Tea polyphenol-derived nanomedicine for targeted photothermal thrombolysis and inflammation suppression.

Thrombotic diseases impose a significant global health burden, and conventional drug-based thrombolytic therapies are encumbered by the risk of bleeding complications. In this study, we introduce a novel drug-free nanomedicine founded on tea polyphenols nanoparticles (TPNs), which exhibits multifaceted capabilities for localized photothermal thrombolysis. TPNs were synthesized through a one-pot process under mild conditions, deriving from the monomeric epigallocatechin-3-gallate (EGCG). Within this process, indocyanine green (ICG) was effectively encapsulated, exploiting multiple intermolecular interactions between EGCG and ICG. While both TPNs and ICG inherently possessed photothermal potential, their synergy significantly enhanced photothermal conversion and stability. Furthermore, the nanomedicine was functionalized with cRGD for targeted delivery to activated platelets within thrombus sites, eliciting robust thrombolysis upon laser irradiation across diverse thrombus types. Importantly, the nanomedicine's potent free radical scavenging abilities concurrently mitigated vascular inflammation, thus diminishing the risk of disease recurrence. In summary, this highly biocompatible multifunctional nanomaterial holds promise as a comprehensive approach that combines thrombolysis with anti-inflammatory actions, offering precision in thrombosis treatment.

Enhancing the bioavailability and activity of natural antioxidants with nanobubbles and nanoparticles.

KEY POLICY HIGHLIGHTSNanobubbles and nanoparticles may enhance the polyphenols' bioavailabilityNanobubbles may stimulate the activation of Nrf2 and detox enzymesArmoured oxygen nanobubbles may enhance radiotherapy or chemotherapy effects.

Polyphenols: immunonutrients tipping the balance of immunometabolism in chronic diseases.

Mounting evidence progressively appreciates the vital interplay between immunity and metabolism in a wide array of immunometabolic chronic disorders, both autoimmune and non-autoimmune mediated. The immune system regulates the functioning of cellular metabolism within organs like the brain, pancreas and/or adipose tissue by sensing and adapting to fluctuations in the microenvironment's nutrients, thereby reshaping metabolic pathways that greatly impact a pro- or anti-inflammatory immunophenotype. While it is agreed that the immune system relies on an adequate nutritional status to function properly, we are only just starting to understand how the supply of single or combined nutrients, all of them termed immunonutrients, can steer immune cells towards a less inflamed, tolerogenic immunophenotype. Polyphenols, a class of secondary metabolites abundant in Mediterranean foods, are pharmacologically active natural products with outstanding immunomodulatory actions. Upon binding to a range of receptors highly expressed in immune cells (e.g. AhR, RAR, RLR), they act in immunometabolic pathways through a mitochondria-centered multi-modal approach. First, polyphenols activate nutrient sensing via stress-response pathways, essential for immune responses. Second, they regulate mammalian target of rapamycin (mTOR)/AMP-activated protein kinase (AMPK) balance in immune cells and are well-tolerated caloric restriction mimetics. Third, polyphenols interfere with the assembly of NLR family pyrin domain containing 3 (NLRP3) in endoplasmic reticulum-mitochondria contact sites, inhibiting its activation while improving mitochondrial biogenesis and autophagosome-lysosome fusion. Finally, polyphenols impact chromatin remodeling and coordinates both epigenetic and metabolic reprogramming. This work moves beyond the well-documented antioxidant properties of polyphenols, offering new insights into the multifaceted nature of these compounds. It proposes a mechanistical appraisal on the regulatory pathways through which polyphenols modulate the immune response, thereby alleviating chronic low-grade inflammation. Furthermore, it draws parallels between pharmacological interventions and polyphenol-based immunonutrition in their modes of immunomodulation across a wide spectrum of socioeconomically impactful immunometabolic diseases such as Multiple Sclerosis, Diabetes (type 1 and 2) or even Alzheimer's disease. Lastly, it discusses the existing challenges that thwart the translation of polyphenols-based immunonutritional interventions into long-term clinical studies. Overcoming these limitations will undoubtedly pave the way for improving precision nutrition protocols and provide personalized guidance on tailored polyphenol-based immunonutrition plans.

Molecular Mechanism of Resveratrol and Its Therapeutic Potential on Female Infertility.

Resveratrol is a polyphenol present in various plant sources. Studies have reported numerous potential health benefits of resveratrol, exhibiting anti-aging, anti-inflammatory, anti-microbial, and anti-carcinogenic activity. Due to the reported effects, resveratrol is also being tested in reproductive disorders, including female infertility. Numerous cellular, animal, and even human studies were performed with a focus on the effect of resveratrol on female infertility. In this review, we reviewed some of its molecular mechanisms of action and summarized animal and human studies regarding resveratrol and female infertility, with a focus on age-related infertility, polycystic ovary syndrome, and endometriosis.

Tea-Derived Polyphenols Enhance Drought Resistance of Tea Plants (Camellia sinensis) by Alleviating Jasmonate-Isoleucine Pathway and Flavonoid Metabolism Flow.

Extreme drought weather has occurred frequently in recent years, resulting in serious yield loss in tea plantations. The study of drought in tea plantations is becoming more and more intensive, but there are fewer studies on drought-resistant measures applied in actual production. Therefore, in this study, we investigated the effect of exogenous tea polyphenols on the drought resistance of tea plant by pouring 100 mg·L-1 of exogenous tea polyphenols into the root under drought. The exogenous tea polyphenols were able to promote the closure of stomata and reduce water loss from leaves under drought stress. Drought-induced malondialdehyde (MDA) accumulation in tea leaves and roots was also significantly reduced by exogenous tea polyphenols. Combined transcriptomic and metabolomic analyses showed that exogenous tea polyphenols regulated the abnormal responses of photosynthetic and energy metabolism in leaves under drought conditions and alleviated sphingolipid metabolism, arginine metabolism, and glutathione metabolism in the root system, which enhanced the drought resistance of tea seedlings. Exogenous tea polyphenols induced jasmonic acid-isoleucine (JA-ILE) accumulation in the root system, and the jasmonic acid-isoleucine synthetase gene (TEA028623), jasmonic acid ZIM structural domain proteins (JAMs) synthesis genes (novel.22237, TEA001821), and the transcription factor MYC2 (TEA014288, TEA005840) were significantly up-regulated. Meanwhile, the flavonoid metabolic flow was significantly altered in the root; for example, the content of EGCG, ECG, and EGC was significantly increased. Thus, exogenous tea polyphenols enhance the drought resistance of tea plants through multiple pathways.

Chlorogenic Acid: A Systematic Review on the Biological Functions, Mechanistic Actions, and Therapeutic Potentials.

Chlorogenic acid (CGA) is a type of polyphenol compound found in rich concentrations in many plants such as green coffee beans. As an active natural substance, CGA exerts diverse therapeutic effects in response to a variety of pathological challenges, particularly conditions associated with chronic metabolic diseases and age-related disorders. It shows multidimensional functions, including neuroprotection for neurodegenerative disorders and diabetic peripheral neuropathy, anti-inflammation, anti-oxidation, anti-pathogens, mitigation of cardiovascular disorders, skin diseases, diabetes mellitus, liver and kidney injuries, and anti-tumor activities. Mechanistically, its integrative functions act through the modulation of anti-inflammation/oxidation and metabolic homeostasis. It can thwart inflammatory constituents at multiple levels such as curtailing NF-kB pathways to neutralize primitive inflammatory factors, hindering inflammatory propagation, and alleviating inflammation-related tissue injury. It concurrently raises pivotal antioxidants by activating the Nrf2 pathway, thus scavenging excessive cellular free radicals. It elevates AMPK pathways for the maintenance and restoration of metabolic homeostasis of glucose and lipids. Additionally, CGA shows functions of neuromodulation by targeting neuroreceptors and ion channels. In this review, we systematically recapitulate CGA's pharmacological activities, medicinal properties, and mechanistic actions as a potential therapeutic agent. Further studies for defining its specific targeting molecules, improving its bioavailability, and validating its clinical efficacy are required to corroborate the therapeutic effects of CGA.

Dietary Cocoa Flavanols Do Not Alter Brain Excitability in Young Healthy Adults.

The ingestion of dietary cocoa flavanols acutely alters functions of the cerebral endothelium, but whether the effects of flavanols permeate beyond this to alter other brain functions remains unclear. Based on converging evidence, this work tested the hypothesis that cocoa flavanols would alter brain excitability in young healthy adults. In a randomised, cross-over, double-blinded, placebo-controlled design, transcranial magnetic stimulation was used to assess corticospinal and intracortical excitability before as well as 1 and 2 h post-ingestion of a beverage containing either high (695 mg flavanols, 150 mg (-)-epicatechin) or low levels (5 mg flavanols, 0 mg (-)-epicatechin) of cocoa flavanols. In addition to this acute intervention, the effects of a short-term chronic intervention where the same cocoa flavanol doses were ingested once a day for 5 consecutive days were also investigated. For both the acute and chronic interventions, the results revealed no robust alteration in corticospinal or intracortical excitability. One possibility is that cocoa flavanols yield no net effect on brain excitability, but predominantly alter functions of the cerebral endothelium in young healthy adults. Future studies should increase intervention durations to maximize the acute and chronic accumulation of flavanols in the brain, and further investigate if cocoa flavanols would be more effective at altering brain excitability in older adults and clinical populations than in younger adults.

Formation, physicochemical properties, and biological activities of theabrownins.

Theabrownins (TBs) are heterogeneous mixtures of water-soluble brown tea pigments, and important constituents to evaluate the quality of dark tea. TBs have numerous hydroxyl and carboxyl groups and are formed by the oxidative polymerization of tea polyphenols. Many biological activities attributed to TBs, including antioxidant, anti-obesity, and lipid-regulating, have been demonstrated. This review summarizes the research progress made on the formation mechanism and physicochemical properties of TBs. It also discusses their protective effects against various diseases and associated potential molecular mechanisms. Additionally, it examines the signaling pathways mediating the bioactivities of TBs and highlights the difficulties and challenges of TBs research as well as their research prospects and applications.

Sustained oxidation of Tea-Fe(III)/H2O2 simultaneously achieves sludge reduction and carbamazepine removal: The crucial role of EPS regulation.

Establishing an economic and sustained Fenton oxidation system to enhance sludge dewaterability and carbamazepine (CBZ) removal rate is a crucial path to simultaneously achieve sludge reduction and harmless. Leveraging the principles akin to "tea making", we harnessed tea waste to continually release tea polyphenols (TP), thus effectively maintaining high level of oxidation efficiency through the sustained Fenton reaction. The results illustrated that the incorporation of tea waste yielded more favorable outcomes in terms of water content reduction and CBZ removal compared to direct TP addition within the Fe(III)/hydrogen peroxide (H2O2) system. Concomitantly, this process mainly generated hydroxyl radical (•OH) via three oxidation pathways, effectively altering the properties of extracellular polymeric substances (EPS) and promoting the degradation of CBZ from the sludge mixture. The interval addition of Fe(III) and H2O2 heightened extracellular oxidation efficacy, promoting the desorption and removal of CBZ. The degradation of EPS prompted the transformation of bound water to free water, while the formation of larger channels drove the discharge of water. This work achieved the concept of treating waste with waste through using tea waste to treat sludge, meanwhile, can provide ideas for subsequent sludge harmless disposal.

Metabolomics Characterization of Phenolic Compounds in Colored Quinoa and Their Relationship with In Vitro Antioxidant and Hypoglycemic Activities.

Chenopodium quinoa Willd. is rich in phenolic compounds and exhibits diverse biological activities. Few studies have focused on the effect of colored quinoa's phenolic profile on potential biological activity. This study used a UPLC-MS/MS-based metabolomic approach to examine the quinoa phenolics and their association with in vitro antioxidant and hypoglycemic properties. In total, 430 polyphenols, mainly phenolic acids, flavonoids, and flavonols, were identified. Additionally, 121, 116, and 148 differential polyphenols were found between the white and black, white and red, and black and red comparison groups, respectively; 67 polyphenols were screened as shared key differential metabolites. Phenylalanine, tyrosine, and the biosynthesis of plant secondary metabolites were the main differently regulated pathways. Black quinoa had better total phenolic contents (643.68 mg/100 g DW) and antioxidant capacity, while white quinoa had better total flavonoid contents (90.95 mg/100 g DW) and in vitro α-amylase (IC50 value of 3.97 mg/mL) and α-glucosidase (IC50 value of 1.08 mg/mL) inhibition activities. Thirty-six polyphenols, including epicatechin and linarin, etc., were highly correlated with in vitro antioxidant activity, while six polyphenols, including tiliroside and chrysoeriol, etc., were highly correlated with in vitro hypoglycemic activity. This study may provide important information for colored quinoa resources to develop their healthy food applications.

Polyphenol nanoparticles based on bioresponse for the delivery of anthocyanins.

Anthocyanin (AN) has good antioxidant and anti-inflammatory bioactivities, but its poor biocompatibility and low stability limit the application of AN in the food industry. In this study, core-shell structured carriers were constructed by noncovalent interaction using tannic acid (TA) and poloxamer 188 (F68) to improve the biocompatibility, stability and smart response of AN. Under different treatment conditions, TA-F68 and AN were mainly bound by hydrophobic interaction. The PDI is less than 0.1, and the particle size of nanoparticles (NPs) is uniform and concentrated. The retention of the complex was 15.50 % higher than that of AN alone after 9 d of light treatment. After heat treatment for 180 min, the retention rate after loading was 13.87 % higher than that of AN alone. The carrier reduce the damage of AN by the digestive environment, and intelligently and sustainedly release AN when the esterase is highly expressed. In vitro studies demonstrated that the nanocarriers had good biocompatibility and significantly inhibited the overproduction of reactive oxygen species induced by oxidative stress. In addition, AN-TA-F68 has great potential for free radical scavenging at sites of inflammation. In conclusion, the constructed nano-delivery system provides a potential application for oral ingestion of bioactive substances for intervention in ulcerative colitis.

Investigation of bioactive compounds and their correlation with the antioxidant capacity in different functional vinegars.

There are complex and diverse substances in traditional vinegars, some of which have been identified as biologically active factors, but the variety of functional compounds is currently restricted. In this study, it was aimed to determine the bioactive compounds in 10 typical functional vinegars. The findings shown that total flavonoids (0.21-7.19 mg rutin equivalent/mL), total phenolics (0.36-3.20 mg gallic acid equivalent/mL), and antioxidant activities (DPPH: 3.17-47.63 mmol trolox equivalent/L, ABTS: 6.85-178.29 mmol trolox equivalent/L) varied among different functional vinegars. In addition, the concentrations of the polysaccharides (1.17-44.87 mg glucose equivalent/mL) and total saponins (0.67-12.46 mg oleanic acid equivalent/mL) were determined, which might play key role for the function of tested vinegars. A total of 8 organic acids, 7 polyphenol compounds and 124 volatile compounds were measured and tentatively identified. The protocatechuic acid (4.81-485.72 mg/L), chlorogenic acid (2.69-7.52 mg/L), and epicatechin (1.18-97.42 mg/L) were important polyphenol compounds in the functional vinegars. Redundancy analysis indicated that tartaric acid, oxalic acid and chlorogenic acid were significantly positively correlated with antioxidant capacity. Various physiologically active ingredients including cyclo (Pro-Leu), cyclo (Phe-Pro), cyclo (Phe-Val), cyclo (Pro-Val), 1-monopalmitin and 1-eicosanol were firstly detected in functional vinegars. Principle component analysis revealed that volatiles profile of bergamot Monascus aromatic vinegar and Hengshun honey vinegar exhibited distinctive differences from other eight vinegar samples. Moreover, the partial least squares regression analysis demonstrated that 11 volatile compounds were positively correlated with the antioxidant activity of vinegars, which suggested these compounds might be important functional substances in tested vinegars. This study explored several new functionally active compounds in different functional vinegars, which could widen the knowledge of bioactive factor in vinegars and provide new ideas for further development of functional vinegar beverages.

Sea Buckthorn Polyphenols Alleviate High-Fat-Diet-Induced Metabolic Disorders in Mice via Reprograming Hepatic Lipid Homeostasis Owing to Directly Targeting Fatty Acid Synthase.

Our previous studies found that Sea Buckthorn polyphenols (SBP) extract inhibits fatty acid synthase (FAS) in vitro. Thus, we continued to explore possible effects and underlying mechanisms of SBP on complicated metabolic disorders in long-term high-fat-diet (HFD)-fed mice. To reveal that, an integrated approach was developed in this study. Targeted quantitative lipidomics with a total of 904 unique lipids mapping contributes to profiling the comprehensive features of disarranged hepatic lipid homeostasis and discovering a set of newfound lipid-based biomarkers to predict the occurrence and indicate the progression of metabolic disorders beyond current indicators. On the other hand, technologies of intermolecular interactions characterization, especially surface plasmon resonance (SPR) assay, contribute to recognizing targeted bioactive constituents present in SBP. Our findings highlight hepatic lipid homeostasis maintenance and constituent-FAS enzyme interactions, to provide new insights that SBP as a functional food alleviates HFD-induced metabolic disorders in mice via reprograming hepatic lipid homeostasis caused by targeting FAS, owing to four polyphenols directly interacting with FAS and cinaroside binding to FAS with good affinity.

Antifungal and Antivirulence Activity of Vanillin and Tannic Acid Against Aspergillus fumigatus and Fusarium solani.

Aspergillus fumigatus and Fusarium solani infections have become severe health threat; both pathogens are considered a priority due to the increasing emergence of antifungal-resistant strains and high mortality rates. Therefore, the discovery of new therapeutic strategies has become crucial. In this study, we evaluated the antifungal and antivirulence effects of vanillin and tannic acid against Aspergillus fumigatus and Fusarium solani. The minimum inhibitory concentrations of the compounds were determined by the microdilution method in RPMI broth in 96-well microplates according to CLSI. Conidial germination, protease production, biofilm formation, and in vivo therapeutic efficacy assays were performed. The results demonstrated that vanillin and tannic acid had antifungal activity against Aspergillus fumigatus, while tannic acid only exhibited antifungal activity against Fusarium solani. We found that vanillin and tannic acid inhibited conidial germination and secreted protease production and biofilm formation of the fungal pathogens using sub-inhibitory concentrations. Besides, vanillin and tannic acid altered the fungal membrane permeability, and both compounds showed therapeutic effect against aspergillosis and fusariosis in an infection model in Galleria mellonella larvae. Our results highlight the antivirulence effect of vanillin and tannic acid against priority pathogenic fungi as a possible therapeutic alternative for human fungal infections.

Dearomatization drives complexity generation in freshwater organic matter.

Dissolved organic matter (DOM) is one of the most complex, dynamic and abundant sources of organic carbon, but its chemical reactivity remains uncertain1-3. Greater insights into DOM structural features could facilitate understanding its synthesis, turnover and processing in the global carbon cycle4,5. Here we use complementary multiplicity-edited 13C nuclear magnetic resonance (NMR) spectra to quantify key substructures assembling the carbon skeletons of DOM from four main Amazon rivers and two mid-size Swedish boreal lakes. We find that one type of reaction mechanism, oxidative dearomatization (ODA), widely used in organic synthetic chemistry to create natural product scaffolds6-10, is probably a key driver for generating structural diversity during processing of DOM that are rich in suitable polyphenolic precursor molecules. Our data suggest a high abundance of tetrahedral quaternary carbons bound to one oxygen and three carbon atoms (OCqC3 units). These units are rare in common biomolecules but could be readily produced by ODA of lignin-derived and tannin-derived polyphenols. Tautomerization of (poly)phenols by ODA creates non-planar cyclohexadienones, which are subject to immediate and parallel cycloadditions. This combination leads to a proliferation of structural diversity of DOM compounds from early stages of DOM processing, with an increase in oxygenated aliphatic structures. Overall, we propose that ODA is a key reaction mechanism for complexity acceleration in the processing of DOM molecules, creation of new oxygenated aliphatic molecules and that it could be prevalent in nature.

Characterization of polyphenols and carbohydrates exuded by Phaeodactylum tricornutum diatom grown under Cu stress.

This study is focused on analysing polyphenols and carbohydrates released by Phaeodactylum tricornutum (P. tricornutum) diatoms cultured in natural seawater enriched with sublethal and lethal Cu doses. Cu concentrations of 0.31, 0.79 and 1.57 µM reduced cell densities by 37, 82 and 91%, respectively, compared to the control. The total sum of all identified polyphenols and total carbohydrates released by cells grown under lethal Cu levels increased up to 18.8 and 107.4 times, respectively, compared to data from a control experiment. Four different in vitro assays were used to estimate the antioxidant activities of the extracellular compounds: 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical inhibition, cupric ion reducing antioxidant capacity (CUPRAC), ferric reducing antioxidant power and Cu complexing ability (CCA). The highest antioxidant activities were observed in the Cu lethal treatments, where the CCA assay exhibited a greater increase (up to 32.2 times higher than that found in the control experiment) to reduce the concentration of free Cu in the medium and its toxicity. The presence of Cu stimulated the release of polyphenols and carbohydrates to the medium as a detoxification mechanism to survive under lethal levels of Cu regulating its speciation.

Liver cancer wars: plant-derived polyphenols strike back.

Liver cancer currently represents the leading cause of cancer-related death worldwide. The majority of liver cancer arises in the context of chronic inflammation and cirrhosis. Surgery, radiation therapy, and chemotherapy have been the guideline-recommended treatment options for decades. Despite enormous advances in the field of liver cancer therapy, an effective cure is yet to be found. Plant-derived polyphenols constitute a large family of phytochemicals, with pleiotropic effects and little toxicity. They can drive cellular events and modify multiple signaling pathways which involves initiation, progression and metastasis of liver cancer and play an important role in contributing to anti-liver cancer drug development. The potential of plant-derived polyphenols for treating liver cancer has gained attention from research clinicians and pharmaceutical scientists worldwide in the last decades. This review overviews hepatic carcinogenesis and briefly discusses anti-liver cancer mechanisms associated with plant-derived polyphenols, specifically involving cell proliferation, apoptosis, autophagy, angiogenesis, oxidative stress, inflammation, and metastasis. We focus on plant-derived polyphenols with experiment-based chemopreventive and chemotherapeutic properties against liver cancer and generalize their basic molecular mechanisms of action. We also discuss potential opportunities and challenges in translating plant-derived polyphenols from preclinical success into clinical applications.

Quality and functional properties of bread containing the addition of probiotically fermented Cicer arietinum.

This study aimed to determine the impact of supplementation with probiotically fermented chickpea (Cicer arietinum L) seeds on the quality parameters and functional characteristics of wheat bread. The addition of chickpea seeds caused significant changes in the chemical composition of the control wheat bread. The legume-supplemented products exhibited higher values of a* and b* color parameters and higher hardness after 24 h of storage than the control. The application of fermented or unfermented chickpeas contributed to an increase in total polyphenol and flavonoid contents, iron chelating capacity, and antioxidant properties of the final product. The variant containing unfermented seeds had the highest riboflavin content (29.53 ± 1.11 µg/100 g d.w.), Trolox equivalent antioxidant capacity (227.02 ± 7.29 µmol·L-1 TX/100 g d.w.), and free radical scavenging activity (71.37 ± 1.30 % DPPH inhibition). The results of this preliminary research have practical importance in the production of innovative bakery products with potential properties of functional food.

Assessment of phenolic and flavonoid contents, antioxidant and antimicrobial activities of Moroccan propolis.

Background: Despite the extensive literature focused on propolis extract, few data exists on the bioactive compounds and biological activities in the Moroccan propolis and its economic value is low. Objective: In this research, the aim was to evaluate the total content of phenols and flavonoids as well as the antioxidant, antibacterial and antifungal activities of Moroccan propolis. Material and Methods: The polyphenol and flavonoid content of the Moroccan propolis from three geographic regions, was quantified in the ethanolic extract by colorimetric methods using folin-ciocalteu and aluminum chloride. The antioxidant activity was evaluated by the DPPH test and expressed as IC50. Disk diffusion and broth microdilution methods were used to examine in vitro antimicrobial activity against known human microorganism pathogens. Results: The obtained data revealed that Moroccan propolis samples presented significant variations in total polyphenols and flavonoids. All samples showed significant antioxidant activity with IC50 values ranging from 4.23±0.5 to 154±0.21 µg/ mL. A strong correlation between total phenolic activity, flavonoids and antioxidant activity was found. The in vitro study of antibacterial activity showed that the propolis samples exhibited a range of growth inhibitory actions against all bacterial strains tested with the highest activity against gram-positive bacteria. Only propolis from the Sidi Bennour region demonstrated an antifungal activity. Conclusion: The study data show that Moroccan propolis extracts have a promising content of antioxidant and antimicrobial compounds that could be exploited to prevent certain diseases linked to oxidative stress and pathogenic infections.

pH-regulated Tannic acid and soybean protein isolate adhesive for enhanced performance in plant-based meat analogues.

A food adhesive comprising tannic acid (TA) and soybean protein isolate (SPI) was developed to establish a cohesive bond between soy protein gel and simulated fat. The impact of varying TA concentrations and pH levels on the adhesive's rheology, thermal stability, chemical structure, and tensile strength were investigated. Rheological results revealed a gradual decrease in adhesive viscosity with increasing TA content. Differential scanning calorimetry (DSC) and thermal gravimetric (TG) results indicated that the stability of the adhesive improved with higher TA concentrations, reaching its peak at 0.50% TA addition. The incorporation of TA resulted in the cross-linking of amino group in unfolded SPI molecules, forming a mesh structure. However, under alkaline conditions (pH 9), adhesive viscosity and stability increased compared to the original pH. This shift was due to the disruption of the SPI colloidal charge structure, an increase in the stretching of functional groups, further unfolding of the structure, and an enhanced binding of SPI to TA. Under the initial pH conditions, SPI reacted with TA's active site to form covalent crosslinked networks and hydrogen bonds. In alkaline condition, beyond hydrogen and ionic bonding, the catechol structure was oxidized, forming an ortho-quinone that crosslinked SPI and created a denser structure. Tensile strength measurements and freeze-thaw experiments revealed that the adhesive exhibited maximum tensile strength and optimal adhesion with 0.75% TA at pH 9, providing the best overall performance. This study provides a new formulation and approach for developing plant-based meat analogues adhesives.