Ekstrakcija ulja iz semena konoplje (Cannabis sativa L.) i njegova primena u sintezi biodizela

The subject of this doctoral dissertation research was to obtain the oil from hemp seeds and to use it for biodiesel production. The main goals of the dissertation were optimization of operating conditions, kinetics modeling and thermodynamic analysis of maceration process, as well as optimization and modeling of hempseed oil methanolysis reaction kinetics. In order to determine the dependence of oil yield on process conditions process conditions and modeling the hempseed oil maceration, the response surface methodology (RSM) in combination with 33 full factorial design with replication, as well as artificial neural network combined with genetic algorithm (ANN-GA) were used. The variance analysis (ANOVA) revealed that extraction temperature had the greatest influence on the hempseed oil yield, followed by seed:solvent ratio and extraction time. Optimal extraction conditions determined by RSM (extraction temperature 70 oC, seed:solvent ratio 1:7.9 g/ml and 12.3 min extraction time) and ANN-GA methods (extraction temperature 70 oC, seed:solvent ratio 1:10 g/ml and 10 min extraction time) were very close. The predicted oil yield values determined by second-order polynomial equation and neural network model agreed very well with experimentally obtained values, so both models are acceptable for oil yield prediction in the investigated extraction conditions range. The two kinetic models were used for modeling the kinetics of hempseed oil maceration: simultaneous washing and diffusion (phenomenological model) and instantaneous washing followed by diffusion (simplified phenomenological model). In both cases, good agreement between the predicted and actual hempseed oil yields was obtained, indicated by low mean MRPD (±2.5% in the case of a phenomenological model and ±2.8% in the case of a simplified model). The thermodynamic analysis results of the hempseed oil extraction have shown that the oil extraction was spontaneous, endothermic and irreversible. For the biodiesel production, hempseed oil was obtained by seed pressing. As the free fatty acids (FFAs) content in the oil was higher than 2%, the synthesis of fatty acid methyl esters (FAMEs) was carried out by a two-stage process including acid-catalyzed esterification of FFAs in the oil followed by base-catalyzed methanolysis of esterified oil. The methanolysis reaction was carried out in the presence of quicklime as a catalyst, at different methanol:oil molar ratios and various amounts of catalyst. According to the ANOVA results, catalyst concentration, reaction time, interaction of the catalyst concentration and reaction time, as well as the square of reaction time had statistically significant influence on the FAMEs content of hempseed oil, while the effects of methanol:oil molar ratio, its interaction with the two other factors as well as squares of methanol:oil molar ratio and catalyst concentration, were statistically insignificant. The reliability of the model in predicting the FAMEs content was confirmed by appropriate statistical criteria and low MRPD value. The irreversible pseudo-first order kinetic model and model that included the changing mechanism of the reaction and the triacylglycerols mass transfer limitation were applied for modeling the methanolysis reaction kinetics of esterified hempseed oil. The catalyst concentration and the initial methanol concentration had no effect on the apparent rate constant of esterified oil methanolysis reaction, and its value, determined using both kinetic models, was 0.141 min-1. Both kinetic models are reliable in presenting a change in the triacylglycerol conversion degree, but the irreversible pseudo-first-order reaction model is more acceptable because it has a slightly lower MRPD value between the predicted and actual values of FAMEs content

Comparison of Box-Behnken, Face Central Composite and Full Factorial Designs in Optimization of Hempseed Oil Extraction by n-Hexane: a Case Study

Statistical multivariate methods like Box-Behnken, face central composite and full factorial designs (BBD, FCCD and FFD, respectively) in combination with the response surface methodology (RSM) were compared when applied in modeling and optimization of the hempseed oil (HSO) extraction by n-hexane. The effects of solvent-to-seed ratio, operation temperature and extraction time on HSO yield were investigated at the solvent-to-seed ratio of 3:1, 6.5:1 or 10:1 mL/g, the extraction temperature of 20, 45 or 70 °C and the extraction time of 5, 10 or 15 min. All three methods were efficient in the statistical modeling and optimization of the influential process variables and led to almost the same optimal process conditions and predicted HSO yield. Having better statistical performances and being economically advantageous over the FFD with repetition, the BBD or FCCD combined with the RSM is recommended for the optimization of liquid-solid extraction processes

Optimizacija proizvodnje biodizela kukuruznog ulja metanolizom katalizovanom pepelom kurdeljke

The use of low-cost or priceless feedstocks such as byproducts in biodiesel production results in a reduced overall process costs. The present paper reports the use of corn germs and corn cobs as byproducts from corn-based starch production in the biodiesel production by the methanolysis of the oil extracted from corn germs, catalyzed by the ash produced by combustion of corn cobs. The major aim was to optimize the methanol-to-oil molar ratio, catalyst loading, and reaction time in a batch stirred reactor with respect to the content of methyl ester fatty acids (FAME). The statistical modeling and optimization were carried out using a second-order polynomial (quadratic) model developed by the response surface methodology combined with a 33 factorial design with 3 central points. The FAME content was determined by a high-pressure liquid chromatography method. The analysis of variance showed that only the catalyst amount, the reaction time, the catalyst amount interaction with reaction time and all three quadratic terms were the significant model terms with the confidence level of 95 %. The optimum reaction conditions (the catalyst amounts of 19.8 %, the methanol-to-oil molar ratio of 9.4 mol/mol and the reaction time of 31 min) provided the FAME content of 98.1 %, which was in an excellent agreement with the predicted FAME content (98.4 %). Thus, both corn germs and corn cobs may be suitable feedstocks for biodiesel production.Upotreba jeftinih ili bezvrednih sirovina, kao što su sporedni proizvodi, u proizvodnji biodizela ima za rezultat smanjene ukupne troškove procesa. U ovom radu su prikazani rezultati upotrebe kukuruznih klica i okrunjenog kukuruznog klipa (kurdeljke, krudeljke) kao sporednih proizvoda iz proizvodnje kukuruznog skroba u proizvodnji biodizela metanolizom ulja izdvojenog iz kukuruznih klica, katalizovane pepelom dobijenim sagorevanjem kurdeljke. Glavni cilj je bila optimizacija molskog odnosa metanol-ulje, količine katalizatora i reakcionog vremena u šaržnom reaktoru sa mešanjem u odnosu na sadržaj metilestra masnih kiselina (MEMK). Statističko modelovanje i optimizacija izvršeni su korišćenjem kvadratnog modela, razvijenog metodologijom odzivne površine, u kombinaciji sa 33 faktorijelnim planom sa 3 centralne tačke. Sadržaj MEMK-a je određen metodom tečne hromatografije pod visokim pritiskom. Analiza varijanse je pokazala da su samo uticaji količine katalizatora, reakcionog vremena, interakcije količine katalizatora sa reakcionim vremenom i sva tri kvadratna člana statistički značajni sa nivoom pouzdanosti od 95 %. Pod optimalnim reakcionim uslovima (količina katalizatora 19,8 %, molski odnos metanol/ulje 9,4 mol/mol i reakciono vreme 31 min) dobijen je sadržaj MEMK-a od 98,1 %, koji se slaže sa predviđenim sadržajem MEMK-a (98,4 %). Prema tome, i kukuruzne klice i kurdeljka mogu biti pogodne sirovine za proizvodnju biodizela

How Can Tufa Deposits Contribute to the Geotourism Offer? The Outcomes from the First UNESCO Global Geopark in Serbia

The study focuses on the present state and the assessments of geotourism development of the two most representative tufa deposits in the Djerdap National Park—the first UNESCO Global Geopark in Serbia. The findings were designated through implementing the freshly upgraded methodology—M-GAM-1-2 based on an early modified geosites assessment model (M-GAM). To overcome the limitations of the previous model, the authors implemented additional enhancements and involved members of the local community (residents and authorities) in the study to comprehensively evaluate the observed sites. The outcomes revealed that the attitudes of all stakeholders should be taken into consideration in order to develop geotourism properly, additionally attract visitors, and preserve tufa deposits for future generations of locals and visitors. Moreover, geotourism at the observed sites can be one of the vital activities of the population, as well as a type of compensation for various limitations in the development, which are imposed by the regimes of natural and cultural heritage protection within the recently established UNESCO Global Geopark

Biodiesel production from camelina oil: Present status and future perspectives

Camelina sativa (L.) Crantz is an oilseed crop with favorable potentials for biodiesel production, such as the high plant yield, high oil content in the seed, high net energy ratio, and low oil production cost. This review paper deals with the present state and perspectives of biodiesel production from camelina oil. First, important issues of camelina seed pretreatment and biodiesel production are reviewed. Emphasis is given to different biodiesel technologies that have been used so far worldwide, the economic assessment of the camelina oil biodiesel (COB) production, the camelina-based biorefineries for the integrated biodiesel production, the COB life cycle analysis, and impact human health and ecosystem. Finally, the perspectives of COB production from the techno-economic and especially genetic engineering points of view are discussed

In vitro digestion of meat- and cereal-based food matrix enriched with grape extracts: How are polyphenol composition, bioaccessibility and antioxidant activity affected?

The aim of this study was to evaluate the effect of enriching a complex food matrix (FM) with grape extracts on polyphenol content, composition, bioaccessibility and antioxidant activity during digestion. The grape extracts and FM were separately tested under the same conditions as controls. The FM by itself contains a significant amount of phenolic acids and flavonols, influencing the final recovery of polyphenols from grape extracts. The FM significantly increased the total recovery of polyphenols after digestion of grape seed extracts compared to those digested without the FM; however, a low recovery of proantocyanidins and total flavonoids was observed. Digestive fluids and FM compounds significantly increased the total polyphenol content of grape digests and significantly contributed to their ABTS(center dot+) scavenging activity and ferrous-ion-chelating capacity. The present study suggested that enrichment of meat-and cereal-based products with grape polyphenol extracts could be a good strategy to formulate a healthier diet

Improvement of lipid metabolism regulation by low-intensity exercise in fructose-fed rats

Excessive dietary fructose consumption in parallel with limited physical activity contributes to the global increase in prevalence of metabolic disorders. Metabolic syndrome represents a collection of cardiometabolic risk factors that includes obesity, insulin resistance, hypertension, and dyslipidemia, and it is undoubtedly linked to increased risk for two global maladies, type 2 diabetes, and cardiovascular diseases. Fructose-rich diet is accompanied by the development of insulin resistance in the heart, and it could change the use of cardiac energy substrates towards increased fatty acid (FA) uptake, and catabolism. Exercise may be beneficial in prevention and treatment of the metabolic syndrome. The aim of this study was to analyse the impact of low-intensity exercise on protein expression of nuclear transcription factors involved in regulating FA β- oxidation in a heart of fructose fed rats. Male Wistar rats were divided into control group, and two groups that received 10% fructose for 9 weeks, one which was sedentary and one which was additionally exposed to low intensity exercise. The protein expression of important transcriptional regulators of fatty acid β-oxidation PPARα, and FOXO1, and coregulators Lipin1, PGC-1, and SIRT1 are analyzed in cardiac lysate and/or nuclear fraction by Western blot. Gene expression of ACADL, the enzyme that catalyzes the initial step of mitochondrial β-oxidation, was quantified by real-time PCR. Fructose-rich diet decreased nuclear PPARα compared to control. Exercise increased nuclear PPARα, nuclear FOXO1, lysate PGC1, and nuclear Lipin1 in fructose-fed rats compared to sedentary fructose-fed rats. Exercise increased lysate PPARα, lysate and nuclear FOXO1, lysate PGC1, lysate and nuclear SIRT1, and nuclear Lipin1 in fructose-fed rats compared to control. In conclusion, running at low intensity is accompanied by increased expression of key regulators of fatty acid oxidation. The results indicate that exercise achieves its effect by increasing the nuclear content of PPARα, Lipin1, and FOXO1

Electrochemical synthesis and characterization of basic bismuth nitrate [Bi6O5(OH)3](NO3)5·2H2O: a potential highly efficient sorbent for textile reactive dye removal

A new method of synthesis was developed for the preparation of basic bismuth nitrate [Bi6O5(OH)3](NO3)5·2H2O (ECBBN). Electrochemical synthesis of the material was carried out by galvanostatic electrodeposition from an acidic Bi(III) solution on a Ti substrate and further thermal treatment in air at 200 °C. Characterization of ECBBN was conducted by employing SEM–EDX, N2 adsorption, XRD and FTIR, and its pI was also determined. The analyses showed that the material obtained was pure [Bi6O5(OH)3](NO3)5·2H2O. Morphologically, ECBBN aggregates were composed of crystals, some smaller than 50 nm. Electrochemically synthesized sorbent (ECBBN) was used for the removal of the textile dye Reactive Blue 19 (RB19) from deionized water and model solutions of polluted river water, and it showed considerably superior sorption performance compared to other inorganic sorbents synthesized by conventional methods reported in the literature. A kinetic study suggests that the sorption process is both under reaction and diffusion control. Equilibration of the sorption process was attained in several minutes, i.e. the sorption process is very fast. The sorption equilibrium data were well interpreted by the Langmuir, Redlich–Peterson and Brouers–Sotolongo isotherm. Using Langmuir isotherm, the maximum sorption capacity of ECBBN was reached at pH 2 and was 1049.19 mg g−1

Phenolic compounds and biopotential of grape pomace extracts from Prokupac red grape variety

Phenolic compounds and biopotential (antioxidant, cellular antioxidant and cytotoxic activity) of grape pomace (GP) skin, seed, stem and whole GP originating from indigenous red grape variety Prokupac were evaluated. The UHPLC-Orbitrap MS4 analysis showed the presence of 75 phenolic compounds (57 non-anthocyanins and 18 anthocyanins), among which considerable content of ethyl gallate was observed and malvidin-3-O-hexoside-(8,8)-methylmethyne-(epi)catechin was identified. The stem had significant content of stilbenoids. The GP seed and the whole GP showed the highest antioxidant activity estimated by ABTS•+ DPPH• and H2O2 scavenging assays that were strongly correlated with the presence of flavan-3-ols, phenolic acids and ethyl gallate. The GP skin exerted cellular antioxidant activity on adenocarcinoma cells (EC50 = 56.4 mg TPCs/mL) which was strongly correlated with the presence of flavonols and anthocyanins. These by-products of Prokupac red grape variety are a notable source of phenolic compounds with good antioxidant activity that can be extensively used in food and pharmaceutical industry.Supplementary material: [https://cherry.chem.bg.ac.rs/handle/123456789/4449

Supplementary data for the article: Pešić, M. B.; Milinčić, D. D.; Kostić, A.; Stanisavljević, N. S.; Vukotić, G. N.; Kojić, M. O.; Gašić, U. M.; Barać, M. B.; Stanojević, S. P.; Popović, D. A.; et al. In Vitro Digestion of Meat- and Cereal-Based Food Matrix Enriched with Grape Extracts: How Are Polyphenol Composition, Bioaccessibility and Antioxidant Activity Affected? Food Chem. 2019, 284, 28–44. https://doi.org/10.1016/j.foodchem.2019.01.107

Supplementary material for: [https://doi.org/10.1016/j.foodchem.2019.01.107]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2843]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/2867