Participation in the 67th Scientific Conference with International Participation “FOOD SCIENCE, ENGINEERING AND TECHNOLOGY – 2020”
The 67-th Scientific Conference with International Participation “FOOD SCIENCE, ENGINEERING AND TECHNOLOGY 2020” was organized on October 23, 2020 at the University of Food Technologies (UFT). The team’s works in three topics were presented.
Abstracts:
Extraction of essential oil from cloves using steam and hydro distillation
Essential oils are used in a wide variety of consumer goods such as detergents, toilet products, cosmetics, pharmaceuticals, confectionery food products, soft drinks, distilled alcoholic beverages and insecticides. The extracts of cloves have a pleasant smell, and direct practical applications as a flavoring agent, antioxidant, antifungal agent, local anesthetic, and nutraceutical. The goal of this study is to isolate the natural product, essential oil, from cloves using the steam and water distillation. Both techniques are often used in industry to essential oils manufacturing. The experiments and detailed procedures of water and steam distillation are developed and presented. The optimal clove-to-distillate ratio [g(cloves)/ml(obtained distillate)] with respect to total oil production were determined. The ratio was varied between 0.125 g/mL and 0.0625g/mL. It was found that the optimal ratio of clove-to-distillate was 0.0833 g/mL. The antibacterial activity of the essential oils obtained by two present techniques was determined by the disk diffusion method against Escherichia coli K12 and Bacillus subtilis 3562. The antioxidant activity of the samples was also analysed by the DPPH free radical method where a gallic acid was used as a reference solution.
This work was supported by the Bulgarian National Science Fund (contract KP-06-H37/14)
Study of the biological activity of essential oil-water mixtures
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 excess of the essential oil. The clove oil formed stable oil-in-water emulsions. The antibacterial activity of lavender oil and its aqueous solution were tested against two model bacterial strains. The growth of Escherichia coli K12 and Bacillus subtilis 3562 in the presence of the analysed samples was determined in 96-well microplates and also by a disk diffusion test (Kirby–Bauer test). The results showed that the lavender aqueous solution did not exhibit antibacterial activity against both – the Gram-negative and Gram-positive strains but the oil itself indicated inhibition zones of around 11.7 mm during the tests against B. subtilis 3562. The DPPH free radical method showed no antioxidant activity for the lavender aqueous solution of lavender oil. At the same time the pure lavender oil exhibit low activity compared to the gallic acid (used as a reference) and the clove essential oil. The inhibitory effect of the lavender samples were further compared with the essential oil from clove and its oil-in-water emulsion.
Keywords: antibacterial activity, antioxidant activity, essential oils
Abbreviations:
DPPH – 2,2-diphenyl-1-picryl-hydrazyl-hydrate
Acknowledgements: This work was supported by the Bulgarian National Science Fund (contract KP-06-H37/14)wledgements: This work was supported by the Bulgarian National Science Fund (contract KP-06-H37/14)
✉Corresponding author: Dr. Nevena Lazarova-Zdravkova, Chief Assistant Prof., Department of Biotechnology, Faculty of Chemical and System Engineering, UCTM, 8 Kliment Ohridski, 1756 Sofia, Bulgaria, tel.: ++359 2 8163312, mobile: ++359 888 283 392; E-mail: nevena@uctm.edu
Poster_2Theoretical assessment of the possibility for fractionation of waste aqueous fractions from the essential oil industry using nanofiltration.
The possibility to fractionate hydrosols and extracts (residual waters) from the distillation of 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 MWCO, structure and composition were analysed. Descriptors in the models were the membrane MWCO and zeta potential as well as the molecular weight, log P and pKa of the solute. 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 calculations were performed using the BIOVIA COSMOsuite software package. The results showed that independently on the membrane material, the polymeric membranes exhibit high retention capability against charged solutes such as the contained in the residual waters phenolic acids. 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 dissolved in the aqueous fractions essential oil components would be easily permeating through the membranes.
Keywords: essential oil, nanofiltration, membrane, fractionation, hydrosol, residual water, phenolic compounds, COSMO-RS
Abbreviations:
MWCO – Molecular Weight Cut-Off
Acknowledgements: This work was supported by the Bulgarian National Science Fund (contract KP-06-H37/14)
✉Corresponding author: Dr. DimitarPeshev, Associate Prof., Department of Chemical Engineering, Faculty of Chemical and System Engineering, UCTM, 8 Kliment Ohridski, 1756 Sofia, Bulgaria, tel.: ++359 2 8163287, mobile: ++359 898 266 880; E-mail: d.peshev@uctm.edu
Poster_3
