Dragan Z. Troter
@tf.ni.ac.rs
Faculty of Technology in Leskovac
University of Niš
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Vesna S. Zlatković, Nada L. Grahovac, Ivana B. Banković Ilić, Petar M. Mitrović, Dragan Z. Troter, Zoran B. Todorović, Ana M. Marjanović Jeromela, and Vlada B. Veljković
Wiley
AbstractThis study aims to explore the influence of screw frequency, nozzle diameter, and press head temperature on critical crude fodder radish seed oil (FRSO) yield, throughput, and fatty acid composition. A quadratic equation, developed using response surface methodology, fitted the experimental data for oil yield. It was substantiated by a non‐significant lack‐of‐fit, commendable coefficient‐of‐determination (R2 = 0.782), and a modest mean relative percentage deviation (±7.27%). The analysis of variance pinpointed the statistical significance of press head temperature, nozzle size, and the squared term of press head temperature. The highest FRSO yield (17.61%)—corresponding to an extraction efficiency of 51.3% was found with a screw frequency of 50 Hz, at 80°C, and an 8 mm nozzle. A linear model highlighted that all three pressing factors significantly influenced the FRSO throughput. FRSO consists of C18:1 (30.9%), C22:1 (20.8%), C18:2 (14.9%), and C18:3 (11.9%), aligning with the compositions reported in other studies on fodder radish oils.Practical applicationsEffective control of cold pressing parameters is paramount to maximize oil yield and throughput during the oil extraction process and to ensure the appropriate oil quality. A comprehensive understanding of the intricacies of this process, while carefully considering key parameters, which is essential to ensure efficiency, is achieved through a combination of experimental and statistical methods. This study marks the inaugural attempt to optimize screw pressing for fodder radish seeds while conducting a comparative analysis with hydraulic pressing and the Soxhlet extraction method, focusing on oil yield, throughput, and fatty acid composition within the system by employing a modeling approach for oil extraction. Through the utilization of the response surface methodology coupled with various experimental designs, the processing conditions are successfully optimized. The valuable data gathered can aid equipment design for an efficient, eco‐friendly oil extraction process. Furthermore, the oil extracted under the optimized conditions met the quality standards.
Zoran B. Todorović, Petar M. Mitrović, Vesna Zlatković, Nada L. Grahovac, Ivana B. Banković-Ilić, Dragan Z. Troter, Ana M. Marjanović-Jeromela, and Vlada B. Veljković
Springer Science and Business Media LLC
Zoran Todorovic, Biljana Djordevic, Dragan Troter, Ljiljana Veselinovic, Miodrag Zdujic, and Vlada Veljkovic
National Library of Serbia
Deep eutectic solvents (DESs) are called 'designer solvents' due to various structural variations and the benefit of tailoring their physicochemical properties. For industrial applications of DESs it is crucial to know their physical and thermodynamic properties such as density, viscosity, and refractive index. These properties were measured for three lecithin (LEC)-based DESs with glycerol (G), triethanolamine (TEOA), and oleic acid (OLA) as functions of temperature. The viscosity was fitted by both Arrhenius-type and Vogel-Tamman-Fulcher equations. The density, viscosity, and refractive index of tested DESs decreased with the increase in temperature. The LEC:G DES exhibited the lowest density at all tested tempe-ratures. This DES was selected as a cosolvent in the ethanolysis of cold-pressed black mustard (Brassica nigra L.) seed oil catalyzed by either calcined or non-calcined CaO. The reaction was carried out in a batch stirred reactor under the following conditions: the temperature of 70 ?C, the ethanol-to-oil molar ratio of 12:1, and the amount of DES and CaO of 20 and 10 wt.% (to oil), respectively. The presence of DES accelerated the reaction, while the separation of the final reaction mixture phases was faster.
Valentina G. Nikolić, Dragan Z. Troter, Ivan M. Savić, Ivana M. Savić Gajić, Jelena B. Zvezdanović, Ina B. Konstantinović, and Sandra S. Konstantinović
Elsevier BV
Aleksandra N. Milenković, Jelena S. Stanojević, Dragan Z. Troter, Milica G. Pejčić, Zorica Z. Stojanović-Radić, Dragan J. Cvetković, and Ljiljana P. Stanojević
Informa UK Limited
ABSTRACT Black (Piper nigrum L.) and cubeb pepper (Piper cubeba L.) fruits from the Serbian market were chosen as unprocessed materials for obtaining market-valuable essential oils. Since pepper fruits are only imported in Serbia, inadequate transportation and storage conditions may lead to their spoilage, negatively affecting their quality as feedstocks. To ensure the highest quality of essential oils, fruits were refrigerated upon purchase, mechanically disintegrated at colder conditions and subjected to hydrodistillation. Black (BPEO) and cubeb pepper essential oil (CPEO) contained 34 and 42 compounds, respectively. CPEO showed better inhibitory effect on B. cereus (ATCC strain) and C. albicans (isolate and ATCC strain). Both oils were not bactericidal against B. cereus (isolate and ATCC strains) and S. enterica (isolate). The best antioxidant properties were shown after 1 h of incubation. These results are valuable for further progress, development and production regarding the aromatic plant industry, pharmaceutical and food industry.
Dušica P. Ilić, Dragan Z. Troter, Ljiljana P. Stanojević, Jelena B. Zvezdanović, Danica D. Vukotić, and Vesna D. Nikolić
Elsevier BV
Biljana S. Đorđević, Zoran B. Todorović, Dragan Z. Troter, Ljiljana P. Stanojević, Gordana S. Stojanović, Ivica G. Đalović, Petar M. Mitrović, and Vlada B. Veljković
Springer Science and Business Media LLC
Bojana Danilovic, Natalija Djordjevic, Ivana Karabegovic, Dragan Troter, Dragisa Savic, and Vlada Veljkovic
National Library of Serbia
In recent years, many researchers have focused on microalgae as a potential source of lipids for various purposes. To improve the lipid yield, different biomass pretreatments have been investigated. The aim of this work was to determine the effect of an ultrasound and deep eutectic solvent (DES) pretreatment on lipid yield from green microalgae Chlorella sp. The chosen DESs were choline chloride:urea (ChCl:U), choline chloride:glycerol (ChCl:G) and choline chloride:acetic acid (ChCl:Aa), all in the mole ratio of 1:2. Lipids were extracted from the pretreated and untreated biomasses by Bligh and Dyer?s method. The results showed that the lipid yields for the untreated and ultrasound-pretreated biomass were 39 and 48%, respectively. The pretreatments with ChCl:U, ChCl:G and ChCl:Aa resulted in lipid yields of 51, 46 and 40%, respectively. Therefore, the use of efficient and environmentally friendly DESs for the microalgae biomass pretreatment resulted in a higher lipid yield.
Ljiljana P. Stanojević, Zoran B. Todorović, Katarina S. Stanojević, Jelena S. Stanojević, Dragan Z. Troter, Ljubiša B. Nikolić, and Biljana Đorđević
Informa UK Limited
ABSTRACT Essential oil from rosemary (Rosmarinus officinalis L.) leaves was isolated by conventional hydrodistillation using hydromodulus of 1/15 m/v and by distillation after the plant material pretreatment with 10% v/v aqueous solution of natural deep eutectic solvent glyceline. Qualitative and quantitative composition of the oil was determined by GC/MS and GC/FID analyses, while its antioxidant activity was investigated by DPPH assay. The yield of the essential oil was higher after the pretreatment of the leaves. The distillation method affected the quantitative composition of essential oil, but not its qualitative composition. The essential oil from the pretreated leaves had a higher content of camphor, verbenone and borneol (33.3%, 12.2% and 8.3%, respectively) and better antioxidant activity than the oil obtained by classical hydrodistillation. The advantage of the pretreatment method is the effective improvement of the extraction efficiency of rosemary essential oil from rosemary leaves.
Biljana S. Đorđević, Dragan Z. Troter, Zoran B. Todorović, Ivica G. Đalović, Ljiljana P. Stanojević, Petar M. Mitrović, and Vlada B. Veljković
Springer Science and Business Media LLC
Biljana Djordjevic, Dragan Troter, Vlada Veljkovic, Mirjana Kijevcanin, Ivona Radovic, and Zoran Todorovic
National Library of Serbia
Different deep eutectic solvents (DESs) of triethanolamine (TEOA) and oxalic acid (OA), glacial acetic acid (AA), L-(+)-lactic acid (LA), oleic acid (OLA), glycerol (G), ethylene glycol (EG), propylene glycol (PEG), choline chloride (ChCl) or 1,3-dimethylurea (DMU) were prepared and characterized regarding their physicochemical (density, viscosity, electrical conductivity, refractive index, coefficient of volume expansion, molecular volume, lattice energy and heat capacity) properties over the temperature range of 293.15?363.15 K at 101.325 kPa. For all tested DESs, the density, viscosity and refractive index decreased with rising temperature, while the electrical conductivity increased. The temperature dependence of viscosity and electrical conductivity are described by the Vogel?Tamman?Fulcher equations. The viscosity and molar conductivity, which exhibited a linear behaviour, were correlated by the fractional Walden rule. Besides, the Fourier transform infrared spectroscopy (FTIR) was used to study the functional groups of these DESs while thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) provided the information about their stability. The tested DESs of TEOA possess desirable properties for use in various industrial processes, such as extractions, separations, chemical technology and biotechnology.
Dušica P. Ilić, Ljiljana P. Stanojević, Dragan Z. Troter, Jelena S. Stanojević, Bojana R. Danilović, Vesna D. Nikolić, and Ljubiša B. Nikolić
Elsevier BV
Zoran B. Todorović, Dragan Z. Troter, Dušica R. Đokić-Stojanović, Ana V. Veličković, Jelena M. Avramović, Olivera S. Stamenković, Ljiljana M. Veselinović, and Vlada B. Veljković
Elsevier BV
Dusica Djokic-Stojanovic, Zoran Todorovic, Dragan Troter, Olivera Stamenkovic, Ljiljana Veselinovic, Miodrag Zdujic, Dragan Manojlovic, and Vlada Veljkovic
National Library of Serbia
Triethanolamine was applied as an efficient ?green? cosolvent for biodiesel production by CaO-catalyzed ethanolysis of sunflower oil. The reaction was conducted in a batch stirred reactor and optimized with respect to the reaction temperature (61.6-78.4?C), the ethanol-to-oil molar ratio (7:1-17:1) and the cosolvent loading (3-36 % of the oil weight) by using a rotatable central composite design (RCCD) combined with the response surface methodology (RSM). The optimal reaction conditions were found to be: the ethanol-to-oil molar ratio of 9:1, the reaction temperature of 75?C and the cosolvent loading of 30 % to oil weight, which resulted in the predicted and actual fatty acid ethyl ester (FAEE) contents of 98.8 % and 97.9?1.3 %, respectively, achieved within only 20 min of the reaction. Also, high FAEE contents were obtained with expired sunflower oil, hempseed oil and waste lard. X-ray diffraction analysis (XRD) was used to understand the changes in the CaO phase. The CaO catalyst can be used without any treatment in two consecutive cycles. Due to the calcium leaching into the product, an additional purification stage must be included in the overall process.
Dusica Djokic-Stojanovic, Zoran Todorovic, Dragan Troter, Olivera Stamenkovic, Ljiljana Veselinovic, Miodrag Zdujic, Dragan Manojlovic, and Vlada Veljkovic
National Library of Serbia
Ten organic solvents (triethanolamine, diethanolamine, ethylene glycol, methyl ethyl ketone, n-hexane, triethylamine, ethylene glycol dimethyl ether, glycerol, tetrahydrofuran and dioxane) were applied as cosolvents in the CaO-catalyzed ethanolysis of sunflower oil performed in a batch stirred reactor under the following reaction conditions: temperature 70 ?C, ethanol-to-oil mole ratio 12:1, initial catalyst concentration 1.374 mol?L-1 and amount of cosolvent 20 % based on the oil amount. The main goals were to assess the effect of the used cosolvents on the synthesis of fatty acid ethyl esters (FAEE) and to select the most efficient one with respect to the final FAEE content, reaction duration and safety profile. In the absence of any cosolvent, the reaction was rather slow, providing a FAEE content of only 89.7?1.7 % after 4 h. Of the tested cosolvents, diethanolamine, triethanolamine and ethylene glycol significantly accelerated the ethanolysis reaction, whereby the last two provided a final FAEE content of 93.1?2.1 and 94.1?1.5 %, respectively, within 0.5 h. However, because of its safety profile, triethanolamine was selected as the best cosolvent for the ethanolysis of sunflower oil catalyzed by calcined CaO.
Dragan Z. Troter, Zoran B. Todorović, Dušica R. Đokić-Stojanović, Ljiljana M. Veselinović, Miodrag V. Zdujić, and Vlada B. Veljković
Elsevier BV
Dragan Troter, Zoran Todorovic, Dusica Djokic-Stojanovic, Biljana Djordjevic, Vanja Todorovic, Sandra Konstantinovic, and Vlada Veljkovic
National Library of Serbia
This paper reports the physicochemical (density, dynamic viscosity, electrical conductivity and refractive index) and the thermodynamic (thermal expansion coefficient, molecular volume, lattice energy and heat capacity) properties of several choline chloride (ChCl) based deep eutectic solvents (DESs), with 1:2 mole ratio, respectively: ChCl:propylene glycol, ChCl:1,3-dimethylurea and ChCl:thiourea, at atmospheric pressure as a function of temperature over the range of 293.15?363.15 K. Their properties were also compared with those of some already characterized ChCl-based DESs, namely ChCl:ethylene glycol, ChCl:glycerol and ChCl:urea (1:2 mole ratio). Density, viscosity and refractive index of all DESs decrease with the increasing temperature while the electrical conductivity increases. Viscosity and conductivity of the tested DESs were fitted by both Arrhenius-type and Vogel?Tamman?Fulcher equations. The changes of molar enthalpy, entropy and Gibbs energy of activation, determined using the Eyring theory, demonstrated the interactional factor as predominant over the structural factor for all DES systems. The fractional Walden rule, used to correlate molar conductivity and viscosity, showed an excellent linear behaviour. It was shown that ChCl:propylene glycol DES had properties similar to ChCl:ethylene glycol and ChCl:glycerol DESs. However, the properties (density, viscosity and electrical conductivity) of ChCl:1,3-dimethylurea and ChCl: :thiourea DESs were inferior to those of the ChCl:urea DES.
Dragan Z. Troter, Zoran B. Todorović, Dušica R. Đokić-Stojanović, Olivera S. Stamenković, and Vlada B. Veljković
Elsevier BV