Публикации

@article{nokey,

title = {Valorization of waste lavender residue from the essential oil industry for production of rosmarinic acid – a study on the solid-liquid extraction},

author = {Chavdar Chilev and Evgeni Simeonov and Borislava Dimitrova and Velislava Yonkova and Swantje Pietsch and Stefan Heinrich and Dimitar Peshev},

editor = {Bogdana Koumanova},

url = {http://www.nanoessential.eu/wp-content/uploads/02_Manuscript.pdf},

year  = {2022},

date = {2022-00-00},

journal = {Journal of Chemical Technology and Metallurgy},

abstract = {The possibility for valorization of the waste lavender residue from the essential oil industry via solvent extraction was studied. The plant residue of Lavandula angustifolia, from which the lavender oil is extracted through steam distillation, contains Key Biologically Active Components (KBAC) such as: rosmarinic acid, caffeic acid, luteolin. The feasibility of the solvent extraction for their isolation was assessed by comparison of the kinetics and equilibrium of extraction of KBAC from spent and raw plant material (collected from the same batch before the steam distillation) using different solvent compositions. The parameters of the extraction process were experimentally and numerically optimized. To determine the most efficient solvent, two pure and two mixed solvents were tested: pure water, 99.9% Ethanol and their mixtures – (40% and 60% Ethanol). Using 40% ethanol as extraction solvent resulted in maximum recovery of KBAC. A mathematical model for the solid-liquid extraction from lavender materials was developed. The values of the model parameters were determined using the Regular regime method. A four-parameter empirical model for prediction of the effective diffusivity, D_eff, was also applied. The model adequacy was experimentally verified. Based on the theoretical and experimental results KBAC recovery the following extraction conditions were recommended: extraction time - 30min, temperature - 30℃, liquid-solid ratio - 0.01  m^3⁄kg, and 40% Ethanol as an extraction solvent



Keywords: solid-liquid extraction, kinetics, lavender, modeling, rosmarinic acid, essential oil.



Acknowledgements: This work was supported by the Bulgarian National Science Fund (contract KP-06-H37/14).},

keywords = {Journal Article},

pubstate = {forthcoming},

tppubtype = {article}

}

@article{Lazarova-Zdravkova2021,

title = {Study of the biological activity of essential oils-water mixtures},

author = {Nevena Lazarova-Zdravkova and Denitsa Tsanova and Yoana Stoyanova and Chavdar Chilev and Nelly Georgieva and Dimitar Peshev},

url = {https://www.ijfsab.com/index.php/fsab/article/view/130/128},

year  = {2021},

date = {2021-03-19},

urldate = {2021-03-19},

journal = {Food Science and Applied Biotechnology},

volume = {4},

number = {1},

pages = {48-56},

abstract = {This study aimed to investigate the biological activity of aqueous mixtures of two essential oils. The mixtures were prepared by mixing certain amounts of lavender and clove oils with distilled water at room temperature. In the case of lavender oil, a relatively clear saturated aqueous phase was obtained after mixing with an excess of the essential oil. The clove oil formed stable oil-in-water emulsions. The antibacterial activity of the samples was tested against two model bacterial strains. The growth of the Gram-negative Escherichia coli K12 and the Gram-positive Bacillus subtilis 3562 was determined in 96-well microplates. A more prominent inhibition activity against E. coli K12 strain compared to B. subtilis 3562 for both oil-water mixtures was observed. A disk diffusion test indicated growth inhibition by the lavender oil during the tests against the Gram-positive strain (zones of around 11.7 mm) while clove oil inhibited both bacteria (12 mm - B. subtilis 3562 and 13.66 mm - E. coli K12). The DPPH free radical method showed no antioxidant activity for the aqueous solution of lavender oil. The pure lavender oil exhibited negligible activity compared to the gallic acid reference solution, the clove essential oil, and its emulsion. A quantitative relationship between the content of cloves essential oil in the emulsion and its radical scavenging capacity was demonstrated.},

keywords = {Journal Article},

pubstate = {published},

tppubtype = {article}

}

@article{D.Peshev2020b,

title = {Възможности за оползотворяване на отпадъчните продукти от производството на етерични масла},

author = {Д. Пешев},

editor = {Е. Николова},

url = {http://www.nanoessential.eu/wp-content/uploads/Peshev_ProPack_Issue_5x2020.pdf},

issn = {0204-9953},

year  = {2020},

date = {2020-10-31},

urldate = {2020-10-31},

journal = {Полиграфия},

volume = {ПроПак},

number = {5},

pages = {4-7},

keywords = {Journal Article},

pubstate = {published},

tppubtype = {article}

}

@article{D.Peshev2020,

title = {Theoretical assessment of the use of nanofiltration for fractionation of waste aqueous fractions from the essential oil industry},

author = {D.Peshev},

url = {http://www.nanoessential.eu/wp-content/uploads/BCC-52-4-2020-532-542-Peshev-MP05-1.pdf},

doi = {10.34049/bcc.52.4.MP05},

year  = {2020},

date = {2020-10-19},

urldate = {2020-10-19},

journal = {Bulgarian Chemical Communications},

volume = {52,},

number = {4},

pages = {532-542},

abstract = {The possibility to fractionate hydrosols and extracts (residual waters) from the distillation of representative essential oil plants using nanofiltration was investigated. The rejections of five commercial nanofiltration membranes with respect to key bioactive components were predicted based on regression models. Membranes of different Molecular Weight Cut-Off (MWCO), structure and composition were analyzed. Descriptors in the models were the membrane MWCO and zeta potential, as well as the molecular weight (Mw), octanol-water partition coefficient (log P) and acidity constant (pKa) of the solutes. For consistency, log P and pKa of all studied components were calculated according to the COSMO-RS method, which has the quantum-chemical basis of the Conductor-like Screening Model (COSMO). The distribution of the key components in the two types of effluents under the process conditions was also predicted using COSMO-RS for modelling of the solid-liquid, liquid-liquid and vapor-liquid equilibrium. The calculations were performed using the BIOVIA COSMOsuite software package. The results showed that independently of the membrane material, the polymeric membranes exhibit high retention capability against charged solutes such as the phenolic acids contained in the residual waters. Since the pKa of the phenolic compounds, representatives of the flavonoid family, is within the range of pH of the aqueous extracts, their retention or permeation could be controlled by slight variations of the pH. The essential oil components dissolved in the aqueous fractions are easily permeating through the membranes.},

keywords = {Journal Article},

pubstate = {published},

tppubtype = {article}

}