Concentrations Of Tyrosol Research Articles

Chemical Profile Characterization of Fruit and Vegetable Juices after Fermentation with Probiotic Strains.

Lactic acid bacteria (LAB) are widely applied for fermentation purposes in dairy and non-dairy food matrices with beneficial technological and health-promoting properties. This study describes the effect of two lactic acid bacteria, namely, Lactiplantibacillus paracasei SP5 and Pediococcus pentosaceus SP2, on the phenolic profiles, antioxidant activities, total phenolic content (TPC), carotenoid content, and sensorial profile of two different mixed fruit juices. After 48 h of fermentation, both LABs retained viability over 9 Log CFU/mL in both juices. The TPC, zeaxanthin + lutein, β-carotene content, and antioxidant activity (AA) were elevated for both LABs and mixed juices after 48 h of fermentation compared to control samples. Regarding the phenolic profile, both juices exhibited a significant decrease in chlorogenic acid levels, while quinic acid and tyrosol concentrations showed notable increases.

Biofilm development of Candida boidinii and the effect of tyrosol on biofilm formation

ObjectivesThe applicability of a simple and high-throughput method for quantitative characterization of biofilm formation by Candida boidinii was tested in order to evaluate the effects of exogenous tyrosol on yeast growth and biofilm formation capacity.ResultsSignificant concentration-, temperature and time-dependent effect of tyrosol (2-(4-hydroxyphenyl)ethanol) was demonstrated, but it differentially affected the growth and biofilm formation (characterized by crystal violet staining and XTT-reduction assay) of Candida boidinii. Testing biofilm based on metabolic activity displayed sensitively the differences in the intensity of biofilm in terms of temperature, tyrosol concentration, and exposure time. At 22 °C after 24 h none of the tyrosol concentrations had significant effect, while at 30 °C tyrosol-mediated inhibition was observed at 50 mM and 100 mM concentration. After 48 h and 72 h at 22 °C, biofilm formation was stimulated at 6.25–25 mM concentrations, meanwhile at 30 °C tyrosol decreased the biofilm metabolic activity proportionally with the concentration.ConclusionsThe research concludes that exogenous tyrosol exerts unusual effects on Candida boidinii growth and biofilm formation ability and predicts its potential application as a regulating factor of various fermentations by Candida boidinii.

A Comparative LC/MS Analysis of Jordanian Olive Stone, Fruits, Leaves, and Oils

The olive (Oleo europaea L.) may be a broadly dispersed plant that began within the Mediterranean locale. Its natural product is commonly utilized to create olive oil, table olives, and other by-products. Olives are rich in carbohydrates, vitamins, and minerals. Most olive items and the dietary composition of olive oil centering on fatty acids, phenolic compounds, and other cancer prevention agents are changed in numerous parts of olive plants. The most chemical constituents important to the natural movement of olive oil were inspected. Fluid-chromatography–mass spectrometry(LC/MS) investigation uncovered more than 50 major phenolic compounds among which oleuropein, hydroxytyrosol apigenin 7-O-glucoside, tyrosol, catechin, and vanillic corrosive were recognized. Olive clears out, wealthy in carotenoids and chlorophyll, the olive stone and seed are vital products produced within the olive oil extraction, as a lingo cellulosic fabric, the hemicellulose, cellulose, and lignin are the most components of olive stone as well as protein, fat, phenols, free sugars, and polyols composition. Both lipophilic and hydrophilic phenolics are conveyed in olive natural products. The most lipophilic phenols are cresols whereas the major hydrophilic phenols incorporate phenolic acids, phenolic alcohols, flavonoids, and secoiridoids; they are shown in nearly all parts of the plant, but their nature and concentration shift incredibly between the tissues. Olive oil is composed primarily of triacylglycerols (triglycerides or fats) and contains little amounts of free greasy acids (FFA), glycerol, phosphatides, shades, flavor compounds, sterols, and minuscule bits of olive. Olive stones have a most noteworthy sum of rutin. Luteolin appeared the most noteworthy sum in takes off, while the least level was found in oils, tall concentrations of tyrosol, vanillic, and caffeic corrosive, and vanillin was found in stones. In common, rutin and luteolin 7-O-glucoside were the two fundamental flavonoids identified in all parts.

Tyrosol induces multiple drug resistance in yeast Saccharomyces cerevisiae.

In yeast, multiple (pleiotropic) drug resistance (MDR) transporters efflux xenobiotics from the cytoplasm to the environment. Additionally, upon the accumulation of xenobiotics in the cells, MDR genes are induced. At the same time, fungal cells can produce secondary metabolites with physico-chemical properties similar to MDR transporter substrates. Nitrogen limitation in yeast Saccharomyces cerevisiae leads to the accumulation of phenylethanol, tryptophol, and tyrosol, which are products of aromatic amino acid catabolism. In this study, we investigated whether these compounds could induce or inhibit MDR in yeast. Double deletion of PDR1 and PDR3 genes, which are transcription factors that upregulate the expression of PDR genes, reduced yeast resistance to high concentrations of tyrosol (4-6 g/L) but not to the other two tested aromatic alcohols. PDR5 gene, but not other tested MDR transporter genes (SNQ2, YOR1, PDR10, PDR15) contributed to yeast resistance to tyrosol. Tyrosol inhibited the efflux of rhodamine 6G (R6G), a substrate for MDR transporters. However, preincubating yeast cells with tyrosol induced MDR, as evidenced by increased Pdr5-GFP levels and reduced yeast ability to accumulate Nile red, another fluorescent MDR-transporter substrate. Moreover, tyrosol inhibited the cytostatic effect of clotrimazole, the azole antifungal. Our results demonstrate that a natural secondary metabolite can modulate yeast MDR. We speculate that intermediates of aromatic amino acid metabolites coordinate cell metabolism and defense mechanisms against xenobiotics.

Sustainable recovery of phenolic antioxidants from real olive vegetation water with natural hydrophobic eutectic solvents and terpenoids

Olive oil production leads to the generation of olive mill wastewater (OMWW). Due to the presence of phenolic compounds, they are difficult to process, but they represent a source of high-added value chemicals since they have antioxidant and therapeutic properties. This work has studied the extraction of phenolic compounds from a type of OMWW, olive vegetation water, which presents these compounds in a more diluted dosage than in other studied to date, to revalue this waste stream. A real olive vegetation water from a Spanish olive oil producer was used, and liquid-liquid extraction was applied. Terpenoids and terpene-based hydrophobic eutectic solvents were systematically used to extract phenolic compounds following the concentrations of tyrosol, catechol, caffeic acid, and total phenolic content. By molecular simulation with the COSMO-RS method, 4 terpenoids, and 2 eutectic solvents were selected and compared with 2 conventional solvents. The Solvent/Feed ratio in the extraction of phenolic compounds was studied, showing that the solvents with the highest extraction results were geraniol, eucalyptol, and eutectic solvent menthol + camphor, which outperformed conventional solvents methyl isobutyl ketone and diisopropyl ether. Menthol + camphor gave total phenol extraction yields of 88.73% at a Solvent/Feed ratio in volume of 0.50, surpassing all solvents tested. A solvent reuse and regeneration process was applied by back-extraction of the 4 solvents: FTIR results showed the stability of the solvents while maintaining yields in the solvent reuse process. The phenolic compounds could be concentrated in the alkaline phase to factors up to 49.3 to the initial concentration in olive vegetation water. The alkaline phases were neutralized to obtain a precipitate with a caffeic acid content of up to 26 % wt%, and a tyrosol-rich supernatant with a concentration of up to 6.54 g/L. This work proposes a process using natural solvents to extract phenolic compounds from olive vegetation water.

Evaluation of the performance of a pilot-scale solar still for olive mill wastewater treatment

A pilot-scale solar still was constructed to evaluate the use of solar distillation for olive mill wastewater management. Conventional distillation experiments were initially conducted and showed that the increase of temperature resulted to higher concentrations of total phenols, tyrosol and hydroxytyrosol in the distillates. Afterwards, four experiments were performed in the pilot system with different types of olive mill wastewater to examine the effect of temperature and the role of underfloor heating system on its performance. The use of the heated underfloor resulted to higher average and maximum daily temperatures in the still and increased the production rates of the distillates, which reached up to 4.10 L/d m2. Liquid chromatography – high resolution mass spectrometry analysis detected concentrations of tyrosol and 4- hydroxybenzoic acid in the collected distillates at concentrations up to 0.70 and 0.10 mg/L, respectively. At the same time, a strong correlation was observed between the average daily temperature in the solar still and the concentrations of total phenols in the recovered distillates. The implementation of mass balances showed that almost 33% of the total input phenols found in olive mill wastewater remained in the solid residue. Eight phenolic compounds were detected in this material at concentrations ranging between 0.04 mg/kg (quinic acid) and 8.8 mg/kg (hydroxytyrosol), while its calorific value ranged from 15.28 MJ/kg up to 25.12 MJ/kg. Economic evaluation was implemented for the case of upscaling the said pilot system for operation at a medium size three-phase Greek olive mill. Taking into consideration that the distillate could be reused for the washing and malaxation of olive fruits, while solid residual could be sold as biofuel, the operational and overall costs were estimated to 0.60 and 1.21 €/m3, respectively.

Treatment of different dairy wastewater with Chlorella sorokiniana: removal of pollutants and biomass characterization

AbstractBACKGROUNDThere is a continuous need for the development of novel processes for the sustainable management of dairy wastewater. The use of microalgae for wastewater decontamination and production of valuable biomass seems a promising alternative; however, limited information currently exists on the chemical characteristics of the biomass cultivated in effluents from the dairy industry. In this paper, experiments were carried out with the microalga Chlorella sorokiniana and different types of dairy effluents (raw dairy wastewater, anaerobically treated dairy wastewater, cheese whey). The collected biomass was characterized for the existence of proteins, starch, lipids, lutein, β‐carotene, polyphenolic compounds and amino acids.RESULTSThe removal of chemical oxygen demand and NH4‐N was higher than 91% and 80%, respectively, for all types of dairy effluents, while the removal of total phosphorus ranged between 20% and 84%. The protein, starch and lipid contents of the microalgal biomass ranged between 28.6% and 52.8%, 10.5% and 13.3%, and 36.8% and 40.2%, respectively. The concentration of lutein increased after treatment, reaching values up to 508 mg kg−1, whereas amino acid concentrations were decreased due to nitrogen inefficiency. The biomass cultivated in anaerobically treated dairy wastewater was characterized by the higher total phenolic content; tyrosol concentration reached 20.2 mg kg−1.CONCLUSIONChlorella sorokiniana can efficiently remove the major pollutants from effluents of dairy industry, while the produced biomass is a source of proteins, carbohydrates and lipids. Additionally, it contains important amounts of pigments, phenolic compounds and amino acids. Further research is required for the conditions that achieve optimal biochemical characteristics of the produced biomass. © 2022 Society of Chemical Industry (SCI).

Enhanced Production of Phenylethanoids Mediated Through Synergistic Approach of Precursor Feeding and Light Regime in Cell Suspension Culture of Rhodiola imbricata (Edgew.).

Precursor feeding is a potential strategy for increasing specialized metabolite production in plant cell culture systems. In the present study, cell suspension cultures were developed and subsequently evaluated for precursor feeding investigations. Cell suspension cultures were established in Murashige and Skoog (MS) medium containing 0.5mg/L thidiazuron (TDZ) + 1mg/L α-naphthalene acetic acid (NAA). The growth biomass and metabolite pattern were analyzed to identify specific culture days required for prolific biomass production. The maximum cell dry weight (DW) was observed in leaf cell suspension (1.22g/100mL) and root cell suspension culture (1.12g/100mL) on day 21. Afterward, the effect of precursor concentrations (tyrosol; 0.5, 1, 2, and 3mM) along with two light regimes, photoperiod (16L/8D h, 70µmol/m2/s) and dark (24h), was evaluated for cell growth and metabolite accumulation. The results revealed that leaf cell suspension treated with 3mM tyrosol concentration detected maximum salidroside content (26.05mg/g DW) on day 15, incubated under photoperiod (16L/8D h) condition. Similarly, under photoperiod (16L/8D h), root cell suspension treated with 3mM tyrosol produced maximum salidroside content (26.62mg/g DW) on day 12. Moreover, the total phenolics content increased significantly (44.21mg/g DW) on day 12 in 3mM tyrosol treatment under photoperiod (16L/8D h). However, precursor concentrations did not influence the total flavonoids content. The present investigation suggests that the immediate pathway precursor, tyrosol, has a strong effect on enhanced production of salidroside, irrespective of explant type and light regimes.

Seasonal Variations in Antioxidant Components of Olea europaea in Leaves of Different Cultivars, Seasons, and Oil Products in Sinai

A mixture experimental design resulted in water-ethanol mixture to replace toxic extractants used to date and enhance greenness of extraction procedure. Oleuropein (OLP) and tyrosol (TYR) contents, in leaves from five olive Egyptian cultivars (North Sinai – Egypt) at different times representing summer, winter, and spring, respectively, were determined by high-performance liquid chromatography (HPLC) attached with photo diode array detector (DAD). The results showed that the concentration of OLP and TYR in leaf samples collected in spring and winter was higher than in summer seasons in different varieties. Tyrosol (TYR) and squalene (SQL) contents in oil, from different six olive oil commercial products that are popularly used in El-Arish, were bought from El-Arish local market and were determined as well using another HPLC-DAD method. This work can help nutraceutical companies attempting to manufacture medical products from olive leaves selecting best cultivar and optimum collection season of olive leaves.

Fluorescence Study of Four Olive Varieties Paste According to Sampling Dates and the Control in the Elaboration of Table Olives of “Ascolana tenera”

A fluorescence method combined with chemometric algorithms has been developed for the fruit characterization of four olive varieties (“Arbequina,” “Piantone di Falerone,” “Piantone di Mogliano,” and “Maurino”) cultivated in Marche (Italy) according to sampling dates. The score values obtained by parallel factor analysis (PARAFAC) were correlated with the hydroxytyrosol and oleuropein concentrations quantified by liquid chromatographic. The analysis of excitation-emission matrices by PARAFAC and unfolding partial least squares, using the three component score values, allowed to differentiate between varieties. The use of the scores of oleuropein and hydroxytyrosol, which were represented each other, allowed to highlight differences between the three sampling dates. Furthermore, a good discrimination of fresh olive, lye table olives, and natural table olives was also achieved in “Ascolana tenera,” another typical olive variety of Marche. Results can be explained by the changes of concentration of tyrosol and oleuropein due to the elaboration method characteristics.

Effect of Sub-Minimum Inhibitory Concentrations of Tyrosol and EDTA on Quorum Sensing and Virulence of Pseudomonas aeruginosa.

IntroductionPseudomonas aeruginosa is considered a dangerous pathogen, as it causes many human diseases, besides that it is resistant to almost all types of antibacterial agents. So, new strategies to overcome P. aeruginosa infection have evolved to attenuate its virulence factors and inhibit its quorum-sensing (QS) activity.PurposeThis study investigated the effect of tyrosol and EDTA as anti-quorum-sensing and antivirulence agents against P. aeruginosa PAO1.MethodsAnti-quorum activity of sub-minimum inhibitory concentrations (sub-MICs) of tyrosol and EDTA was tested using Chromobacterium violaceum (CV 12,472) biosensor bioassay. Miller assay was used to assess the inhibition of QS signal molecules by β-galactosidase activity determination. Also, their effects on the production of protease, lipase, lecithinase, and motility were tested. The inhibitory effects of these molecules on QS regulatory genes and exotoxins genes expression were evaluated by real-time PCR.ResultsTyrosol and EDTA at sub-MICs inhibited the production of violacein pigment. Both compounds inhibited QS molecules production and their associated virulence factors (protease, lipase, lecithinase, and motility) (P≤ 0.05). Besides, the expression levels of QS regulatory genes (lasI, lasR, rhƖI, rhIR, pqsA, and pqsR) and exotoxins genes (exoS and exoY) were significantly reduced (P≤ 0.05).ConclusionBoth tyrosol and EDTA can be used to fight P. aeruginosa infection as anti-quorum-sensing and antivirulence agents at their sub-MICs.

Design of immobilized biocatalyst and optimal conditions for tyrosol β-galactoside production.

Tyrosol β-galactoside (TG) is a phenylethanoid glycoside with proven neuroprotective properties. This work deals with its biocatalytic production from tyrosol and lactose using Aspergillus oryzae β-galactosidase in immobilized form. Six commercial carriers were examined to find the optimal biocatalyst. Besides standard biocatalyst performance characteristics, adsorption of the hydrophobic substrate on immobilization carrier matrices was also investigated. The adsorption of tyrosol was significant, but it did not have adverse effects on TG production. On the contrary, TG yield was improved for some biocatalysts. A biocatalyst prepared by covalent binding of β-galactosidase on an epoxy-activated carrier was used for detailed investigation of the effect of reaction conditions on glycoside production. Temperature had a surprisingly weak effect on the overall process rate. A lactose concentration of 0.83M was found to be optimal to enhance TG formation. The impact of tyrosol concentration was rather complex. This substrate caused inhibition of all reactions. Its concentration had a strong effect on the hydrolysis of lactose and all products. Higher tyrosol concentrations, 30-40g/L, were favorable as pseudo-equilibrium concentrations of TG and galactooligosaccharide were reached. Repeated batch results revealed excellent operational stability of the biocatalyst.

Evaluation of tyrosol and farnesol as inducer in pigment production by Monascus purpureus ATCC16365.

This study focused on investigating the effect of exogenously applied two quorum sensing molecules (tyrosol and farnesol) on the synthesis of bioactive metabolites (pigments, lactic acid, ethanol, and citric acid) in Monascus purpureus ATCC16365. None of the tested concentrations (62.5, 125, 250, and 500 µl/L) of farnesol affected the synthesis of metabolites as well as cell growth. As with farnesol application, none of the tested concentrations (3.45, 6.9, 13.8, and 27.6 mg/L) of tyrosol caused a significant change in the synthesis of lactic acid and citric acid as well as cell growth. Conversely, all of the tested concentrations of tyrosol increased pigment synthesis but reduced ethanol synthesis, compared with the control. Maximum increases (3.16-, 2.68-, and 2.87-fold increase, respectively) in yellow, orange, and red pigment production were achieved, especially when 6.9-mg/L tyrosol was added to the culture on day 3. On the contrary, 6.9-mg/L tyrosol reduced the content of citrinin by approximately 51.5%. This is the first report on the effect of tyrosol and farnesol on the synthesis of Monascus metabolites. Due to potential properties, such as low price, nonhuman toxicity, promotion of pigment synthesis, and reduction in citrinin synthesis, tyrosol can be used as a novel inducer in the fermentative production of Monascus pigments.

Recovery and determination of cholesterol-lowering compounds from Olea europaea seeds employing pressurized liquid extraction and gas chromatography-mass spectrometry

Our previous work demonstrated the presence of compounds with hypocholesterolemic capacity in olive seeds. These compounds were extracted using CO2-expanded ethyl acetate and identified as tyrosol, hydroxytyrosol, and β-sitosterol using GC–MS. This work describes the extraction of these compounds from different olive seeds using pressurized ethyl acetate. Their solubility in ethyl acetate at temperatures ranging from 40–200 °C was theoretically predicted by Hansen solubility parameters. The content of these compounds was estimated by GC–MS, as well as, the reduction of the micellar cholesterol solubility (RMCS) capacity of extracts enabling to establish the optimum extraction temperature at 100 °C. A GC–MS method was developed and validated in terms of its analytical characteristics for a sensitive determination and quantification of tyrosol, hydroxytyrosol, and β-sitosterol in different olive seeds. Within varieties, Manzanilla seeds presented the highest concentration of tyrosol, hydroxytyrosol, and the lowest concentration of β-sitosterol, as well as the highest RMCS capacity.

Screening of Commercial Enzymes for Transfructosylation of Tyrosol: Effect of Process Conditions and Reaction Network.

Enzymatic fructosylation of organic acceptors other than saccharides brings new possibilities to synthesize molecules that do not exist in nature. The introduction of fructosyl moiety may lead to glycosides possessing enhanced physicochemical and bioactive properties which could be useful in the pharmaceutical and cosmetic industry. In this work, the regioselective synthesis of tyrosol β-d-fructofuranoside (TF) catalyzed by β-fructofuranosidase is investigated. In the first step, 32 commercial enzyme preparations are screened for fructoside-hydrolyzing activity. The most active preparations are subsequently examined for fructofuranosyl transfer from sucrose to tyrosol. The best candidate, Novozym 188, is chosen to study the effect of reaction conditions on the product formation in a batch reactor. The effects of substrate concentration, temperature, pH, time, and enzyme dosage on the concentration of TF produced are studied using the design of experiments methodology. The maximal product concentration of 3.8 g L-1 is achieved for the sucrose concentration of 1.5 m, tyrosol concentration of 29 g L-1 , temperature of 41 °C, and pH 5.1. Besides the main transfructosylation reaction between sucrose and tyrosol, several side reactions take place. A reaction network includes also the formation of fructooligosaccharides and the hydrolysis of sucrose and all reaction products.

Effect of Light Exposure on the Quality and Phenol Content of Commercial Extra Virgin Olive Oil during 12‐Month Storage

AbstractStorage conditions influence the maximum time for which the composition and sensory characteristics of olive oils can be guaranteed. The purpose of this research was to study the quality and phenol content of extra virgin olive oil (EVOO) after storage for 1 year in different types of containers under darkness or light. Three Spanish cultivars with quantitatively different phenol contents were selected for the study. Storage under light conditions impaired the physicochemical and sensorial properties of the three cultivars, and reduced total phenolics, but there was an increase in hydroxytyrosol and tyrosol concentrations. It also markedly decreased their total phenolic content, especially when kept in polyethylene containers exposed to light, with reductions ranging from 4.28% for vanillic acid in Picual oils stored in dark glass containers under dark conditions to 97.82% for ferulic acid in Arbequina oils stored in polyethylene containers under light conditions. There was a reduced concentration of flavonoid and lignan concentrations after 1 year of storage, with the greatest decrease (98.01% of initial content) being observed for in the flavonoid apigenin. These results indicate that EVOO should be stored in dark glass containers under dark conditions for the optimal preservation of its quality and phenol content.

Fast and direct amperometric analysis of polyphenols in beers using tyrosinase-modified screen-printed gold nanoparticles biosensors

In this work it is explored a real applicability of miniaturised and portable biosensing technology for the estimation of total phenolic content in 15 different commercial beers by applying direct amperometry. Gold nanoparticles screen-printed electrodes were thoroughly modified with tyrosinase (Tyr-AuNPS-SPCEs), which was immobilised on the surface by crosslinking with glutaraldehyde. All chemical and instrumental variables involved in the electrochemical method were optimised to develop a reliable and powerful tool to estimate rapidly the content of phenolic compounds in complex beer samples. Catechol, phenol, caffeic acid and tyrosol were analysed individually using the proposed methodology and good analytical and kinetic performances were obtained. Total phenolic content in tested beers (high fermented, low fermented and non-alcoholic) were expressed as mg L−1 of tyrosol, which is one of the major phenolic compound reported in beer. Moreover, the developed amperometric methodology was successfully benchmarked against standardised Folin-Ciocalteau spectrophotometric method with a good Pearson correlation (r = 0.821, p < 0.01). Hierarchical Cluster Analysis (HCA) was also applied on electrochemical results and a good capability to group tested beers based on their tyrosol concentration was demonstrated.

Bioconversion of p-Tyrosol into Hydroxytyrosol under Bench-Scale Fermentation.

Tyrosol hydroxylating Pseudomonas strain was previously isolated from olive mill wastewaters-irrigated soil. In the present work, experimental design was used to study the bioconversion of tyrosol in laboratory fermenters aiming at the recovery of the highest yields of hydroxytyrosol. The effects of biocatalyst loading and tyrosol concentration were studied. The bioconversion yield reached 86.9% (37.3 mM hydroxytyrosol) starting from a tyrosol concentration of 43 mM. Under these conditions, the specific productivity relative to the biocatalyst was 4.78 μM/min/g. The established model to predict bioconversion yield was validated in two bench-scale fermenters. At the downstream stage, the reaction product was recovered as a hydroxytyrosol rich solution after microfiltration and concentration under vacuum. Subsequent to this operation, hydroxytyrosol composition yielded 73.8% of the total dry matter.

The LC-MS/MS characterization of phenolic compounds in leaves allows classifying olive cultivars grown in South Tunisia

Olive (Olea europaea L.) is one of the most important fruit species in the Mediterranean basin, where 95% of the world's olive orchards are planted, and has become an economically valuable crop worldwide due to an increasing demand in olive oil for human consumption. The aim of the present research was to classify Tunisian olive cultivars based on their phenolic profile and to test the potentiality of chemometrics as a tool for cultivars discrimination. The phenolic compounds present in 21 samples of olive leaves, collected during the normal picking period for olive oil production in South Tunisia, were analysed by liquid chromatography mass spectrometry. Models based on principal component analysis (PCA) and hierarchical cluster analysis (HCA) was used for discrimination purposes as a function of the tree varieties and cultivation zone.Qualitative and quantitative compositional analysis revealed 12 major phenolic compounds among which oleuropein (110.38–4741.62 mg/kg), hydroxytyrosol (5.40–290.19 mg/kg), apigenin 7-O-glucoside (9.44–2475.53 mg/kg), tyrosol (2.10–174.62 mg/kg), catechin (0–37.60 mg/kg) and vanillic acid (3.23–256.57 mg/kg) were identified. Oleuropein showed the highest amount in Fougi cultivar (4741.62 mg/kg), whereas the lowest level was registered in Zarrazi injassi cultivar (110.38 mg/kg). However, Zalmati Zarzis exhibited high concentrations of tyrosol, vanillic and caffeic acid, and vanillin. In general, rutin and luteolin 7-O-glucoside were the two main flavonoids detected. Dendrogram analysis revealed three main clusters, further confirmed through PCA.

Removal of tyrosol from water by adsorption on carbonaceous materials and electrochemical advanced oxidation processes

This work compares the ability of physical and chemical treatments, namely adsorption and electrochemical advanced oxidation processes, to remove tyrosol from aqueous medium. Adsorption on graphene nanoplatelets (GNPs) performed much better than that with a graphite intercalation compound. Adsorption isotherms were found to follow the Freundlich model (R2 = 0.96), which is characteristic of a chemisorption process. Successful electrochemical regeneration enables 5 successive adsorption/regeneration cycles before corrosion of GNPs occurs. Other typical aromatic contaminants that may coexist with tyrosol can be also adsorbed on GNPs. Percentage of regeneration efficiency of GNPs showed a higher affinity towards Lewis acids group compounds and a lower one towards Lewis base. The treatment of 100 mL of 0.723 mM tyrosol solutions in non-chlorinated and chlorinated matrices at pH 3.0 was carried out by electrochemical oxidation with electrogenerated H2O2 (EO-H2O2), electro-Fenton (EF) and UVA photoelectro-Fenton (PEF). Trials were made with a BDD anode and an air-diffusion cathode at 10–30 mA cm−2. Hydroxyl radicals formed at the anode from water oxidation and/or in the bulk from Fenton's reaction between added Fe2+ and generated H2O2, along with active chlorine produced in chlorinated medium, were the main oxidants. Tyrosol concentration always decayed following a pseudo-first-order kinetics and its mineralization rose as EO-H2O2 < EF < PEF, more rapidly in the chlorinated matrix. The potent photolysis of intermediates under UVA radiation explained the almost total mineralization achieved by PEF in the latter medium. The effect of current density and tyrosol content on the performance of all processes was examined.