The production of fatty acid methyl esters (FAME) from crude tobacco seed oil (TSO) having high free fatty acids (FFA) was investigated. Due to its high FFA, the TSO was processed in two steps: the ...acid-catalyzed esterification (ACE) followed by the base-catalyzed methanolysis (BCM). The first step reduced the FFA level to less than 2% in 25
min for the molar ratio of 18:1. The second step converted the product of the first step into FAME and glycerol. The maximum yield of FAME was about 91% in about 30
min. The tobacco biodiesel obtained had the fuel properties within the limits prescribed by the latest American (ASTM D 6751-02) and European (DIN EN 14214) standards, except a somewhat higher acid value than that prescribed by the latter standard (<0.5). Thus, tobacco seeds (TS), as agricultural wastes, might be a valuable renewable raw material for the biodiesel production.
The sunflower oil methanolysis was studied in a stirred reactor at different agitation speeds. The measurements of drop size, drop size distribution and the conversion degree demonstrate the effects ...of the agitation speed in both non-reaction (methanol/sunflower oil) and reaction (methanol/KOH/sunflower oil) systems. Drop size distributions were found to become narrower and shift to smaller sizes with increasing agitation speed as well as with the progress of the methanolysis reaction at a constant agitation speed. During the methanolysis reaction, the Sauter-mean drop diameter stays constant in the initial slow reaction region, rapidly decreases during the fast reaction period and finally reaches the equilibrium level. Due to the fact that the interfacial area increases, one can conclude that the rate of reaction occurring at the interface will also be enhanced progressively. The “autocatalytic” behavior of the methanolysis reaction is explained by this “self-enhancement” of the interfacial area, due to intensive drop breakage process.
The ultrasonic extraction (UE) of oil from the seeds of a semi-oriental tobacco (Nicotiana tabacum L.) plant strain by using n-hexane and petroleum ether was studied at different temperatures and ...seeds-to-solvent ratios. The oil yield depended on the seed comminution, the extraction temperature, the seeds-to-solvent ratio and the type of solvent. The oil yield was much higher if the seeds were ground before extraction. The oil yield increased with increasing the extraction temperature and with decreasing the seeds-to-solvent ratio. n-Hexane was somewhat more efficient in the oil extraction than petroleum ether. In recovering the tobacco seed oil (TSO), the UE was less efficient than the Soxhlet extraction. The advantage of the UE was a relatively high oil yield at 25°C in a shorter time. The kinetics of UE of TSO was described using the model of unsteady diffusion through plant material.
Loess-palaeosol sequences represent important palaeoclimatic and palaeoenvironmental archives on land. Furthermore, loess deposits in the Vojvodina region (North Serbia) can be regarded as one of the ...most important European terrestrial records of climatic and environmental changes during the last million years which makes them valuable scientific resource. Unfortunately, these sites are endangered by numerous, mostly human, factors and could be degraded permanently. Besides the scientific community, these geosites could be presented and interpreted (geotourism) to a much wider audience. This paper presents an introduction with general overview of the evaluation and conservation methods and sustainable promotion of loess sediments and their possible implications in the Vojvodina region. The proposed methods could also be further applied to other geologically equivalent locations worldwide.
Properties of poly (lactic acid) (PLA) and its nanocomposites, with silica
nanoparticles (SiO2), as filler were investigated. Neat PLA films and PLA
films with different percentage of hydrophobic ...fumed silica nanoparticles
(0.2, 0.5, 1, 2, 3 and 5 wt. %) were prepared by solution casting method.
Several tools were used to characterize the influence of different silica
content on crystalline behavior, and thermal, mechanical and barrier
properties of PLA/SiO2 nanocomposites. Results from scanning electron
microscope (SEM) showed that the nanocomposite preparation and selection of
specific hydrophobic spherical nano filler provide a good dispersion of the
silica nanoparticles in the PLA matrix. Addition of silica nanoparticles
improved mechanical properties, the most significant improvement being
observed for lowest silica content (0.2wt.%). Barrier properties were
improved for all measured gases at all loadings of silica nanoparticles. The
degree of crystallinity for PLA slightly increased by adding 0.2 and 0.5 wt.
% of nano filler.
The methanolysis of sunflower oil was studied in the presence of CaO previously calcined at various temperatures and the optimal temperature for CaO calcination was determined. The sigmoidal process ...kinetics was explained by the initial triglyceride (TG) mass transfer controlled region, followed by the chemical reaction controlled region in the latter reaction period. The TG mass transfer limitation was due to the small available active specific catalyst surface, which was mainly covered by adsorbed molecules of methanol. In the later phase, the adsorbed methanol concentration decreased, causing the increase of both the available active specific catalyst surface and the TG mass transfer rate, and the chemical reaction rate become smaller than the TG mass transfer rate.
The kinetics of the sunflower oil methanolysis process was studied at lower temperatures (10–30
°C). The sigmoidal kinetics of the process was explained by the mass transfer controlled region in the ...initial heterogenous regime, followed by the chemical reaction controlled region in the pseudo-homogenous regime. A simple kinetic model, which did not require complex computation of the kinetic constants, was used for simulation of the TG conversion and the FAME formation in the latter regime: the fast irreversible second-order reaction was followed by the slow reversible second-order reaction close to the completion of the methanolysis reaction. The mass transfer was related to the drop size of the dispersed (methanol) phase, which reduced rapidly with the progress of the methanolysis reaction. This was attributed to the formation of the emulsifying agents stabilizing the emulsion of methanol drops into the oil.
•Microwave-assisted extraction (MAE) of total polyphenols from chokeberries was optimized.•Optimization of extraction conditions was enabled by the RSM and ANN methods.•Optimum and economic ...extraction conditions were proposed.•MAE can be recommended as rapid and cost effective method for chokeberry extraction.
Response surface methodology (RSM) and artificial neural network (ANN) were used for modeling and optimizing microwave-assisted extraction (MAE) of total polyphenolic content (TPC) from chokeberries (Aronia melanocarpa) as a function of microwave power (300, 450 and 600W), ethanol concentration (25%, 50% and 75%) and extraction time (5, 10 and 15min). The set of the optimal operational conditions, as well as the conditions which gave the maximum yield of TPC while minimizing extraction time, solvent and energy consumption, (economic conditions), were proposed. Statistical indicators such as the coefficient of determination (R2), root-mean-square error (RMSE) and mean absolute error (MAE) demonstrated the superiority of the ANN. In order to scale-up a MAE procedure of chokeberries TPC from the laboratory to the industrial scale, the following set of conditions was proposed: an ethanol concentration of 53.6%, the microwave power of 300W and the extraction time of 5min corresponded to a TPC yield of 420.1mg gallic acid equivalents (GAE)/100g of fresh plant material.
Autochthones grape variety of ‘Prokupac’ (Vitis vinifera L.) is being increasingly cultivated in the Republic of Serbia and is one of the predominant varieties in the vineyards of southern Serbia. ...‘Prokupac’ grapes are used to produce red wine with specific and distinctive varietal aromatic characteristics. Medicinal herbs can be effectively combined in alcoholic beverages. The aim of this study was to evaluate the effect of medicinal herbs on the aroma profile and sensory characteristics of ‘Prokupac’ red wine. The analysis of the aromatic composition was conducted on ‘Prokupac’ wine (control) and ‘Prokupac’ wine aromatised with selected medicinal herbs: anise (Pimpinella anisum L.), cinnamon (Cinnamomum verum J. Presl.), wormwood (Artemisia absinthium L.) and licorice (Glycyrrhiza glabra L.). The analysis of volatile aromatic compounds in the wines, performed by the gas chromatography-mass spectrometry (GC/MS) method, identified 48 compounds that were classified in the following groups: alcohols, aldehydes, ketones, acids, ethyl esters and terpenes. Sensory analysis of wines was performed including visual, olfactory, gustatory and gustatory-olfactory perceptions. Terpenes were not identified in the ‘Prokupac’ control wine, while the highest content of all identified aromatic compounds was found in wines aromatised with anise, wormwood and cinnamon. The results indicated that selected medicinal herbs affected the composition and content of volatile aromatic compounds, as well as the sensory characteristics of analyzed wines. The unique aroma profile and pleasant taste of the wine aromatised with cinnamon contributed to its differentiation from other wines, and classification as very good wine.
The aim of this work was to evaluate the simultaneous effect of glycerol
(30%, 40%, 50%) and guar-xanthan gum addition (0.1%, 0.3%, 0.5%) effect on
starch based edible film mechanical and barrier ...properties. According to
Response Surface Methodology, the most influential parameter in the second
order polynomial models calculation was the percentage of glycerol, while the
linear term of guar-xanthan content was important only for second order
polynomial model calculation for tensile strength and water vapor
permeability. According to Principal Component Analysis, samples grouping
along the first component are primarily due to the content of glycerol, which
is also confirmed by ANOVA analysis. According Cluster Analysis, two separate
clusters are observed on the dendrogram, which includes the right (with the
increased value of tensile strength) and the left cluster (with the increased
value of elongation break and water vapor permeability). The observed
distance the two clusters is considerable (approx. 80).
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