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•Microwave was used for extraction of phenolic compounds from hibiscus.•Microwave potencies of 200, 300 and 700 W were used on hibiscus.•The use combined of microwave and aqueous ...acidic solution for extraction was studied.
Hibiscus is an edible flower with great industrial potential due to the presence of bioactive compounds. The aim of this study was to compare three extraction procedures of phenolic compounds from the calyx of hibiscus using only microwave assisted extraction (MAE), using a solution of citric acid followed by MAE, and MAE followed by extraction using a solution of citric acid. The results indicated that the best extraction condition was the combined extraction of 700 W for 8 min and subsequent extraction in acidic aqueous solution for 6 h, with the contents of 1.63 mg g−1, 29.62 mg g−1, 133.25 μmol g−1 for anthocyanins, total phenolics, and antioxidant activity, respectively. In extractions obtained by exhaustive extraction with methanol for 25 min and MAE at 700 W and 8 min, 13 compounds were found: six phenolic acids, two anthocyanins, and five flavonoids derived from quercetin, kaempferol, and myricetin. The major phenolic compounds were 3-caffeoylquinic acid (2.58 and 1.32 mg g−1) and 5-caffeoylquinic acid (1.71 and 0.90 mg g−1) for exhaustive extraction and MAE, respectively. The results suggest that MAE followed by extraction in acidic aqueous solution was the best alternative to recovery of phenolic compounds from hibiscus.
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•First attempt to utilize kenaf biomass (KB) for cost effective, sustainable PHB production.•Studied various pretreatment methods to utilize KB as feedstock for PHB ...production.•Pretreatment process enhanced saccharification of KB without fermentation inhibitors.•PHB produced exhibited similar structural and thermal properties alike standard PHB.•PHA accumulation, PHB yield using KB hydrolsates was similar to the synthetic sugars mixture.
Kenaf biomass (KB) was employed as feedstock for the synthesis of polyhydroxybutyrate (PHB) using Ralstonia eutropha to replace conventional petroleum-derived polymers. Various pretreatments followed by enzymatic saccharification were applied to release monomeric sugars from KB for PHB production. The effects of increasing concentration of Na2CO3 + Na2SO3 (NaC + NaS) pretreated KB hydrolysates (20–40 g/L) on PHB production were investigated. NaC + NaS pretreated KB hydrolysates (30 g/L) exhibited maximum 70.0% PHA accumulation, with PHB titers of 10.10 g/L and PHB yields of about 0.488 g/g of reducing sugar produced within 36 h of fermentation. PHA accumulation, PHB yield and R. eutropha growth performance using KB hydrolysates were found to be comparable with those of synthetic sugar mixture. Characterization of the produced PHB in terms of crystalline structure, and thermal properties was done using various analytical techniques and results coincide with standard PHB. Thus, green liquor pretreated KB hydrolysates deliver a promising and economically feasible carbon substrate for PHB production.
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•Temperature, co-solvent and pressure were evaluated by Response-surface methodology.•The phenolic characterization of extract conditions was analyzed by HPLC-ESI-TOF-MS.•Each ...chemical group showed different behavior against SFE.•The highest phytochemical content was obtained at 50 °C, 250 bar and 16.7% ethanol.
Hibiscus sabdariffa is used as potent phytochemical agent due to its phenolic composition. On the other hand, Supercritical Fluid Extraction (SFE) is considered a green extraction technique that provides a selective extraction using a supercritical solvent. In this work, extraction parameters such as temperature, pressure of CO2 and percentage of co-solvent were evaluated on the chemical composition of Hibiscus sabdariffa by Response Surface Methodology (RSM). After that, individual compound concentration was determined by HPLC-ESI-TOF-MS. This design, allowed found the optimal conditions for total phenolic and organic acids content. Each chemical group showed different behavior against SFE. Despite organic acids exhibited an irregular trend; the quadratic model was fitted for total phenolic compounds. Therefore, SFE has demonstrated to be a suitable and selective technique to maximize the extraction of several phytochemical compounds from H. sabdariffa calyces.
Soil amendments may increase the slate tolerance of plants consequently; it may increase the opportunity of using saline water in agricultural production. In the present pot trial, the effects of ...biochar (BIC) and compost (COM) on roselle (Hibiscus sabdariffa L.) irrigated with saline water (EC = 7.50 dS m
) was studied. Roselle plants were amended with biochar (BIC
and BIC
) or compost (COM
and COM
) at rates of 1 and 2% (w/w), as well as by a mixture of the two amendments (BIC
+). The experiment included a control soil without any amendments. Biochar and compost significantly enhanced the soil quality and nutrients availability under saline irrigation. Compost and biochar improved the degree of soil aggregation, total soil porosity and soil microbial biomass. BIC
+ COM
increased the soil microbial biomass carbon and nitrogen over the individual application of each amendments and control soil. BIC
+ COM
increased the activity of dehydrogenase and phosphatase enzymes. Growth of roselle plants including: plant height, shoot fresh and dry weight, and chlorophyll were significantly responded to the added amendments. The maximum sepal's yield was achieved from the combined application of compost and biochar. All the investigated treatments caused remarkable increases in the total flavonol and anthocyanin. BIC
+ COM
increased the total anthocyanin and flavonol by 29 and 17% above the control. Despite the notable improvement in soil and roselle quality as a result of the single addition of compost or biochar, there is a clear superiority due to mixing the two amendments. It can be concluded that mixing of biochar and compost is recommended for roselle plants irrigated with saline water.
Natural cellulosic fibres, such as kenaf, have potential for use as replacement of man-made fibres in polymeric composites. The rapid depletion of synthetic resources, such as petroleum, and the ...growing consciousness of global environmental problems related to synthetic products push toward the acceptance of natural fibres as biocomposite components. Kenaf (
Hibiscus cannabinus
L.) is a multipurpose hibiscus species used to make engineered wood, clothing, packing material, rope and twine. Kenaf is essentially made up of cellulose (about 70%), predicting its excellent mechanical performance. Kenaf fibres are chemically treated before mixing with other polymer resins to enhance their fibre properties. Based on the previous literature, the effect of chemical treatment on the dynamic mechanical performance of kenaf cellulosic biocomposites remains unexplored. The present review focuses on the recent works on the influence of major chemical treatments used on kenaf fibre, such as alkaline, silane and acetylation on fabricated biocomposites. The present review also unveils other chemical treatments (e.g. zein and amino acid) and combined treatments on the fibre to improve the biocomposites’ dynamic mechanical behaviour.
•Supercritical carbon dioxide (SC-CO2) extraction was applied for extraction of oil from Roselle seed.•Effects of temperature and pressure on the extraction yield were studied.•Optimization of the ...process was conducted using response surface methodology (RSM).•Optimized particle size of 300 μm and SC-CO2 flow rate at 5 mL/min was chosen for extraction.•Coefficient determination R2 for extraction oil yield and gamma tocopherol were 0.9723 and 0.9754.
Hibiscus sabdariffa L. (Roselle) seeds are rich in proteins, carbohydrates and unsaturated fatty acids, and are a good source of minerals and antioxidants. Supercritical carbon dioxide (SC-CO2) extraction was applied for extraction of oil from Roselle seed at temperatures of 40 °C to 80 °C and pressures of 20 MPa to 30 MPa. The effects of temperature and pressure on the extraction yield and solubility of oil were determined. Process optimization was carried out using response surface methodology (RSM). A particle size of 300 μm, SC-CO2 flow rate of 5 mL/min and extraction time of 180 min were held constant throughout this study. The overall oil yield increased as pressure and temperature was increased, while a reverse effect was observed at higher temperatures. The optimum extraction conditions for Roselle seed oil corresponded to a pressure of 30 MPa and temperature of 40 °C. According to the analysis of variance (ANOVA), the coefficient of determination R2 for oil yield and gamma tocopherol concentration were 0.9723 and 0.9754, respectively, indicating a good correlation and agreement between the experimental and predicted values.
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•Antioxidant, antimicrobial and antityrosinase activities of kenaf leaves were studied.•Ethanol extracted kenaf leaves extract (KLE) offered better performances.•This provides ...indication to the industries in selecting suitable extraction solvents for the kenaf leaves.
This work aimed to assess the effect of different extraction solvents (water, methanol, ethanol, and acetone) on the pulsed ultrasonic assisted extraction of Hibiscus cannabinus L. (kenaf) leaves extract (KLE), including extraction yield, antioxidation evaluation, antimicrobial analysis, tyrosinase inhibitory, Fourier transform infrared spectroscopy (FTIR) and ultra high performances liquid chromatography (UPLC) study. Results showed that the ethanol extracted KLE exhibited the highest content of total phenolic content (98.17 mg/g KLE). The ethanol extracted KLE also presented a good performances on 2,2-diphenyl-1- picrylhydrazyl (DPPH) radical scavenging capacity assay, 2,2′- azino- bis (3- ethylbenzo thiazoline- 6-sulphonic acid) (ABTS) radical scavenging assay, ferric reducing antioxidant power (FRAP) assay, and antimicrobial activity. Good correlation was obtained between the antioxidant activities analysis and total phenolic contents. Additionally, the ethanol extracted KLE showed the strong tyrosinase inhibitory (70.42%), although it was lower than the water extracted KLE (77.50%). Three phenolic compounds (caffeic acid, catechin hydrate, and tannic acid) were identified in the ethanol extracted KLE by UPLC. These findings clearly indicate that ethanol was the most effective solvent for extraction of phenolic and flavonoid compounds from kenaf leaves. The results suggest that the kenaf leaves can be a promising source of natural antioxidant, antimicrobial, and antityrosinase constituent for application in the food, cosmetic and pharmaceutical industries.
•Studied the process intensification and kinetics of phenolics from Hibiscus sabdariffa.•Considered microwave-assisted extraction process parameters altered the recovery process.•Second-order rate ...law can best describe the MAE of phenolics from H. sabdariffa.•First study to report a total number of 77 phenolics identified in the H. sabdariffa.
Hibiscus sabdariffa is a multi-cropping system endowed with wide ranges of benefits to humans. Being a plant rich in phenolic compounds, the process intensification of extraction method used for recovering the phenolic compounds from this essential plant is inevitable to easily proffer keen information on the extraction behaviours. Thus, the process intensification and kinetic behaviour of microwave-assisted extraction (MAE) for recuperating total phenolics (TP) content from H. sabdariffa calyces were investigated. The impacts of MAE factors such as solid/sample ratio, microwave power and temperature at varied irradiation time were studied. The effective diffusivity was also estimated. In addition, the extract was characterized to tentatively assign the phenolics using Liquid chromatography tandem mass spectrometry of quadrupole time-of-flight (LC-ESI-MS-MS). The achieved results clearly indicated that the MAE process intensification was acheived with TP content of 70.53 mg GAE/g extract in 3 min at solvent/sample ratio of 14:1 mL/g, microwave power of 500 W and 60 °C of temperature where the highest effective diffusivity coefficient was obtained. Out of the two considered kinetic models (second-order rate and power law), the second-order rate model best describes the MAE process intensification with higher coefficients of determination (R2 > 0.99). Moreover, an aggregate of 77 phenolic compounds was assigned in the extract of H. sabdariffa calyx; signifying the wider potentials of the extract industrially. Thus, this study clearly outlined that H. sabdariffa calyx is an embodiment of diverse phenolic compounds; indicating its potential in pharmaceutical and food industries.
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•Twenty-five different components were determined from Hibiscus surratensis L. essential oil.•Hibiscus surratensis L. essential oil has an antibacterial effect.•Antibacterial effects ...are due to phytochemicals found in the plant’s structure.•The most powerful antibacterial effect was determined on Listeria monocytogenes.•Essential oil indicated bactericidal effects on Listeria monocytogenes, Escherichia coli and Staphylococcus aureus.
Hibiscus surratensis L. calyces essential oil can be used as potential natural antibacterial. In this study, composition of essential oil obtained from calyces of Hibiscus surattensis L. and the antibacterial effect of this essential oil on some important food-borne pathogens were examined. Essential oil of hibiscus calyces obtained from hydro-distillation method were analyzed by GC-MC. As a result of the analyses main compounds, β-caryophyllene (11.68%), menthol (9.44%), methyl salicylate (8.32%), camphor (8.47%) and germacrene D (5.13%) were identified in essential oil of calyces of the Hibiscus surattensis L. plant. Antibacterial effects of calyces essential oils were determined by disc diffusion method. Also minimal inhibitory concentration and minimal bactericidal concentration values were determined. The most powerful antibacterial effect was observed on Listeria monocytogenes with a diameter zone of 25.26 mm, followed by a diameter zone of 23.42 mm on Staphylococcus aureus and with a diameter zone of 22.93 mm on Escherichia coli (*P < 0.05). In addition, according to detected MIC/MBC rates, it was revealed that Hibiscus surattensis L. essential oils had bactericidal effect on Escherichia coli, Staphylococcus aureus and Listeria monocytogenes, it had bacteriostatic effect on Enterococcus aerogenes, Salmonella typhimurium and Shigella flexneri which were foodborne pathogens used in the research.
Roselle-Hibiscus sabdariffa L. leaves at different stages of growth, calyces and seeds were analyzed for nutritional and anti-nutritional factors. All the treatments contained a good but varied ...proportion of carbohydrate in a range of 26.93-54.13%, crude protein from 5.7 to 27.06%, crude fat 1.16-13.09%, crude fibre 15.75-36.10%, energy 631.36-1065 kJ, ash 6.08-13.74% and moisture content 6.00-9.7%. The vitamins A, C and E were also found to be present in all the treatments in a different but substantial amount. The calcium, magnesium and iron contents in all the treatments were higher than the recommended daily allowance of 1250, 350, and 15 mg for adults, while the phosphorus and sodium values in all the treatments were below 1000 and 1500 mg RDA for adults. However, the Na + /K + for all the treatments were lower than 1. The values of anti-nutrients in the samples were small except post-flowering red which had high phytate content of 21.02%, although this can be easily reduced during processes like boiling and cooking. Thus, both cultivars of roselle contain high nutritional, elemental, and vitamins compositions and small content of anti-nutrients.
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