A comprehensive review on innovative and advanced stabilization approaches of anthocyanin by modifying structure and controlling environmental factors

Chemical stability of carboxylpyranocyanidin-3-O-glucoside under β-glucosidase treatment and description of their interaction

Anthocyanins are susceptible to degradation by β-glycosidase, resulting in color loss. This study analyzed the impact of β-glycosidase on carboxylpyranocyanidin-3-O-glucoside (Carboxyl-pycy-3-gluc) and its precursor cyanidin-3-O-glucoside (Cy-3-gluc). Carboxyl-pycy-3-gluc exhibited enhanced stability upon treatment with β-glucosidase. Ultraviolet-visible and circular dichroism spectroscopy revealed slight changes in the microenvironment and secondary structure of β-glycosidase when carboxyl-pycy-3-gluc was present. The fluorescence experiment indicated that anthocyanins quench the fluorescence of β-glycosidase through static quenching via hydrophobic interactions. Molecular docking of six types of carboxylpyranoanthocyanins and their precursors with β-glycosidase revealed that carboxylpyranoanthocyanins exhibited lower binding affinity than their precursors, consistent with the enzyme kinetic experiment results. The incorporation carboxyl-pycy-3-gluc into Sanhua Plum Juice and Wine endowed them with vivid and stable coloration. The study illustrated that carboxyl-pycy-3-gluc exhibits low binding affinity with β-glycosidase, thereby maintaining stability and confirming its potential as a colorant.

Valorization and protection of anthocyanins from strawberries (Fragaria×ananassa Duch.) by acidified natural deep eutectic solvent based on intermolecular interaction

This study introduces an innovative approach for the valorization and protection of anthocyanins from 'Benihoppe' strawberry (Fragaria × ananassa Duch.) based on acidified natural deep eutectic solvent (NADES). Choline chloride-citric acid (ChCl-CA, 1:1) was selected and acidified to enhance the valorization and protection of anthocyanins through hydrogen bond. The optimal conditions (ultrasonic power of 318 W, extraction temperature of 61 °C, liquid-to-solid ratio of 33 mL/g, ultrasonic time of 19 min), yielded the highest anthocyanins of 1428.34 μg CGE/g DW. UPLC-Triple-TOF/MS identified six anthocyanins in acidified ChCl-CA extract. Stability tests indicated that acidified ChCl-CA significantly increased storage stability of anthocyanins in high temperature and light treatments. Molecular dynamics results showed that acidified ChCl-CA system possessed a larger diffusion coefficient (0.05 m2/s), hydrogen bond number (145) and hydrogen bond lifetime (4.38 ps) with a reduced intermolecular interaction energy (-1329.74 kcal/mol), thereby efficiently valorizing and protecting anthocyanins from strawberries.

Combinatorial preparation and structural characterization of anthocyanins and aglycones from Purple-heart Radish for evaluation of physicochemical stability and pancreatic lipase inhibitory activity

In this study, an efficient approach to preparation of different anthocyanins from Purple-heart Radish was developed by combining microwave-assisted extraction (MAE), macroporous resin purification (MRP) and ultrasound-assisted acid hydrolysis (UAAH) for evaluation of physicochemical stability and pancreatic lipase (PL) inhibitory activity. By optimization of MAE, MRP and UAAH processes, the anthocyanins reached the yield of 6.081 ± 0.106 mg/g, the purity of 78.54 ± 0.62 % (w/w) and the content of 76.29 ± 1.31 % (w/w), respectively. With high-resolution UHPLC-Q-Orbitrap/MS, 15 anthocyanins were identified as pelargonins with diverse glucosides and confirmed by pelargonidin standard. By glycosylation, pelargonins exhibited higher stability in different pH, temperature, light, metal ions environments than that of pelargonidin. However, PL inhibitory assay, kinetic analysis and molecular docking demonstrated that pelargonidin had higher PL inhibitory activity than pelargonins even though with similar binding sites and a dose-effect relationship. The above results revealed that the effect of glycosylation and deglycosylation on PL inhibitory activity and physicochemical stability.

Unveiling the multifaceted world of anthocyanins: Biosynthesis pathway, natural sources, extraction methods, copigmentation, encapsulation techniques, and future food applications

Numerous datasets regarding anthocyanins have been noted elsewhere. These previous studies emphasized that all processes must be carried out meticulously from the source used to obtain anthocyanins to their inclusion in relevant applications. However, today, full standardization has not yet been achieved for these processes. For this, presenting the latest developments regarding anthocyanins under one roof would be a useful approach to guide the scientific literature. The current review was designed to serve the stated points. In this context, their biosynthesis pathway was elaborated. Superior potential of fruits and certain by-products in obtaining anthocyanins was revealed compared to their other counterparts. Health-promoting benefits of anthocyanins were detailed. Also, the situation of innovative techniques (ultrasound-assisted extraction, subcritical water extraction, pulse electrical field extraction, and so on) in the anthocyanin extraction was explained. The stability issues, which is one of the most important problems limiting the use of anthocyanins in applications were discussed. The role of copigmentation and various encapsulation techniques in solving these stability problems was summarized. This critical review is a map that provides detailed information about the processes from obtaining anthocyanins, which stand out with their functional properties, to their incorporation into various systems.

Study of UV-Vis molar absorptivity variation and quantitation of anthocyanins using molar relative response factor

The effects of anthocyanin's substitution groups on the UV-Vis molar absorptivity were examined by analyzing a group of 31 anthocyanidin/anthocyanin reference standards with ultra-high performance liquid chromatography-diode array detector (UHPLC-DAD). The substitution groups on aglycones were found to associate with molar absorptivity variations, often neglected in anthocyanin quantitation, resulting in significant analytical errors. A simple yet comprehensive strategy based on the molar relative response factors (MRRFs) and a single master reference calibration (i.e., cyanidin-3-glucoside) was proposed to quantify anthocyanins in red cabbage, blueberry, and strawberry samples with improved analytical accuracy. The results indicate this approach provides an effective, inexpensive, and accurate analytical method for anthocyanins in food materials without using individual reference standards. MRRFs of 617 anthocyanins/anthocyanidins were calculated, and the information is freely available at https://BotanicalDC.online/anthocyanin/. This study could be critical to developing new reference methods for anthocyanin analysis and harmonizing results and data from various sources.

Pharmacokinetics of cyanidin-3-O-galactoside and cyanidin-3-O-arabinoside after intravenous administration in rats

Cyanidin-3-O-galactoside and cyanidin-3-O-arabinoside (purity >98%) were isolated from black chokeberry by preparative high-performance liquid chromatography, and an animal experiment was conducted to investigate the pharmacokinetics of two anthocyanin monomers after intravenous administration. The results showed that cyanidin-3-O-galactoside has preferable druggability than cyanidin-3-O-arabinoside in pharmacokinetic area.

Enhanced stability and bioavailability of mulberry anthocyanins through the development of sodium caseinate-konjac glucomannan nanoparticles

This study was carried out to improve the stability of anthocyanins (ACNs) by developing MA-SC-KGM nanoparticles using a self-assembly method that involved the combination of sodium caseinate (SC) and konjac glucomannan (KGM) with mulberry anthocyanin extract (MA). Atomic force microscopy (AFM) analysis showed SC encapsulated MA successfully. Multispectral techniques demonstrated the presence of hydrogen bonds and hydrophobic interactions in the nanoparticles. MA-SC-KGM ternary mixture improved storage stability, color stability and anthocyanin retention better compared to the MA-SC binary mixture. Notably, MA-SC-KGM nanoparticles significantly inhibited the thermal degradation of ACNs, improved pH stability, and showed stability and a slow-release effect in gastrointestinal digestion experiments. In addition, MA-SC-KGM nanoparticles were effective in scavenging DPPH· and ABTS+ free radicals, with enhanced stability and antioxidant capacity even during the heating process. This study successfully developed a novel MA-SC-KGM protein-polysaccharide composite material that effectively stabilized natural ACNs, expanding the application of ACNs in various industries.

Ion presence during thermal processing modulates the performance of rice albumin/anthocyanin binary system

Thermal processing with salt ions is widely used for the production of food products (such as whole grain food) containing protein and anthocyanin. To date, it is largely unexplored how salt ion presence during thermal processing regulates the practical performance of protein/anthocyanin binary system. Here, rice albumin (RA) and black rice anthocyanins (BRA) were used to prepare RA/BRA composite systems as a function of temperature (60-100 °C) and NaCl concentration (10-40 mM) or CaCl2 concentration (20 mM). It was revealed that the spontaneous complexing reaction between RA and BRA was driven by hydrophobic interactions and hydrogen bonds and becomes easier and more favorable at a higher temperature (≤90 °C), excessive temperature (100 °C), however, may result in the degradation of BRA. Moreover, the salt ion presence during thermal processing may bind with RA and BRA, respectively, which could restrict the interaction between BRA and RA. Additionally, the inclusion of Na+ or Ca2+ at 20 mM endowed the binary system with strengthened DPPH radical scavenging capacity (0.95 for Na+ and 0.99 for Ca2+). Notably, Ca2+ performed a greater impact on the stability of the system than Na+.

Dietary Sources, Stabilization, Health Benefits, and Industrial Application of Anthocyanins-A Review

Natural phytochemicals are well known to protect against numerous metabolic disorders. Anthocyanins are vacuolar pigments belonging to the parent class of flavonoids. They are well known for their potent antioxidant and gut microbiome-modulating properties, primarily responsible for minimizing the risk of cardiovascular diseases, diabetes, obesity, neurodegenerative diseases, cancer, and several other diseases associated with metabolic syndromes. Berries are the primary source of anthocyanin in the diet. The color and stability of anthocyanins are substantially influenced by external environmental conditions, constraining their applications in foods. Furthermore, the significantly low bioavailability of anthocyanins greatly diminishes the extent of the actual health benefits linked to these bioactive compounds. Multiple strategies have been successfully developed and utilized to enhance the stability and bioavailability of anthocyanins. This review provides a comprehensive view of the recent advancements in chemistry, biosynthesis, dietary sources, stabilization, bioavailability, industrial applications, and health benefits of anthocyanins. Finally, we summarize the prospects and challenges of applications of anthocyanin in foods.

RuBisCo can conjugate and stabilize peonidin-3-O-p-coumaroylrutinoside-5-O-glucoside in isotonic sport models: Mechanisms from kinetics, multispectral, and libDock assays

The co-pigmentation behaviour of RuBisCo proteins (with different concentrations) on peonidin-3-O-p-coumaroylrutinoside-5-O-glucoside (P3C5G, extracted from Rosetta potato's peels) conjugates in isotonic sport drinks (ISD) was examined using multispectral, thermal stability kinetics, and libDock-based molecular docking approaches. The colorant effects of RuBisCo on P3C5G were also studied in spray-dried microencapsulated ISD-models. RuBisCo, especially at a concentration of 10 mg/mL in ISD, showed a co-pigmentation effect on the color of P3C5G, mostly owing to its superior hyperchromicity, pKH-levels, and thermal stability. Results from multispectral approaches also revealed that RuBisCo could noncovalently interact with P3C5G as confirmed by libDock findings, where P3C5G strongly bound with RuBisCo via H-bonding and π-π forces, thereby altering its secondary structure. RuBisCo also preserved color of P3C5G in ISD-powdered models. These detailed results imply that RuBisCo could be utilized in ISD-liquid and powder models that might industrially be applied as potential food colorants in products under different conditions.

Enhancement of pyranoanthocyanin formation in blueberry wine with non-Saccharomyces yeasts

The development of blueberry wine provides an alternative method for maintaining the nutritional value and extending the shelf life of blueberries. However, anthocyanin loss and off-flavor compound generation during fermentation impair blueberry wine color and quality. Hydroxycinnamate decarboxylase from yeast can catalyze the conversion of hydroxycinnamic acids to vinylphenols, which later may condense with anthocyanins to form more stable vinylphenolic pyranoanthocyanins. In this study, 10 non-Saccharomyces yeasts from Daqu that showed hydroxycinnamate decarboxylase activity were screened. Among the 10 strains, Wickerhamomyces anomalus Y5 showed the highest consumption (34.59%) of the total tested phenolic acids and almost no H2S production. Furthermore, Y5 seemed to produce four vinylphenol pyranoanthocyanins (cyanidin-3-O-galactoside/glucoside-4-vinylcatechol, cyanidin-3-O-galactoside/glucoside-4-vinylsyringol, malvidin-4-vinylguaiacol, and malvidin-4-vinylcatechol) during blueberry wine fermentation, which may improve the color stability of blueberry wine. These findings provide new insights for improving the quality of blueberry wine using non-Saccharomyces yeasts.

Advancements in the promotion of pyranoanthocyanins formation in wine: A review of current research

Pyranoanthocyanin (PACN) is a class of anthocyanin (ACN)-derived pigments found in aged red wines, which has certain advantages over the prototype ACN in terms of stability, and biological activity. However, the efficiency and yield of PACNs in the natural fermentation system are low. This article summarizes five frequently employed physical processing techniques that can accelerate the formation of PACN. From a mechanistic standpoint, these techniques can produce large amounts of active substances, further promoting the extracellular release of phenolics and the formation of some cofactors and PACNs' pyran rings. Precursor substances and environmental factors affecting PACN yields are also pointed out. It mainly included the parent ring substitution in ACNs, the type and quantity of glycosides, the electron donating ability and concentration of cofactors, etc. Thus, this article aims to provide an overview of the advancements in processing techniques, thereby facilitating their wider utilization in the food and beverage industry.

Microencapsulation with fructooligosaccharides and whey protein enhances the antioxidant activity of anthocyanins and their ability to modulate gut microbiota in vitro

Anthocyanins are the primary functional pigments in the diet. However, anthocyanins exhibit instability during digestion, coupled with limited bioavailability. Microencapsulation offers anthocyanins a sheltered environment, enhancing their stability and bioactivity. Fructooligosaccharides (FOS) and whey protein (WP) commonly serve as wall materials in microencapsulation and represent a significant source of probiotic functionality. Our prior research successfully established a robust microencapsulation system for anthocyanins utilizing FOS and WP. This study investigates the antioxidative capacity, stability during in vitro digestion, modulation on gut microbiota, and short-chain fatty acids (SCFAs) production of black soybean skin anthocyanins microencapsulated with FOS and WP (anthocyanin-loaded microencapsule particles, ALM). The results demonstrate that ALM exhibits a superior antioxidant capacity compared to free anthocyanins (ANCs) and cyanidin-3-glucoside (C3G). During simulated digestion, ALM exhibits enhanced anthocyanin retention compared with ANC in both gastric and intestinal phases. In comparison with ANC and even non-loaded microcapsules (NLM), in vitro fermentation demonstrates that ALM exhibits the highest gas production and lowered pH, indicating excellent fermentation activity. Furthermore, in comparison with ANC or NLM, ALM exerts a positive influence on the diversity and composition of gut microbiota, with potentially beneficial genera such as Faecalibacterium and Akkermansia exhibiting higher relative abundance. Moreover, ALM stimulates the production of SCFAs, particularly acetic and propionic acids. In conclusion, microencapsulation of anthocyanins with FOS-WP enhances their antioxidative capacity and stability during in vitro digestion. Simultaneously, this microencapsulation illustrates a positive regulatory effect on the intestinal microbiota community and SCFA production, conferring potential health benefits.

Unlocking the health potential of anthocyanins: a structural insight into their varied biological effects

Anthocyanins have become increasingly important to the food industry due to their colorant features and many health-promoting activities. Numerous studies have linked anthocyanins to antioxidant, anti-inflammatory, anticarcinogenic properties, as well as protection against heart disease, certain types of cancer, and a reduced risk of diabetes and cognitive disorders. Anthocyanins from various foods may exhibit distinct biological and health-promoting activities owing to their structural diversity. In this review, we have collected and tabulated the key information from various recent published studies focusing on investigating the chemical structure effect of anthocyanins on their stability, antioxidant activities, in vivo fate, and changes in the gut microbiome. This information should be valuable in comprehending the connection between the molecular structure and biological function of anthocyanins, with the potential to enhance their application as both colorants and functional compounds in the food industry.

The promising stability of carboxylpyranocyanidin-3-O-glucoside during food processing and simulated digestion and its bioavailability research

BACKGROUND

Pyranoanthocyanins are stable anthocyanin derivatives. Carboxylpyranoanthocyanin is one of the simplest pyranoanthocyanin, among which the production of carboxylpyranocyanidin-3-O-glucoside (crboxyl-pycy-3-gluc) is most feasible as a result of the abundance of its reactant, cyanidin-3-O-glucoside (Cy-3-gluc).

RESULTS

In the present study, carboxyl-pycy-3-gluc was synthesized and its stability during processing and after ingestion as well as its bioavailability in vivo were comprehensively evaluated. Our results indicated that the color of carboxyl-pycy-3-gluc remained more stable compared to Cy-3-gluc when facing the large-span pH variation. The high retention of anthocyanin symbolized the superb stability under thermal processing, sulfur dioxide bleaching and ultrasonic treatment of carboxyl-pycy-3-gluc. Because of the stability under the alkaline condition, carboxyl-pycy-3-gluc is more stable after oral-gastrointestinal digestion. After in vitro gut microbiota fermentation, the retention of carboxyl-pycy-3-gluc was significantly higher than that of Cy-3-gluc. The larger molecular size made absorption of carboxyl-pycy-3-gluc into blood more difficult than its precursor.

CONCLUSION

The present study demonstrated the promising stability of carboxyl-pycy-3-gluc during food processing and after digestion, confirming the potential of carboxyl-pycy-3-gluc as a colorant. © 2023 Society of Chemical Industry.

A critical review on the stability of natural food pigments and stabilization techniques

This comprehensive review article delves into the complex world of natural edible pigments, with a primary focus on their stability and the factors that influence them. The study primarily explores four classes of pigments: anthocyanins, betalains, chlorophylls and carotenoids by investigating both their intrinsic and extrinsic stability factors. The review examines factors affecting the stability of anthocyanins which act as intrinsic factors like their structure, intermolecular and intramolecular interactions, copigmentation, and self-association as well as extrinsic factors such as temperature, light exposure, metal ions, and enzymatic activities. The scrutiny extends to betalains which are nitrogen-based pigments, and delves into intrinsic factors like chemical composition and glycosylation, as well as extrinsic factors like temperature, light exposure, and oxygen levels affecting for their stability. Carotenoids are analyzed concerning their intrinsic and extrinsic stability factors. The article emphasizes the role of chemical structure, isomerization, and copigmentation as intrinsic factors and discusses how light, temperature, oxygen, and moisture levels influence carotenoid stability. The impacts of food processing methods on carotenoid preservation are explored by offering guidance on maximizing retention and nutritional value. Chlorophyll is examined for its sensitivity to external factors like light, temperature, oxygen exposure, pH, metal ions, enzymatic actions, and the food matrix composition. In conclusion, this review article provides a comprehensive exploration of the stability of natural edible pigments, highlighting the intricate interplay of intrinsic and extrinsic factors. In addition, it is important to note that all the references cited in this review article are within the past five years, ensuring the most up-to-date and relevant sources have been considered in the analysis.

A Review of the Ethnobotany, Biological Activity, and Phytochemistry of the Plants in the Gundelia Genus

A comprehensive literature search was conducted in PubMed, Cochrane Library, Web of Science, Scopus, the National Library of Medicine (NLM) catalog, and Google Scholar from January 1980 up until October 2023 on plants in the Gundelia genus. Gundelia L. (Asteraceae) has been treated as a monospecific genus with Gundelia tournefortii L. (1753: 814) in most recent floras with wide variation in corolla color, but nowadays, the genus consists of 17 species. The unripe inflorescences of these species, especially G. tournefortii L., are consumed in many ways. 'Akkoub' or 'akko' in Arabic, "Kangar" in Persian, and "Silifa" in Greek are the common names of G. tournefortii L., also known as tumble thistle in English. They have been used in traditional medicine to treat bronchitis, kidney stones, diarrhea, stomach pain, inflammation, liver and blood diseases, bacterial and fungal infections, and mumps. Based on recent studies, their extracts have exhibited hepatoprotective, hypolipidemic, antioxidant, anti-inflammatory, and antimicrobial effects. Moreover, a variety of phytochemicals, including terpenoids, sterols, and fatty acids, as well as vitamins and minerals, have been identified in this genus. This study reviewed the ethnobotany, phytochemicals, and biological activities of the plants in the Gundelia genus as functional foods and herbal remedies.

First Insights on the Bioaccessibility and Absorption of Anthocyanins from Edible Flowers: Wild Pansy, Cosmos, and Cornflower

Edible flowers are regaining interest among both the scientific community and the general population, not only for their appealing sensorial characteristics but also from the growing evidence about their health benefits. Among edible flowers, those that contain anthocyanins are among the most consumed worldwide. However, little is known regarding the bioaccessibility and absorption of their bioactive compounds upon ingestion. The aim of this work was to explore, for the first time, the behavior of anthocyanin-rich extracts from selected edible flowers under different food processing conditions and after ingestion using simulated digestions, as well as their absorption at the intestinal level. Overall, the results showed that the monoglucoside and rutinoside anthocyanin extracts were less stable under different pH, temperature, and time conditions as well as different digestive processes in the gastrointestinal tract. There was a prominent decrease in the free anthocyanin content after the intestinal phase, which was more pronounced for the rutinoside anthocyanin extract (78.41% decrease from the oral phase). In contrast, diglucoside and rutinoside anthocyanin extracts showed the highest absorption efficiencies at the intestinal level, of approximately 5% after 4 h of experiment. Altogether, the current results emphasize the influence of anthocyanins' structural arrangement on both their chemical stability as well as their intestinal absorption. These results bring the first insights about the bioaccessibility and absorption of anthocyanins from wild pansy, cosmos, and cornflower and the potential outcomes of such alternative food sources.

Anthocyanin-Loaded Polymers as Promising Nature-Based, Responsive, and Bioactive Materials

Anthocyanins are a specific group of molecules found in nature that have recently received increasing attention due to their interesting biological and colorimetric properties that have been successfully applied in several fields such as food preservation and biomedicine. Consequently, reviews devoted to a general overview of these flavonoids have proliferated in recent years. Meanwhile, the incorporation of anthocyanins into polymeric systems has become an interesting strategy to widen the applicability of these molecules and develop new smart and functional polymers in the above cited areas. However, anthocyanin-based polymers have been scarcely reviewed in the literature. Accordingly, this review aims to be a systematic summary of the most recent approaches for the incorporation of anthocyanins into macro-, micro-, or nanostructured polymers. Moreover, this work describes the fundamentals of the applicability of smart anthocyanin-based polymers and offers an updated review of their most interesting applications as sensors, biological regulators, and active materials.

The structure of anthocyanins and the copigmentation by common micromolecular copigments: A review

Under natural physiological conditions, anthocyanins can keep bright and stable color for a long time due to the relatively stable acid-base environment of plant vacuoles and the copigmentation from various copigment substances, such as polyphenols, nucleotides, metallic ions and other substances. Therefore, the copigmentation caused by copigments is considered an effective way to stabilize anthocyanins against adverse environmental conditions. This is attributed to the covalent and noncovalent interactions between colored forms of anthocyanins (flavylium ions and quinoidal bases) and colorless or pale yellow organic molecules (copigments). These interactions are usually manifested in both hyperchromic effect and bathochromic shifts. In addition to making anthocyanins more stable, the copigmentation also could make an important contribution to the diversification of their tone. Based on the molecular structure of anthocyanins, this review focuses on the interaction mode of auxochrome groups or copigments with anthocyanins and their effects on the chemical and color stability of anthocyanins.

Mechanism of action of anthocyanin on the detoxification of foodborne contaminants-A review of recent literature

Foodborne contaminants refer to substances that are present in food and threaten food safety. Due to the progress in detection technology and the rising concerns regarding public health, there has been a surge in research focusing on the dangers posed by foodborne contaminants. These studies aim to explore and implement strategies that are both safe and efficient in mitigating the associated risks. Anthocyanins, a class of flavonoids, are abundantly present in various plant species, such as blueberries, grapes, purple sweet potatoes, cherries, mulberries, and others. Numerous epidemiological and nutritional intervention studies have provided evidence indicating that the consumption of anthocyanins through dietary intake offers a range of protective effects against the detrimental impact of foodborne contaminants. The present study aims to differentiate between two distinct subclasses of foodborne contaminants: those that are generated during the processing of food and those that originate from the surrounding environment. Furthermore, the impact of anthocyanins on foodborne contaminants was also summarized based on a review of articles published within the last 10 years. However, further investigation is warranted regarding the mechanism by which anthocyanins target foodborne contaminants, as well as the potential impact of individual variations in response. Additionally, it is important to note that there is currently a dearth of clinical research examining the efficacy of anthocyanins as an intervention for mitigating the effects of foodborne pollutants. Thus, by exploring the detoxification effect and mechanism of anthocyanins on foodborne pollutants, this review thereby provides evidence, supporting the utilization of anthocyanin-rich diets as a means to mitigate the detrimental effects of foodborne contaminants.

Enhancing the stability of natural anthocyanins against environmental stressors through encapsulation with synthetic peptide-based gels

The instability of anthocyanin to environmental stressors severely limits its applications as a natural bioactive pigment. To overcome these limitations, this proof-of-concept study utilizes the high biocompatibility of peptide molecules and the unique gel microstructure to develop innovative peptide-based gels. Characterization of the gels was conducted through AFM, SEM, rheological analysis, and CD spectrum. These analyses confirmed the fibrous mesh structure and impressive mechanical strength of the peptide-based gels. The cytotoxicity evaluation using MTT and hemolysis analysis showed high biocompatibility. Encapsulation efficiency analysis and fluorescence microscopy images demonstrated successful and efficient encapsulation of anthocyanins in all four peptide-based gels, with uniform distribution. Moreover, systematic investigations were conducted to assess the impact of peptide-based gels on the stability of natural anthocyanins under environmental stressors such as temperature, pH variations, and exposure to metal ions. Notably, the results revealed a significant enhancement in stability, including improved long-term storage and antioxidant activity. In conclusion, this study successfully developed four novel peptide-based gels that effectively protect natural anthocyanins from environmental stressors, highlighting their potential in various fields such as food and biology.

Advances in embedding techniques of anthocyanins: Improving stability, bioactivity and bioavailability

The health benefits of anthocyanins have attracted extensive research interest. However, anthocyanins are sensitive to certain environmental and gastrointestinal conditions and have low oral bioavailability. It has been reported that delivery systems made in different ways could improve the stability, bioavailability and bioactivity of anthocyanins. This present review summarizes the factors affecting the stability of anthocyanins and the reasons for poor bioavailability, and various technologies for encapsulation of anthocyanins including microcapsules, nanoemulsions, microemulsions, Pickering emulsions, nanoliposomes, nanoparticles, hydrogels and co-assembly with amphiphilic peptides were discussed. In particular, the effects of these encapsulation technologies on the stability, bioavailability and bioactivities of anthocyanins in vitro and in vivo experiments are reviewed in detail, which provided scientific insights for anthocyanins encapsulation methods. However, the application of anthocyanins in food industry as well as the biological fate and functional pathways in vivo still need to be further explored.

Interaction between a Commercial Mannoprotein and Cyanidin-3-O-glucoside-4-vinylphenol and Its Stability and Antioxidative Properties as a Novel Functional Pigment

Hydroxyphenyl-pyranoanthocyanins, which are derived from anthocyanins and phenolic acids during the fermentation and aging of red wine, are prone to polymerization and precipitation, which largely limits their application and bioactivity research. In the present study, cyanidin-3-O-glucoside-4-vinylphenol (C3GVP), a hydroxyphenyl-pyranoanthocaynin, was prepared from C3G and p-coumaric acid, and mannoprotein (MP) was employed to improve its stability in various complex solvents by forming a stable anthocyanin-MP complex. We used scanning electron microscopy, ultraviolet-visible spectroscopy, Fourier-transform infrared spectroscopy, and circular dichroism spectroscopy to observe structural changes in C3GVP and MP. The results demonstrated that the intermolecular polymerization of C3GVP was mitigated and the secondary conformation of MP was changed slightly. Fluorescence spectroscopy and molecular docking indicated that C3GVP and MP interacted via hydrogen bonds and hydrophobic interactions. Importantly, the C3GVP-MP complex exhibited better thermal stability and antioxidant capacity than C3G.

Vitisin A, as a Type of Pyranoanthocyanin, Suppresses Inflammation by Restricting Hematopoietic Stem Cell Differentiation toward Monocytes in Bone Marrow

Hematopoietic stem and progenitor cells (HSPCs) could be differentiated into mature myeloid and lymphoid cells, maintaining the requirements of immune cells. Atherosclerosis and ulcerative colitis (UC) drive HSPC homeostasis destruction, which triggers expansive HSPC proliferation and Ly6Chi monocyte production, contributing to aggravated inflammation. Vitisin A belongs to the anthocyanin derivatives with excellent stability and bioactivity in vitro. However, there is no report about the anti-inflammation of Vitisin A via reprogramming HSPC differentiation toward monocytes. In this study, we found that Vitisin A presents anti-inflammatory ability during the development of atherosclerosis and UC by depressing Ly6Chi monocyte production from bone marrow. This performance depended on restricted HSPC differentiation, which suggested that Vitisin A participated in monocyte generation and carried out the immunomodulation. Together, Vitisin A ameliorates inflammation during atherosclerosis and UC via the suppressed differentiation of HSPCs toward monocytes, which could be considered an ideal functional component with immunomodulatory effects.

Protein and Peptide-Based Nanotechnology for Enhancing Stability, Bioactivity, and Delivery of Anthocyanins

Anthocyanin, a unique natural polyphenol, is abundant in plants and widely utilized in biomedicine, cosmetics, and the food industry due to its excellent antioxidant, anticancer, antiaging, antimicrobial, and anti-inflammatory properties. However, the degradation of anthocyanin in an extreme environment, such as alkali pH, high temperatures, and metal ions, limits its physiochemical stabilities and bioavailabilities. Encapsulation and combining anthocyanin with biomaterials could efficiently stabilize anthocyanin for protection. Promisingly, natural or artificially designed proteins and peptides with favorable stabilities, excellent biocapacity, and wide sources are potential candidates to stabilize anthocyanin. This review focuses on recent progress, strategies, and perspectives on protein and peptide for anthocyanin functionalization and delivery, i.e., formulation technologies, physicochemical stability enhancement, cellular uptake, bioavailabilities, and biological activities development. Interestingly, due to the simplicity and diversity of peptide structure, the interaction mechanisms between peptide and anthocyanin could be illustrated. This work sheds light on the mechanism of protein/peptide-anthocyanin nanoparticle construction and expands on potential applications of anthocyanin in nutrition and biomedicine.

Rice bran protein increases the retention of anthocyanins by acting as an encapsulating agent in the spray drying of grape juice

Rice bran protein concentrate (RPC), an industrial by-product, may emerge as a green alternative for substituting animal proteins in microencapsulating compounds of interest. This study applied RPC, combined with maltodextrin (MD) as carrier agents, in the spray drying of grape juice, a product rich in these bioactive compounds, seeking to protect anthocyanins from degradation. The effects of carrier agent concentration [C: 0.75, 1.00, and 1.25 g of carrier agents (CA)/g of soluble solids of the juice (SS)] and RPC:CA ratio (P: 0%, as a control sample, 5%, 10%, 15%, and 20%) on anthocyanin retention and powder properties were evaluated. At 1.00 g CA/g SS, the internal and total retentions of anthocyanins improved by 2.4 and 3.2 times, respectively, when the RPC:CA ratio increased from 0% to 20%. The protein also exhibited excellent surface activity on the grape juice and positively influenced the physicochemical properties of the microparticles. There was a reduction in stickiness, degree of caking, and hygroscopicity, in addition to an increased antioxidant capacity when protein was used in combination with MD, especially at 1.00 and 1.25 g CA/g SS. Therefore, this study demonstrated that RPC could enhance the protection of anthocyanins during the spray drying of grape juice.

Alginate microbeads incorporated with anthocyanins from purple corn (Zea mays L.) using electrostatic extrusion: Microencapsulation optimization, characterization, and stability studies

Microencapsulation of purple corn anthocyanins was carried out via an electrostatic extruder using alginate as a wall material. The influence of alginate concentration (1-2 %), extract concentration (20-30 %), and extrusion voltage (3-5 kV) on encapsulation efficiency and mean particle size was evaluated using response surface methodology. Optimal conditions were obtained to produce two different extract-loaded microbeads. Microbeads with the highest encapsulation efficiency (EE) and minimum particle size were achieved at 1 % alginate, 20 % extract, and 5 kV extrusion voltage (EEC3G = 70.26 %, EETPC = 91.59 %, particle size = 1.29 mm). In comparison, the microbeads with the efficient entrapment and maximum particle size were obtained at 1 % alginate, 26 % extract, and 3 kV (EEC3G = 81.15 %, EETPC = 91.01 %, particle size = 1.87 mm). Brunauer-Emmett-Teller (BET) surface area, pore size, and pore volume decreased after the inclusion of extract, with the lowest values reported for the smallest microbeads containing the extract. Scanning electron microscopy confirmed the results obtained by BET method and demonstrated fewer cracks and lower shrinkage of encapsulated samples. Fourier-transform infrared results proved the presence of anthocyanins and further possible interactions between phenolics and alginate. Stability studies revealed the color maintenance of anthocyanins-loaded microbeads during 4 weeks of storage at 4 °C and 8 °C. Moreover, the small and large particles showed a 7.6 and 3.4-fold reduction in degradation rate at 4 °C compared to their unencapsulated counterparts. Anthocyanins-loaded alginate microbeads retained over 80 % of cyanidin-3-glucoside at 4 °C and 8 °C, suggesting a promising potential of optimized microbeads for intelligent packaging applications.

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.

Progress on molecular modification and functional applications of anthocyanins

Anthocyanins have attracted a lot of attention in the fields of natural pigments, food packaging, and functional foods due to their color, antioxidant, and nutraceutical properties. However, the poor chemical stability and low bioavailability of anthocyanins currently limit their application in the food industry. Various methods can be used to modify the structure of anthocyanins and thus improve their stability and bioavailability characteristics under food processing, storage, and gastrointestinal conditions. This paper aims to review in vitro modification methods for altering the molecular structure of anthocyanins, as well as their resulting improved properties such as color, stability, solubility, and antioxidant properties, and functional applications as pigments, sensors and functional foods. In industrial production, by mixing co-pigments with anthocyanins in food systems, the color and stability of anthocyanins can be improved by using non-covalent co-pigmentation. By acylation of fatty acids and aromatic acids with anthocyanins before incorporation into food systems, the surface activity of anthocyanins can be activated and their antioxidant and bioactivity can be improved. Various other chemical modification methods, such as methylation, glycosylation, and the formation of pyranoanthocyanins, can also be utilized to tailor the molecular properties of anthocyanins expanding their range of applications in the food industry.

Interaction of preheated whey protein isolate with rose anthocyanin extracts in beverage model system: Influence on color stability, astringency and mechanism

Preheating proteins have the potential to improve anthocyanin stability. Our aim was to investigate the effect of preheated whey protein isolate (WPI) on the color stability and astringency of the beverage model system in the presence of rose anthocyanin extracts (RAEs), and to explore the mechanism of interaction between preheated WPI and RAEs. The secondary structure, particle size and transparency of WPI were obviously changed by preheating. WPI preheated at 100°C  (WPI100) could effectively improve the color stability of RAEs in the beverage model system. Importantly, the WPI100-RAEs in the beverage model system exhibited the smallest particle size and the weakest astringency effect. In addition, different preheated WPIs could interact with RAEs non-covalently, and the interaction forces are hydrogen bonding and van der Waals forces, among which WPI100 had the strongest binding ability to RAEs. These results will provide a new insight into the development of protein-anthocyanin beverages.

High-efficiency foam fractionation of anthocyanin from perilla leaves using surfactant-free active Al2O3 nanoparticle as collector and frother: Performance and mechanism

Anthocyanin (ACN) is a natural pigment with significant industrial applications. However, foam fractionation of ACN from perilla leaves extract presents theoretical challenges due to its limited surface activity and foaming capacity. This work developed a surfactant-free active Al₂O₃ nanoparticle (ANP) as a collector and frother, which was modified with adipic acid (AA). The ANP-AA efficiently collected ACN through the electrostatic interaction, condensation reaction, and hydrogen bonding, with a Langmuir maximum capacity of 129.62 mg/g. Moreover, ANP-AA could form a stable foam layer by irreversibly adsorbing on the gas-liquid interface, reducing surface tension, and alleviating liquid drainage. Under the appropriate conditions of ANP-AA 400 mg/L and pH 5.0, we achieved a high ACN recovery of 95.68% with an enrichment ratio of 29.87 after ultrasound-assisted extraction of ACN from perilla leaves. Additionally, the recovered ACN displayed promising antioxidant properties. These findings hold significant importance in the food, colorant, and pharmaceutical industries.

Stability of Purple Corn Anthocyanin Encapsulated by Maltodextrin, and Its Combinations with Gum Arabic and Whey Protein Isolate

Purple corn anthocyanins are important natural colourants with cheap prices and rich bioactivities. However, their stability is limited. Microencapsulation is an effective way to improve anthocyanin stability and the influence of the type of wall material on the stability of encapsulated anthocyanin is very important. In this study, maltodextrin (MD) and its combination with whey protein isolate (WPI) or gum arabic (GA) were utilised as wall materials to obtain encapsulated purple corn anthocyanins (PCAs) (MD-PCA, MD-WPI-PCA, MD-GA-PCA) using spray drying. The effect of the amount of the wall material was determined by encapsulation efficiency, anthocyanin content, and colour. On this basis, the effects of the types of wall materials on the physicochemical characteristics, storage, and digestion stabilities of encapsulated PCA, as well as their stabilities in chewing tablets, were investigated. The highest encapsulation efficiency, suitable colour, and anthocyanin content were obtained with the mass ratios 1:1 PCA to MD, 2:3 PCA to MD-GA, and 1:1 PCA to MD-WPI. Microencapsulation increased PCA storage and digestion stabilities. All three types of PCA microcapsules had low water content and hygroscopicity and good water solubility. MD-PCA had the strongest stability when stored at 25 °C; MD-GA-PCA-when stored at 40 °C, or in the presence of 5000 Lux light illumination; MD-WPI-PCA-when stored in 75% relative humidity or during gastric-intestinal digestion, but its resistance to 40 °C temperature and light illumination was lower than those for the two others. When used in chewing tablets, MD encapsulation was most stable in the presence of Ca²⁺, V_C, or Fe²⁺ and improved PCA digestion stability. In conclusion, MD is a good choice for PCA encapsulation in regular conditions. MD-GA and MD-WPI can be used when considering high storage temperature (or light illumination) and high humidity (or for high digestion stability), respectively. The results of this study provide a reference for the storage and application of PCA.

Investigation of the difference in color enhancement effect on cyanidin-3-O-glucoside by phenolic acids and the interaction mechanism

Co-pigmentation effect of phenolic acids on cyanidin-3-O-glucoside (C3G) and the mechanisms were investigated. Sinapic acid (SIA), ferulic acid (FA), p-coumaric acid (p-CA) and syringic acid (SYA) significantly enhanced C3G stability (P < 0.05), whereas vanillic acid (VA) and gallic acid (GA) showed no influence (P > 0.05). Among these phenolic acids, SIA and FA had higher binding coefficient with C3G (48.83 and 43.38), reduced degradation rate constant by 40.0 ∼ 50.0 %, prolonged half-life by 74.6 ∼ 94.7 % at 323 K, and significantly inhibited C3G hydration reaction (pK_h = 2.87 and 2.80, P < 0.05). Molecular docking revealed that C3G and co-pigments were connected by hydrogen bond and π-π stacking interaction. Hydroxycinnamic acids of SIA, FA and p-CA bound with ring B and ring C of C3G, while hydroxybenzoic acids of SYA, VA and GA hardly interacted with ring C. Generally, the protection effect of hydroxycinnamic acids on C3G was better than that of hydroxybenzoic acids, exhibiting stronger hyperchromic effect.

A visual bi-layer indicator based on mulberry anthocyanins with high stability for monitoring Chinese mitten crab freshness

In this study, a bilayer film (BIF) was fabricated to improve the stability of an anthocyanin-based freshness indicator film. The sensor layer consists of gellan gum (GG) and mulberry anthocyanin (MAE) for freshness indication. The oxygen barrier layer was constructed from chitosan (CS), polyvinyl alcohol (PVA), sodium alginate (SA), and pullulan (Pu) to the protection of MAE from oxidation. The highest antioxidant activity of BIF was 91.28 %. BIF was used to monitor the Chinese mitten crab freshness. The total volatile basic nitrogen (TVB-N) level was increased to 31.23 mg/100 g on day 8, and the color of the indicator presented a visible change from pink to dark green. The acquired results revealed a good correlation between TVB-N, pH, and color change of the indicator. The research indicated that the BIF was applied for freshness monitoring of Chinese mitten crab and displayed significant color changes that would be effective in commercial environments.

Biological Activities and Solubilization Methodologies of Naringin

Naringin (NG), a natural flavanone glycoside, possesses a multitude of pharmacological properties, encompassing anti-inflammatory, sedative, antioxidant, anticancer, anti-osteoporosis, and lipid-lowering functions, and serves as a facilitator for the absorption of other drugs. Despite these powerful qualities, NG's limited solubility and bioavailability primarily undermine its therapeutic potential. Consequently, innovative solubilization methodologies have received considerable attention, propelling a surge of scholarly investigation in this arena. Among the most promising solutions is the enhancement of NG's solubility and physiological activity without compromising its inherent active structure, therefore enabling the formulation of non-toxic and benign human body preparations. This article delivers a comprehensive overview of NG and its physiological activities, particularly emphasizing the impacts of structural modification, solid dispersions (SDs), inclusion compound, polymeric micelle, liposomes, and nanoparticles on NG solubilization. By synthesizing current research, this research elucidates the bioavailability of NG, broadens its clinical applicability, and paves the way for further exploration and expansion of its application spectrum.

Effects of whey protein isolate and ferulic acid/phloridzin/naringin/cysteine on the thermal stability of mulberry anthocyanin extract at neutral pH

In this study, the effects of whey protein isolate (WPI) and four copigments, including ferulic acid (FA), phloridzin, naringin, and cysteine (Cys), on the thermal stability (80 °C/2h) of mulberry anthocyanin extract (MAE) pigment solution at pH 6.3 were studied. WPI addition or copigment (except for Cys) addition alone could protect anthocyanin from degradation to a certain degree, and FA exhibited the best effect among copigments. Compared with the MAE-WPI and MAE-FA binary systems, ΔE of the MAE-WPI-FA ternary system decreased by 20.9% and 21.1%, respectively, and the total anthocyanin degradation rate decreased by 38.0% and 39.3%, respectively, indicating the best stabilizing effect. Remarkably, interactions between anthocyanins and Cys, which generate four anthocyanin derivatives with 513-nm UV absorption during heat treatment, did not alter the color stability of MAE solution; however, they accelerated anthocyanin degradation. These results favor the combined use of multiple methods to stabilize anthocyanins at neutral conditions.

Formation of hydroxyphenyl-pyranoanthocyanins derived from cyanidin-3-O-glucoside and effects of high-pressure processing on the transformation efficiency

Hydroxyphenyl-pyranoanthocyanins (PACNs), derived from anthocyanins (ACNs) reacted with hydroxycinnamic acids, have higher practical application value because of better physicochemical stability than their precursors. However, the slow formation rate restricted their broader applications. In the present study, cyanidin-3-O-glucoside (C3G) was chosen to react with four kinds of hydroxycinnamic acids in a model solution. Changes of color and the production of hydroxyphenyl-PACNs were monitored. The formation of derivatives was time-dependent, and the orange-yellow changing trend was correlated with the formation of PACNs and the consumption of C3G. In addition, high-pressure processing (HPP) as a widely-used non-thermal processing method in the food industry was conducted to investigate its impact on hydroxyphenyl-PACNs formation. The results showed that HPP significantly improves the yield of two types of hydroxyphenyl-PACNs (C3G-4-vinylcatechol and C3G-4-vinylphenol) and the retention of total residual pigments during 56 days of storage. Therefore, HPP contributed to color-protecting and the transformation of hydroxyphenyl-PACNs.

Liposome Formulations for the Strategic Delivery of PARP1 Inhibitors: Development and Optimization

The development of a lipid nano-delivery system was attempted for three specific poly (ADP-ribose) polymerase 1 (PARP1) inhibitors: Veliparib, Rucaparib, and Niraparib. Simple lipid and dual lipid formulations with 1,2-dipalmitoyl-sn-glycero-3-phospho-rac-(1'-glycerol) sodium salt (DPPG) and 1,2-dipalmitoyl-sn-glycero-3-phosphocoline (DPPC) were developed and tested following the thin-film method. DPPG-encapsulating inhibitors presented the best fit in terms of encapsulation efficiency (>40%, translates into concentrations as high as 100 µM), zeta potential values (below -30 mV), and population distribution (single population profile). The particle size of the main population of interest was ~130 nm in diameter. Kinetic release studies showed that DPPG-encapsulating PARP1 inhibitors present slower drug release rates than liposome control samples, and complex drug release mechanisms were identified. DPPG + Veliparib/Niraparib presented a combination of diffusion-controlled and non-Fickian diffusion, while anomalous and super case II transport was verified for DPPG + Rucaparib. Spectroscopic analysis revealed that PARP1 inhibitors interact with the DPPG lipid membrane, promoting membrane water displacement from hydration centers. A preferential membrane interaction with lipid carbonyl groups was observed through hydrogen bonding, where the inhibitors' protonated amine groups may be the major players in the PARP1 inhibitor encapsulation mode.

The chromogenic mechanism of natural pigments and the methods and techniques to improve their stability: A systematic review

Pigments have become a very important part of food research, not only adding sensory properties to food, but also providing functional properties to the food system. In this paper, we review the source, structure, modification, encapsulation and current status of the three main types of natural pigments that have been studied in recent years: polyphenolic flavonoids, tetraterpenoids and betaines. By examining the modification of pigment, the improvement of their stability and the impact of new food processing methods on the pigments, a deeper understanding of the properties and applications of the three pigments is gained, the paper reviews the research status of pigments in order to promote their further research and provide new innovations and ideas for future research in this field.

The stability of phenolic compounds and the colour of lingonberry juice with the addition of different sweeteners during thermal treatment and storage

Lingonberries (Vaccinium vitis-idaea L.) are rich in phenolic compounds associated with several health benefits. The berries are also astringent, sour, and bitter and the addition of a sweetener is necessary to increase the palatability of lingonberry products. The addition of a sweetener may, however, affect the stability of phenolic compounds in the product. The aim of this study was thus to determine the effects of the addition of sweeteners (sucrose, acesulfame K or sucralose) and temperature on the stability of anthocyanins, flavonols, flavan-3-ols, hydroxycinnamic acids and the colour of lingonberry juice during thermal treatment and storage. The addition of sweeteners did not affect the stability of phenolic compounds or the colour of lingonberry juice during thermal treatment or storage. The stability of the phenolic compounds was significantly affected by temperature. Anthocyanins were the least stable of the phenolic compounds. The half-lives of total anthocyanins were 3.8, 2.0 and 0.8 h at 75, 85 and 95 °C, respectively. The half-lives during storage were 12.8 and 2.7 weeks at 6 and 22 °C, respectively. Cyanidin-3-galactoside, the major anthocyanin in lingonberries, was extensively degraded during storage, probably due to galactoside side-activities of the enzyme preparation used in juice production. After thermal treatment, the juices were darker and bluer, with lower chromaticity, while after storage, the juices were lighter, more yellow, and had higher chromaticity.

Pharmacological Activities and Chemical Stability of Natural and Enzymatically Acylated Anthocyanins: A Comparative Review

Anthocyanins (ANCs) are naturally occurring water-soluble pigments responsible for conferring red, blue, and purple colors to fruits, vegetables, flowers, and grains. Due to their chemical structure, they are highly susceptible to degradation by external factors, such as pH, light, temperature, and oxygen. Naturally acylated anthocyanins have proven to be more stable in response to external factors and exhibit superior biological effects as compared with their non-acylated analogues. Therefore, synthetic acylation represents a viable alternative to make the application of these compounds more suitable for use. Enzyme-mediated synthetic acylation produces derivatives that are highly similar to those obtained through the natural acylation process, with the main difference between these two pathways being the catalytic site of the enzymes involved in the synthesis; acyltransferases catalyze natural acylation, while lipases catalyze synthetic acylation. In both cases, their active sites perform the addition of carbon chains to the hydroxyl groups of anthocyanin glycosyl moieties. Currently, there is no comparative information regarding natural and enzymatically acylated anthocyanins. In this sense, the aim of this review is to compare natural and enzyme-mediated synthetic acylated anthocyanins in terms of chemical stability and pharmacological activity with a focus on inflammation and diabetes.

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.

In vitro and in vivo bioaccessibility, antioxidant activity, and color of red radish anthocyanins as influenced by different drying methods

This study aims to examine the effects of various drying methods, namely vacuum freeze drying (VFD), vacuum drying (VD), hot air drying (HAD), sun drying (SD), and air-impingement jet drying (AIJD), on in vitro and in vivo bioaccessibility of red radish anthocyanins. By color parameters, VFD- and AIJD-dried red radish showed redder color to HAD-, SD-, and VD-dried red radish. SEM images of dried red radish showed multiple holes and loose interior structure. Forty-six anthocyanins were identified in red radish. Original, in vitro and in vivo digestive samples from VFD-dried red radish contained more anthocyanins and were more bioaccessibility than fresh and other dried red radishes. In vitro and in vivo research revealed that dried red radish showed weaker and stronger FRAP and ABTS^·+ scavenging activities than fresh red radish. Colon content of mice had significantly higher FRAP and ABTS^·+ scavenging activities than the stomach, small intestine, and cecum contents.

Mechanism of sugar degradation product 5-hydroxymethylfurfural reducing the stability of anthocyanins

The coexistence of anthocyanin with the sugar degradation product 5-hydroxymethylfurfural (5-HMF) is inevitable during the processing and storage of anthocyanin-rich juices. It was determined from our study that lower concentrations of 5-HMF have little effect on the stability of Cyanidin-3-O-glucoside (C3G), and even cause a slight increase for a short period of time. As the concentration of 5-HMF increased, the retention of C3G decreased and the color of the solution changed from orange-red to purple-red. The reaction sites of 5-HMF and C3G in its hemiketal form were predicted by quantum chemical calculations in order to investigate the pathways of action of the two. The degradation mechanism of 5-HMF on anthocyanin was verified by Ultraviolet and Visible spectrophotometer and Ultra performance liquid chromatography-mass spectrometry. Therefore, this article provides further theoretical support for the study of the effect of furfural compounds, which are sugar degradation products, on the stability of anthocyanins.

Cyanidin-3-O-glucoside and protocatechuic acid alleviate heat stress-induced testicular damage

Testicular hyperthermia induced by unhealthy living habits and pathological or occupational factors can cause spermatogenic dysfunction with an outcome of sub-fertility or even infertility. Cyanidin-3-O-glucoside (C3G) is the most typical anthocyanin in foods that has been recognized as an antioxidant with promising protection for male reproduction. However, its specific effect against testicular hyperthermia and the mechanisms involving its primary gastrointestinal metabolite protocatechuic acid (PCA) are still unexplored. In the present study, testicular hyperthermia in mice was established by employing a single hot water bath at 43 °C for 30 min. C3G and PCA were intragastrically given to investigate their prevention ability against heat stress-induced testicular damage. It was found that C3G and PCA restored the external diameter and thickness, and alleviated atrophy and vacuolation of seminiferous tubules. Simultaneously, C3G and PCA enhanced testicular heat stress tolerance through reducing superfluous eIF2α phosphorylation and stress granule formation. C3G and PCA effectively improved the testicular antioxidant system and regulated the IRE1α-XBP1 pathway, contributing to mitigatory spermatogenesis dysfunction and testicular damage. This finding revealed that anthocyanins were the novel compounds for alleviating testicular damage, and provided a reliable theoretical basis for improving male fertility disturbed by heat stress.

Stabilization of Anthocyanins from Coffee (Coffea arabica L.) Husks and In Vivo Evaluation of Their Antioxidant Activity

Coffee (Coffea arabica L.) is one of the most popular and widely consumed products throughout the world, mainly due to its taste, aroma, caffeine content, and natural antioxidants. Among those antioxidants, anthocyanins are one of the most important natural pigments, which can be found in coffee husks. It is widely known that anthocyanins have multiple health benefits partially linked to their antioxidant properties. However, anthocyanins have low stability and are sensitive to all types of changes. In order to prevent its degradation, anthocyanins can be stabilized with nanoparticles. Thus, the main objective of this study was to evaluate the stability of the anthocyanins extracted from coffee husks, using three different extracting agents (ethanol, methanol, and water) and stabilizing them through conjugation with zinc oxide nanoparticles. The anthocyanins extracts were mainly composed of cyanidin-3-rutinoside (97%) and the total phenolic compounds of the fresh extracts were 458.97 ± 11.32 (methanol), 373.53 ± 12.74 (ethanol), and 369.85 ± 15.93 (water) mg GAE/g. On the other hand, the total phenolic compounds of the nanoparticle-anthocyanin conjugates underwent no significant changes after stabilization as the major loss was less than 3%. Furthermore, the percentage of anthocyanins' degradation was less than 5% after 12 weeks of storage. On top of that, fresh anthocyanin extracts and anthocyanin-nanoparticle conjugates exhibited a strong protective effect against oxidative stress and increased the survival rate of Caenorhabditis elegans.

Bioactive Natural Pigments' Extraction, Isolation, and Stability in Food Applications

Color in food has multiple effects on consumers, since this parameter is related to the quality of a product, its freshness, and even its nutrient content. Each food has a characteristic color; however, this can be affected by the technological treatments that are applied during its manufacturing process, as well as its storage. Therefore, the development of new food products should take into account consumer preferences, the physical properties of a product, food safety standards, the economy, and applications of technology. With all of this, the use of food additives, such as dyes, is increasingly important due to the interest in the natural coloring of foods, strict regulatory pressure, problems with the toxicity of synthetic food colors, and the need for globally approved colors, in addition to current food market trends that focus on the consumption of healthy, organic, and natural products. It is for this reason that there is a growing demand for natural pigments that drives the food industry to seek or improve extraction techniques, as well as to study different stability processes, considering their interactions with the food matrix, in order to meet the needs and expectations of consumers.