Search Results (9)

The recent increase in sustainability awareness has triggered the industry to establish novel, eco-friendly sources of plant-based ingredients. In the present study, hibiscus flowers (Hibiscus sabdariffa L.) were investigated as a sustainable source of anthocyanins for use in spray-dried ingredients with antioxidant capacity. To this end, the extraction and spray-drying microencapsulation of hibiscus flower anthocyanins were optimized and the final products were evaluated for their oxidative stability index. Initially, preliminary experiments were carried out to evaluate the effects of selected processing parameters on anthocyanin extraction. Next, the extraction was optimized through a 2² central composite design, considering ethanol concentration (44–56% v/v) and extraction time (1.6–6.4 h) as independent factors. The optimum extraction conditions (8 h, 41.6% v/v ethanol concentration) were used to produce anthocyanin-rich extracts, which were microencapsulated by spray drying using a 2² central composite design with the carrier addition rate (1–3% w/v) and inlet temperature (160–192 °C) as factors. Maximum values of solids recovery (60.8%) and anthocyanin retention (96.0%) were reached when 3.2% w/v of starch–alginate carrier blend and a 170.7 °C inlet temperature were used. Finally, when hibiscus microcapsules were added to soybean oil, higher oxidative stability was achieved compared to the control. Overall, we demonstrate an industrially friendly and scalable approach that takes advantage of abundant hibiscus flowers as a viable source of anthocyanins for multiple applications. Full article

Lactic acid bacteria (LAB) produce important metabolites during fermentation processes, such as exopolysaccharides (EPS), which represent powerful natural antioxidants. On the other hand, H. sabdariffa L. anthocyanin extracts protect LAB and support their development. This study uncovers for the first time, the antioxidant profile of Weissella confusa PP29 probiotic media and focuses on elevating its impressive antioxidant attributes by synergistically integrating H. sabdariffa L. anthocyanin extract. The multifaceted potential of this innovative approach is explored and the results are remarkable, allowing us to understand the protective capacity of the fermented product on the intestinal mucosa. The total phenolic content was much lower at the end of the fermentation process compared to the initial amount, confirming their LAB processing. The DPPH radical scavenging and FRAP of the fermented products were higher compared to ascorbic acid and antioxidant extracts, while superoxide anion radical scavenging and lipid peroxidation inhibitory activity were comparable to that of ascorbic acid. The antioxidant properties of the fermented products were correlated with the initial inoculum and anthocyanin concentrations. All these properties were preserved for 6 months, demonstrating the promising efficacy of this enriched medium, underlining its potential as a complex functional food with enhanced health benefits. Full article

An on-package colorimetric label was fabricated using Hibiscus sabdariffa L. anthocyanin as a freshness indicator because its color depends on pH. The anthocyanins were embedded within a chitosan matrix. The colorimetric labels were applied to estimate the spoilage of fish food during storage at 25 °C for 3 days. According to scanning electron microscopy results, the inclusion of the anthocyanins in chitosan matrix resulted in formation dense and uniform film. The chitosan colorimetric labels had acceptable thicknesses (78–85 µm), moisture contents (14–16%), swelling indices (84–102%), water vapor permeabilities (3.0–3.2 × 10⁻¹¹ g m/m² s Pa), tensile strengths (11.3–12.3 MPa), and elongation at breaks (14–39%). It is noteworthy that the label can distinguish fish spoilage by color turn from light brown (fresh) to grayish (spoiled) by the naked-eye, due to alterations in the pH content and formation of volatile basic nitrogen during storage. Our results indicate that all-natural color labels can be an effective method to monitor the fish spoilage during storage, which may improve food quality and sustainability. Full article

To date, there are very few data regarding new efficient probiotics’ development with their own prebiotic substrate. All commercial products contain prebiotic substrate that was previously purified from external sources and added to the final product. The present study describes Weissella confusa strain fermentations in media with different anthocyanin concentrations from Hibiscus sabdariffa L., in order to increase the exopolysaccharide (EPS) yield, leading to augmented probiotic and prebiotic properties. The extracted and purified EPS were characterized by Gel permeation chromatography, Fourier-transform infrared, and nuclear magnetic resonance spectroscopy; thermal analysis measurements and the whole fermented media’s probiotic properties were evaluated by testing low pH and bile salt resistance, along with hydrophobicity and auto-aggregation capacity. The anthocyanins increased biomass and EPS yields and the high EPS molecular mass improved nutrient access by allowing a good microbial suspension in media. The confirmed dextran structure provides media biocompatibility and very good probiotic properties compared with existing literature. Simultaneously, the anthocyanins in media protected the strain cells against low pH and bile salt compared with the control fermentation. These very good results show that the whole fermented culture media is suitable for further in-vitro and in-vivo studies regarding its probiotic and prebiotic activity. Full article

Two successive field trials were carried out at the experimental farm of the Agriculture Department of Fayoum University, Fayoum, Egypt, to investigate the sole or dual interaction effect of applying a foliar spray of Aloe saponaria extract (Ae) or potassium silicate (KSi) on reducing the stressful salinity impacts on the development, yield, and features of roselle (Hibiscus sabdariffa L.) plants. Both Ae or KSi were used at three rates: 0% (0 cm³ L⁻¹), 0.5% (5 cm³ L⁻¹), and 1% (10 cm³ L⁻¹) and 0, 30, and 60 g L⁻¹, respectively. Three rates of salinity, measured by the electrical conductivity of a saturated soil extract (ECe), were also used: normal soil (ECe < 4 dS/m) (S1); moderately-saline soil (ECe: 4–8 dS/m) (S2); and highly-saline soil (ECe: 8–16 dS/m) (S3). The lowest level of salinity yielded the highest levels of all traits except for pH, chloride, and sodium. Ae at 0.5% increased the values of total soluble sugars, total free amino acids, potassium, anthocyanin, a single-photon avalanche diode, stem diameter, fruit number, and fresh weight, whereas 1% of Ae resulted in the highest plant height, chlorophyll fluorescence (Fv/Fm), performance index, relative water content, membrane stability index, proline, total soluble sugars, and acidity. KSi either at 30 or 60 g L⁻¹ greatly increased these abovementioned attributes. Fruit number and fruit fresh weight per plant also increased significantly with the combination of Ae at 1% and KSi at 30 g L⁻¹ under normal soil conditions. Full article

Hibiscus sabdariffa L. (H.s.) is a polyphenolic-rich plant commonly consumed either as a beverage or spice. The aim of the present study was to evaluate the in vitro digestibility of H.s. polyphenols using an in vitro model of digestion which simulates the human stomach and small intestine. The bioaccessible polyphenols released in the digested samples were analyzed by liquid chromatography coupled to photodiode array and mass spectrometry detection. H.s. anthocyanins (cyanidin-3-O-sambubioside and delphinidin-3-O-sambubioside) content drastically dropped during the digestion process from 2.91 ± 0.03 µg g⁻¹ and 8.53 ± 0.08 µg g⁻¹ (w/w) CG (Cyanidin-glucoside) in the raw extract, respectively, to 0.12 ± 0.01 µg g⁻¹ 0.12 ± 0.01 µg g⁻¹ (w/w) CG at the end of duodenal digestion. Total polyphenols also have shown a decrease from 1192.65 ± 30.37 µg g⁻¹ (w/w) in the raw extract to 282.24 ± 7.21 µg g⁻¹ (w/w) by the end of gastric digestion, in contrast to their increase by the end of duodenal digestion 372.91 ± 3.97 µg g⁻¹ (w/w). On the other hand, the decrease in certain compounds (e.g., caffeoylquinicandcoumaroylquinic acids) was observed during gastric digestion resulting in an increase of quinic acid in the duodenal aliquots, thus suggesting that this compound was derived from the degradation of the more complex hydroxycinnamic acids. H.s. extract also exhibited a bacteriostatic effect against Staphylococcus aureus ATCC 6538 (MIC of 2.5 mg mL⁻¹) and a bactericidal effect against a food isolate of Listeria monocytogenes (MBC of 2.5 mg mL⁻¹). The undigested polyphenols of H.s. in the upper gastrointestinal tract enters the colon, where they are metabolized by the gut microbiota. The present study results showed that resistance of H.s. polyphenols during gastrointestinal digestion might affect their uptake, resulting in a decrease in their digestibility. Full article

Background/Objectives: Hibiscus sabdariffa L. (H. sabdariffa (HS)) extract has a vascular relaxant effect on isolated rat thoracic aorta, but data on small resistance arteries, which play an important role on the development of hypertension, are still missing. The purposes of this study were (1) to assess the effect on isolated mesenteric arteries (MA) from normotensive (Wistar and Wistar-Kyoto (WKY)) and spontaneous hypertensive rats (SHR); (2) to elucidate the mechanism(s) of action underling the relaxant effect in light of bioactive components. Methods: Vascular effects of HS aqueous fraction (AF) on isolated MA rings, as well as its mechanisms of action, were assessed using the contractility and intracellular microelectrode technique. The patch clamp technique was used to evaluate the effect of HS AF on the L-type calcium current. Extraction and enrichment of AF were carried out using liquid–liquid extraction, and the yield was analyzed using HPLC. Results: The HS AF induced a concentration-dependent relaxant effect on MA rings of SHR (EC₅₀ = 0.83 ± 0.08 mg/mL), WKY (EC₅₀ = 0.46 ± 0.04 mg/mL), and Wistar rats (EC₅₀ = 0.44 ± 0.08 mg/mL) pre-contracted with phenylephrine (10 µM). In Wistar rats, the HS AF maximum relaxant effect was not modified after endothelium removal or when a guanylate cyclase inhibitor (ODQ, 10 µM) and a selective β2-adrenergic receptor antagonist (ICI-118551, 1 µM) were incubated with the preparation. Otherwise, it was reduced by 34.57 ± 10.66% when vascular rings were pre-contracted with an 80 mM [K+] solution (p < 0.001), which suggests an effect on ionic channels. HS AF 2 mg/mL significantly decreased the peak of the L-type calcium current observed in cardiac myocytes by 24.4%. Moreover, though the vasorelaxant effect of HS, AF was reduced by 27% when the nonselective potassium channels blocker (tetraethylammonium (TEA) 20 mM) was added to the bath (p < 0.01). The extract did not induce a membrane hyperpolarization of smooth muscle cells, which might suggest an absence of a direct effect on background potassium current. Conclusion: These results highlight that the antihypertensive effect of HS probably involves a vasorelaxant effect on small resistance arteries, which is endothelium independent. L-type calcium current reduction contributes to this effect. The results could also provide a link between the vasorelaxant effect and the bioactive compounds, especially anthocyanins. Full article

Hibiscus species (Malvaceae) have been long used as an antihypertensive folk remedy. The aim of our study was to specify the optimum solvent for extraction of the angiotensin-converting enzyme inhibiting (ACEI) constituents from Hibiscus sabdariffa L. The 80% methanol extract (H2) showed the highest ACEI activity, which exceeds that of the standard captopril (IC50 0.01255 ± 0.00343 and 0.210 ± 0.005 µg/mL, respectively). Additionally, in a comprehensive metabolomics approach, an ultra-performance liquid chromatography (UPLC) coupled to the high resolution tandem mass spectrometry (HRMS) method was used to trace the metabolites from each extraction method. Interestingly, our comprehensive analysis showed that the 80% methanol extract was predominated with secondary metabolites from all classes including flavonoids, anthocyanins, phenolic and organic acids. Among the detected metabolites, phenolic acids such as ferulic and chlorogenic acids, organic acids such as citrate derivatives and flavonoids such as kaempferol have been positively correlated to the antihypertensive potential. These results indicates that these compounds may significantly contribute synergistically to the ACE inhibitory activity of the 80% methanol extract. Full article

Crude, phenolic-rich extracts (CPREs) were isolated from different sources, such as Hibiscus sabdariffa (H. sabdariffa), Brassica oleracea var. capitata f. rubra (B. oleracea) and Beta vulgaris (B. vulgaris) and characterized. These CPREs showed potential antibacterial and antifungal activities. H. sabdariffa CPRE (HCPRE) is the most potent, as it inhibited all tested bacteria and fungi. Total anthocyanins content (TAC), total phenolic content (TPC) and total flavonoid content (TFC) were estimated in all three CPREs. H. sabdariffa contained 4.2 mg/100 g TAC, 2000 mg/100 g of TPC and 430 mg/100 g of TFC in a dry weight sample. GC–MS analysis of HCPRE showed 10 different active compounds that have antimicrobial effects against pathogenic bacteria and fungi, especially alcoholic compounds, triazine derivatives and esters. Scanning and transmission electron microscopy images of Staphylococcus aureus DSM 1104 and Klebsiella pneumonia ATCC 43816 treated with HCPRE (50 μg/mL) exhibited signs of asymmetric, wrinkled exterior surfaces, cell deformations and loss of cell shapes; and adherence of lysed cell content led to cell clumping, malformations, blisters, cell depressions and diminished cell numbers. This indicates death of bacterial cells and loss of cell contents. Aspergillus ochraceus EMCC516 (A. ochraceus, when treated with 100 μg/mL of HCPRE showed irregular cell organelles and cell vacuolation. Full article