Anthocyanins: Modified New Technologies and Challenges

Lactic acid bacterial fermentation as a biotransformation strategy to enhance the bioavailability of phenolic antioxidants in fruits and vegetables: A comprehensive review

Fruits and vegetables (FVs) are rich sources of macro and micro-nutrients crucial for a healthy diet. In addition to these nutrients, FVs also contain fibre and phytochemicals known for their antioxidant properties. Despite the growing evidence of the disease-preventive role of antioxidants in FVs, their bioavailability and bioaccessibility vary significantly and have not been adequately explored. Lactic acid bacterial (LAB) fermentation is considered the most appropriate and accessible biotechnological approach to maintain and enhance the safety, nutritional, sensory and shelf-life properties of perishable foods such as FVs. This review critically assesses how LAB fermentation could be utilised as a promising biotransformation strategy to enhance the bioavailability of antioxidants in FVs. Furthermore, it discusses the potential use of uniquely nutritious Australian native fruits as suitable candidates for LAB fermentation. Further research is essential to identify the beneficial properties of bioactive compounds and effective LAB-based biotransformation strategies to improve the bioavailability and bioaccessibility of antioxidants in FVs.

Recent advances in improving anthocyanin stability in black carrots

This review focuses on the methods of enhancing the stability of black carrot anthocyanins, which are susceptible to degradation due to temperature, pH, light, and oxygen. These anthocyanins are valued for their health benefits and blue-violet color, but their instability limits their application in the food industry. It is hypothesized that implementing advanced stabilization techniques can significantly improve the stability and usability of black carrot anthocyanins. Key methods to improve anthocyanin stability, including encapsulation, co-pigmentation, and acylation, are comprehensively reviewed. Encapsulation techniques such as spray drying, freeze drying, and liposomes have shown effectiveness in protecting anthocyanins during food processing and storage. Co-pigmentation with non-anthocyanin phenolics and using whey proteins significantly enhance thermal and pH stability, thereby improving color retention. Additionally, innovative strategies like genetic modification and nanoencapsulation have demonstrated potential in further stabilizing anthocyanins by enhancing their structural resilience and bioavailability. These innovative approaches represent a significant advancement in the ability to maintain the integrity of black carrot anthocyanins. Advanced techniques for preserving the functional properties and nutritional benefits of black carrot anthocyanins facilitate broader use in health-oriented food products. Combining these modern methods is essential for optimal stability, and further research is needed to optimize these techniques.

Comparative analysis of physicochemical properties, antioxidant activities, and metabolomic profiles in daylily-supplemented craft beer fermented with different Saccharomyces strains

This study investigated the use of daylily as a novel adjunct in craft beer production with four Saccharomyces yeast strains. The addition of daylily powder and yeast selection significantly influenced the physicochemical properties, antioxidant activity, and overall metabolome of the beers. Yeast strains exhibited variations in color, alcohol content, phenolic and flavonoid levels, and antioxidant capacity. Metabolomic analysis revealed differences in lipid, amino acid, tannin, and fatty acid synthesis between strains. Volatile profiles also differed markedly in esters, terpenes, higher alcohols, acids, and aldehydes. While 90 % of metabolites were conserved, key differences reflected distinct metabolic regulation among strains. These findings highlight the potential of daylily as a flavorful and bioactive beer ingredient, and emphasize the importance of targeted yeast selection for optimizing beer quality and metabolome. This work provides a practical framework for brewers to develop innovative beers with enhanced functional properties and specialized flavor profiles.

Enhancing sensitivity and stability of natural pigments in pH-responsive freshness indicators: A review

Natural pigments are an indicator component in the freshness indicator, which is advantageous due to their safety, renewability, and low cost. However, freshness indicator with natural pigments as pH indicators has the problems of low stability and the color rendering domain could not effectively cover the shelf life of food. This paper describes the types and structures of natural pigments commonly used in freshness indicators and their color change mechanisms under different pH conditions. Also, the preparation methods of natural pigments freshness indicators are reviewed. Based on the current limitations and shortcomings faced by natural pigments freshness indicators, this paper highlights optimization strategies to enhance their sensitivity and stability, including modification, co-pigmentation, natural pigments mixing, encapsulation, and metal-ion complexation. The exploitation of these optimization strategies can help develop natural pigment-based intelligent packaging with superior performance to meet the food industry's needs for quality and safety monitoring.

Whey Protein Hydrogels and Emulsion Gels with Anthocyanins and/or Goji Oil: Formation, Characterization and In Vitro Digestion Behavior

Whey protein isolate (WPI) has functional properties such as gelation and emulsification. Emulsion gels combine the benefits of both emulsions and hydrogels. In this study, WPI hydrogels and emulsion gels were developed with goji oil (GO) as the oil phase by the inclusion of blueberry extract (BE) in the protein matrix. Heat-denatured WPI (hWPI) particles and emulsions were characterized in terms of size distribution, ζ-potential, interfacial protein, and anthocyanin partition. The inclusion of anthocyanins-rich blueberry extract led to the aggregation of hWPI particles, but it also increased the interfacial protein of 10% goji oil emulsions to 20% and decreased their size distribution to 120 and 325 nm. WPI hydrogels and emulsion gels were analyzed in terms of their water-holding capacity, which decreased from 98% to 82% with the addition of blueberry extract and goji oil. Syneresis, rheological, and morphological characteristics were also analyzed. The gelation time of hWPI particles and emulsions was shortened from 24 h to 12 h when incorporating blueberry extract to form a dense network. The network was the most homogeneous and densest in the presence of 3% blueberry extract and 5% goji oil. The co-inclusion of blueberry extract and goji oil increased the syneresis during the freeze-thaw cycles, with the values rising from 13% to 36% for 5% BE hydrogel and BE-containing emulsion gels after the first cycle. All WPI hydrogels and emulsion gels exhibit predominantly elastic behavior. Moreover, anthocyanin release, antioxidant activity, and the fatty acid composition profile were also analyzed during in vitro digestion. Soluble and free anthocyanins in the digested medium were reduced with the goji oil content but increased with the blueberry extract content. The stability of polyunsaturated fatty acids in the digested medium was improved by the addition of blueberry extract. The antioxidant activity of the digested medium increased with the content of blueberry extract but decreased with the content of goji oil. The ABTS∙+ scavenging capacities decreased from 63% to 49% by increasing the content of GO from 0% to 10% and they increased from 48% to 57% for 5% BE and 10% GO emulsion gels as the BE content increased from 0% to 5% after 6 h of digestion. The data gathered should provide valuable insights for future efforts to co-encapsulate hydrophilic and hydrophobic agents, thereby enhancing their stability, bioavailability, and functional properties for potential applications in food industries.

Preparation and characterization of W/O/W purple potato anthocyanin nanoparticles: Antioxidant effects and gut microbiota improvement in rats

Purple potato anthocyanins (PPAs) are recognized for their broad physiological activities, including significant antioxidant, antimicrobial, and gut microbiota-regulating effects. However, their limited bioavailability in biological systems restricts the full realization of these potentials. In order to improve the bioavailability of PPA, this paper established and optimized the preparation process of W/O/W purple potato anthocyanin nanoparticles (PPA-NPs). Based on the determination of the metabolites of PPA-NPs, in vivo experiments were conducted in rats to investigate the absorption and metabolism, antioxidant activity, and the impact on the intestinal microbiota of PPA-NPs. UPLC-Q-TOF-MSMS analysis showed that the absorption of anthocyanins was increased by 220.36% in rats gavaged with PPA-NPs compared to rats gavaged with PPA directly. Subsequent in vivo experiments revealed that PPA-NPs significantly bolster primary antioxidant markers, evidenced by elevated glutathione and superoxide dismutase levels and reduced malondialdehyde content. Moreover, PPA-NPs were found to positively alter the gut microbiome structure in aged rats, notably increasing the abundance of beneficial bacteria, such as Lactobacillus and Rothia, and improving microbial diversity. These findings suggest that W/O/W PPA-NPs markedly improve the bioavailability of PPAs, showcasing promising antioxidant properties and potential health benefits for gut health in vivo. Overall, this research presents a novel approach for developing nanodelivery systems aimed at enhancing the bioavailability of water-soluble substances.

Formulation and characterization of nanocapsules loaded with roselle anthocyanins extract and enhancement of anthocyanins bioaccessibility

Hibiscus sabdariffa L. (roselle) is a medicinal and edible plant which rich in anthocyanins with potent antioxidant properties. To enhance the stability of roselle anthocyanins, they were encapsulated in nanocapsules composed of carboxymethyl chitosan (CMC), chitosan hydrochloride (CHC), and β-lactoglobulin (β-Lg). In vitro simulated digestion assays evaluated the impact of various core-to-wall ratios and β-Lg concentrations on the bioaccessibility of seven anthocyanins. Nanocapsules with a core-to-wall ratio of 1:2 and β-Lg at 10 mg/mL exhibited the highest encapsulation efficiency (EE). Cyanidin-3-glucoside had the highest EE, while cyanidin-3-sambubioside showed the outstanding retention rate. Furthermore, simulated digestion experiments combined with molecular docking revealed that peonidin-3-glucoside and petunidin-3-glucoside likely interact with and bind to the outer β-Lg layer of the nanocapsules, increasing their release during in vitro digestion. This study demonstrates that encapsulating roselle anthocyanins in CMC, CHC, and β-Lg nanocapsules significantly enhances their bioaccessibility.

Euonymus maximowiczianus aril-derived long-term suspension-cultured cells: Light and methyl jasmonate impact in the anthocyanin and VLCFA accumulation

The genus Euonymus (L.) consists of shrubs and woody plants, distributed mainly in the Northern Hemisphere. Several hundred of secondary metabolites have been isolated from Euonymus spp. In addition, fatty oil was found in the fruits of some Euonymus spp., which accumulates not only in the seeds but also in the arils. This study presents the research of unique over ten-year-old suspension cell cultures of the endemic plant Euonymus maximoviczianus Prokh., obtained from the aril tissue of unripe capsules. The suspension cells retain the ability to form oil droplets containing neutral lipids. Both cells growing in the dark (Em-D culture) and cells growing in the light (Em-L culture) can synthesize very-long-chain fatty acids (VLCFAs) as well as cyanidin-3-O-hexoside, delphinidin-3-O-hexoside, and peonidin-3-O-hexoside. Here, we researched the VLCFA and anthocyanin accumulation dynamics during subcultivation, as well as the influence of methyl jasmonate (MeJA) and light on these processes. In the darkness, the formation of VLCFAs was more intense, while the biosynthesis of anthocyanins was significantly activated in the light. In Em-L cells, more than 76% of anthocyanins were represented by cyanidin-3-O-hexoside, and in Em-D cells delphinidin-3-O-hexoside was more actively synthesized (45%). MeJA substantially enhanced the accumulation of anthocyanins (especially in the light) and, surprisingly, the formation of VLCFAs in both Em-L and Em-D cell cultures. The possible competition between the biosynthetic pathways of VLCFAs and anthocyanins is discussed in connection with the commonality of the cytosolic pool of their precursor, malonyl-CoA.

Esterification of black bean anthocyanins with unsaturated oleic acid, and application characteristics of the product

Esterification of anthocyanins with saturated fatty acids have been widely investigated, while that with unsaturated fatty acids is little understood. In this study, crude extract (purity ∼ 35 %) of cyanidin-3-O-glucoside (C3G) from black bean seed coat was utilized as reaction substrate, and enzymatically acylated with unsaturated fatty acid (oleic acid). Optimization of various reaction parameters finally resulted in the highest acylation rate of 54.3 %. HPLC-MS/MS and NMR analyses elucidated the structure of cyanidin-3-O-glucoside-oleic acid ester (C3G-OA) to be cyanidin-3-O-(6″-octadecene)-glucoside. Introduction of oleic acid into C3G improved the lipophilicity, antioxidant ability, and antibacterial activity. Further, the color and substance stability analyses showed that the susceptibility of C3G and C3G-OA to different thermal, peroxidative, and illuminant treatments were highly pH dependent, which suggested individual application guidelines. Moreover, C3G-OA showed lower toxicity to normal cell (QSG-7701) and better inhibitory effect on the proliferation of HepG2 cells than C3G, which indicated its potential anti-tumor bioactivity.

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.

Development of a chitosan and whey protein-based, biodegradable, colorimetric/fluorescent dual-channel monitoring label for real-time sensing of shrimp freshness

To address the growing and urgent need for quick and accurate food spoilage detection systems as well as to reduce food resource wastage, recent research has focused on intelligent bio-labels using pH indicators. Accordingly, we developed a dual-channel intelligent label with colorimetric and fluorescent capabilities using black lycium anthocyanin (BLA) and 9,10-bis(2,2-dipyridylvinyl) anthracene (DSA4P) as colorimetric and fluorescent indicators within a composite film consisting of chitosan (Cs), whey protein (Wp), and sodium tripolyphosphate (STPP). The addition of STPP as a cross-linking agent significantly improved the hydrophobicity, mechanical properties, and thermal stability of the Cs/Wp composite films under low pH conditions. After the incorporation of BLA and DSA4P, the resulting dual-channel intelligent label (Cs/Wp/STPP/BLA/DSA4P) exhibited superior hydrophobicity, as indicated by a water contact angle of 78.03°. Additionally, it displayed enhanced mechanical properties, with a tensile strength (TS) of 3.04 MPa and an elongation at break (EAB) of 81.07 %, while maintaining a low transmittance of 28.48 % at 600 nm. After 25 days of burial in soil, the label was significantly degraded, which showcases its eco-friendly nature. Moreover, the label could visually detect color changes indicating volatile ammonia concentrations (25-25,000 ppm). The color of the label in daylight gradually shifted from brick-red to light-red, brownish-yellow, and finally light-green as the ammonia concentration increased. Correspondingly, its fluorescence transitioned from no fluorescence to green fluorescence with increasing ammonia concentration, gradually intensifying under 365-nm UV light. Furthermore, the label effectively monitored the freshness of shrimp stored at temperatures of 4 °C, 25 °C, and - 18 °C. Thus, the label developed in this study exhibits significant potential for enhancing food safety monitoring.

Cloned genes and genetic regulation of anthocyanin biosynthesis in maize, a comparative review

Anthocyanins are plant-based pigments that are primarily present in berries, grapes, purple yam, purple corn and black rice. The research on fruit corn with a high anthocyanin content is not sufficiently extensive. Considering its crucial role in nutrition and health it is vital to conduct further studies on how anthocyanin accumulates in fruit corn and to explore its potential for edible and medicinal purposes. Anthocyanin biosynthesis plays an important role in maize stems (corn). Several beneficial compounds, particularly cyanidin-3-O-glucoside, perlagonidin-3-O-glucoside, peonidin 3-O-glucoside, and their malonylated derivatives have been identified. C1, C2, Pl1, Pl2, Sh2, ZmCOP1 and ZmHY5 harbored functional alleles that played a role in the biosynthesis of anthocyanins in maize. The Sh2 gene in maize regulates sugar-to-starch conversion, thereby influencing kernel quality and nutritional content. ZmCOP1 and ZmHY5 are key regulatory genes in maize that control light responses and photomorphogenesis. This review concludes the molecular identification of all the genes encoding structural enzymes of the anthocyanin pathway in maize by describing the cloning and characterization of these genes. Our study presents important new understandings of the molecular processes behind the manufacture of anthocyanins in maize, which will contribute to the development of genetically modified variants of the crop with increased color and possible health advantages.

Echinacoside: A promising active natural products and pharmacological agents

Echinacoside, a natural phenylethanoid glycoside, was discovered and isolated from the garden plant Echinacea angustifolia DC., belonging to the Compositae family, approximately sixty years ago. Extensive investigations have revealed that it possesses a wide array of pharmacologically beneficial activities for human health, particularly notable for its neuroprotective and anticancer activity. Several crucial concerns surfaced, encompassing the recognition of active metabolites that exhibited inadequate bioavailability in their prototype form, the establishment of precise molecular signal pathways or targets associated with the aforementioned effects of echinacoside, and the scarcity of dependable clinical trials. Hence, the question remains unanswered as to whether scientific research can effectively utilize this natural compound. To support future studies on this natural product, it is imperative to provide a systematic overview and insights into potential future prospects. The current review provides a comprehensive analysis of the existing knowledge on echinacoside, encompassing its wide distribution, structural diversity and metabolism, diverse therapeutic applications, and improvement of echinacoside bioavailability for its potential utilization.

The Efficiency of Selected Green Solvents and Parameters for Polyphenol Extraction from Chokeberry (Aronia melanocarpa (Michx)) Pomace

Chokeberry pomace is a potential source of natural colourants, antimicrobial agents, and anti-senescence compounds due to its high polyphenols content. Therefore, this study assessed the efficiency of green solvents (50% ethanol, 50% glycerol, and 100% distilled water, all acidified with 1% citric acid or 1% formic acid) for anthocyanin and total phenolic content (TPC) extraction from lyophilised chokeberry pomace. Extraction was performed in a water bath at 40, 50, and 60 °C for 60 and 120 min, followed by ultrasonic treatment for 15 and 30 min. Based on the results, 50% ethanol + 1% citric acid yielded significantly higher total anthocyanin content in the case of both spectrometric and HPLC measurements (1783 ± 153 mg CGE/100 g DW and 879.5 mg/100 g DW) at 50 °C for 60 min. Citric acids seem more effective compared to formic acid. The highest values of TPC were obtained with 50% glycerol + 1% formic acid at 50 °C for 60 min (12,309 ± 759 mg GAE/100 g DW). This study provides evidence that a substantial quantity of polyphenols, which can potentially be used as a natural food additive, can be efficiently extracted with 50% ethanol + 1% citric acid or 50% glycerol at 50 °C for 60 min from chokeberry pomace.

Transcriptome and metabolome analysis reveals the effect of flavonoids on flower color variation in Dendrobium nobile Lindl

Introduction

Dendrobium nobile L. is a rare orchid plant with high medicinal and ornamentalvalue, and extremely few genetic species resources are remaining in nature. In the normal purple flower population, a type of population material with a white flower variation phenotype has been discovered, and through pigment component determination, flavonoids were preliminarily found to be the main reason for the variation.

Methods

This study mainly explored the different genes and metabolites at different flowering stages and analysed the flower color variation mechanism through transcriptome- and flavonoid-targeted metabolomics. The experimental materials consisted of two different flower color phenotypes, purple flower (PF) and white flower (WF), observed during three different periods.

Results and discussion

The results identified 1382, 2421 and 989 differentially expressed genes (DEGs) in the white flower variety compared with the purple flower variety at S1 (bud stage), S2 (chromogenic stage) and S3 (flowering stage), respectively. Among these, 27 genes enriched in the ko00941, ko00942, ko00943 and ko00944 pathways were screened as potential functional genes affecting flavonoid synthesis and flower color. Further analysis revealed that 15 genes are potential functional genes that lead to flavonoid changes and flower color variations. The metabolomics results at S3 found 129 differentially accumulated metabolites (DAMs), which included 8 anthocyanin metabolites, all of which (with the exception of delphinidin-3-o-(2'''-o-malonyl) sophoroside-5-o-glucoside) were found at lower amounts in the WF variety compared with the PF variety, indicating that a decrease in the anthocyanin content was the main reason for the inability to form purple flowers. Therefore, the changes in 19 flavone and 62 flavonol metabolites were considered the main reasons for the formation of white flowers. In this study, valuable materials responsible for flower color variation in D. nobile were identified and further analyzed the main pathways and potential genes affecting changes in flavonoids and the flower color. This study provides a material basis and theoretical support for the hybridization and molecular-assisted breeding of D. nobile.

Improving Blueberry Anthocyanins' Stability Using a Ferritin Nanocarrier

Blueberries are fruits known for their high level of anthocyanins, which have high nutritional value and several biological properties. However, the chemical instability of anthocyanins is one of the major limitations of their application. The stability of blueberry anthocyanin extracts (BAEs) encapsulated in a ferritin nanocarrier was investigated in this study for several influencing parameters, including pH, temperature, UV-visible light, redox agents, and various metal ions. The outcomes supported the positive role of protein nanoparticles in enhancing the stability of blueberry anthocyanins by demonstrating that the stability of encapsulated BAE nanoparticles with ferritin carriers was significantly higher than that of free BAEs and a mixture of BAEs and ferritin carriers. This study provides an alternative approach for enhancing blueberry anthocyanin stability using ferritin nanocarrier encapsulation.