Roselle Anthocyanins Research Articles

Anthocyanin Extraction from Roselle (Hibiscus sabdariffa L.) Calyces: A Microwave-Assisted Approach Using Box-Behnken Design

Roselle (Hibiscus sabdariffa L.) is a widely consumed edible flower, often utilized as a natural coloring agent. The bright red color of roselle is due to its anthocyanin content. Beyond their role as colorants, anthocyanins are known for their potent antioxidant properties, which have drawn significant interest for their potential health benefits. To fully harness the advantages of roselle's anthocyanins, developing a reliable extraction method is crucial. This study aimed to establish a fast, efficient, and environmentally friendly extraction technique using microwave-assisted extraction (MAE). Key factors, such as temperature (30, 65, and 100 °C), solvent concentration (30%, 50%, and 70% ethanol in water), and solvent-to-solid ratio (10:1, 25:1, 40:1), were optimized using the Box-Behnken design combined with response surface methodology. The extraction time (5-30 minutes) was also evaluated to maximize anthocyanin recovery. Two major anthocyanins, delphinidin-3-sambubioside and cyanidin-3-sambubioside, were identified using UHPLC-PDA-QToF-MS and quantified using a cyanidin-3-glucoside calibration curve. The optimal extraction conditions were found to be 72 °C, using 70% ethanol in water with a 40:1 solvent-to-solid ratio for 15 minutes. This method was validated with high accuracy (>98% recovery) and precision (CV <6%). It was successfully applied to quantify the anthocyanin content in both purple and red roselle varieties. This rapid and effective MAE method offers a more sustainable, energy-efficient, and time-saving alternative to conventional extraction methods, benefiting industries that rely on natural colorants and antioxidants.

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.

Extraction Effects on Roselle Functionalities: Antioxidant, Antiglycation, and Antibacterial Capacities.

This study investigated the effects of certain roselle (Hibiscus sabdariffa Linnaeus) extraction methods on various functional properties, including the antioxidant and antiglycation capacities and bacterial growth inhibition. Roselle anthocyanins were extracted using water and ethanol solvents at different temperatures and concentrations. The results revealed that the extraction rate increased with higher temperatures and ethanol concentrations (p < 0.05). Ethanol extracts exhibited higher total organic acid and total anthocyanin contents compared to water extracts, while water extracts showed higher total saccharide, total polyphenol, and total flavonoid contents (p < 0.05). Furthermore, the water extracts demonstrated superior Trolox equivalent antioxidant capacity (TEAC) values, while the ethanol extracts exhibited better 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability, antiglycation capacity, and bacterial growth inhibition. A Pearson correlation analysis revealed strong associations between specific components and functional properties, such as a positive correlation between the total anthocyanin content and antiglycation capacity (R2 = 0.9862). A principal component analysis and agglomerative hierarchical clustering highlighted distinct clusters of water and ethanol extracts, indicating solvent-dependent variations in functional properties. This study assessed roselle extraction models for antioxidant, antiglycation, and antibacterial activities, which could be used for the development of functional alcoholic or non-alcoholic beverages.

Chitosan-coated nanoliposome: An approach for simultaneous encapsulation of caffeine and roselle-anthocyanin in beverages

The objective of the present research was to develop chitosan-coated nanoliposomes using a modified heating method as a delivery system for simultaneous encapsulation of caffeine and roselle anthocyanin to fortify beverage. Response surface methodology was used to ascertain the optimized formulation, aiming to maximize the encapsulation efficiency, minimize the particle size, and maximize the zeta potential. The liposomes fabricated under the optimized conditions (lecithin to cholesterol ratio of 13 and wall to core ratio of 2.16) showed encapsulation efficiency values of 66.73 % for caffeine and 97.03 % for anthocyanin, with a size of 268.1 nm and a zeta potential of −39.11 mV. Fourier transform infrared spectroscopy confirmed the formation of hydrogen bonds between the polar sites of lecithin and the loaded core compounds. Thermal analysis suggested the successful encapsulation of the caffeine and anthocyanin. Transmission and scanning electron microscopy images confirmed a uniform spherical shape with a smooth surface. Fortifying the model beverage with the liposome and the chitosan-coated nanoliposome revealed higher values of encapsulation efficiency of anthocyanin (70.33 ± 3.11 %), caffeine (86.37 ± 2.17 %) and smaller size (280.5 ± 0.74 nm) of the chitosan-coated nanoliposomes at the end of 60the days. A hedonic sensory test of the fortified beverage with chitosan-coated nanoliposomes confirmed an improvement in the organoleptic properties of the beverage by masking its bitterness (receiving three more sensory scores in perceiving the bitterness intensity). Overall, our study indicates that the high potential of the chitosan-coated nanoliposomes for the simultaneous loading of the caffeine and anthocyanin, as well as their possible application in food and beverage formulations.

Non-covalent interactions of roselle anthocyanins with milk proteins and egg white protein

Roselle (Hibiscus sabdariffa L.) anthocyanins (RA) provides limited stability against hydration and pH changes during digestion which limit their bio-accessibility. The formation of protein-anthocyanin complexes offers a promising strategy for maintaining the stability of RA. Animal proteins are potential candidates for these interactions due to their high digestibility and balanced essential amino acid profile. In this study, we investigated the interactions of RA with animal proteins, specifically whey protein (WHEY) and casein (CAS) from milk, as well as ovalbumin (OVA) from egg white. Highly purified RA was obtained using XAD-7HP, SCX, and C18 column chromatography to facilitate the study of protein-anthocyanin interactions. Fluorescence spectra indicate that RA bound to the three proteins, leading to the quenching of their intrinsic fluorescence. UV–visible absorption spectra reveal changes in the polypeptide skeletons of the proteins after interacting with RA. Circular dichroism (CD) spectra show alterations in the secondary structure contents of α-helix, β-sheet, β-turn, and random coil upon interaction with RA. Molecular docking studies elucidate the docking active sites of proteins with RA. These interactions resulted in enhanced stability of RA during in vitro simulated digestion for all three proteins. Whey protein emerges as the most promising candidate for enhancing the stability of RA, thereby contributing to the potential application of RA in various food products. Our research provides a theoretical foundation for the utilization of WHEY-RA complexes in beverages and dairy products.

Development of Multilayered pH-Sensitive Chitosan–Gelatin-Agar Intelligent Film Incorporated with Roselle Anthocyanin Extract for Monitoring of the Freshness of Snapper Fish

Development of Multilayered pH-Sensitive Chitosan–Gelatin-Agar Intelligent Film Incorporated with Roselle Anthocyanin Extract for Monitoring of the Freshness of Snapper Fish

The Preservation Behavior and Modification Effect of Roselle Anthocyanin–Based Film on Penaeus Vannamei: Biochemical Property Evaluation and Flavor Composition Characterization

The Preservation Behavior and Modification Effect of Roselle Anthocyanin–Based Film on Penaeus Vannamei: Biochemical Property Evaluation and Flavor Composition Characterization

Microencapsulation of roselle (Hibiscus sabdariffa L.) anthocyanins: Effects of maltodextrin and trehalose matrix on selected physicochemical properties and antioxidant activities of spray-dried powder

This research was conducted to improve the stability of roselle anthocyanins by spray-drying using a single matrix (maltodextrin) and a binary matrix (maltodextrin-trehalose = 1:1). Each matrix was added to the core material at three different ratios: 30:70, 40:60, and 50:50. The physicochemical characteristics and antioxidant activity of microencapsulated powders were compared. The process using a single matrix with a 50:50 maltodextrin-to-extract ratio (MD-3) was identified as optimal. Spray-drying yield of MD-3 was 73.6 %, significantly higher (P < 0.05) than the other formulas. Encapsulation efficiency of MD-3 was 50.28 % and the powders was light red with a non-sticky texture, 2.5 % moisture content, and its red color was stable at pH 2.6–5. Average particle size of MD-3 was 4.48 μm with homogeneous distribution (PDI = 0.41400), spherical and amorphous particles. In the DPPH scavenging method, MD-3 powders exhibited antioxidant activity with an IC50 of 3397.55 μg/mL. Although the addition of trehalose to maltodextrin in the binary matrix did not produce better physicochemical characteristics, it significantly (P < 0.05) improved encapsulation efficiency (66.65–76.53 %). Therefore, further exploration is necessary to determine the appropriate maltodextrin-to-trehalose ratio in microencapsulating roselle extract. These findings enable further industrial application of different matrices to encapsulate anthocyanin as well as other bioactive compounds.

Intelligent food tag: A starch-anthocyanin-based pH-sensitive electrospun nanofiber mat for real-time food freshness monitoring

A starch-based nanofiber mat was prepared for real-time monitoring of food freshness for the first time. UV–vis results showed that roselle anthocyanins (RS) conferred a wide pH sensing range on the nanofiber mat. The prepared nanofiber mats demonstrated good color visibility (total color difference value (ΔE) increased to 56.4 ± 0.7) and a reversible response (within 120 s). Scanning electron microscopy and Fourier transform infrared spectroscopy results suggested that the nanofibers had smooth surfaces without beaded fibers and that RS was well embedded into the nanofibers. The introduction of RS improved the thermal stability of the nanofibers. Color stability tests revealed that the nanofibers exhibited excellent color stability (maximum change ΔE = 1.57 ± 0.03) after 14 days of storage. Pork and shrimp freshness tests verified that the nanofibers could effectively reflect the dynamic freshness of pork and shrimp. Nontoxic, degradable and responsive characteristics make the pH-sensitive nanofiber mat a smart food label with great application potential.

Scaling up stirring-assisted extraction and transformation of roselle anthocyanins into dried powder using spray-drying and oven-drying

Roselle (Hibiscus sabdariffa L.) is a source of anthocyanins with double functions as natural colorants and pharmacologically active ingredients in the food and pharmaceutical industries. Optimizing its extraction by upscaling and engineering the derived extract into its concentrated form or dry powder are thus needed. This study optimized the conditions of stirring-assisted extraction (SAE) of roselle calyces at an upscaled volume, determined the physicochemical and antioxidant properties of extract concentrated with rotary evaporation, and evaluated the effects of spray-drying and oven-drying on the powdered extract characterized from both properties. Results show that anthocyanin extraction from roselle was successfully upscaled using SAE with these optimized conditions: 50 % ethanol acidified with 2 % citric acid as the solvent, an S/L ratio of 1:15 g/mL, and three extraction cycles with a duration of 60 min each. Concentrated extracts (moisture content = 1.38–2.35 %) can be used as an alternative form of storage. Spray-drying with the matrix maltodextrin proved effective in producing dry powder with superior properties than oven-drying. Spray-drying and a 1:1 extract-to-maltodextrin ratio created more favorable dry powder: smooth surface, light red color, amorphous structure, spherical morphology, homogenous particle size (avg. 1.951 µm), total anthocyanin of 2.15 mg/g, antioxidant activity at IC50 = 203.56 µg/mL, and color stability maintained at pH = 2.6–4.0. These conditions enable extraction scale-ups for industrial production. Further, storage in thick concentrations and oven-drying can alternatives in specific cases when spray-drying is not doable.

The highly stable indicator film incorporating roselle anthocyanin co-pigmented with oxalic acid: Preparation, characterization and freshness monitoring application

A novel stable PVA/HPMC/roselle anthocyanin (RAE) indicator film co-pigmented with oxalic acid (OA) was prepared, its properties, application effects and stability enhancement mechanism were investigated correspondingly. The structural characterization revealed that more stable network was formed due to the co-pigmentation facilitated generation of molecular interactions. Meanwhile, the co-pigmentation improved film mechanical and hydrophobic properties compared to both PVA/HPMC/RAE newly prepared (PHRN) or stored (PHRS) film, expressing as higher tensile strength values (12.25% and 14.44% higher than PHRN and PHRS), lower water solubility (7.22% and 10.09% lower than PHRN and PHRS) and water vapor permeability values (33.20% and 21.05% lower than PHRN and PHRS) of PVA/HPMC/RAE/OA newly prepared (PHON) or stored (PHOS) film. Compared with the PHRS film, the PHOS film still presented more distinguishable color variations when being applied to monitor shrimp freshness, owing to the stabilization behaviors of co-pigmentation in anthocyanin conformation. Hence, the co-pigmentation was an effective strategy to enhance film stability, physical and pH-responsive properties after long term storage, leading to better film monitoring effects when applied in real-time freshness monitoring.

The stable co-pigmented roselle anthocyanin active film extended shelf life of Penaeus vannamei better: Mechanism revealed by the TMT-labeled proteomic strategy

In order to investigate the influences of modified RAE-based film on shrimp quality, the proteomic approach was performed to elucidate preservation mechanism. Results showed that the modified RAE-based film kept better shrimp quality compared with natural RAE-based film in terms of determined biochemical parameters and estimated shelf-life. Totally, 49 differentially abundance proteins (DAPs) were identified compared with shrimp without packaging. Bioinformatics analysis demonstrated that the modified RAE-based film could maintain functional DAPs which were mainly distributed in the binding, catalytic activity, etc., and metabolic signaling pathways like melanogenesis signaling pathway were remarkably enriched. Meanwhile, there were 25 DAPs showing close relationship with quality traits, and some of them, such as myosin chains, troponin I and heat shock protein were considered as the potential biomarkers to evaluate shrimp quality deterioration. In conclusion, this study revealed the preservation mechanism of modified RAE-based active film on shrimp quality at the protein molecular level.

Fabrication and characterization of colorimetric indicator for Salmon freshness monitoring using agar/polyvinyl alcohol gel and anthocyanin from different plant sources

In order to investigate the sensitivity of anthocyanins from different plant origin as indicators for salmon freshness, nine plant anthocyanins were extracted and fabricated into colorimetric sensor arrays to detect NH3, trimethylamine (TMA), dimethylamine (DMA) to indicate salmon freshness. Rosella anthocyanin had the highest sensitivity for amines, ammonia and salmon. HPLC-MSS analysis indicated that Delphinidin-3 glucoside accounted for 75.48 % of the Rosella anthocyanin. UV–visible spectral analysis showed that the maximum absorbance band of Roselle anthocyanins for acid and alkaline forms were located at 525 nm and 625 nm which showed a relatively broader spectrum than other anthocyanins. An indicator film was fabricated by combining Roselle anthocyanin with agar and polyvinyl alcohol (PVA), which showed visible changes from red to green when employed to monitor the freshness of salmon stored at 4 °C. The ΔE value of Roselle anthocyanin indicator film was changed from 5.94 to >10. The ΔE value also can predict the chemical quality indicators of salmon effectively, especially with characteristic volatile components, and the predictive correlation coefficient was above 0.98. Therefore, the proposed indicating film showed great potential monitoring salmon freshness.

The Effect of Cinnamon and Ginger Spices on Anthocyanins in Sweetened Roselle Beverages

This study explores the potential benefits of spices (cinnamon and ginger) on Roselle anthocyanins within a sweetened Roselle beverage matrix. Anthocyanins and other related properties of the beverage (colour, antioxidant capacity, total phenolics, and pH) were observed from the start and monitored for 30 days at accelerated storage conditions (40 °C). The sweeteners at the amounts used (80 g/L granulated sugar and 0.32 g/L Stevia Reb A) did not have a significant effect on the initial anthocyanin content in the beverage and did not significantly impact degradation. Upon the addition of spices to the sweetened beverage, ginger (1 g/L) did not result in significant changes, initially or during storage. However, following the addition of cinnamon (1 g/L) to the beverages (unsweetened and sweetened), an initial increase in the total phenolic and FRAP antioxidant activity in the Roselle beverages was observed; furthermore, it reduced the degradation of anthocyanins and improved colour stability during storage. This effect is postulated to be due to a co-pigmentation reaction or the acylation of anthocyanins with a complex formed from the reaction of glucose with the phenolic compounds contained in cinnamon.

A double-layer smart film based on gellan gum/modified anthocyanin and sodium carboxymethyl cellulose/starch/Nisin for application in chicken breast

In order to overcome this challenge of poor stability of natural anthocyanins in intelligent packaging materials, roselle anthocyanin (RA) was first modified by acetic acid, and then a double-layer smart indication antimicrobial film was developed using modified roselle anthocyanin (MRA)-gellan gum (GG) as the inner layer and sodium carboxymethyl cellulose (CMC)-starch (ST)-Nisin as the outer layer. UV spectra revealed that acetic acid was successfully grafted onto RA, which dramatically improved their thermal stability, antioxidant capabilities, photostability, and pH stability. The bilayer films were successfully prepared, as revealed by scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction measurements. In comparison to GG-MRA and CMC-ST-Nisin films, the water content, water solubility, mechanical characteristics, water vapor barrier, oxygen barrier, and hydrophobicity of GG-MRA@CMC-ST-Nisin films were significantly enhanced. The presence of the outer layer films significantly enhanced the UV–vis light barrier, opacity, antioxidant and antibacterial properties of the inner layer films. When the films were applied to chicken breast, it was found that the indicator films not only monitored the freshness of the chicken in real-time but also that the GG-MRA film and the double-layer film were effective in extending the shelf life of the chicken by 1 and 2 days, respectively, compared to the control group.

Improved thermal stability of roselle anthocyanin by co-pigmented with oxalic acid: Preparation, characterization and enhancement mechanism

The enhancement effects of co-pigmentation on thermal stability of roselle anthocyanin extract (RAE) were investigated. The introduction of organic acids maintained color stability of RAE, and RAE co-pigmented with oxalic acid (OA) presented less color fading rates (19.46 ± 0.33 %) and higher redness (41.33 ± 3.51). Subsequently, suitable co-pigmentation concentration (OA:RAE = 1:2) was obtained regarding with lower ΔE (48.70 ± 2.36). Then, improvement behaviors of co-pigmentation on OA-RAE were evaluated. Results demonstrated that OA-RAE exhibited better thermal stability, as manifested by larger retention rates and more favorable thermal degradation kinetic parameters. Furthermore, both molecular docking simulation and experimental structural characterization revealed that hydrogen bonds and other non-covalent bonds made up the main parts of molecular interactions, leading to formation of stable binary complex. As a result, the aromatic ring of RAE was protected. In conclusion, the co-pigmentation of RAE via introduction of OA was effective in stability enhancement due to the generation of molecular bindings.

The modification effects of roselle anthocyanin film on shrimp texture via water distribution controlling and protein conformation maintenance

The food's perishable properties and people's eco-friendly requirements have driven the biodegradable active packaging development. In this study, modification behaviors of polyviniyl alcohol/hydroxypropyl methylcellulose/roselle anthocyanin-based (PHR) film on textural profiles of Penaeus vannamei were investigated. Shrimp samples were packaged by PHR film with different roselle anthocyanin contents and stored at 4 ± 1 °C. The results indicated that PHR groups exhibited better texture with higher values of hardness (435.56 ± 75.52 g), springiness (0.53 ± 0.04 mm), chewiness (198.83 ± 40.98 N) and resilience (0.45 ± 0.04). The PHR film exerted positive influences on water migration by reducing drip loss and promoting conversion of free water into immobilized water. Meanwhile, the PHR film retarded protein denaturation via increasing myofibrillar protein and sulfhydryl group contents, decreasing TCA (trichloroacetic acid)-soluble peptide contents and maintaining protein secondary structure (higher α-helix ratio and lower β-sheet ratio). In conclusion, the PHR film improved shrimp texture by rearrangement of water distribution and stabilization of protein conformation. Hence, the PHR film was a novel potential active packaging for shrimp texture enhancement.

Characterization of Natural Anthocyanin Indicator Based on Cellulose Bio-Composite Film for Monitoring the Freshness of Chicken Tenderloin.

Intelligent packaging with indicators that provide information about the quality of food products can inform the consumer regarding food safety and reduce food waste. A solid material for a pH-responsive indicator was developed from hydroxypropyl methylcellulose (HPMC) composited with microcrystalline cellulose (MCC). MCC at 5%, 10%, 20%, and 30% w/w was introduced into the HPMC matrix and the physical, barrier, thermal, and optical properties of the HPMC/MCC bio-composite (HMB) films were analyzed. At 5, 10, and 20% MCC, improved mechanical, transparency, and barrier properties were observed, where HMB with 20% of MCC (H20MB) showed the best performance. Therefore, H20MB was selected as the biodegradable solid material for fabricating Roselle anthocyanins (RA) pH sensing indicators. The performance of the RA-H20MB indicator was evaluated by monitoring its response to ammonia vapor and tracking freshness status of chicken tenderloin. The RA-H20MB showed a clear color change with respect to ammonia exposure and quality change of chicken tenderloin; the color changed from red to magenta, purple and green, respectively. These results indicated that RA-H20MB can be used as a biodegradable pH sensing indicator to determine food quality and freshness.

Microencapsulation of roselle anthocyanins with β‐cyclodextrin and proteins enhances the thermal stability of anthocyanins

A Roselle extract was used in spray-drying encapsulation with three different wall materials (soy protein isolate, gelatin, and β-cyclodextrin) and combinations of those. The encapsulation efficiency, thermal stability, and microstructural evaluation of the encapsulated powder were further analyzed. The results showed that the encapsulation efficiency of gelatin, β-cyclodextrin, and soy protein isolate for purified roselle anthocyanins was 73.99 ± 2.66%, 89.75 ± 0.14%, and 98.51 ± 0.45%. The encapsulation efficiency of anthocyanins by the composite wall materials (β-cyclodextrin+gelatin, β-cyclodextrin + soy protein isolate, and soy protein isolate+gelatin) could reach above 99%. The microcapsules with β-cyclodextrin and soy protein isolate exhibited the smoothest curves of Fourier transform infrared spectroscopy within the characteristic peak of anthocyanins. The microcapsules containing gelatin have a surface structure with the least obvious holes or gaps and showed optimum thermal behavior. Novelty impact statement The pairwise combination of soy protein isolate, gelatin, and β-cyclodextrin as carriers of purified roselle anthocyanins yielded high encapsulation efficiency of over 99% The addition of β-cyclodextrin prevented the self-aggregation of proteins, making the encapsulation efficiency of composite wall materials higher than that of single-wall materials. The β-turn of the heated protein was enhanced during the formation of the microcapsules. This change made the wall material combine more tightly.

Separation and purification of anthocyanins from Roselle by macroporous resins

Anthocyanin is a kind of natural pigment with wide-range industrial application. In the present study, anthocyanins from Roselles were purified through macroporous resins adsorption and desorption process. Roselle anthocyanins were first extracted by water containing 0.2% HCl. Then, the adsorption/desorption performance of six resins was compared. The results showed that the adsorption capacity of DM28 was the largest, while the adsorption rate of DM21 was the fastest among the six resins. The static adsorption isotherm of the resins was simulated by Langmuir and Freundlich models, and the Freundlich model fitted better. The mass transfer zone model was used to analyze the dynamic adsorption of resins on a fixed bed. The mass transfer zone of each resin was calculated and the length of DM21 was the shortest. Anthocyanins in Roselle extract were successfully adsorbed by DM21 fixed bed, and then desorbed by 70% ethanol. After lyophilization, the anthocyanin content in the product was 6-fold increased with value of 214 mg/g. UPLC-QTOF analysis showed that delphinidin-3-O-sambubioside and cyanidin-3-O-sambubioside are the dominant anthocyanins in the product.