to aggregate on the SPI and inhibit the freezing aggregation of proteins. These results provide a strong basis for the improvement of cryogenic soy protein gel performance by SHMP and MC.

Comparative investigation of various protein or protein-based powders addition on texture properties of egg white and yolk gels

ABSTRACT The objective of this research was to investigate and compare the effects of various protein or protein-based powders (WPC, SPI, BSA and hemoglobin) addition on transform of texture properties in egg white (EW)/egg yolk (EY) gels. Results showed that the highest hardness value (38.5 N) was detected in BSA-treated EW gels, while the lowest values (46.6 N) were obtained in hemoglobin-treated EY gels. Additionally, significantly increased value of free –SH groups was obtained in SPI/BSA/hemoglobin-treated EW/EY solutions, and increased value of protein solubility was obtained in EY solutions treated by WPC/SPI/BSA/hemoglobin relative to those of the control. The EW solutions treated by BSA/hemoglobin reached significantly higher H 0 values than those of other groups. SDS-PAGE analysis showed that the hemoglobin-treated EW solution had slightly intense bands of ovoinhibitor, ovotransferrin and ovalbumin, and the EY solutions treated by WPC/SPI/BSA had higher level of covalent crosslinking. The EW gels treated by WPC/hemoglobin exhibited relatively more ordered protein secondary structures (α-helix and β-sheet) than those of the SPI group. SEM results suggested that WPC/BSA-treated EW gels developed uniform, porous and fiber-like structure, while SPI/BSA-treated EY gels developed rougher structure.

Effect of Thermal Treatment on Gelling and Emulsifying Properties of Soy β-Conglycinin and Glycinin.

This study investigated the impact of different preheat treatments on the emulsifying and gel textural properties of soy protein with varying 11S/7S ratios. A mixture of 7S and 11S globulins, obtained from defatted soybean meal, was prepared at different ratios. The mixed proteins were subjected to preheating (75 °C, 85 °C, and 95 °C for 5 min) or non-preheating, followed by spray drying or non-spray drying. The solubility of protein mixtures rich in the 7S fraction tended to decrease significantly after heating at 85 °C, while protein mixtures rich in the 11S fraction showed a significant decrease after heating at 95 °C. Surprisingly, the emulsion stability index (ESI) of protein mixtures rich in the 7S fraction significantly improved twofold during processing at 75 °C. This study revealed a negative correlation between the emulsifying ability of soy protein and the 11S/7S ratio. For protein mixtures rich in either the 7S or the 11S fractions, gelling proprieties as well as emulsion activity index (EAI) and ESI showed no significant changes after spray drying; however, surface hydrophobicity was significantly enhanced following heating at 85 °C post-spray drying treatment. These findings provide insights into the alterations in gelling and emulsifying properties during various heating processes, offering great potential for producing soy protein ingredients with enhanced emulsifying ability and gelling property. They also contribute to establishing a theoretical basis for the standardized production of soy protein isolate with specific functional characteristics.

Structure and functional properties of starches from Xiaozhan rice: Effects of varieties and growing regions

This study aimed to understand structure and functionality of starches from different Xiaozhan rice varieties grown in the same region and from the same variety grown in different regions. The amylose content varied from 15.6% to 23.2% among all rice starches, and the proportions of A, B1, B2, and B3 chains of amylopectin were in the range of 28.4%–38.1%, 46.2%–51.4%, 8.0%–13.4%, and 2.5%–12.0%, respectively. Significant differences were noted in swelling power, gelatinization, pasting, gel textural properties and in vitro enzymic digestibility of rice starches from different varieties grown at the same region and from the same variety grown in different regions. Correlation analysis results showed that amylose content and chain length distribution of amylopectin were the major determinants for the functional properties and amylolysis of starches, respectively. This study suggests that the quality of Xiaozhan rice related to starch properties was affected by the rice varieties and growing regions. The results obtained in this study are of importance for optimizing breeding strategies to produce better rice varieties.

Impacts of Konjac Glucomannan on the Pasting, Texture, and Rheological Properties of Potato Starch with Different Heat–Moisture Treatments

AbstractFew studies reported the impact of hydrocolloid addition on starches after heat moisture treatment (HMT). In this study, potato starch is modified by HMT under different moisture content (18–35%), and the impact of konjac glucomannan (KGM) addition on the pasting, gel texture, and rheological properties of potato starch after HMT are investigated. The results showed that after HMT, the granule structure of the starch is changed with higher heat stability, shown as higher pasting temperature and trough viscosity. The impact of KGM addition is similar on the potato starch before and after HMT, but the change extent of the latter is larger in most cases, such as decreased pasting temperature and gel hardness, increased peak viscosity, breakdown viscosity, and final viscosity. This indicated that KGM benefited the gelatinization behavior of HMT starch but might not enhance the retrogradation process. The intrinsic high viscosity of KGM in water resulted in a softer starch gel and also contributed to the enhanced shear stress of the mixture paste. Therefore, the impact of KGM on the HMT starch is more significant than the original starch, and this guided the use of HMT starch in the food industry with other hydrocolloid involvement.

Effect of Ultrasonic Treatment on the Physicochemical Properties of Bovine Plasma Protein-Carboxymethyl Cellulose Composite Gel.

In order to improve the stability of bovine plasma protein-carboxymethyl cellulose composite gels and to expand the utilization of animal by-product resources, this study investigated the impact of different ultrasound powers (300, 400, 500, 600, and 700 W) and ultrasound times (0, 10, 20, 30, and 40 min) on the functional properties, secondary structure and intermolecular forces of bovine plasma protein-carboxymethyl cellulose composite gel. The results showed that moderate ultrasonication resulted in the enhancement of gel strength, water holding capacity and thermal stability of the composite gels, the disruption of hydrogen bonding and hydrophobic interactions between gel molecules, the alteration and unfolding of the internal structure of the gels, and the stabilization of the dispersion state by electrostatic repulsive forces between the protein particles. The content of α-helices, β-turns, and β-sheets increased and the content of random curls decreased after sonication (p < 0.05). In summary, appropriate ultrasound power and time can significantly improve the functional and structural properties of composite gels. It was found that controlling the thermal aggregation behavior of composite gels by adjusting the ultrasonic power and time is an effective strategy to enable the optimization of composite gel texture and water retention properties.

Influence of Heat Moisture, Ultrasonication, and Gamma Irradiation on Pasting, Thermal, Morphological, and Physicochemical Properties of Indian Teff (Eragrostis tef) Starch

AbstractThe present work is conducted to study the effect of heat‐moisture treatment (HMT), ultrasonication (US), and gamma‐irradiation (GI) on various properties of teff starch. Starch is subjected to HMT at 28% moisture level, US at a frequency of 20 kHz for 30 and 60 min, and GI at 5 and 10 kGy. US has an increased swelling power (8.22–9.39 g g−1) and solubility (9.5–10.5%). Water binding and Oil binding capacity are improved in modified starches than native. The highest amylose content (24.94–25.24%) is observed in US than native (20.82%). Thermal characteristics show an increment in the modified teff starches with enthalpies varied from 2.30 to 3.81 J g−1. Significant differences in starch gel textural properties are identified. Similar outcomes for native and modified findings are seen in Fourier transform infrared spectroscopy spectra. X‐ray diffraction shows a similar X‐ray pattern with crystallinity decreases for HMT (28.07%) and gamma irradiated starches (30.21%) and increases for ultrasonicated samples (32.23%). The morphological changes in teff starch are observed after physical modification. All in all, significant improvements have been reported in modified teff starch, which not only increases its industrial application but also improves the utilization of teff grain globally.

Enhancement mechanism of glycation with l-arabinose and xylose on texture properties of silver carp mince gel.

Glycation is a green processing technology. Based on our previous studies, glycation with l-arabinose and xylose was beneficial to enhance the texture properties of silver carp mince (SCM) gels. However, the possible enhancement mechanism remained unclear. Therefore, in this study, SCM gels with different types of reducing sugar (glucose, l-arabinose, and xylose) were prepared based on our previous study. The possible mechanism of texture enhancement of SCM gels was analyzed by investigating the changes in water distribution, protein structures, and microstructure in the gel system. The glycation of l-arabinose and xylose enhanced the hardness, cohesiveness, chewiness, and resilience of SCM gels. Hardness increased from 1883.04 (control group) to 3624.54 (l-arabinose group) and 4348.18 (xylose group). Low-field nuclear magnetic resonance (LF-NMR) showed that glycation promoted the tight binding of immobilized water to proteins. Raman spectroscopic analysis showed that glycation increased the surface hydrophobicity and promoted the formation of disulfide bonds. Scanning electron microscopy (SEM) showed that glycation promoted the formation of uniform and dense three-dimensional network structure in SCM gels. In summary, glycation enhanced the binding ability of immobilized water to proteins, improved the surface hydrophobicity, promoted the formation of disulfide bonds, and led to a more uniform and dense gel network structure of proteins, thus enhancing the texture properties of SCM gels. This research provided a theoretical basis for a better understanding of the mechanism of the effect of glycation on the quality of gel products and also provided technical support for the application of l-arabinose and xylose in new functional gel foods. © 2024 Society of Chemical Industry.

Oxidative Modification, Structural Conformation, and Gel Properties of Pork Paste Protein Mediated by Oxygen Concentration in Modified Atmosphere Packaging

The objective of this study was to investigate the effect of pork oxidation through modified atmosphere packaging (MAP) on gel characteristics of myofibrillar proteins (MP) during the heat-induced gelation process. The pork longissimus thoracis (LT) was treated by MAP at varying oxygen concentrations (0, 20, 40, 60, and 80% O2) with a 5-day storage at 4 °C for the detection of MP oxidation and gel properties. The findings showed the rise of O2 concentration resulted in a significant increase of carbonyl content, disulfide bond, and particle size, and a decrease of sulfhydryl content and MP solubility (p &lt; 0.05). The gel textural properties and water retention ability were significantly improved in MAP treatments of 0–60% O2 (p &lt; 0.05), but deteriorated at 80% O2 level. As the concentration of O2 increased, there was a marked decrease in the α-helix content within the gel, accompanied by a simultaneous increase in β-sheet content (p &lt; 0.05). Additionally, a judicious oxidation treatment (60% O2 in MAP) proved beneficial for crafting dense and uniform gel networks. Our data suggest that the oxidation treatment of pork mediated by O2 concentration in MAP is capable of reinforcing protein hydrophobic interaction and disulfide bond formation, thus contributing to the construction of superior gel structures and properties.

Enhancing the textural and rheological properties of fermentation-induced pea protein emulsion gels with transglutaminase.

The aim of this study was to assess how transglutaminase (TG) impacts the microstructure, texture, and rheological properties of fermentation-induced pea protein emulsion gels. Additionally, the study examined the influence of storage time on the functional properties of these gels. Fermentation-induced pea protein gels were produced in the presence or absence of TG and stored for 1, 4, 8, 12, and 16 weeks. Texture analysis, rheological measurements, moisture content and microstructure evaluation with confocal laser scanning microscopy (CLSM) and 3D image analysis were conducted to explore the effects of TG on the structural and rheological properties of the fermented samples. The porosity of the protein networks in the pea gels decreased in the presence of TG, the storage modulus increased and the textural characteristics were significantly improved, resulting in harder and more springy gels. The gel porosity increased in gels with and without TG after storage but the effect of storage on textural and rheological properties was limited, indicating limited structural rearrangement once the fermentation-induced pea protein emulsion gels are formed. Greater coalescence was observed for oil droplets within the gel matrix after 16 weeks of storage in the absence of TG, consistent with these protein structures being weaker than the more structurally stable TG-treated gels. This study shows that TG treatment is a powerful tool to enhance the textural and rheological properties of fermentation-induced pea protein emulsion gels.

Effects of Lactiplantibacillus plantarum dy-1 fermentation on multi-scale structure and physicochemical properties of barley starch.

The effects of fermentation on barley starch were studied using Lactiplantibacillus plantarum dy-1. Changes in multi-scale structure and physicochemical properties of barley starch were studied. The chain structure results revealed that fermentation could increase the content of short chain and medium short chain by breaking down long amylopectin side chains in barley and increase amylose content by debranching amylopectin. Also, fermentation promoted the arrangement of short chains into short order structure, leading to the enhancement of hydrogen bond interaction. Furthermore, it improved the helical structure content and relative crystallinity of barley starch by degrading the amorphous structure of barley starch. In terms of physicochemical properties, fermentation inhibited the hydration characteristics of barley starch, thus improving its thermal stability. It also enhanced shear stability, resistance to short-term aging and digestion, and improved gel texture properties. These findings offer potential for the processing and nutritional regulation of fermented barley products.

Dough rheology and internal structure of bread produced with wheat flour partially substituted by buckwheat flour: A step towards enhancing nutritional value

Buckwheat flour is a pseudocereal that can be used to improve the nutritional value of staple food, such as bread. However, substituting wheat flour can be challenging due to potential loss of the final product's technological quality. Therefore, understanding the influence of buckwheat inclusion level on dough rheology and bread quality is essential. This study evaluated the effect of wheat flour substituted by buckwheat flour on dough rheology and bread quality over the staling process. Wheat flour was replaced by 0%, 10%, 20% and 30% of buckwheat flour and the resulting dough mixing properties, viscosity profile, gel texture, rheology behaviour and extensibility properties were analysed. Internal bread structure (C-Cell and confocal microscopy), specific volume, density and crumb texture profile were also assessed. The increase in buckwheat level gradually decreased flour water absorption (p < 0.05), dough stability and development time, with increased gluten weakening as evidenced by decreased C2 values (protein strength) of Mixolab. As a result, the dough was less resistant to extension, with decreased extensibility. The highest viscosity profile of the starch paste was observed with 30% buckwheat inclusion level, which may lead to faster bread staling process. A solid-like and elastic behaviour was observed in the rheology evaluation, suggesting an interaction between fibre and starch from buckwheat with gluten proteins. Although changes in dough rheology occurred, the bread quality remained unchanged at levels of up to 20% buckwheat level (p > 0.05), with similar specific volume, density, internal structure and texture profile compared to the control bread (0% buckwheat). In conclusion, buckwheat was found to be a viable wheat flour substitute with only minimal changes in dough behaviour and maintenance of bread technological quality, while enhancing the nutritional profile by increasing fibre content and total essential amino acid.

Synergistic formulation approach for developing pea protein and guar gum enriched olive oil-in-water emulsion gels as solid fat substitutes: Formulation optimization, characterization, and molecular simulation

This study aimed to optimize the formulation of olive oil-in-water (O/W) emulsion gels by incorporating Pea Protein (PP) and Guar Gum (GG) as alternative options for solid fats. The optimum rheological (consistency index, apparent viscosity, recovery) and texture (firmness) properties of the emulsion gels were obtained using a mixture of 2 % PP, 1 % GG, 60 % Olive Oil (OO), and 37 % Water (W). The blend of PP2/GG1 showed the highest results for recovery and firmness, 111.27 % and 33.89 g, respectively. PP/GG blend emulsion gels exhibited higher absolute ζ-potential values, ranging between −72.3 and −77.4 mV. The polydispersity index (PDI) ranged from 0.185 to 0.535, with the most uniform distributions found in the PP/GG blend emulsion gels. Strong phase separation resistance indicated strong stability of PP-GG complex emulsion gels. Higher PP concentrations decreased emulsion oxidation. FTIR and XRD research showed that PP and GG interact strongly, indicating good compatibility. The free binding energy of the most stable configuration of the molecules was −6.8 kcal mol−1, indicating a high affinity. PP interacted with GG through 9 amino acid residues, with notable residues being Asp 224, Thr 235, Ala 332, Ile 334, and Arg 336, and their respective interaction distances ranged between 2.69 Å and 3.87 Å.

Characteristics of rice starches modified by single and dual heat moisture and osmotic pressure treatments

The effect of osmotic pressure treatment (OPT), heat moisture treatment (HMT), and their dual combination as HMT-OPT and OPT-HMT on functional and pasting properties, gel texture, crystallinity, thermal, morphological, and rheological properties, and in vitro digestibility of modified starches were investigated. HMT was done with 29 % moisture at 111 °C for 45 min while OPT was performed at 117 °C for 35 min with saturated sodium sulphate solution. All modifications increased amylose content, improved pasting stability, and reduced swelling power and solubility. Dual modifications caused higher morphological changes than single modified starches. HMT and OPT increased pasting temperature, setback and final viscosity while decreased peak viscosity and breakdown, whereas HMT-OPT and OPT-HMT reduced all pasting parameters except pasting temperature. 1047/1022 and 995/1022 ratios and relative crystallinity decreased. V-type polymorphs were formed, and gelatinization temperature range increased with lower gelatinization enthalpy. Starch gel elasticity, RS and SDS content were enhanced to a greater extent after HMT-OPT and OPT-HMT. HMT as a single and dual form with OPT showed prominent effect on pasting, thermal, crystalline, and rheological properties. Application of HMT, OPT and dual modified starches with improved functionalities may be targeted for suitable food applications such as noodles.

Fibrous whey protein mediated homogeneous and soft-textured emulsion gels for elderly: Enhancement of bioaccessibility for curcumin

Homogeneous and soft-textured food gels are critical for designing precise and personalized nutrient food for elderly. Effects of whey protein morphology (fibrous and granular) with/without NaCl addition on oil-water state and texture properties of protein emulsion gels were investigated, to explore the feasibility of developing homogeneous and soft-textured food for elderly. Lower gelation temperature and higher stability of its emulsion droplets, resulted in fibrous whey protein emulsion gels (FWPG) had even distribution of embedded oil droplets, compared to native whey protein emulsion gels. FWPG had the lowest hardness and chewiness, and exhibited better tolerance to the harden effects of NaCl on emulsion gels. FWPG can deliver curcumin more effectively during simulated gastrointestinal digestion, as evidenced by higher retention ratio and enhancement of bioaccessibility (increased by ∼ 20 %). This study provided new strategy to fabricate a homogenous emulsion gel using fibrous whey protein and to design multi-nutrient food gels for elderly.

Mechanism on the Synergistic Gelation of the Myofibrillar Protein Composite Gel Enhanced by "Clean-Label" Skin Functional Protein Powders.

The concept of healthiness and sustainability has promoted the innovation and development of "clean-label" products. Herein, this study aims to explore the influence mechanism of "clean label" skin protein powder (FPP) on the gelation properties of myofibrillar proteins (MPs). Specifically, the addition of FPP (0.2-4.0%) can improve the water holding capability and texture properties of MP composite gels. When the FPP concentration is over 1.0%, the composite gels exhibit no significant water loss during centrifugation. Dynamic rheology and sodium-dodecyl sulfate-polyacrylamide gel electrophoresis results revealed that FPP can slow the aggregation and denaturation of myosin and promote the formation of disulfide bonds between myofibril proteins, thus forming a stable network structure. Structural observation revealed that FPP can fill into the MP gel and lead to the formation of compact gel structures. Besides, with the increase of FPP concentration, the chemical forces involved in structural stabilization change significantly. Specifically, hydrophobic interaction and hydrogen bonding are the dominant forces at a lower FPP concentration (0.2 and 0.4%), while the ionic bond and disulfide bond are the dominant forces at a higher concentration. Overall, this work demonstrated that FPP can significantly improve the gel functionality of MP by altering the gel structure and strengthening the molecular forces.

Structural and physicochemical characteristics of wheat starch as influenced by freeze-thawed cycles and antifreeze protein from Sabina chinensis (Linn.) Ant. cv. Kaizuca leaves

The effects of freeze-thawed cycles (FTs) and a new antifreeze protein from Sabina chinensis (Linn.) Ant. cv. Kaizuca leaves (ScAFP) on the structure and physicochemical characteristics of wheat starch were studied. The mechanical breaking exerted by ice crystals on starch granules during FTs gradually deepened, sequentially squeezing the surface (2–6 FTs), amorphous region (8 FTs) and crystalline region (10 FTs) of starch granules. These changes led to reduced thermal stability, increased retrogradation tendency, and weakened gel network structure. The addition of ScAFP retarded the damage of ice crystals on starch granule structure and crystal structure during FTs, and significantly reduced the retrogradation tendency. Compared with native starch, the hardness of freeze-thawed starch without and with added ScAFP after 10 FTs decreased by 17.85% and 9.22%, respectively, indicating ScAFP improved the gel texture properties of freeze-thawed starch. This study provides new strategies for improving the quality of frozen starch-based foods.