Stability Of Anthocyanins Research Articles

Anthocyanins stabilization of Hibiscus sabdariffa extract with sepiolite: Analytical and reactive force fields approaches

Anthocyanins are natural pigments responsible for color in fruits and flowers. They are unstable to diverse ambient conditions like pH, light, or the presence of ions. Thus, in industry, several techniques are employed to protect and use anthocyanins. Likewise, ancient Mayas used clay and indigo extract to prepare a pigment known as Maya Blue, resistant to time and chemicals. For this reason, this work aims to characterize the hibiscus extract and sepiolite bio-hybrids created according to Maya methodology and observe the stability of anthocyanins, which are color-responsible in flowers and fruits. Spectral analysis shows that anthocyanins and color were more stable than controls. Powder bio-hybrids show less color change under UV radiation and allochroic behavior in acid or alkaline atmospheres. At the same time, spectroscopy analyses and X-ray diffraction show no chemical interaction between sepiolite and hibiscus compounds. Our molecular dynamics with Reactive Force Fields (ReaxFF) studies reveal a similar behavior. Thus, our method protected the color of anthocyanins, in the temperature range from 15 to 35 °C. The interaction of hibiscus compounds with clay is due to van der Waals forces.

The Green Extraction of Blueberry By-Products: An Evaluation of the Bioactive Potential of the Anthocyanin/Polyphenol Fraction.

In the context of a circular economy, this study explores the valorization of blueberry pomace (BP) as a source of bioactive compounds using sustainable extraction methods. Microwave-assisted extraction (MAE) and microwave-assisted subcritical water extraction (MASWE) were employed to obtain two distinct fractions: MAE 1° and MASWE 2°. The first extract, MAE 1°, obtained at 80 °C, had a high total anthocyanin content (21.96 mgCya-3-glu/gextract), making it suitable as a natural pigment. Additionally, MAE 1° exhibited significant enzyme inhibition, particularly against α-amylase and β-glucosidase, suggesting potential anti-diabetic and anti-viral applications. The second extract, MASWE 2°, obtained at 150 °C, contained a higher total phenolic content (211.73 mgGAE/gextract) and demonstrated stronger antioxidant activity. MASWE 2° showed greater inhibition of acetylcholinesterase and tyrosinase, indicating its potential for use in Alzheimer's treatment, skincare, or as a food preservative. MASWE 2° exhibited cytotoxicity against HeLa cells and effectively mitigated H2O2-induced oxidative stress in HaCat cells, with MAE 1° showing similar but less pronounced effects. A tested formulation combining MAE 1° and MASWE 2° extracts in a 3:2 ratio effectively enhanced anthocyanin stability, demonstrating its potential as a heat-stable pigment. The extract characteristics were compared with a conventional method (MeOH-HCl in reflux condition), and the protocol's sustainability was assessed using several green metric tools, which provided insights into its environmental impact and efficiency.

Exploring the Biological Value of Red Grape Skin: Its Incorporation and Impact on Yogurt Quality.

The study was conducted to study the sustainability and enhanced nutrition gains obtained from incorporating grape skin powder (GSP) extracted from both Fetească Neagră and Rară Neagră grape varieties into yogurt. Grape skins are major leftovers from wineries, having high amounts of phenolic compounds and dietary fiber responsible for their ability to improve the characteristics of food. The research aimed to evaluate the effect of GSP addition at varying concentrations (0.5%, 1.0%, and 1.5%) on the yogurt's physicochemical properties, antioxidant activity, color parameters, and sensory attributes. Analysis revealed that both Fetească Neagră and Rară Neagră GSP increased the total phenolic content and antioxidant activity; however, Fetească Neagră showed greater improvements, with TPC reaching 1.52 mg GAE/100 g and DPPH inhibition up to 26.63%. Although slightly lower, TPC rose to 1.43 mg GAE/100 g and DPPH inhibition increased to 18.93% with Rară Neagră enhancing these parameters conversely. Color changes were observed in fortified yogurts where lightness decreased (L*) and redness increased (a*) due to the pH-dependent anthocyanin stability. Syneresis, indicative of yogurt's water-holding capacity, was reduced at higher concentrations of GSP from both varieties, suggesting improved textural integrity. Sensory evaluation indicated that consumers generally favored yogurts with lower concentrations of GSP. Yogurts fortified with Fetească Neagră GSP received higher overall preference, while those with Rară Neagră GSP were also well-received for their distinct flavor profiles when used at suitable levels. These results show that GSP from both types of grapes improves the nutritional value of yogurt and complies with the principles of sustainable food production through reutilizing agro-industrial waste.

Understanding the molecular structure of natural anthocyanins during recovery with ionic liquids: A combined COSMO-RS and experimental study

Anthocyanins, water-soluble vacuolar pigments found in various fruits and vegetables, exhibit vibrant red, purple, or blue hues contingent upon their pH levels. The stability of these pigments depends on pH. Due to that, conventional extraction methods use volatile organic acidic solvents in solid-liquid extractions (SLE). Despite the widespread use of such solvents, the molecular mechanisms governing the stability of anthocyanins during SLE with different solvents remain inadequately explored. This study aimed to enhance the understanding of anthocyanin stability by identifying alternative neoteric solvents, specifically hydrophilic ionic liquids (ILs). A COSMO-RS prescreening was conducted to evaluate the impact of solvent cations and anions on the anthocyanin skeleton during extraction from grape pomace. The results revealed that acetate-based ILs exhibited the highest affinity for anthocyanins. However, experimental validation demonstrated that hydrogen sulfate anion-based ILs, particularly [bmim][HSO4], yielded the most favorable outcomes, with approximately 4 mg/g of total anthocyanin equivalent at 298.15K while maintaining low pH values ensuring stability for anthocyanin molecules. Interestingly, the choice of cations within the ILs did not significantly influence the results. The main extraction mechanism is attributed to hydrogen bonding interaction. Thus, this research not only identifies an effective solvent for anthocyanin extraction but also sheds light on the crucial role of the neoteric solvent's acid characteristics in maintaining the structural integrity of these valuable pigments.

Effects of collagen hydrolysate on the stability of anthocyanins: Degradation kinetics, conformational change and interactional characteristics

Anthocyanins are desirable compounds in the food industry owing to their attractive color and high biological activity; however, their poor stability remains a substantial challenge. Here, we show that low-concentration (15 mg/mL) collagen hydrolysate (CH) exhibits a potent stabilization effect on red cabbage anthocyanins (RCAs). CH extended the half-life of RCA by 6.2-fold from 40.7 to 251.1 h. Dynamic light scattering and transmission electron microscopy confirmed the formation of CH–RCA complexes, which exhibited stronger antioxidant activity than RCA alone. Ultraviolet-vis and infrared spectra demonstrated that RCA binding resulted in a more open and disordered CH structure. Centaureidin-3-O-glucoside (C3G) exhibited high affinity for CH, with a binding ratio close to 1.5:1. 1H nuclear magnetic resonance confirmed that the main interaction sites with CH were at the C3G A- and C-rings. This study clarifies how protein hydrolysates protect against anthocyanin degradation from experimental and theoretical aspects.

Application of green deep eutectic solvents for anthocyanins extraction from grape pomace: Optimization, stability, antioxidant activity, and molecular dynamic simulation

The wine-making industry produces a large amount of grape pomace, which is rich in anthocyanins. To avoid wasting these resources, choline chloride: lactic acid (molar ratio of 1:2) (DES-1) was selected as the optimal solvent. The optimal extraction conditions were as follows: temperature 60°C, time 60 min, water content 25%. The anthocyanins yield was 5.73 mg (cyanidin-3-glucoside) equivalent/ g under the optimal conditions, which was significantly higher than that obtained by DES-3 (Choline chloride: 1,4 butanediol), DES-5 (Choline chloride: 1,2 propylene glycol), and ethanol. The DES-1 extract showed significant higher color stability and antioxidant activities compared with the anthocyanins extracted by DES-3, DES-5, and ethanol. A total of eight individual anthocyanin compounds were identified in each extract, with delphinidin 3-O-glucoside, peonidin 3-O- glucoside, petunidin, and delphinidin as the dominant compounds. Molecular dynamics simulation confirmed that DES-1 system showed a larger average number of hydrogen bonds (11.63), average lifetime of hydrogen bonds (364.21 ps) and with a reduced total interaction energy (-706.82 kJ/moL), thus improving the extraction efficiency and stability of anthocyanins. This study would provide new protocols for the extraction of anthocyanins from grape pomace.

Polysaccharide-potato protein coacervates for enhanced anthocyanin bioavailability and stability

Anthocyanins (ACNs) possess strong antioxidants, anti-cancer, anti-obesity, anti-diabetic, and anti-inflammatory properties but are limited use by their susceptibility to environmental factors. This study aims to overcome these limitations by developing and assessing a novel coacervate system, consisting of potato protein isolate (PPI) combined with various polysaccharides, to stabilize and encapsulate anthocyanins from black carrot concentrate The polysaccharides included in this system include inulin, gum Arabic, guar gum, pectin, and soluble fiber. The coacervate system's effectiveness in maintaining stability and increasing the bioavailability of anthocyanins was evaluated compared to conventional soybean protein-based systems. The results show that pH considerably influences potato protein solubility, with maximum solubility at strongly acidic (pH 2) conditions. Hygroscopicity and moisture content analysis of the coacervates showed significant variations, with potato protein-guar gum (PPIGG) microcapsules having the lowest moisture content and potato protein gum Arabic (PPIGA) microcapsules having the highest moisture content. SEM imaging illustrated distinct microcapsule morphologies, while FT-IR measurement verified the successful integration of proteins and polysaccharides. The significance of the research reflects its proof that potato protein isolate (PPI) based coacervate systems consists of potato protein with polysaccharides, particularly those containing gum Arabic and pectin, have significant potential for improving anthocyanin stability and bioavailability. These findings guide future studies to investigate other polysaccharides, improve coacervation processes, and explore applications in the food and nutraceutical sectors. It also offers valuable insights for creating efficient encapsulation techniques for bioactive substances.

Effects of L-Proline on the Stability of Mulberry Anthocyanins and the Mechanism of Interaction between L-Proline and Cyanidin-3-O-Glycoside.

The protective effects of L-aspartic acid, L-valine, and L-proline on the stability of mulberry anthocyanins were investigated. Results showed that L-aspartic acid, L-valine, and L-proline significantly enhanced (p < 0.05) the stability of mulberry anthocyanins under constant light or ascorbic acid (AA). L-Proline had the best protective effect against anthocyanin degradation. The interaction between L-proline and cyanidin-3-O-glucoside (C3G) through hydrogen bonding and van der Waals forces, which improved the stability of C3G, was confirmed using FT-IR, 1H NMR, XRD, and molecular docking analyses, as well as molecular dynamics modes. In vitro digestion experiments yielded that both 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical scavenging capacities of the C3G/Pro group were increased in the intestinal fluid (p < 0.05). The above findings suggest that L-proline effectively slowed down the degradation of mulberry anthocyanins, and that it could be used as an auxiliary pigment and food additive to extend the optimal flavor period of products containing mulberry anthocyanins, and can improve the bioavailability of mulberry anthocyanins.

Do anthocyanins affect acrylamide formation in wholemeal bakery products? A study on near-isogenic wheat lines

Near-isogenic wheat lines (NILs) derived from the variety Novosibirskaya 67, differing in grain color, were used to analyze the content of acrylamide in bakery products, as well as its precursors (glucose, fructose, asparagine) and anthocyanins, in key steps of bread preparation. The total anthocyanin content of the flour averaged 2.49 and 30.8 mg/kg for the purple and blue NILs, respectively. However, purple NILs showed higher anthocyanin stability during processing compared to blue NILs, with the total content changing to 113 and 37% of the initial value in the flour. The acrylamide content of the product ranged from 83.3 to 132 μg/kg and was moderately positively correlated with the dough's asparagine (r = 0.529) and fructose (r = 0.441) content. The non-significant negative correlation found between acrylamide and anthocyanins (r = −0.268) indicates that anthocyanins do not significantly affect the formation of this process contaminant and therefore, their presence in wheat grain does not pose a health risk to consumers.

Blueberry (Vaccinium spp.) Anthocyanins and Their Functions, Stability, Bioavailability, and Applications.

Blueberry fruits are rich in anthocyanins. There are 25 known anthocyanidins found in blueberries (Vaccinium spp.) until now. Anthocyanins found in blueberries have attracted considerable interest for their outstanding abilities as antioxidants, anti-inflammatory agents, anti-diabetic, anti-obesity, and neuroprotection compounds, as well as their potential for preventing cardiovascular diseases, protecting vision, and inhibiting cancer development. However, their application is constrained by issues related to instability and relatively low bioavailability. Thus, this review provides a detailed overview of categories, functions, stability, and bioavailability of blueberry anthocyanins and their practical applications. The available studies indicate that there is more potential for the industrial production of blueberry anthocyanins.

Sweet potato protein hydrolysates solidified calcium-induced alginate gel for enhancing the encapsulation efficiency and long-term stability of purple sweet potato anthocyanins in beads

Based on the previous research, this work aimed to reveal the effect of sweet potato protein hydrolysates (SPPHs) with different molecular weights (1000, 3000, and 8000 Da) at 0.5 % on the gelation behavior of calcium-induced sodium alginate (SA), and the encapsulation efficiency and storage stability of purple sweet potato anthocyanins (PSPA) in calcium-induced alginate gel beads was determined. Results indicated that SPPHs with a molecular weight of 8000 Da formed hydrogen bonds and other interactions with SA, which strengthened the internal network connections of the gel, significantly enhanced the gel and effectively filled its pores. The highest encapsulation efficiency was achieved at 87.27 %, compared to 61.73 % without SPPHs. Additionally, stored at 37 °C for 21 days after commercial sterilization, the residual concentration of PSPA with SPPHs was 2.50 times higher than that without SPPHs. SPPHs can enhance the encapsulation efficiency of PSPA and retard their release in gel beads.

Can natural pigments in different emulgel phases stabilize each other against UV radiation? Anthocyanin and β-carotene co-loaded in an emulgel based on soy protein isolate-gellan gum conjugates

Despite poor stability of natural pigments against degradation, using these colorants have attracted great interest due to their various beneficial effect on human health. Accordingly, in the present study, an emulgel based on soy protein isolate-gellan gum conjugate was fabricated via Millard reaction. Then, the effectiveness of emulgel on improving the stability of anthocyanin (ACN) and β-carotene (BC) with different loading concentration (5, 10, and 15 mg/mL) against UV-C irradiation was investigated. Degradation kinetic results exhibited the higher stability of ACN upon co-loading with BC, as the half-life of ACN in free aqueous solution, loaded and co-loaded in emulgel was found to be 0.698, 2.648 and 3.164 days, respectively. The emulgel effectively improved the stability of BC, as well, and no degradation was observed during storage time. The release studies of the pigments showed Fickian diffusion mechanism. Furthermore, their release patterns were found to be independent and differences among the release from individual or simultaneous loaded system were rather small. Overall, our findings elucidated the promising potential of co-loading within emulgel as a safe delivery system in stability enhancement of natural pigments.

Exploring the effects of whey protein components on the interaction and stability of cyanidin-3-O-glucoside.

Anthocyanins are susceptible to degradation due to external factors. Despite the potential for improved anthocyanin stability with whey protein isolate (WPI), the specific effects of individual components within WPI on the stability of anthocyanins have yet to be studied extensively. This study investigated the interaction of WPI, β-lactoglobulin (β-Lg), bovine serum albumin (BSA), and lactoferrin (LF) with cyanidin-3-O-glucoside (C3G), and also considered their effects on stability. Fluorescence analysis revealed static quenching effects between C3G and WPI, β-Lg, BSA, and LF. The binding constants were 1.923 × 103 L · mol⁻¹ for WPI, 24.55 × 103 L · mol⁻¹ for β-Lg, 57.25 × 103 L · mol⁻¹ for BSA, and 1.280 × 103 L · mol⁻¹ for LF. Hydrogen bonds, van der Waals forces, and electrostatic attraction were the predominant forces in the interactions between C3G and WPI and between C3G and BSA. Hydrophobic interaction was the main binding force in the interaction between C3G and β-Lg and between C3G and LF. The binding of C3G with WPI, β-Lg, BSA, and LF was driven by different thermodynamic parameters. Enthalpy changes (∆H) were -38.76 kJ · mol⁻¹ for WPI, -17.59 kJ · mol⁻¹ for β-Lg, -16.09 kJ · mol⁻¹ for BSA, and 39.50 kJ · mol⁻¹ for LF. Entropy changes (∆S) were -67.21 J · mol⁻¹·K⁻¹ for WPI, 3.72 J · mol⁻¹·K⁻¹ for β-Lg, 37.09 J · mol⁻¹·K⁻¹ for BSA, and 192.04 J · mol⁻¹·K⁻¹ for LF. The addition of C3G influenced the secondary structure of the proteins. The decrease in the α-helix content suggested a disruption and loosening of the hydrogen bond network structure. The presence of proteins enhanced the light stability and thermal stability (stability in the presence of light and heat) of C3G. In vitro simulated digestion experiments demonstrated that the addition of proteins led to a delayed degradation of C3G and to improved antioxidant capacity. The presence of WPI and its components enhanced the thermal stability, light stability, and oxidation stability of C3G. Preheated proteins exhibited a more pronounced effect than unheated proteins. These findings highlight the potential of preheating protein at appropriate temperatures to preserve C3G stability and bioactivity during food processing. © 2024 Society of Chemical Industry.

Design of a liposome casein hydrogel as an efficient front-end homeostatic anthocyanin loading system

Proteins have been studied and applied to improve the stability of anthocyanins (ACNs), but the changes in the pH microenvironment during the preparation of steady-state systems are often ignored, and more attention is given to the stability of the system after preparation. In this study, we propose the “anthocyanin front-end homeostasis strategy”, which involves designing a system can protect anthocyanins under acidic conditions so that more anthocyanin prototypes can be loaded inside the protein. Anthocyanins are encapsulated in liposomes (Lip) at pH 3.0 and combined with casein methacrylate (CSMA) to form Anthocyanin-loaded liposomes/CSMA hydrogel (Lip@ACNs/CSMA), with good physical properties and good blood compatibility. The system increased the hydrogen peroxide scavenging capacity by 1.16 mg Vc equiv./mg ACNs and the cellular antioxidant activity by 17.55 μM quercetin/100 mg ACNs, the photo and thermal storage stability increased by 36.50 % and 30.71 %, the digestive rate increased by 17.50 %, and the biological availability increased by 0.0049 mg/mL. This study designed a liposome casein hydrogel as an efficient front-end homeostatic anthocyanin loading system and provided a new approach for improving the stability of anthocyanins.

Storage stability and in vitro release characteristics of black rice anthocyanins microencapsulated by pectin and sodium carboxymethyl cellulose

To improve the stability of black rice anthocyanins (ANS), microcapsules based on ANS, pectin, or/and sodium carboxymethyl cellulose (CMC) were successfully prepared. The encapsulation efficiency (EE), FTIR, color, storage stability, antioxidant activity, and release character of encapsulated anthocyanins during in vitro digestion were determined. The results indicated that the EE using pectin, CMC, and pectin/CMC were 81.6 ± 0.3%, 70.4 ± 0.4%, and 79.4 ± 0.2%, respectively. The microcapsules showed a red-purple color, and the interactions between ANS and pectin/CMC were confirmed by FTIR analysis. The retention rate of anthocyanins was 53.8%, 58.7%, 75.6%, and 85.2% in the sample of ANS, pectin, CMC, and pectin/CMC microcapsules, respectively, after 60 days of storage. Furthermore, encapsulation also decreased the loss of antioxidant activity of ANS, and the pectin and CMC combination at a ratio of 1:1 showed a better protective effect than the individual using of pectin or CMC. The in vitro release experiments revealed that the ANS was majorly released in the intestine, and the release rate in pectin microcapsules was lower than that in CMC microcapsules. In conclusion, compared with the individual wall material, microencapsulation using the combination of pectin and CMC improved the storage stability to protect against the degradation of ANS.

Preparation and structural characterization of chitosan‑sodium alginate nanocapsules and their effects on the stability and antioxidant activity of blueberry anthocyanins

This study prepared a nanocapsule (NPs) from chitosan (CS) and sodium alginate (ALG) and used them to enhance the stability of blueberry anthocyanins (BA) The optimal NPs was obtained at pH value of 3.25, BA concentration of 0.5 mg/mL and mixing ratio of CS to ALG of 1:1 (W/W). Further, the formation of composite NPs was confirmed by a series of characterization methods. The CS-BA-ALG NPs appeared spherical, smooth, and evenly distributed when observed under an optical microscope and transmission Electron Microscope. The X-ray Diffractometer and Fourier Transform Infrared spectroscopy data proved that electrostatic interaction and hydrogen bonding are dominant forces to form NPs. Thermogravimetric analysis and differential scanning calorimetry results demonstrated that the CS-BA-ALG NPs system significantly improved the thermal stability of anthocyanins. In addition, it was also proved that CS-BA-ALG NPs showed high antioxidant capacity and protection capacity.

Ultrasound-assisted glycosylation of ovalbumin and dextran conjugate carrier for anthocyanins and their stability evaluation

Anthocyanins (AC) are vulnerable to degradation when affected by external factors. The present study employed ultrasound-assisted glycosylation of ovalbumin (OVA) and dextran (Dex) to generate conjugate carrier for AC to improve its stability. The results showed that sonication significantly improved the progression of Maillard reaction to OVA. Compared to traditional glycosylation, ultrasound treatment showed a higher degree of grafting, a lower number of free-SH, and smaller particle size and uniform distribution. The SDS-PAGE results indicated covalent interaction. Intrinsic fluorescence (INF), Fourier transform infrared spectroscopy (FTIR), and Circular dichroism (CD) analysis results suggested that ultrasound-assisted glycosylation altered the OVA structure. The scanning electron microscope (SEM) and X-ray diffractometer (XRD) observed that the ultrasound-assisted complex had a more compact and smoother structure and protein unfolding were better. The protein solubility increased significantly after glycosylation. Thermal gravimetric analysis (TGA) and Differential scanning calorimetry (DSC) indicated that the glycosylated conjugates can significantly improve the thermal stability of AC In addition, the AC showed an improved processing and storage stability when conjugated with glycosylated carrier. The glycosylated protein-anthocyanins complex may help provide new ideas and scientific basis for the development of naturally sourced anthocyanins-relevant products in pharmaceutical and food industry applications.

Starch-Based Functional Films Enhanced with Bacterial Nanocellulose for Smart Packaging: Physicochemical Properties, pH Sensitivity and Colorimetric Response.

Starch-based pH-sensing films with bacterial nanocellulose (BNC) and red cabbage anthocyanins (RCA) as active components were investigated in this research. Their structural, physical, surface and colorimetric properties were analyzed, mainly as a function of BNC concentration. The aim of the research was to relate the changes in the intermolecular interactions between the components of the films (starch, anthocyanins and BNC) to the physical, surface and colorimetric properties that are important for the primary intended application of the produced films as pH indicators in smart packaging. The results showed that maize starch (MS) was more suitable as a matrix for the stabilization of anthocyanins compared to potato starch (PS). PS-based films showed a lower value of water contact angle than MS-based films, indicating stronger hydrophilicity. The swelling behavior results indicate that the concentrations of BNC in MS-based films (cca 10%) and the concentration of about 50% BNC in PS-based films are required if satisfactory properties of the indicator in terms of stability in a wet environment are to be achieved. The surface free energy results of PS-based films with BNC were between 62 and 68 mJ/m2 and with BNC and RCA between 64 and 68 mJ/m2; for MS-based films, the value was about 65 mJ/m2 for all samples with BNC and about 68 mJ/m2 for all samples with BNC and RCA. The visual color changes after immersion in different buffer solutions (pH 2.0-10.5) showed a gradual transition from red/pink to purple, blue and green for the observed samples. Films immersed in different buffers showed lower values of 2 to 10 lightness points (CIE L*) for PS-based films and 10 to 30 lightness points for MS-based films after the addition of BNC. The results of this research can make an important contribution to defining the influence of intermolecular interactions and structural changes on the physical, surface and colorimetric properties of bio-based pH indicators used in smart packaging applications.

Identification and characterization of HCT genes in blackberry: Overexpression of RuHCT1 enhances anthocyanin contents

Emerging as a new generation of economic fruit, blackberries are rich in flavonoids and anthocyanins. Acylation can change the pharmacological activity and structural stability of anthocyanins and is of great significance to plant growth and secondary metabolism. In this study, based on the transcriptome data of the blackberry fruit, five blackberry hydroxycinnamoyl transferase (HCT) genes were screened and identified, all of which belong to the BAHD superfamily. Among them, RuHCT1, RuHCT2 and RuHCT3 have similar tertiary structures and functions. RuHCT1, the gene with the largest difference in expression between immature and mature blackberry fruits, was selected for overexpression research. The results showed that the content of anthocyanin in the leaves of transgenic plants was significantly increased, while the content of secondary metabolites such as lignan and chlorogenic acid was decreased. Moreover, the expression levels of the NtCCOMT, NtCHS and NtCYP98A genes in transgenic tobacco were lower than those in nontransgenic plants. In conclusion, RuHCT1 may be an important structural gene regulating anthocyanin synthesis in blackberry. RuHCT1 may also inhibit lignan synthesis and affect the expression of other key structural genes. This study provides a theoretical reference regarding the biosynthesis and regulatory mechanisms of anthocyanins in blackberry, contributing to the breeding of new blackberry cultivars with high anthocyanin content.

The Effect of pH and Temperature on The Stability of Anthocyanins from Black Soybean Skin Extracts

Anthocyanins are natural dyes of purple and red. Anthocyanin dyes are applied in various industries as a drink or food coloring. As natural dyes, anthocyanins have an important role in human health. This research aimed to analyze the stability of anthocyanins from black soybean skin extract at varying pH and temperature. Anthocyanins from black soybean skins are macerated using two kinds of solvents. The solvents are distilled water + 30% citric acid and 70% ethanol + 1% HCl. Maceration was carried out at a temperature of 4℃. Then the anthocyanin was treated at a temperature range of 40-90℃ and pH of 5-9 and its absorbance was measured using UV-Vis’s spectrometry. The concentration of anthocyanin from black soybean skins is from the solvent distilled water + 30% citric acid of 1.992 mg/L, while from the solvent 70% ethanol + 1% HCl it was 1.936 mg/L. The color stability temperature t of black soybean skin extract was carried out at temperatures of 40°C, 50°C, 60°C, 70°C, 80°C, and 90°C. with respective absorbance of 0.274; 0.247; 0.237; 0.227; and 0.214. The higher the temperature, the anthocyanin content decreases. pH test was carried out at pH 5, 6, 7, 8, and 9 with respective absorbance values of 1.831; 1,759; 1,229; 1,118; and 1,066. The pH test showed that the higher the pH, the anthocyanin content was reduced, while the application of additional anthocyanin to white agar as food coloring showed that the anthocyanin content was only 0.125. It can be concluded that anthocyanins have good stability at low temperatures and acidic pH.