The dose-dependent effects of polyphenols and malondialdehyde on the emulsifying and gel properties of myofibrillar protein-mulberry polyphenol complex

Visible light-driven multichannel concerted antibacterial films with Photodynamically enhanced self-cascading Chemodynamic actions for long-term preservation of perishable food

This work pioneered an innovative visible light-powered, self-cascading peroxide antimicrobial packaging system (RPFe-CS), featuring a photodynamic enhancement effect achieved through the demand-oriented design of riboflavin sodium phosphate and Fe coordination complexes (RPFe) fillers with photodynamic and peroxidase activities, and the ingenious selection of slightly acidic chitosan (CS) film matrix. In this system, the photo-responsive properties of RPFe particles not only generate the •O2-, •OH, and 1O2 required for photodynamic sterilization, but also the produced H2O2 serves as a necessary substrate for peroxidase to exert its bactericidal effect, endowing the packaging system with a "self-production and self-marketing" cascade process. The RPFe0.3-CS film achieved efficient eradication to bacteria and fungi reaching up to 99.9 % and 90.6 %, respectively, thereby demonstrating an excellent effect that significantly extends the storage period of cherry tomatoes by 1.5 times. These desirable properties underscore the significant advantages of RPFe0.3-CS film in addressing the challenges of food microbial spoilage.

Heat-Induced Preparation of Myofibrillar Protein Gels Reinforced Through Ferulic Acid, α-Cyclodextrin and Fe(III)

Phenolic acids have a positive effect on the processing quality of myofibrillar protein (MP) gels. However, in this study, the addition of ferulic acid (FA) did not have a positive effect on MP gels. To address this issue, we performed the addition and observed the effects on the structure of MP gels by both surface coating and internal cross-linking: addition of FA alone, addition of α-cyclodextrin (CD) to encapsulate FA (MP-FA/CD), and addition of Fe(III) to form a metal-phenolic network structure (Fe @MP-FA) and a metal-cyclodextrin-phenolic acid structure (Fe@MP-FA /CD). It was found that both Fe @MP-FA formed by surface coating and internal cross-linking were able to improve the textural properties of MP gels, including hardness, elasticity, chewability, adhesion, etc. FA effectively promoted the conversion of some of the non-fluidizable water to the bound water morphology, and the addition of Fe(III) effectively enhanced this trend. In particular, the composite network structure formed by Fe@MP-FA/CD more significantly promoted the conversion to bound water and improved the water retention of the gel. Hydrophobic interactions and hydrogen bonding in non-covalent bonding as well as disulfide bonding in covalent bonding were always the main factors promoting the formation of gels from MP after different additions. Meanwhile, different gel treatments lead to changes in the structure of different proteins. Internal cross-linking with the addition of FA promotes protein oxidation, whereas CD reduces the occurrence of oxidation and promotes a homogeneous gel structure. Surface coating with the addition of FA/CD resulted in a reduction in pores in the MP gels and a denser gel structure. However, the addition of internal cross-linking resulted in a gel with a loose and rough network structure. In this study, we compared the common methods of gel enhancement, with the objective of providing a reference for the improvement in the gel texture of meat products.

Interactions between polyphenols and polysaccharides/proteins: Mechanisms, effect factors, and physicochemical and functional properties: A review

Polyphenols have attracted much attention in the food industry and nutrition because of their unique biological activities. However, the health benefits of polyphenols are compromised due to their structural instability and sensitivity to the external environment. The interaction between polyphenols and polysaccharides/proteins largely determines the stability and functional characteristics of polyphenols in food processing and storage. Hence, this topic has attracted widespread attention in recent years. This review initially outlines the basic properties of polyphenols and their applications in food. Subsequently, the interaction mechanisms between polyphenols and polysaccharides/proteins are discussed in detail including non-covalent bonding, covalent modification, and conformational changes. These interactions can display profound impacts on the nutritional value, taste, stability, and safety of food. Additionally, this article also systematically reviews the influencing factors (type, concentration, temperature, pH, and other factors) of interaction between polyphenols and proteins/polysaccharides. Finally, this paper also summarizes systematically the effects of the interaction between polyphenols and polysaccharides/proteins on the physicochemical and functional properties of polyphenols/proteins. The findings provide prospects for the application of composite materials in food preservation, functional food development, and nanocarrier development, which can provide theoretical references for the in-depth development of polyphenols in the food industry.

Double network emulsion gel prepared with different polyphenol modified egg white protein: A promising fat substitute for oral processing and fatty taste supplement

This study investigated the effects of differential modification of the structural flexibility of egg white protein (EWP) by different polyphenols, which in turn enhanced the oral processing properties and fat perception of EWP-based double network emulsion gel (DNEG). After modification with polyphenols, the skeleton of gel became more delicate, which improved the hardness and cohesion of DNEG. This transformation was attributed to the shift from hydrophobic interactions to hydrogen and covalent bonds. Notably, proanthocyanidins (PC) effect was better, which resulted in a 58.5 % increase in oral wettability and a more appropriate oral tribological performance (0.53). Besides, DNEG increased fatty taste perception via the "ball bearing" effect as a fat substitute in sausage. In summary, this study could enhance the refined design of gels and provide ideas for improving the fatty taste of low-fat, healthy foods.

Insight into the effect of sesamol on the structural and gel properties of yak myofibrillar proteins

Different concentrations of sesamol (0, 20, 40, 80 and 160 mg/g protein) were incorporated for evaluating the effects of sesamol on the structural and gel properties of yak myofibrillar proteins (MPs). The results manifested that the contents of active thiol and free amine diminished and the carbonyl contents elevated when the MPs modified with sesamol. The intrinsic fluorescence intensity progressively decreased and surface hydrophobic value displayed a down-up trend after binding with the increasement of sesamol. Moreover, the presence of sesamol reduced protein solubility and increased particle size of MPs. For the protein gels, inclusion of sesamol effectively improved water-holding capacity and gel strength but decremented gel whiteness and the proportion of free water, and significantly enhanced the hydrogen bonds, hydrophobic interactions and disulfide bonds in the gel matrix. Microstructure analysis revealed that a more compact microstructure was formed for the MP-sesamol gels. This study suggests that sesamol is capable of improving the functional properties of MPs, and the complexes of MP-sesamol have potential applications in the food industry.

Effect of Sinapine on Microstructure and Anti-Digestion Properties of Dual-Protein-Based Hydrogels

Sinapine is a natural polyphenol from the cruciferous plant family that has anti-aging effects but is low in bioavailability. To improve the bioavailability and therapeutic effect of sinapine, sinapine-crosslinked dual-protein-based hydrogels were prepared using soy protein isolate as a cross-linking agent. The preparation conditions were optimized by single-factor experiments, and the optimal ratios were obtained as follows: the concentration of sinapine was 300 μg/mL; the water-oil ratio was 1:3. The encapsulation rate was greater than 95%, and the drug loading capacity was 3.5 mg/g. In vitro, digestion experiments showed that the dual-protein-based hydrogels as a drug carrier stabilized the release of sinapine and improved the bioavailability of sinapine by 19.3%. The IC50 of DPPH antioxidants was 25 μg/mL as determined by in vitro digestion, and the antioxidant capacity of ABTS was about 20% higher than that of glutaraldehyde control. This is due to the addition of sinapine to enhance the antioxidant properties of the system. It can be seen that the developed hydrogels have potential applications in related fields, such as food nutrition fortification and drug delivery.

Effect of γ-oryzanol/β-sitosterol-based oleogels on the physicochemical and gel properties of Nemipterus virgatus myofibrillar protein

BACKGROUND

The effect of oleogels prepared with peanut oil and different concentrations of γ-oryzanol and β-sitosterol mixture (γ/β; 20, 40, 60, 80 and 100 g kg-1) on the physicochemical and gel properties of myofibrillar protein (MP) was investigated.

RESULTS

The solubility and average particle size of MP first decreased and then increased with increasing γ/β concentration. Peanut oil or oleogels could induce the exposure of hydrophobic amino acids and the unfolding of MP, thus significantly increasing the surface hydrophobicity, sulfhydryl content and absolute value of zeta potential, which reached maximum values when the γ/β concentration was 60 g kg-1 (P < 0.05). The addition of peanut oil decreased the gel strength and water holding capacity of MP gel. However, oleogels prepared with 60 g kg-1 γ/β could significantly increase the hydrophobic interactions and disulfide bond content of MP gel (P < 0.05), which promoted the crosslinking and aggregation of MP, enhancing the gel properties. Peanut oil had no significant influence on the secondary structure of MP, while oleogels promoted the transition of MP conformation from α-helix to β-sheet structure. The results of light microscopy and confocal laser scanning microscopy indicated that oleogels prepared with 60 g kg-1 γ/β filled in the pores of MP gel network to form denser and more uniform structure.

CONCLUSION

Oleogels prepared with 60 g kg-1 γ/β could effectively improve the quality of MP gel and have promising application prospects in surimi products. © 2024 Society of Chemical Industry.

Controlled dual release of phenol compounds from phospholipid complexes of short-chain lipophenols

Ethanol evaporation method was applied to synthesize phospholipid complexes from phosphatidylcholine (PC) and short-chain alkyl gallates (A-GAs, a typical representative of lipophenols) including butyl-, propyl- and ethyl gallates. 1H NMR, UV and FTIR showed that A-GAs were interacted with PC through weak physical interaction. Through the analysis of concentrations of A-GAs and gallic acid (GA) by an everted rat gut sac model coupled with HPLC-UV detection, phospholipid complexes were found to gradually release A-GAs. These liberated A-GAs were further hydrolyzed by intestinal lipases to release GA. Both of GA and A-GAs could cross intestinal membrane. Especially, the transmembrane A-GAs could also be hydrolyzed to produce GA. Undoubtedly, the dual release of phenol compounds from phospholipid complexes of short-chain lipophenols will be effective to extend the in vivo residence period of phenol compounds. More importantly, such behavior is easily adjusted by changing the acyl chain lengths of lipophenols in phospholipid complexes.

Effects of catechin on the stability of myofibrillar protein-soybean oil emulsion and the adsorbed properties of myosin at the oil-water interface

The effects of different concentrations of catechin on the stability of myofibrillar protein-soybean oil emulsions and the related mechanisms were investigated. Adding 10 μmol/g catechin had no obvious effects on the emulsion stability and myosin structure, but 50, 100 and 200 μmol/g catechin decreased the emulsion stability. The microstructure observations showed that 10 μmol/g catechin caused a dense and uniform emulsion to form, whereas 50, 100 and 200 μmol/g catechin induced the merging of oil droplets. The addition of 50, 100 and 200 μmol/g catechin caused a decline in both the total sulfhydryl content and surface hydrophobicity, suggesting protein aggregation, which decreased the adsorption capacity of myosin and the elasticity of interfacial film. These results suggested that higher concentrations of catechin were detrimental to the emulsifying properties of myosin and that the dose should be considered when it is used as an antioxidant.

Effects of calcium chloride on the gelling and digestive characteristics of myofibrillar protein in Litopenaeus vannamei

In this study, the effects of CaCl2 (0, 25, 50, 75, and 100 mM) on the gelling and digestive properties of the myofibrillar protein (MP) in Litopenaeus vannamei were investigated. The results showed that increasing CaCl2 concentration led to changes in the tertiary structure of MP. Specifically, compared with the control group, a 64.31 % increase in surface hydrophobicity and a 45.90 % decrease in the sulfhydryl group were observed after 100 mM CaCl2 treatment. Correspondingly, the water holding capacity and strength of the MP gel increased by 24.46 % and 55.99 %, respectively. These changes were positively correlated with the rheological properties, microstructure pore size, and content of non-flowable water. The mechanical properties of MP gel were improved, and the microstructure became more compact with the increase in CaCl2 concentration. Furthermore, the particle size of the digested MP gels decreased in the presence of CaCl2, which improved the digestion characteristics of MP gels.

Effects of Gnaphalium affine Extract on the Gel Properties of •OH-Induced Oxidation of Myofibrillar Proteins

This study aimed to investigate the effect of Gnaphalium affine extract (GAE) (0.04, 0.2 and 1 mg/g protein) on the gel properties of porcine myofibrillar proteins (MPs) in a simulated Fenton oxidation system, using tea polyphenols (TPs) at similar concentrations of 0.04, 0.2, and 1 mg/g protein, respectively, as a contrast. The findings revealed that as the TP concentration increased, the water retention of MP gels decreased significantly (p < 0.05). In contrast, MP gels containing medium and high concentrations of GAE exhibited significantly higher water retention than those with low concentrations of GAE (p < 0.05). When the concentration of GAE was increased to 1 mg/g protein, the strength of MP gels was significantly reduced (p < 0.05) by 33.32% compared with the oxidized control group, suggesting that low and medium GAE concentrations support MP gel formation. A texture profile analysis indicated that an appropriate GAE concentration improved gel structure and texture. Dynamic rheological characterization revealed that low concentrations of TP (0.04 mg/g protein) and low and medium concentrations of GAE (0.04 and 0.2 mg/g protein) strengthened the protein gel system. Conversely, high concentrations of TP and GAE (1.0 mg/g protein) damaged the protein gel system or even promoted the collapse of the gel system. Scanning electron microscopy revealed that higher TP concentrations disrupted the gel, whereas low and medium GAE concentrations maintained a more continuous and complete gel network structure compared with the oxidized control group. This indicates that an appropriate GAE concentration could effectively hinder the destruction of the gel network structure by oxidation. Therefore, based on the obtained results, 0.2 mg/g protein is recommended as the ideal concentration of GAE to be used in actual meat processing to regulate the oxidization and gel properties of meat products.

Emerging challenges and efficacy of polyphenols-proteins interaction in maintaining the meat safety during thermal processing

Polyphenols are well documented against the inhibition of foodborne toxicants in meat, such as heterocyclic amines, Maillard's reaction products, and protein oxidation, by means of their radical scavenging ability, metal chelation, antioxidant properties, and ability to form protein-polyphenol complexes (PPCs). However, their thermal stability, low polarity, degree of dispersion and polymerization, reactivity, solubility, gel forming properties, low bioaccessibility index during digestion, and negative impact on sensory properties are all questionable at oil-in-water interface. This paper aims to review the possibility and efficacy of polyphenols against the inhibition of mutagenic and carcinogenic oxidative products in thermally processed meat. The major findings revealed that structure of polyphenols, for example, molecular size, no of substituted carbons, hydroxyl groups and their position, sufficient size to occupy reacting sites, and ability to form quinones, are the main technical points that affect their reactivity in order to form PPCs. Following a discussion of the future of polyphenols in meat-based products, this paper offers intervention strategies, such as the combined use of food additives and hydrocolloids, processing techniques, precursors, and structure-binding relationships, which can react synergistically with polyphenols to improve their effectiveness during intensive thermal processing. This comprehensive review serves as a valuable source for food scientists, providing insights and recommendations for the appropriate use of polyphenols in meat-based products.

Catechins affect the oil-holding capacity of meat batters by changing the structure and emulsifying properties of surface proteins at the fat globules

The effects of different concentrations of catechins on the oil-holding capacity, myofibrillar proteins (MPs) structure and adsorbed properties of interfacial proteins in meat batters were investigated. The addition of 100 mg/kg catechin had no negative effects on the physicochemical properties of meat batter. However, 500 and 1500 mg/kg catechin caused an increase in drip loss and deterioration of dynamic rheological properties; the total sulfhydryl content, surface hydrophobicity and α-helix ratio of MPs decreased significantly (p < 0.05); in meat emulsions, the emulsifying property was reduced, the particle size increased, and less interfacial protein was absorbed on the fat globules. All concentrations of catechins significantly (p < 0.05) inhibited lipid oxidation in meat batters. Medium and high concentrations of catechins induced aggregation of MPs via covalent and noncovalent interactions between MPs and MPs or MPs and catechins, which destroyed the gel and emulsifying property of protein and eventually decrease the oil-holding capacity of meat batters.

The primary neurotoxic factor, Lansamide I, from Clausena lansium fruits and metabolic dysfunction invoked

Wampee (Clausena lansium) is a common fruit in South Asia. The pulp is a tasty food, and the seed is a typical traditional herb in China. However, we identified a primary toxic compound, Lansamide I, by NMR and X-ray diffraction of single-crystal. The compound occurred at 4.17 ± 0.16 mg/kg of dried seed and 0.08 ± 0.01 g/kg of fresh fruit. In our phenotype-based toxicity investigation, the compound caused decreased hatchability of zebrafish eggs, increased malformations such as enlarged yolk sacs and pericardial edema, and delayed body length development. Moreover, the compound also caused nerve cell damage and decreased locomotor activity. The compound caused an increase in peroxidation levels in vivo, with increases in both malondialdehyde and superoxide dismutase levels, but did not interfere with acetylcholinesterase levels. Metabolomic studies found that the compound caused significant up-regulation of 16 metabolites, mainly amino acids and peptides, which were involved in the nucleotide metabolism pathway and the betaine biosynthesis module. The qRT-PCR revealed that the substance interfered with the mRNA expression of tat and dctpp. These discoveries offer fresh perspectives on the toxicity mechanisms and metabolic response to the primary harmful molecules in wampee, which could inform the rational usage of wampee resources.

Suppression mechanism of L-lysine on the Epigallocatechin-3-gallate-induced loss of myofibrillar protein gelling potential

As a natural antioxidant, Epigallocatechin-3-gallate (EGCG) needed to be added in high doses to maintain the quality of meat products. However, high doses of EGCG caused the excessive aggregation of myofibrillar protein (MP), which damaged the gel properties of MP gels. Therefore, the purpose of this study was to investigate the mitigation of EGCG-induced loss of MP gelling potential by L-Lysine (L-Lys). The results showed that the addition of 20 mM L-Lys induced excessive unfolding and loose aggregation of MP at 10 µmol/g EGCG, and hence, reducing the solubility (14.5%) and the tryptophan fluorescence, and forming a network structure with a large aperture. Therefore, the cooking loss was decreased from 29.20% to 15.13%, and the strength of MP gels was decreased from 0.35 N to 0.17 N. However, L-Lys hindered the hydrogen bonding interactions and hydrophobic interactions between MP and EGCG by competing the binding sites of MP at 50 µmol/g EGCG, which was supported by the Zeta potential, surface hydrophobicity, FTIR and molecular docking analysis. Thus L-Lys mitigated the protein aggregation caused by 50 µmol/g EGCG, improved the solubility (23.02%∼86.99%) and apparent viscosity, which were beneficial for the formation of a continuous network structure in MP gels. Therefore, the cooking loss of MP gels was decreased from 52.40% to 41.30%, and the gel strength was enhanced from 0.13 N to o.22 N with 20 mM L-Lys addition. The present study could provide a new strategy for increasing the amounts of EGCG in meat products without damaging the gel properties of meat products.

Regulation mechanism of curcumin-loaded oil on the emulsification and gelation properties of myofibrillar protein: Emphasizing the dose-response of curcumin

The regulation mechanism of curcumin (CUR) in the oil phase on the emulsification and gelation properties of myofibrillar protein (MP) was investigated. CUR enhanced the emulsifying activity index (EAI) of MP but decreased its turbiscan stability index (TSI) and surface hydrophobicity, which exacerbated oil droplet aggregation. Medium amounts (200 mg/L) of CUR changed the 3D network architectures of emulsion gels from lamellar to reticular, improving the gels' water-holding capacity (WHC), storage modulus, springiness, and cohesiveness. Besides, the LF-NMR revealed that CUR had limited effects on the mobility of immobilized and free water. The α-helix of MP in gels with medium amounts of CUR decreased from 51% to 45%, but the β-sheet increased from 23% to 27% compared to those without CUR. Overall, CUR has the potential to become a novel structural modifier in emulsified meat products due to its dose-response.

Assessment of the physicochemical and sensory characteristics of fermented camel milk fortified with Cordia myxa and its biological effects against oxidative stress and hyperlipidemia in rats

Natural feed additives and their potential benefits in production of safe and highly nutritious food have gained the attention of many researchers the last decades. Cordia myxa is a nutrient-dense food with various health benefits. Despite this fact, very limited studied investigated the physicochemical and sensory impacts of incorporation of fermented camel milk with Cordia myxa and its biological effects. The current study aimed to assess the physical, chemical, and sensory characteristics of fermented camel milk (FCM) fortified with 5, 10, and 15% Cordia myxa pulp. The study demonstrated that fortification of camel milk efficiently enhanced protein, total solids, ash, fiber, phenolic substance, and antioxidant activity. When compared to other treatments, FCM supplemented with 10% Cordia myxa pulp had the best sensory features. In addition, FCM fortified with 10% Cordia myxa pulp was investigated as a potential inhibitor of hypercholesterolemia agents in obese rats. Thirty-two male Wistar rats were split into two main groups including normal pellet group (n = 8) served as negative control group (G1) and a group of hyperlipidemic animals (n = 24) were feed on a high-fat diet (HFD). Hyperlipidemic rats group (n = 24) were then divided into three subgroups (8 per each); second group or positive control (G2) which include hyperlipidemic rats received distilled water (1 mL/day), the third group (G3) involved hyperlipidemic rats feed on FCM (10 g/day) and the fourth group (G4) included hyperlipidemic animals feed on 10 g/day FCM fortified with 10% of Cordia myxa pulp by oral treatment via an intestinal tube for another 4 weeks. In contrast to the positive control group, G4 treated with Cordia myxa showed a substantial decrease in malondialdehyde, LDL, cholesterol, triglycerides, AST, ALT, creatinine, and urea levels, while a significant increase in HDL, albumin, and total protein concentrations. The number of large adipocytes decreased while the number of small adipocytes increased after consumption of fortified FCM. The results indicated that fermented milk fortified with Cordia myxa pulp improved the functions of the liver and kidney in hyperlipidemic rats. These results demonstrated the protective effects of camel milk and Cordia myxa pulp against hyperlipidemia in rats.

Concentration-dependent effect of eugenol on porcine myofibrillar protein gel formation

The effects of different concentrations of eugenol (EG = 0, 5, 10, 20, 50, and 100 mg/g protein) on the structural properties and gelling behavior of myofibrillar proteins (MPs) were investigated. The interaction of EG and MPs decreased free thiol and amine content, and reduced tryptophan fluorescence intensity and thermal stability, but enhanced surface hydrophobicity and aggregation of MPs. Compared with the control (EG free), the MPs' gels treated with 5 and 10 mg/g of EG had a higher storage modulus, compressive strength, and less cooking loss. A high microscopic density was observed in these EG-treated gels. However, EG at 100 mg/g was detrimental to the gelling properties of the MPs. The results indicate that an EG concentration of 20 mg/g is a turning point, i.e., below 20 mg/g, EG promoted MPs gelation, but above 20 mg/g, it impeded gelation by interfering with protein network formation. The EG modification of MPs could provide a novel ingredient strategy to improve the texture of comminuted meat products.

Alkali-Induced Phenolic Acid Oxidation Enhanced Gelation of Ginkgo Seed Protein

The effect of alkali-induced oxidation of three phenolic acids, namely gallic acid, epigallocatechin gallate, and tannic acid, on the structure and gelation of ginkgo seed protein isolate (GSPI) was investigated. A mixture of 12% (w/v) GSPI and different concentrations of alkali-treated phenolic acids (0, 0.06, 0.24, and 0.48% w/w) were heated at 90 °C, pH 6.0, for 30 min to form composite gels. The phenolic treatment decreased the hydrophobicity of the GSPI sol while enhancing their rheological properties. Despite a reduced protein solubility, water holding capacity, stiffness, and viscoelasticity of the gels were improved by the treatments. Among them, the modification effect of 0.24% (w/v) EGCG was the most prominent. Through the analysis of microstructure and composition, it was found to be due to the covalent addition, disulfide bond formation, etc., between the quinone derivatives of phenolic acids and the side chains of nucleophilic amino acids. Phenolic acid modification of GSPI may be a potential ingredient strategy in its processing.

Physicochemical Properties and Oxidative Stability of an Emulsion Prepared from (-)-Epigallocatechin-3-Gallate Modified Chicken Wooden Breast Myofibrillar Protein

The deterioration of wooden breast myofibrillar protein (WBMP) causes a decline in its processing performance, and the protein becomes easier to oxidize. Previous studies have revealed that the use of (-)-epigallocatechin-3-gallate (EGCG) may improve the physicochemical properties and oxidative stability of proteins in aqueous solutions. The effects of varying concentrations (0.01%, 0.02%, 0.03%, and 0.04% w/v) of EGCG on the physicochemical properties of a WBMP emulsion (1.2% WBMP/10% oil) and the inhibition of lipid and protein oxidation were studied. The results revealed that a moderate dose of EGCG (0.03%) could significantly (p < 0.05) improve the emulsion activity index (4.66 ± 0.41 m2/g) and emulsion stability index (91.95 ± 4.23%), as well as reduce the particle size of the WBMP emulsion. According to the micrographs and cream index, 0.03% EGCG retarded the phase separation by stopping the aggregation of droplets and proteins, thus significantly improving the stability of WBMP emulsions. During storage at 50 °C for 96 h, 0.03% EGCG inhibited lipid oxidation (lipid hydroperoxide and 2-thiobarbituric acid-reactive substance formation) and protein oxidation (carbonyl formation and sulfhydryl loss). In contrast, lower and higher EGCG concentrations (0.01%, 0.02%, and 0.04%) demonstrated shortcomings (such as weak antioxidant capacity or protein over-aggregation) in improving the quality and oxidation stability of the emulsion. In conclusion, a moderate dose of EGCG (0.03%) can be used to improve the quality and shelf life of WBMP emulsions.

Gel-type emulsified muscle products: Mechanisms, affecting factors, and applications

The gel-type emulsified muscle products improve fatty acid composition, maintain the oxidative stability, and achieve a better sensory acceptability. This review emphasizes the stabilization mechanisms of these emulsified muscle products. In particular, factors associated with the stability of the emulsified muscle systems are outlined, including the processing conditions (pH and heating), lipids, and emulsifiers. Besides, some novel systems are further introduced, including the Pickering emulsions and organogels, due to their great potential in stabilizing emulsified gels. Moreover, the promising prospects of emulsion muscle products such as improved gel properties, oxidative stability, freeze-thaw stability, fat replacement, and nutraceutical encapsulation were elaborated. This review comprehensively illustrates the considerations on developing gel-type emulsified products and provides inspiration for the rational design of emulsified muscle formulations with both oxidatively stable and organoleptically acceptable performance.

Effects of Fermented Camel Milk Supplemented with Sidr Fruit (Ziziphus spina-christi L.) Pulp on Hyperglycemia in Streptozotocin-Induced Diabetic Rats

Diabetes is one of the most common chronic metabolic diseases, and its occurrence rate has increased in recent decades. Sidr (Ziziphus spina-christi L.) is a traditional herbaceous medicinal plant. In addition to its good flavor, sidr has antidiabetic, anti-inflammatory, sedative, analgesic, and hypoglycemic activities. Camel milk has a high nutritional and health value, but its salty taste remains the main drawback in relation to its organoleptic properties. The production of flavored or fortified camel milk products to mask the salty taste can be very beneficial. This study aimed to investigate the effects of sidr fruit pulp (SFP) on the functional and nutritional properties of fermented camel milk. SFP was added to camel milk at rates of 5%, 10%, and 15%, followed by the selection of the best-fermented product in terms of functional and nutritional properties (camel milk supplemented with 15% SFP), and an evaluation of its hypoglycemic activity in streptozotocin (STZ)-induced diabetic rats. Thirty-two male adult albino rats (weighing 150–185 g) were divided into four groups: Group 1, nontreated nondiabetic rats (negative control); Group 2, diabetic rats given STZ (60 mg/kg body weight; positive control); Group 3, diabetic rats fed a basal diet with fermented camel milk (10 g/day); and Group 4, diabetic rats fed a basal diet with fermented camel milk supplemented with 15% SFP (10 g/day). The results revealed that supplementation of camel milk with SFP increased its total solids, protein, ash, fiber, viscosity, phenolic content, and antioxidant activity, which was proportional to the supplementation ratio. Fermented camel milk supplemented with 15% SFP had the highest scores for sensory properties compared to other treatments. Fermented camel milk supplemented with 15% SFP showed significantly decreased (p < 0.05) blood glucose, malondialdehyde, low-density lipoprotein-cholesterol, cholesterol, triglycerides, aspartate aminotransferase, alanine aminotransferase, creatinine, and urea, and a significantly increased (p < 0.05) high-density lipoprotein-cholesterol, total protein content, and albumin compared to diabetic rats. The administration of fermented camel milk supplemented with 15% SFP in diabetic rats restored a series of histopathological changes alonsgside an improvement in various enzyme and liver function tests compared to the untreated group, indicating that fermented camel milk supplemented with 15% SFP might play a preventive role in such patients.

Glochidion wallichianum Leaf Extract as a Natural Antioxidant in Sausage Model System

This study highlighted the role of an 80% ethanolic Mon-Pu (Glochidion wallichianum) leaf extract (MPE), a novel natural antioxidative ingredient, in controlling the oxidative stability and physicochemical properties of a cooked sausage model system (SMS). MPE had a total extractable phenolic content of 16 mg/100 g, with DPPH● scavenging activity, ABTS●+ scavenging activity, and ferric reducing antioxidant power of 2.3, 1.9, and 1.2 mmole Trolox equivalents (TE)/g, respectively. The effects of different concentrations of MPE (0.01−10%, w/w) formulated into SMS on lipid oxidation, protein oxidation, and discoloration were compared to synthetic butylated hydroxyl toluene (BHT; 0.003%, w/w) and a control (without antioxidant). The peroxide value (PV), thiobarbituric acid reactive substances (TBARS), and protein carbonyl contents of SMS tended to increase with increasing MPE concentration (p < 0.05), indicating that high MPE excipient has a pro-oxidative effect. The lowest lipid oxidation (PV and TBARS) and protein carbonyl contents were observed when 0.01% MPE was used to treat SMS (p < 0.05), which was comparable or even greater than BHT-treated SMS. High concentrations (1−10%) of MPE incorporation led to increases in the discoloration of SMS (p < 0.05) with a negligible change in pH of SMS. The water exudate was reduced when MPE was incorporated into SMS compared to control (p < 0.05). Furthermore, MPE at 0.01% significantly reduced lipid oxidation in cooked EMS during refrigerated storage. According to the findings, a low amount of MPE, particularly at 0.01%, in a formulation could potentially maintain the oxidative stability and physicochemical qualities of cooked SMS that are comparable to or better than synthetic BHT.

Loadings of lycopene in emulsion and sodium alginate-K-carrageenan composite systems: Preparation, characterization, bioaccessibility, and kinetics

This research aims to prepare capsules emulsion using gallic acid (GA), dextran (DEX), bovine serum albumin (BSA), sodium alginate, and K-carrageenan (K-Car) as the biological delivery system of lycopene. The stability and bioaccessibility of lycopene were further improved through encapsulation of covalent complex of sodium alginate and K-Car. The molecular weight distribution and secondary structure of the conjugates were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Fourier transform infrared spectroscopy (FTIR). The storage stability of the emulsion stabilized by conjugates was measured with Turbiscan stability index (TSI) and fluctuation of the particle size. The TSI value of ternary conjugates was 18.7 (37℃) with particle sizes ranging from 208 to 319 nm. Then, the changes of three-dimensional reticulate structures and physical properties of sodium alginate-K were analyzed by scanning electron microscopy (SEM) and TPA. The thermal stability of the sodium alginate-K-Car composite systems was increased compared with sodium alginate. The bioaccessibility of lycopene was significantly improved under the dual embedding of BSA-DEX-GA conjugate emulsion and sodium alginate-K-Car composite systems.

Impact of covalent grafting of two flavonols (kaemperol and quercetin) to caseinate on in vitro digestibility and emulsifying properties of the caseinate-flavonol grafts

Covalent grafting of one of the two flavonols (kaemperol and quercetin) to caseinate was achieved by a reaction between the heat-oxidized flavonols and caseinate at flavonol-lysine molar ratios of 1:100 and 1:200. Grafted caseinate products (GCPs) showed - NH₂ content reduction and respective kaemperol and quercetin contents of 1.08-6.13 and 3.23-6.64 mmol/kg protein. Quercetin was more reactive than kaemperol under the same conditions, while long-time flavonol heat and higher flavonol-lysine molar ratio caused greater flavonol-grafting. GCPs subjected to 180-day storage had further flavonol-grafting, -NH₂ content decrease, and weak protein crosslinking. GCPs consistently had higher surface hydrophobicity but lower emulsification and digestibility than caseinate, while greater flavonol-grafting caused a remarkable value change. Meanwhile, the Kjeldahl method was more suitable than the UV-absorption method to evaluate protein digestibility, because the grafted flavonols in this case did not interfere with data results. Collectively, the covalent flavonol-grafting of proteins can impact the assayed protein functionalities.

Muscle protein oxidation and functionality: a global view of a once neglected phenomenon

Muscle is a highly organized apparatus with a hierarchicmicrostructure that offers the protection of cellular components againstreactive oxygen species (ROS). However, fresh meat immediately postmortem andmeat undergoing processing become susceptible to oxidation due to physicaldisruption and the influx of molecular oxygen. Upon the activation byendogenous prooxidants, oxygen species are rapidly produced, and bothmyofibrillar and sarcoplasmic proteins become their primary targets. Direct ROSattack of amino acid sidechains and peptide backbone leads to proteinconformational changes, conversion to carbonyl and thiol derivatives, andsubsequent aggregation and polymerization. Interestingly, mild radical andnonradical oxidation enables orderly protein physicochemical changes, which explainswhy gels formed by ROS-modified myofibrillar protein has improved rheologicalproperties and binding potential in comminuted meat and meat emulsions. Theincorporation of phenolic and other multi-functional compounds promotes gelnetwork formation, fat emulsification, and water immobilization; however,extensive protein modification induced by high levels of ROS impairs proteinfunctionality. Now recognized to be a natural occurrence, once-neglectedprotein oxidation has drawn much interest and is being intensively studiedwithin the international community of meat science. This review describes thehistory and evolution of muscle protein oxidation, the mechanism andfunctionality impact hereof, and innovative oxidant/antioxidant strategies tocontrol and manipulate oxidation in the context of meat processing, storage,and quality. It is hoped that the review will stimulate in-depth discussion of scientificas well as industrial relevance and importance of protein oxidation and inspirerobust international collaboration in addressing this global challenge.&nbsp;

Protein carbonylation in food and nutrition: a concise update

Protein oxidation is a topic of indisputable scientific interest given the impact of oxidized proteins on food quality and safety. Carbonylation is regarded as one of the most notable post-translational modifications in proteins and yet, this reaction and its consequences are poorly understood. From a mechanistic perspective, primary protein carbonyls (i.e. α-aminoadipic and γ-glutamic semialdehydes) have been linked to radical-mediated oxidative stress, but recent studies emphasize the role alternative carbonylation pathways linked to the Maillard reaction. Secondary protein carbonyls are introduced in proteins via covalent linkage of lipid carbonyls (i.e. protein-bound malondialdehyde). The high reactivity of protein carbonyls in foods and other biological systems indicates the intricate chemistry of these species and urges further research to provide insight into these molecular mechanisms and pathways. In particular, protein carbonyls are involved in the formation of aberrant and dysfunctional protein aggregates, undergo further oxidation to yield carboxylic acids of biological relevance and establish interactions with other biomolecules such as oxidizing lipids and phytochemicals. From a methodological perspective, the routine dinitrophenylhydrazine (DNPH) method is criticized not only for the lack of accuracy and consistency but also authors typically perform a poor interpretation of DNPH results, which leads to misleading conclusions. From a practical perspective, the biological relevance of protein carbonyls in the field of food science and nutrition is still a topic of debate. Though the implication of carbonylation on impaired protein functionality and poor protein digestibility is generally recognized, the underlying mechanism of such connections requires further clarification. From a medical perspective, protein carbonyls are highlighted as markers of protein oxidation, oxidative stress and disease. Yet, the specific role of specific protein carbonyls in the onset of particular biological impairments needs further investigations. Recent studies indicates that regardless of the origin (in vivo or dietary) protein carbonyls may act as signalling molecules which activate not only the endogenous antioxidant defences but also implicate the immune system. The present paper concisely reviews the most recent advances in this topic to identify, when applicable, potential fields of interest for future studies.