Plant polyphenols regulating myoglobin oxidation and color stability in red meat and certain fish: A review

Effect of 6-gingerol on oxidative stability and quality characteristics of mutton meatballs during refrigerated storage

Meat products are high in nutrients but easily spoiled; adding antioxidants is the most straightforward and efficient approach in the food industry. In this study, different concentrations of 6-gingerol (6-GG) were added to refrigerated (4°C) mutton meatballs to evaluate the effect of 6-GG on their oxidative stability and quality characteristics. The results demonstrated that 6-GG prevented the increase in protein carbonyl content and decreased the loss of protein sulfhydryl content as storage times increased. Moreover, the thiobarbituric acid reactive substances (0.4643 mg MDA/kg) in the 0.0440% 6-GG treatment group did not exceed the pertinent fresh meat standards on day 7. The texture, water-holding capacity, and microstructure of the meatballs were also improved, suggesting that the addition of 6-GG is a feasible strategy to improve the quality of meatballs and meat products.

Development and characterization of bilayer chitosan/alginate cling film reinforced with essential oil based nanocomposite for red meat preservation

With a goal to finding suitable alternatives to plastic packaging in the food industry, we developed a multifunctional bio-based active packaging film to enhance the shelf life of red meat. A chitosan/alginate (Chi + Alg) bilayer film was developed through layer-by-layer (LBL) assembly and an active material i.e. lemongrass nanoemulsion with silver nanoparticles-based nanocomposite (NC1) was loaded into the alginate layer to improve the quality of the bio-based film (Chi + Alg + NC1). The Chi + Alg + NC1 film was characterized in terms of its microstructure, mechanical strength, thermal stability, and antimicrobial activity. Scanning electron microscopy (SEM) revealed a film (22.5 ± 1.44 μm thickness) with a smooth and even surface and a cross-sectional structure. The incorporation of NC1 improves the quality of the film by enhancing its mechanical strength and thermal stability. FT-IR spectra showed the successful interaction between chitosan and alginate in the LBL assembly and the incorporation of NC1 in the alginate layer. The red meat preservation test demonstrated that the shelf life improved when the meat was covered with the fabricated bio-based film. The color of the meat was retained for up to 7 days compared to that of the control (Chi alone and Chi + Alg). Additionally, a reduction in the microbial count in the Chi + Alg + NC1 film was observed, corroborating the shelf-life improvement. In addition to its inherent antimicrobial properties, NC1 induced hydrophilic properties to the film, which further aids in its antimicrobial activity against E. coli. These findings suggest that Chi + Alg + NC1 film could be a potent alternative to plastic packaging and can be used as a cling film to prolong the shelf life of red meat.

Application of Lactiplantibacillus plantarum hydrogel coating in combination with ice temperature for the preservation of fresh yak meat

Fresh yak meat is highly nutritious and prone to spoilage, so developing suitable preservation methods is crucial. In this study, hydrogel coatings composed of konjac glucomannan, Lactiplantibacillus plantarum and gallic acid (KGX) were applied to preserve fresh yak meat under ice temperature (-1 °C). After 16 days, KGX group showed lowest total viable count (5.3 ± 0.1 log cfu/g) and total volatile basic nitrogen (13.02 ± 1.40 mg/100 g), which did not exceed the relevant standards of fresh meat. Combined assessments of color, texture, pH, drip loss rate, and thiobarbituric acid reactive substances indicated that KGX coating effectively prolonged yak meat preservation. High-throughput sequencing revealed that KGX coating effectively reduced the abundance of Pseudomonas and Candida. The application of L. plantarum hydrogel coatings in conjunction with ice temperature increased the shelf life of fresh yak meat to 16-20 days, suggesting its potential as a viable preservation method for fresh meat.

Recent advances in dietary polyphenols (DPs): antioxidant activities, nutrient interactions, delivery systems, and potential applications

Dietary polyphenols (DPs) have garnered growing interest because of their potent functional properties and health benefits. Nevertheless, the antioxidant capabilities of these substances are compromised by their multifarious structural compositions. Furthermore, most DPs are hydrophobic and unstable when subjected to light, heat, and varying pH conditions, restricting their practical application. Delivery systems based on the interactions of DPs with food constituents such as proteins, polypeptides, polysaccharides, and metal ions are being created as a viable option to improve the functional activities and bioavailability of DPs. In this review, the latest discoveries on the dietary sources, structure-antioxidant activity relationships, and interactions with nutrients of DPs are discussed. It also innovatively highlights the application progress of polyphenols and their green nutraceutical delivery systems. The conclusion drawn is that the various action sites and structures of DPs are beneficial for predicting and designing polyphenols with enhanced antioxidant attributes. The metal complexation of polyphenols and green encapsulation systems display promising outcomes for stabilizing DPs during food processing and in vivo digestion. In the future, more novel targeted delivery systems of DPs for nutrient fortification and intervention should be developed. To expand their usage in customized food products, they should meet the requirements of specific populations for personalized food and nutrition.

Keeping quality of raw ground beef patties fortified with polyphenols extracted from Acacia mearnsii bark and leaves

Acacia mearnsii byproducts are naturally endowed with a plethora of diverse polyphenols that exhibit antioxidant properties indicating potential application in enhancing oxidative shelf-life of perishable foods. The current study evaluated the oxidative shelf-life of raw ground beef patties fortified with 450 μg/g of polyphenolic extracts from A. mearnsii bark (AMBE) or leaves (AMLE) compared to positive (sodium metabisulphite; SMB) and negative (no extract; CTL) controls for 9 d at 4 °C in a simulated retail display. The AMBE had higher (P ≤ 0.05) contents of proanthocyanidins, and total phenols, flavonoids and tannins, and consequently demonstrated greater (P ≤ 0.05) in vitro antioxidant activity than AMLE. The polyphenolic extracts increased (P ≤ 0.05) antioxidant activity in beef patties compared to the CTL though they were outperformed (P ≤ 0.05) by the SMB. Fortification of beef patties with the polyphenolic extracts, particularly AMBE, delayed colour deterioration and oxidation of myoglobin during retail display relative to the CTL but were less efficient than SMB (P ≤ 0.05). Beef patties fortified with the polyphenolic extracts and SMB had comparable (P > 0.05) peroxide values, TBARS and p-Anisidine values which were all lower (P ≤ 0.05) than those for the CTL patties. The order of protein thiol content in beef patties was as follows: CTL ≥ AMLE ≥ AMBE ≥ SMB (P ≤ 0.05). Findings suggest that A. mearnsii-derived polyphenolic antioxidants, particularly AMBE has great potential to extend oxidative shelf-life of raw beef patties.

Changes in meat quality, metabolites and microorganisms of mutton during cold chain storage

During the cold chain storage process, changes in metabolites and microorganisms are highly likely to lead to changes in meat quality. To elucidate the changes in the composition of metabolites and microbiota during cold chain storage of mutton, this study utilized untargeted metabolome and 5R 16S rRNA sequencing analyses to investigate the changes in the longissimus dorsi under different cold chain temperatures (4 °C and -20 °C). With the extension of cold chain storage time, the meat color darkened and the content of C18:2n-6, C20:3n-6, and C23:0 were significantly increased in mutton. In this study, nine metabolites, including 1,2-Dioleoyl-sn-glycero-3-phosphoethanolamine, alanylphenylala-nine, indole-3-acrylic acid and the others, were significantly altered during cold chain storage. The abundance of the dominant microorganisms, including Brachymonas, Aeromonas, Corynebacterium and Steroidobacter, was significantly altered. Furthermore, a high correlation was observed between the different metabolites and microorganisms. These findings provide an in-depth understanding of the effects of different cold chain storage temperatures and times on the quality of mutton.

Young apple polyphenols confer excellent physical and oxidative stabilities to soy protein emulsions for effective β-carotene encapsulation and delivery

Protein emulsions' poor physical and oxidative stabilities restrict their use in functional foods. Soy protein isolate (SPI) emulsions' physical stability was enhanced by adding young apple polyphenols (YAP) in this study, but decreased when YAP was 0.12%. YAP binding prefolded SPI's structure, which promotes efficient SPI stacking at the interface. YAP also improved SPI emulsions' oxidation resistance in a dose-dependent manner. SPI-YAP interaction promoted more YAP adsorption (>80%) at the interface, which increased emulsions' antioxidant capacities twofold. Furthermore, over 90% of unsaturated fatty acids were preserved, and the oxidation of lipid-SPI-β-carotene appeared to be reduced as YAP increased. In addition, SPI-YAP emulsions were effective in encapsulating and safeguarding β-carotene during emulsion storage and in vitro digestion, leading to a delayed and maximum release of β-carotene. This study improves the understanding of polyphenols inhibition on lipid-protein oxidation through interface strengthening and broadens the potential applications of YAP and SPI in functional foods.

Study on the interaction mechanism between (-)-epigallocatechin-3-gallate and myoglobin: Multi-spectroscopies and molecular simulation

(-)-Epigallocatechin-3-gallate (EGCG) is remarkably efficacious in inhibiting the browning of red meat. We therefore propose a hypothesis that EGCG forms complexes with myoglobin, thereby stabilizing its structure and thus preventing browning. This study investigated the interaction mechanism between EGCG and myoglobin. EGCG induced static quenching of myoglobin. Noncovalent forces, including hydrogen bonds and van der Waals, primarily governing the interactions between myoglobin and EGCG. The interactions primarily disrupted myoglobin's secondary structure, thus significantly reducing surface hydrophobicity by 53% (P < 0.05). The modification augmented the solubility and thermal stability of myoglobin. The radius of gyration (Rg) value fluctuated between 1.47 and 1.54 nm, and the hydroxyl groups in EGCG formed an average of 2.93 hydrogen bonds with myoglobin. Our findings elucidated the formation of stable myoglobin-EGCG complexes and the myoglobin-EGCG interaction, thus confirming our initial hypothesis.

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.

Effects of Different Phenolic Compounds on the Redox State of Myoglobin and Prevention of Discoloration, Lipid and Protein Oxidation of Refrigerated Longtail Tuna (Thunnus tonggol) Slices

Effects of different phenolic compounds on the redox state of myoglobin and their potential for preserving the color and chemical quality of refrigerated longtail tuna (Thunnus tonggol) slices were studied. Purified myoglobin from dark muscle (15.83 kDa) was prepared. Catechin, EGCG, quercetin, and hyperoside affected the absorption spectra and redox state of metmyoglobin (metMb) at 4 °C for up to 72 h differently. Reduction of metMb to oxymyoglobin (oxyMb) was notably observed for two flavonols (EGCG and quercetin) at 50 and 100 ppm. Based on the reducing ability of metMb, EGCG and quercetin were selected for further study. Longtail tuna slices were treated with EGCG and quercetin at 200 and 400 mg/kg. Color (a* and a*/b*), proportion of myoglobin content, and quality changes were monitored over 72 h at 4 °C. Tuna slices treated with 200 mg/kg EGCG showed better maintenance of oxyMb and color as well as lower lipid oxidation (PV and TBARS) and protein oxidation (carbonyl content) than the remaining samples. Nevertheless, EGCG at 400 mg/kg exhibited lower efficacy in retaining the quality of tuna slices. Thus, EGCG at 200 mg/kg could be used to maintain the color and prolong the shelf life of refrigerated longtail tuna slices.

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.

Inhibitory effects of longan seed extract on polycyclic aromatic hydrocarbons formation and muscle oxidation in baked mutton kebabs

Longan seeds, rich in phenolic compounds with antioxidant properties, are an underestimated by-product of longan processing. Polycyclic aromatic hydrocarbons (PAHs), which are carcinogenic and mutagenic, are produced during the cooking of meat products at high temperatures. The effects of different concentrations of longan seed extract (LSE, 0.2, 0.6, 1.0 mg/mL) on the formation of PAHs and muscle oxidation in mutton kebabs were investigated. Mutton kebabs were baked at 150, 200, 250 °C for 20 min, respectively, and the contents of PAHs, the degree of lipid and protein oxidation were evaluated. The results showed that LSE exhibited positive effects in inhibiting total PAHs formation (range from 14.9 to 48.8 %), decreasing the thiobarbituric acid reactive substances (TBARS) values (range from 17.1 to 39.1 %), reducing carbonyl content (range from 22.0 to 51.2 %) and increasing sulfhydryl content (range from 18.6 to 51.8 %). This study provided a guidance and potential solution for reducing the content of PAHs and muscle oxidation levels in baked meat.

Application of White-Wine-Pomace-Derived Ingredients in Extending Storage Stability of Fresh Pork Burgers

White wine pomace, a by-product from winemaking, was stabilized after the application of thermal blanching (with the aim of deactivating the polyphenoloxidase enzyme), milling, and processing by hydrostatic high-pressure treatment (with the aim of reducing initial microbial loads while preserving phenolic compounds content). The valorized pomace (VP) ingredient was added at different proportions to pork burgers (0.5%, 1%, and 3% w/w) to improve their preservation, and the effect was compared to those produced by sulfites and with a control (without sulfites or VP). Burgers were vacuum-packed and refrigerated for 7 days. Microbiological, color, oxidation, and sensory parameters were analyzed. Neither sulfites nor VP reduced the microbial development of most microorganism groups evaluated (p > 0.05); however, both prevented coliform growth during storage (p < 0.01). The use of sulfites prevented the discoloration of burgers during storage, while VP had no effect (p < 0.001). On the contrary, VP limited lipid and protein oxidation development during storage (p > 0.05), while sulfites had no effect. Therefore, the use of VP from white wine production could have an antioxidant effect but a limited antimicrobial or color-protective effect for the preservation of pork burgers.

Review of the Greening Reaction by Thermal Treatment: New Insights Exploring the Structural Implications of Myoglobin

Myoglobin is the main factor responsible for muscle pigmentation in tuna; muscle color depends upon changes in the oxidative state of myoglobin. The tuna industry has reported muscle greening after thermal treatment involving metmyoglobin (MetMb), trimethylamine oxide (TMAO), and free cysteine (Cys). It has been proposed that this pigmentation change is due to a disulfide bond between a unique cysteine residue (Cys10) found in tuna MetMb and free Cys. However, no evidence has been given to confirm that this reaction occurs. In this review, new findings about the mechanism of this greening reaction are discussed, showing evidence of how free radicals produced from Cys oxidation under thermal treatment participate in the greening of tuna and horse muscle during thermal treatment. In addition, the reaction conditions are compared to other green myoglobins, such as sulfmyoglobin, verdomyoglobin, and cholemyoglobin.

Development and Characterization of Antioxidant and Antibacterial Films Based on Potato Starch Incorporating Viola odorata Extract to Improve the Oxidative and Microbiological Quality of Chicken Fillets during Refrigerated Storage

In this research, the antioxidant and antibacterial activities of active films based on potato starch containing Viola odorata extract (VOE) were investigated both in vitro and in chicken fillets. The VOE was added to the starch film formulation at 0, 1, 2, and 3% (w/v). The results showed that by increasing the extract level, the total phenol content and antioxidant and antibacterial activity of the films against Escherichia coli, Staphylococcus aureus, and Salmonella typhimurium improved remarkably. The results of the meat tests indicated the significant antioxidant and antimicrobial activity of active films containing different levels of VOE in chicken fillets, and a direct relationship was observed between the concentration of the extract and the functional activity of the films, so with the increase in the concentration of the extract in the films, the rate of lipid oxidation and growth of microorganisms in the chicken fillets decreased significantly during the storage period, and less volatile nitrogen bases, metmyoglobin, and oxidation products were produced in the fillets. In general, the results of this research demonstrated that an active film based on potato starch containing VOE (especially 2 and 3% levels) has the ability to extend the oxidative and microbiological shelf life of chicken fillets during cold storage for at least eight days.

Elderberry (Sambucus nigra L.) Encapsulated Extracts as Meat Extenders against Lipid and Protein Oxidation during the Shelf-Life of Beef Burgers

In this work, we studied the impact of encapsulated elderberry extracts as natural meat extenders to preserve both the quality and the oxidative stability of beef burgers. In particular, the comprehensive chemical changes of beef burgers treated with different antioxidants, namely, (a) a control without antioxidants, (b) 0.5 g/kg sodium erythorbate (ERY), (c) 2.5 g/kg encapsulated elderberry extract (EE 2.5), and (d) 5 g/kg encapsulated elderberry extract (EE 5), each one packaged under modified atmosphere (80% O2 and 20% CO2) for 13 days storage at 2 ± 1 °C, were deeply evaluated. Overall, EEs showed a wide array of antioxidant compounds, namely polyphenols like anthocyanins, flavonols, and phenolic acids. Multivariate statistics provided marked chemical differences between burgers manufactured with EEs and synthetic antioxidants (ERY) during 13-days storage in terms of both metabolomic profiles and typical lipid/protein oxidation markers (such as malondialdehyde and total carbonyls). Most of the differences could be attributed to some discriminant compounds, namely glutathione, 4-hydroxy-2-nonenal, hydroxy/peroxy-derivatives of fatty acids, carbonyl compounds (such as 5-nonen-2-one and 1,5-octadien-3-one), and cholesterol. Interestingly, significant correlations (p < 0.01) were observed between malondialdehyde, total carbonyls, and these discriminant metabolites. The combination of spectrophotometric approaches and a high-throughput untargeted metabolomics analysis outlined a strong modulation of both lipid and protein oxidations, likely promoted by the encapsulated meat extender (elderberry), thus confirming its ability to delay oxidative phenomena during the shelf-life of beef burgers.