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This study reports the effect of antioxidant fractions from rosemary (Rosma-rinus officinalis), sage (Salvia officinalis), thyme (Thymus vulgaris) and hyssop (Hyssop officinalis) on the oxidative stability of sunflower oil at elevated tempe¬rature. In order to isolate antioxidant fractions, the method of fractional super¬critical extraction with carbon dioxide at 35 MPa and 100 C was applied. Anti¬oxidant fractions were added to sunflower oil at concentrations of 200 mg/kg oil and the samples were stored in an oven maintained at 98 C. The antioxidant activity of the extracts was determined by measuring peroxide values (PV). Among investigated extracts, the rosemary extract was most effective on retarding lipid oxidation of sunflower oil. The antioxidant activity of the extracts was com¬pared to the activity of butylated hydroxyanisole (BHA) and a commercial rose¬mary extract Flavor’ Plus. On the basis of PV assay, the antioxidant activity of the investigated plant extracts after 12 h of storage at 98 C followed the order: rosemary extract > BHA > sage extract > Flavor’ Plus > thyme extract > hyssop extract.

The present study deals with the supercritical carbon dioxide (SC-CO2) extraction and hydrodistillation (HD) of dried bay leaves (Laurus nobilis L.). The chemical composition and antibacterial activity of the SC-CO2 extract and essential oil (EO) from dried leaves of bay were compared to each other and literature data. Qualitative and quantitative analyses of the SC-CO2 extract and EO were performed using GC–FID and GC–MS analytical methods. A significant difference in the chemical composition of the SC-CO2 extract and EO was observed. The EO comprised high contents of monoterpenes and their oxygenated derivates (98.4 %), principally 1,8-cineole (33.4 %), linalool (16.0 %) and α-terpinyl acetate (13.8 %), sabinene (6.91 %) and methyl eugenol (5.32 %). The SC-CO2 extract comprised twice less monoterpenes and their oxygenated derivates (43.89 %), together with sesquiterpenes (12.43 %), diterpenes (1.33 %) and esters (31.13 %). The major components were methyl linoleate (16.18 %), α-terpinyl acetate (12.88 %), linalool (9.00 %), methyl eugenol (8.67 %), methyl arachidonate (6.28 %) and eugenol (6.14 %). An investigation of the antibacterial activity of bay SC-CO2 extract and EO was completed on different Staphylococcus strains using the broth macrodilution method. Staphylococcus intermedius strains were the most susceptible to both the SC-CO2 extract and EO (MIC = 640 µg/ml).

The present study was aimed to investigate and compare the efficiency of different methods for the isolation extract from a plant material. Extracts from dried leaves of Aloe vera (A. barbadensis Mill.) and Sweet Bay (Laurus nobilis L.) were obtained applying the following techniques: supercritical carbon dioxide (SC CO2) extraction at 30 MPa and 100 °C, a combined ultrasonic extraction and pre-treatment using SC CO2 (US-SCCO2), and a conventional ultrasonic extraction (US) with 96% ethanol. US-SCCO2 resulted in much higher yields of extracts of aloe and bay compared to SC CO2 extraction. Determined extract’s yield was used for calculating the maximum useful work and exergy loss as a measure of irreversibility of the extraction process. Calculated maximum useful work per 1 kg of the extract was ranged from 0.7 to 226 kJ while estimated values of the exergy loss were from 48 to 416 kJ per 1 kg of the extract. The maximum useful work and exergy loss have the largest value for SCE much more than for other processes of extraction (US and US-SCCO2). The pre-treatment of the plant material with SC CO2 before an ultrasound-assisted extraction or the decrease of a particle size used for ultrasound-assisted extraction of Aloe vera has led to the decrease of maximum useful work and exergy loss. Unlike, pre-treatment with SC CO2 followed by ultrasound-assisted extraction increased the exergy loss when bay was used as the plant material.

The aim of the present study was to isolate and characterize antioxidant extracts obtained from dried leaves of rosemary (Rosmarinus officinalis L.) and sage (Salvia officinalis L.), originating from the southern Balkan Region. The antioxidant fraction was isolated from the plant material by supercritical carbon dioxide (SC-CO2) fractional extraction under a pressure of 30 MPa and at temperatures of 40 and 100 °C. In the present study, kinetic data and yields of antioxidant extracts obtained from dried leaves of rosemary and sage under different conditions were determined. Electron spin resonance (ESR) spectroscopy assay on the ability of the extracts to scavenge stable 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radicals and reactive hydroxyl radicals during the Fenton reaction trapped by 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) showed that the investigated extracts had antioxidant activity comparable to that of butylated hydroxyanisole (BHA) and commercial rosemary extract. The antioxidant fractions isolated at the higher temperature had higher antioxidant activities. A tentative analysis of the chemical composition of the antioxidant fractions obtained at the higher temperature was accomplished by LC-DAD and LC-MS analytical methods. Abietane-type diterpenoids, flavonoids and fatty acids were identified in the SC-CO2 extract of rosemary and sage.

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The olive growing in Tunisia has an economic dominance and agricultural importance. However, the huge extraction of olive oil generates a large quantity of olive mill wastewater (OMW), which is discharged to the surroundings. The highly polluting potential (organic load) of OMW threatens the environment and requires an urgent solution. Supercritical fluid extraction (SFE) is a green extraction method that can be applied to purify OMW and, at the same time, to isolate a high quality oil from this wastewater.In order to explore and to valorize the compositions of Olive mill wastewater (OMW), extraction in different solvents (supercritical CO2, hexane) was carried out and chemical composition of the extracted oils were established by GC-FID. The Tunisia OMW were collected from two different zones namely Sousse and Sfax.In this work, we have investigated the effects pressure (P) and temperature (T) on the yield and the quality of oil. The suitable conditions for the extraction of oil from lyophilized OMW by Supercritical carbon dioxide (SC-CO2) were found to be the pressure of 30 MPa and the temperature of 60 °C. In order to simulate the process, the model of broken and intact cells (Sovova’s model) was applied. The model well represented the experimental data.Oil yields ranged from 21.3 % to 33.87 % depending on the extraction solvent used. Monounsaturated fatty acids (MUFA) were the major compounds of the oils, based on the fatty acid analysis. Chromatographic analysis revealed that the chemical compositions vary from one region to another, extraction solvent as well as the conditions of pressure and temperature.

The study explores the grafting of cellulose acetate microfiltration membranes with an aminosilane to attain antibiofilm properties. The grafting reaction was performed in the supercritical carbon dioxide used as a transport and reaction medium. The FTIR analyses and dissolution tests confirmed the covalent bonding between the aminosilane and polymer. The membranes’ microstructure was investigated using a dual-beam SEM and ion microscopy, and no adverse effects of the processing were found. The modified membranes showed a more hydrophilic nature and larger water permeate flow rate than the neat cellulose acetate membranes. The tests in a cross-filtration unit showed that modified membranes were considerably less blocked after a week of exposure to Staphylococcus aureus and Escherichia coli than the original ones. Microbiological investigations revealed strong antibiofilm properties of the grafted membranes in experiments with Staphylococcus aureus, Listeria monocytogenes, Escherichia coli, and Salmonella Enteritidis.

This study investigated supercritical solvent impregnation of polyamide microfiltration membranes with carvacrol and the potential application of the modified membranes in ventilation of open surgical wounds. The impregnation process was conducted in batch mode at a temperature of 40 °C under pressures of 10, 15, and 20 MPa for contact times from 1 to 6 h. FTIR was applied to confirm the presence of carvacrol on the membrane surface. In the next step, the impact of the modification on the membrane structure was studied using scanning electron and ion beam microscopy and cross-filtration tests. Further, the release of carvacrol in carbon dioxide was determined, and finally, an open thoracic cavity model was applied to evaluate the efficiency of carvacrol-loaded membranes in contamination prevention. Carvacrol loadings of up to 43 wt.% were obtained under the selected operating conditions. The swelling effect was detectable. However, its impact on membrane functionality was minor. An average of 18.3 µg of carvacrol was released from membranes per liter of carbon dioxide for the flow of interest. Membranes with 30–34 wt.% carvacrol were efficient in the open thoracic cavity model applied, reducing the contamination levels by 27% compared to insufflation with standard membranes.

This study investigates the modification of commercial cellulose acetate microfiltration membranes by supercritical solvent impregnation with thymol to provide them with antibacterial properties. The impregnation process was conducted in a batch mode, and the effect of pressure and processing time on thymol loading was followed. The impact of the modification on the membrane’s microstructure was analyzed using scanning electron and ion-beam microscopy, and membranes’ functionality was tested in a cross-flow filtration system. The antibiofilm properties of the obtained materials were studied against Staphyloccocus aureus and Pseudomonas aeruginosa, while membranes’ blocking in contact with bacteria was examined for S. aureus and Escherichia coli. The results revealed a fast impregnation process with high thymol loadings achievable after just 0.5 h at 15 MPa and 20 MPa. The presence of 20% of thymol provided strong antibiofilm properties against the tested strains without affecting the membrane’s functionality. The study showed that these strong antibacterial properties could be implemented to the commercial membranes’ defined polymeric structure in a short and environmentally friendly process.

In the present study, supercritical solvent impregnation (SSI) has been applied to incorporate thymol into bio-composite polymers as a potential active packaging material. Thymol, a natural component with a proven antimicrobial activity, was successfully impregnated into starch-chitosan (SC) and starch-chitosan-zeolite (SCZ) films using supercritical carbon dioxide (scCO2) as a solvent. Experiments were performed at 35 °C, pressures of 15.5 and 30 MPa, and an impregnation time in the range of 4–24 h. The highest impregnation yields of SC films with starch to chitosan mass ratios of 1:1 and 1:2 were 10.80% and 6.48%, respectively. The addition of natural zeolite (15–60%) significantly increased the loading capacity of films enabling thymol incorporation in a quantity of 16.7–27.3%. FTIR and SEM analyses were applied for the characterization of the films. Mechanical properties and water vapor permeability of films before and after the impregnation were tested as well. Thymol release kinetics in deionized water was followed and modeled by the Korsmeyer-Peppas and Weibull model. SCZ films with thymol loading of approximately 24% exhibited strong antibacterial activity against E. coli and methicillin-resistant Staphylococcus (S.) aureus (MRSA).

Supercritical fluid extraction as an environmentally friendly technology was applied to isolate biologically active extracts from celery and parsley fruits for potential applications in the food industry. The extractions were performed under mild temperature conditions of 39.85 °C and at pressures of 10 and 30 MPa. The extracts were analyzed regarding their chemical composition, antibacterial activity, and cytotoxic effect. Sedanolide was the dominant component of the celery fruit extracts, comprising more than 70% of the obtained fraction, while the content of apiole in the parsley fruit SC CO2 extracts exceeded 85%. The celery fruit extracts showed strong and moderately strong antibacterial activity against tested Staphylococcus aureus, Bacillus (B.) cereus, B. subtilis, B. circulans, Listeria (L.) greyi, L. seeligeri and L. welshimeri, with minimal inhibitory concentration (MIC) values between 160 and 640 µg/mL, and weak activity against the selected Salmonella isolates with a MIC of 2560 µg/mL. The parsley extract obtained at 10 MPa showed strong and moderately strong antibacterial effects against Bacillus strains with obtained MICs of 160–640 µg/mL, and weak activity against Staphylococcus, Listeria, and Salmonella with a MIC of 2560 µg/mL. Cytotoxicity investigation showed that the extracts with proven antibacterial activity had no cytotoxic effect on rabbit kidney cells at concentrations of up to 640 µg/mL.

Bacterial resistance to antibiotics is one of the biggest problems in the modern world. The prevention of bacterial spreading from hospitals to the community and vice versa is an issue we have to deal with. This review presents a vast potential of contemporary high-pressure techniques in the design of materials with antimicrobial activity. Scientists from all over the world came up with ideas on how to exploit extraordinary properties of supercritical fluids in the production of advantageous materials in an environmentally friendly way. The review summarizes reported methods and results.

Supercritical CO2 was used as a green solvent and impregnation medium for loading cellulose acetate beads with carvacrol in order to obtain a biomaterial with antibacterial properties. Supercritical solvent impregnation was performed in a high-pressure view cell at temperature of 50°C and pressures of 10, 21, and 30 MPa with the processing time ranging from 2 to 18 h. The rate of impregnation increased with the pressure increase. However, maximum impregnation yield (round 60%) was not affected by the pressure applied. Selected samples of the impregnated cellulose acetate containing 6–60% of carvacrol were proven to have considerable antibacterial effect against Gram-positive and Gram-negative bacterial strains including methicillin-resistant Staphylococcus aureus which causes severe infections in humans and animals. In addition, cellulose acetate beads containing 6.0–33.6% of carvacrol were shown to have a porous structure with submicron pores which is of interest for the controlled delivery applications.

For the first time, extracts from clove buds obtained by supercritical carbon dioxide extraction were screened for antioxidant and antibacterial activities. Additionally, antioxidant and antibacterial activities of extracts obtained by the supercritical extraction of the clove bud–oregano leaf mixtures were studied. Supercritical extract of pure clove had the highest eugenol (64%) and total phenolic content (530.56 mg GAE/gextract). All extracts had antioxidant activity comparable to synthetic antioxidants against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals and formation of peroxides. Presence of 0.6% and 5% of oregano extract in the clove extracts obtained from the clove–oregano plant mixtures improved their antioxidant activity with respect to the extract from pure clove. Clove extract showed moderate antibacterial activities against selected Staphylococcus and Enterococcus bacterial strains. Presence of 50% of the oregano extract improved antibacterial activity of clove extract against all tested strains and resulted in a synergistic antibacterial activity against Methicillin-resistant Staphylococcus haemolyticus strain (MIC ⩽ 1.25 μg/mL). Study demonstrated great potential of supercritical clove extract as natural functional ingredient and the possibility of increasing its antioxidant and antibacterial efficiencies in order to apply lower concentrations and to reduce undesirable flavour notes and toxicological effects in final products.