Stability and structural characteristics of amylopectin nanoparticle-binding anthocyanins in Aronia melanocarpa

Can agriculture and food waste be a solution to reduce environmental impact of plastic pollution? zero-waste approach for sustainable clean environment

Agriculture and food waste, especially from fruits, vegetables, and plant byproducts like banana peels, avocado seeds, and durian seeds, have emerged as promising alternatives for bioplastic production. These materials, rich in polysaccharides and cellulose, offer a sustainable solution to reduce plastic pollution and mitigate the environmental impact of traditional plastics. This review focuses on the potential of utilizing agricultural and food waste to create starch-based bioplastics, emphasizing the importance of a zero-waste approach to enhance the economic value of these byproducts while promoting a cleaner environment. We include a SWOT analysis of this innovative approach, assess the environmental implications of bioplastic production, and highlight the potential for turning agricultural waste into a key player in the fight against plastic pollution. This review also explores the future prospects of harnessing agriculture and food waste as valuable resources for sustainable bioplastics, contributing to a greener, more sustainable world.

Nano techniques: an updated review focused on anthocyanin stability

Anthocyanins (ACNs) are one of the subgroups of flavonoids and getting intensive attraction due to the nutritional values. However, their application of ACNs is limited due to their poor stability and bioavailability. Accordingly, nanoencapsulation has been developed to enhance its stability and bio-efficacy. This review focuses on the nano-technique applications of delivery systems that be used for ACNs stabilization, with an emphasis on physicochemical stability and health benefits. ACNs incorporated with delivery systems in forms of nano-particles and fibrils can achieve advanced functions, such as improved stability, enhanced bioavailability, and controlled release. Also, the toxicological evaluation of nano delivery systems is summarized. Additionally, this review summarizes the challenges and suggests the further perspectives for the further application of ACNs delivery systems in food and medical fields.

Research progress on the regulation of starch-polyphenol interactions in food processing

Starch is a fundamental material in the food industry. However, the inherent structural constraints of starch impose limitations on its physicochemical properties, including thermal instability, viscosity, and retrogradation. To address these obstacles, polyphenols are extensively employed for starch modification owing to their distinctive structural characteristics and potent antioxidant capabilities. Interaction between the hydroxyl groups of polyphenols and starch results in the formation of inclusion or non-inclusion complexes, thereby inducing alterations in the multiscale structure of starch. These modifications lead to changes in the physicochemical properties of starch, while simultaneously enhancing its nutritional value. Recent studies have demonstrated that both thermal and non-thermal processing exert a significant influence on the formation of starch-polyphenol complexes. This review meticulously analyzes the techniques facilitating complex formation, elucidating the critical factors that dictate this process. Of noteworthy importance is the observation that thermal processing significantly boosts these interactions, whereas non-thermal processing enables more precise modifications. Thus, a profound comprehension and precise regulation of the production of starch-polyphenol complexes are imperative for optimizing their application in various starch-based food products. This in-depth study is dedicated to providing a valuable pathway for enhancing the quality of starchy foods through the strategic integration of suitable processing technologies.

The effects of the interaction between cyanidin-3-O-glucoside (C3G) and walnut protein isolate (WPI) on the thermal and oxidative stability of C3G

This study explores the interaction between cyanidin-3-O-glucoside (C3G), a water-soluble pigment known for its diverse functional activities, and walnut protein isolate (WPI) as a potential stabilizing agent. Given the inherent instability of C3G, particularly its limited application in the food industry due to sensitivity to thermal and oxidative conditions, this research study aims to enhance its stability. According to the results of the fluorescence quenching experiment, C3G can efficiently quench WPI's intrinsic fluorescence through static quenching. Structural exploration revealed that C3G bound WPI via hydrophobic interaction force, with the number of bound C3G molecules (n) almost equivalent to 1. The ΔG value denoting change in Gibbs free energy for C3G binding with WPI was -8.05 kJ/mol, which indicated that the interaction between C3G and WPI is spontaneous. Moreover, the conformational structures of WPI were altered by C3G binding with a decrease in α-helix contents and an increase in β-turn, β-sheet, and random coil contents. The thermal degradation kinetics indicate that after interacting with WPI, the half-life of C3G increased by 1.62 times and 1.05 times at 80 and 95°C, respectively. The results of the oxidation stability test showed that the presence of WPI effectively reduced the discoloration and degradation of C3G caused by oxidation, and improved the oxidation stability of C3G. This study's findings will help to clarify the interaction mechanism between C3G and WPI, and broaden C3G's application scope in the food processing field.

Formation and Application of Starch-Polyphenol Complexes: Influencing Factors and Rapid Screening Based on Chemometrics

Understanding the nuanced interplay between plant polyphenols and starch could have significant implications. For example, it could lead to the development of tailor-made starches for specific applications, from bakinag and brewing to pharmaceuticals and bioplastics. In addition, this knowledge could contribute to the formulation of functional foods with lower glycemic indexes or improved nutrient delivery. Variations in the complexes can be attributed to differences in molecular weight, structure, and even the content of the polyphenols. In addition, the unique structural characteristics of starches, such as amylose/amylopectin ratio and crystalline density, also contribute to the observed effects. Processing conditions and methods will always alter the formation of complexes. As the type of starch/polyphenol can have a significant impact on the formation of the complex, the selection of suitable botanical sources of starch/polyphenols has become a focus. Spectroscopy coupled with chemometrics is a convenient and accurate method for rapidly identifying starches/polyphenols and screening for the desired botanical source. Understanding these relationships is crucial for optimizing starch-based systems in various applications, from food technology to pharmaceutical formulations.

Unravelling the anthocyanin-binding capacity of native starches from different botanical origins

In this study, the cyanidin-3-O-glucoside (C3G)-binding capacities of three native starches were investigated. While potato starch had the largest binding capacity of 0.34 mg/100 mg, corn and pea starch had binding capacities of 0.17 and 0.06 mg/100 mg. Confocal microscopy confirmed the binding results and revealed close associations between the surface properties and binding capacities. These findings were further substantiated with wettability and gelatinization results. The morphological observations showed that corn starch had advantageous particle sizes and more surface gullies, providing more opportunities to bind C3G. The zeta potential results, however, indicated that potato starch had the highest negative surface charges (-24 mV). These favorable electronic characteristics were believed to be responsible for the strongest electrostatic interactions. Hydrogen bonds, however, had a negligible effect on the formation of complexes. Overall, the negative surface charges and specific surface areas of the native starches were the most important factors determining C3G-binding capacities.

A multi-omics analysis strategy reveals the molecular mechanism of the inhibition of Escherichia coli O157:H7 by anthocyanins from Aronia melanocarpa and its application

Water pollution causes the propagation of pathogenic microorganisms, which poses a serious threat to human life. Escherichia coli O157:H7, as a representative organism that can directly exhibit molecular response to stress, was selected as the indicator bacteria for the study. Tandem mass tag (TMT) quantitative proteomics and non-targeted metabolomics were used to study the response of Escherichia coli O157:H7 to Aronia melanocarpa anthocyanin (AMA) treatment. The results showed that 628 proteins and 1338 metabolites changed significantly after treatment with AMAs. According to bioinformatics analysis, integrated proteomics and metabolomics analysis differentially expressed proteins (DEPs) and metabolites participate in pyruvate metabolism, glycolysis/gluconeogenesis, alanine, aspartate and glutamate metabolism and the pentose phosphate pathway. This study preliminarily proposed the inhibition mechanism of AMAs on Escherichia coli O157:H7 from the perspective of multi-omics, providing a theoretical basis for the application of natural preservatives in fresh cut vegetables.

Influence of Storage Conditions on Stability of Phenolic Compounds and Antioxidant Activity Values in Nutraceutical Mixtures with Edible Flowers as New Dietary Supplements

This paper investigates the effects of storage conditions on the stability of phenolics and their antioxidant activities in unique nutraceutical supplements containing non-traditional cereal flakes, edible flowers, fruits, nuts, and seeds. Significant total phenolic content (TPC) of 1170-2430 mg GAE/kg and total anthocyanin content (TAC) with the values of 322-663 mg C3G/kg were determined with the highest TPC content established in free phenolic fractions. The most notable declines in TPC (by 53%), TAC (by 62%), phenolics (e.g., glycosylated anthocyanins by 35-67%), and antioxidant activity (by 25% using DPPH) were established in the presence of sunlight at 23 °C followed by the storage at 40 °C. Quercetin, rutin, peonidin, pelargonidin, p-coumaric, ellagic, and p-hydroxybenzoic acids were identified as the least stable phenolics when exposed to sunlight. Furthermore, glycosylated forms of anthocyanins demonstrated a greater stability when compared with anthocyanidins. The mixtures considerably eliminated ABTS and DPPH radicals. In all samples, water-soluble substances showed a higher antioxidant activity than lipid-soluble substances with the main contributors in the following order: delphinidin-3-glucoside (r = +0.9839) > p-coumaric > gallic > sinapic > p-hydroxybenzoic acids > delphinidin > peonidin and malvidin (r = +0.6538). Gluten-free nutraceutical mixtures M3 (containing red rice and black quinoa flakes, red and blue cornflowers, blueberries, and barberries) and M4 (containing red and black rice flakes, rose, blue cornflower, blueberries, raspberries, and barberries) were evaluated as the least stable under all storage conditions although they showed considerable phenolic concentrations. Phenolic contents and antioxidant activity of the nutraceutical mixtures were the highest at 23 °C without the presence of sunlight with the most stable M1 nutraceutical mixture (containing oat and red wheat flakes, hibiscus, lavender, blueberries, raspberries, and barberries).

Anthocyanins: Modified New Technologies and Challenges

Anthocyanins are bioactive compounds belonging to the flavonoid class which are commonly applied in foods due to their attractive color and health-promoting benefits. However, the instability of anthocyanins leads to their easy degradation, reduction in bioactivity, and color fading in food processing, which limits their application and causes economic losses. Therefore, the objective of this review is to provide a systematic evaluation of the published research on modified methods of anthocyanin use. Modification technology of anthocyanins mainly includes chemical modification (chemical acylation, enzymatic acylation, and formation of pyran anthocyanidin), co-pigmentation, and physical modification (microencapsulation and preparation of pickering emulsion). Modification technology of anthocyanins can not only increase bioavailability and stability of anthocyanin but also can improve effects of anthocyanin on disease prevention and treatment. We also propose potential challenges and perspectives for diversification of anthocyanin-rich products for food application. Overall, integrated strategies are warranted for improving anthocyanin stabilization and promoting their further application in the food industry, medicine, and other fields.

Biomedical applications of aptamer-modified chitosan nanomaterials: An updated review

Among polysaccharides of environmental and economic interest, chitosan (CS) is receiving much attention, particularly in the food and biotechnology industries to encapsulate active food ingredients and immobilize enzymes. CS nanoparticles (CS NPs) combine the intrinsic beneficial properties of both natural polymers and nanoscale particles such as quantum size effect, biocompatibility, biodegradability, and ease of modification, and have great potential for bioimaging, drug delivery, and biosensing applications. Aptamers are single-stranded oligonucleotides that can fold into predetermined structures and bind to the corresponding biomolecules. They are mainly used as targeting ligands in biosensors, disease diagnostic kits and treatment strategies. They can deliver contrast agents and drugs into cancer cells and tissues, control microorganism growth and precisely target pathogens. Aptamer-conjugated CS NPs can significantly improve the efficacy of conventional therapies, minimize their side effects on normal tissues, and overcome the enhanced permeability retention (EPR) effect. Further, aptamer-conjugated carbohydrate-based nanobiopolymers have shown excellent antibacterial and antiviral properties and can be used to develop novel biosensors for the efficient detection of antibiotics, toxins, and other biomolecules. This updated review aims to provide a comprehensive overview of the bioapplications of aptamer-conjugated CS NPs used as innovative diagnostic and therapeutic platforms, their limitations, and potential future directions.

Colorimetric porous microspheres of natural sodium alginate for chilled pork visual monitoring

Chilled meat is subject to deterioration by various factors during storage and distribution. Therefore, it is very important to monitor the quality of meat in real time. This study aims at preparing a natural, low-cost indicating microsphere to visualize the freshness of meat by the combination of sodium alginate (SA) and chitosan with 0-10 wt% anthocyanins derived from chokeberry as a colorant using ionic gelation method. Size-controlled porous SA microspheres with were further constructed by freeze-drying and their physicochemical properties were characterized by SEM, FTIR, DSC, and XRD. Results showed that microspheres with 1 wt% anthocyanin showed good responsiveness to different concentrations of ammonia and were able to effectively identify the freshness of chilled meat by color change. Principal component analysis showed that the color difference of the porous microspheres was highly significantly correlated with pH, TVB-N, total plate count and thiobarbituric acid active substance (p < 0.01), suggesting a visible satisfactory capability of the microspheres to identify the spoilage in pork. Principal component analysis showed that the color difference of the porous microspheres was highly significantly correlated with pH, TVB-N, total plate count and thiobarbituric acid active substance (P < 0.01), suggesting a visible satisfactory capability of the microspheres to identify the spoilage in pork.

Effects of encapsulation methods on bioaccessibility of anthocyanins: a systematic review and meta-analysis

Anthocyanins have multiple health benefits. However, they are prone to degradation during gastrointestinal digestion, impeding their utilization. Various encapsulation systems have been proposed to improve their bioaccessibility and bioavailability. This review aims to provide a systematic evaluation and meta-analysis of published studies examining the effect of microencapsulation on the bioaccessibility of anthocyanins. A comprehensive and systematic literature search of three databases (Scopus, PubMed, and Web of Science) was conducted. Studies were selected according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses criteria and were reviewed independently by two investigators. Overall, 34 articles were included in the systematic review and 24 were included in the meta-analysis. The fold changes in bioaccessibility between encapsulated and non-encapsulated anthocyanins from eligible studies were calculated. The median and 95% confidence intervals (CI) of the fold changes for spray-drying (median 1.23, 95% CI 0.91-1.92), freeze-drying (median 1.19, 95% CI 0.61-1.28), simple coacervation (median 1.80, 95% CI 1.41-3.20), and complex coacervation (median 1.61, 95% CI 0.21-25.00) were calculated. Simple coacervation showed a promising protection against degradation during in vitro digestion. However, when a large number of anthocyanins cannot be released from the microparticles during digestion, encapsulation impedes the bioaccessibility of anthocyanins.

Anthocyanins from Aronia melanocarpa Bound to Amylopectin Nanoparticles: Tissue Distribution and In Vivo Oxidative Damage Protection

The in vivo applications of anthocyanins are limited by their instability. Nano-encapsulation using amylopectin nanoparticles (APNPs) stabilizes anthocyanins to deliver them to tissues to ameliorate their physiological functions. Herein, rats are fed four Aronia melanocarpa anthocyanins encapsulated with APNPs, and their subsequent distributions and bioactivity in nine tissues are revealed using UHPLC-MS. Among digestive tissues, the concentration of the APNP-protected cyanidin 3-O-arabinoside in the stomach is 134.54% of that of the free anthocyanin, while among non-digestive tissues, the APNP-protected cyanidin 3-O-glucoside concentration in the lungs improved by 125.49%. Concentration maxima "double peaks" in the liver and kidney arise from different modes of transport. Sustained release of anthocyanins from anthocyanin-APNPs and stable concentration curves suggest controlled delivery, with most APNPs consumed in the digestive system. APNPs did not affect the overall anthocyanin absorption time or tissues. The superoxide dismutase and malondialdehyde concentrations indicate that APNPs enhance the oxidative damage protection in vivo.

Nanofibers of Jussara Pulp: A Tool to Prevent the Loss of Thermal Stability and the Antioxidant Activity of Anthocyanins after Simulated Digestion

Electrospinning can produce a new composite for coating sensitive bioactive compounds, such as anthocyanins, and the product obtained from this process presents characteristics that potentialize the application of natural pigments in foodstuffs. The present work aimed to develop a new nanofiber composite with incorporated anthocyanins from jussara pulp using polyethylene oxide through electrospinning. A decay in the percentage of anthocyanins during digestion was observed. However, the polymeric solution and composites produced maintained the antioxidant activity, showing their protective effect on bioactive compounds; furthermore, both nanofibers and polymer solution improved the thermal stability of the anthocyanins. Thus, the results obtained potentiate electrospinning composites in processed food products since the nanofibers presented superior thermal stability and antioxidant activity, even after the digestion process in vitro.

Addition of Chelators Increased the Stability of Black Rice Anthocyanins against the Metallic Ions in Tap Water and Improved the Coloration of Steamed Cold Noodles

The anthocyanins in black rice extract (BRA) are sensitive to metallic ions, which restrict its application in the coloration of steamed cold noodles in China that uses tap water as the solvent. Food-grade chelators were added to check if they could increase the stability of BRA. The results indicated that the color decay of BRA in tap water was mainly caused by Fe3+, Cu2+, and Fe2+, and the addition of chelators could effectively antagonize this effect. Coloration with the BRA solution containing the optimized chelator formulation of 0.01% ethylenediaminetetraacetic acid disodium, 0.08% sodium hexametaphosphate, and 0.064% sodium tartrate conferred comparable appearance and chromatic attributes with those of the noodle colored by deionized water-dissolved BRA. The steamed cold noodles colored by the chelators-containing BRA exhibited increased springiness and decreased starch retrogradation, and possessed potential health functions due to its slightly increased resistant starch content and markedly enhanced antioxidant capacity. Hence, the addition of chelators is a feasible way to increase the color stability of BRA in tap water, and the chelators-supplemented BRA could be used to produce steamed cold noodles with attractive color and health benefits.

Transcriptomic and Metabolomic Analyses Providing Insights into the Coloring Mechanism of Docynia delavayi

The metabolome and transcriptome profiles of three different variations of mature Docynia delavayi fruit were synthesized to reveal their fruit color formation mechanism. A total of 787 secondary metabolites containing 149 flavonoid metabolites, most of which were flavonoids and flavonols, were identified in the three variations using ultra performance liquid chromatography- tandem mass spectrometry (UPLC-MS/MS), and we found that the secondary metabolites cyanidin-3-O-galactoside and cyanidin-3-O-glucoside were the major coloring substances in D. delavayi. This was associated with the significant upregulation of the structural genes F3H and F3′H in the anthocyanin synthesis pathway and the control genes WRKY, MYB, bZIP, bHLH, and NAC in RP. F3′H expression may play a significant role in the selection of components for anthocyanin synthesis. Our results contribute to breeding and nutritional research in D. delavayi and provide insight into metabolite studies of the anthocyanin biosynthetic pathway.

TMT-Based Quantitative Proteomics Analyses Reveal the Antibacterial Mechanisms of Anthocyanins from Aronia melanocarpa against Escherichia coli O157:H7

Aronia melanocarpa anthocyanins (AMAs), as natural plant extracts, can control pathogens and are attracting increasing attention. In this study, a tandem mass tag (TMT) quantitative proteomics method combined with multiple reaction monitoring (MRM) was used to explore the antibacterial mechanism of AMAs against Escherichia coli at the protein level. The results showed that 1739 proteins were identified in E. coli treated with AMAs, of which 628 were altered, including 262 downregulated proteins and 366 upregulated proteins. Bioinformatics analysis showed that these differentially expressed proteins have different molecular functions and participate in different molecular pathways. AMAs can affect E. coli protein biosynthesis, DNA replication and repair, oxidative stress response, peptidoglycan biosynthesis, and homeostasis. These pathways induce morphological changes and cell death. The results of this study help understand the molecular mechanism of the inhibitory effect of AMAs on food-borne pathogens and provide a reference for further development of plant-derived antimicrobial agents.

Fermented Jussara: Evaluation of Nanostructure Formation, Bioaccessibility, and Antioxidant Activity

Among the species of plants present in the Atlantic Forest, the jussara (Euterpe edulis Mart.) stands out for the contents of bioactive compounds present in its composition. Fermentation processes can be essential in converting bioproducts and bioactive compounds, improving their biological properties. In addition, the improvement of procedures for the maintenance of the features of bioactive compounds has been a research focus in recent years, and the nanotechnology features that can potentially solve this issue have been highlighted among the most reviewed paths. The present work focused on tailoring nanostructures applying polyethylene oxide, assembling fermented jussara pulp nanofibers, and assessing their characteristics. The results revealed the formation of fermented jussara nanofibers with a diameter of 101.2 ± 26.2 nm. Also, the obtained results allow us to state that it is possible to maintain or even increase the antioxidant activity of anthocyanins and their metabolites after fermentation processes.

Effect of Issatchenkia terricola WJL-G4 on Deacidification Characteristics and Antioxidant Activities of Red Raspberry Wine Processing

Our previous study isolated a novel Issatchenkia terricola WJL-G4, which exhibited a potent capability of reducing citric acid. In the current study, I. terricola WJL-G4 was applied to decrease the content of citric acid in red raspberry juice, followed by the red raspberry wine preparation by Saccharomyces cerevisiae fermentation, aiming to investigate the influence of I. terricola WJL-G4 on the physicochemical properties, organic acids, phenolic compounds and antioxidant activities during red raspberry wine processing. The results showed that after being treated with I. terricola WJL-G4, the citric acid contents in red raspberry juice decreased from 19.14 ± 0.09 to 6.62 ± 0.14 g/L, which was further declined to 5.59 ± 0.22 g/L after S. cerevisiae fermentation. Parameters related to CIELab color space, including L*, a*, b*, h°, and ∆E* exhibited the highest levels in samples after I. terricola WJL-G4 fermentation. Compared to the red raspberry wine pretreated without deacidification (RJO-SC), wine pretreated by I. terricola WJL-G4 (RJIT-SC) exhibited significantly decreased contents of gallic acid, cryptochlorogenic acid, and arbutin, while significantly increased contents of caffeic acid, sinapic acid, raspberry ketone, quercitrin, quercetin, baicalein, and rutin. Furthermore, the antioxidant activities including DPPH· and ABTS+· radical scavenging were enhanced in RJIT-SC group as compared to RJO-SC. This work revealed that I. terricola WJL-G4 had a great potential in red raspberry wine fermentation.

Pharmacokinetic and excretion study of Aronia melanocarpa anthocyanins bound to amylopectin nanoparticles and their main metabolites using high-performance liquid chromatography-tandem mass spectrometry

Anthocyanins of Aronia melanocarpa are known for their therapeutic properties; however, they are unstable and easily degrade in the environment and in vivo. Herein, we investigated the stability and bioavailability of four anthocyanins bound to amylopectin nanoparticles (APNPs) through a pharmacokinetic and excretion study using high-performance liquid chromatography-tandem mass spectrometry. An EC-C18 column with methanol and 0.1% formic acid as the mobile phase was used during the analysis. After APNP treatment, anthocyanins and metabolites exhibited a marked increase, whereas their maximum oral bioavailability reached 440% and 593%, respectively. The delayed elimination half time demonstrated that APNPs had a sustained-release effect on anthocyanins. Pharmacokinetic results revealed that APNPs effectively protect anthocyanins in vivo. Excretion studies in urine and feces had shown a decrease in excretion of anthocyanins and most of the metabolites after APNP treatment. The results of excretion study further proved the protective effect of APNPs on anthocyanins in vivo.

Nanoencapsulation in low-molecular-weight chitosan improves in vivo antioxidant potential of black carrot anthocyanin

BACKGROUND

Anthocyanins are flavonoids that are potential antioxidant, anti-inflammatory, anti-obesity, and anti-carcinogenic nutraceutical ingredients. However, low chemical stability and low bioavailability limit the use of anthocyanins in food. Nanoencapsulation using biopolymers is a recent successful strategy for stabilization of anthocyanins. This study reports the development, characterization, and antioxidant activity of black carrot anthocyanin-loaded chitosan nanoparticles (ACNPs).

RESULTS

The ionic gelation technique yielded the ACNPs. The mean hydrodynamic diameter d and polydispersity index PDI of chitosan nanoparticles and ACNPs were found to be d = 455 nm and PDI = 0.542 respectively for chitosan nanoparticles and d = 274 nm and PDI = 0.376 respectively for ACNPs. The size distribution was bimodal. The surface topography revealed that the ACNPs are spherical and display a coacervate structure. Fourier transform infrared analysis revealed physicochemical interactions of anthocyanins with chitosan. The loading process could achieve an encapsulation efficiency of 70%. The flow behavior index η of encapsulated ACNPs samples revealed Newtonian and shear thickening characteristics. There was a marginal reduction in the in vitro antioxidant potential of anthocyanins after nanoencapsulation, as evidenced from 2,2-diphenyl-1-picrylhydrazyl, ferric reducing antioxidant power, and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) assays. Interestingly, the in vivo antioxidant potential of anthocyanins improved following nanoencapsulation, as observed in the serum antioxidant assays.

CONCLUSION

The optimized nanoencapsulation process resulted in spherical nanoparticles with appreciable encapsulation efficiency. The nanoencapsulation process improved the in vivo antioxidant activity of anthocyanins, indicating enhanced stability and bioavailability. The promising antioxidant activity of the ACNPs suggests a potential for utilization as a nutraceutical supplement. © 2021 Society of Chemical Industry.

Physicochemical stability-increasing effects of anthocyanin via a co-assembly approach with an amphiphilic peptide

To enhance the stability of anthocyanin, an amphiphilic peptide C6 with tryptophan amino acid was used to co-assemble with anthocyanin C3G. The characterization, stabilities, and antioxidant activity of peptide-anthocyanin (C6-C3G) nanocomposites (70.82 ± 12.41 nm) were investigated. To illustrate the interaction between peptide and anthocyanin, circular dichroism spectroscopy and fluorescence quenching method were used. Here, the peptide C6 switches from random coil structure to β-sheet structure and the fluorescence of tryptophan amino acid in peptide quenched during the intermolecular interaction between them, which was further confirmed a static quenching. The nanocomposites significantly enhance the stabilities of anthocyanin to different alkaline conditions, high temperature of 80 °C, long time storage, and various concentration of Cu²⁺ ion. In addition, it maintained the excellent intrinsic capacity of anthocyanin to scavenge free radicals. The approach of using an amphiphilic peptide to enhance the stabilities of anthocyanin presents a high potential to expand its application.

Assembling cyanidin-3-O-glucoside by using low-viscosity alginate to improve its in vitro bioaccessibility and in vivo bioavailability

In this work, an enteric soluble alginate was proposed to improve the absorption efficiency of cyanidin-3-O-glucoside (C3G) through molecular self-assembly. Under the optimized conditions, the obtained low-viscosity alginate (LVA) was released completely during the simulated gastrointestinal digestion and an LVA-C3G complex with 84.2% binding efficiency was acquired. Fourier transform infrared spectroscopy displayed that the characteristic spectrum of C3G had disappeared after the LVA conjugation. Furthermore, based on the analysis of scanning electron microscopy and differential scanning calorimetry, a porous network structure and the shifted endothermic peak in the thermograms were observed, further confirming the formation of a complex between LVA and C3G. The results of simulated gastrointestinal digestion reveal that the LVA assembly significantly (p < 0.05) improved the bioaccessibility of C3G. Correspondingly, the C3G level in mouse plasma was increased by 27.4% in the C3G-LVA group. This suggests the suitability of LVA as an oral delivery vehicle for dietary anthocyanins.

Enhanced physicochemical stabilities of cyanidin-3-O-glucoside via combination with silk fibroin peptide

Applications of cyanidin-3-O-glucoside (C3G) are limited due to the poor stabilities. In this work, we proposed using silk fibroin peptide (SFP) to bind with C3G and form nanocomposites (134.73 ± 4.51 nm) for stabilization. When interacted with C3G, the fluorescence of SFP contributed by tyrosine and phenylalanine amino acids was quenched, which was proved a static quenching with the β-sheet structure of SFP unchanged. With the further exploration of the physicochemical stabilities of C3G in the nanocomposites, we demonstrated that the tolerance of C3G to the alkaline environment and the retention ratio of C3G in various concentrations of metallic ion Cu²⁺ were significantly improved. In addition, the heat resistance of C3G in SFP at 80 °C was also enhanced with up to an increase of 2.5 times for the average half-life of C3G. Our results shed light on SFP could enhance physicochemical stabilities of C3G with maintaining its antioxidant activity.

A new cyanine from oxidative coupling of chlorogenic acid with tryptophan: Assessment of the potential as red dye for food coloring

A red pigment was prepared by reaction of chlorogenic acid (CGA) with tryptophan (TRP) in air at pH 9 (37% w/w yield) and evaluated as food dye. The main component of pigment was formulated as an unusual benzochromeno[2,3-b]indole linked to a TRP unit, featuring a cyanine type chromophore (λ_max 542, 546 nm, 1% extinction coefficient of the sodium salt = 244 ± 2). The chromophore showed a minimal pH dependence and proved stable for at least 3 h at 90 °C, both at pH 3.6 or 7.0, whereas red wine anthocyanins showed a substantial (30%) and betanin a complete abatement after 1 h at the acidic pHs. An intense coloring of different food matrices was obtained with the pigment at 0.01 % w/w. No toxicity was observed up to 0.2 mg/mL on hepatic and colonic cell lines. These data make this dye a promising alternative for red coloring of food.

Effects of high hydrostatic pressure on the binding capacity, interaction, and antioxidant activity of the binding products of cyanidin-3-glucoside and blueberry pectin

In this study, the effects of high hydrostatic pressure (HP) treatment on the binding capacity, interaction, and antioxidant activity of the binding products of blueberry pectin (BP) and cyanidin-3-glucoside (C3G) were assessed. HP was found to significantly improve the adsorption between C3G and BP. After binding, the C3G concentration was found to be the highest (382.1 ± 13.2 μg/mg for BP) when using a C3G-BP mass ratio of 1:2, a pressure of 400 MPa, and a holding time of 15 min. HP processing decreased particle size and altered the characteristics of C3G-BP complexes. The main binding form of the complexes before HP treatment was pectin-wrapped C3G by hydrogen bond interaction, while HP caused charged groups in pectin to be more exposed and improve the electrostatic interaction between C3G and BP. The antioxidant activity results showed that the presence of BP could protect the ferric-reducing antioxidant power of C3G after HP treatment.