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Analiza uzoraka organski proizvedenog meda i meda proizvedenog na konvencionalni način na području Zapadne Srbije
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Controllable ablative machining of Al/Ti and Ti/Al nano-layers on a Si substrate by single-pulse femtosecond laser irradiation
No full textResults concerning the controllable ablation of nano-layered thin films (NLTF) by femtosecond laser pulses are presented. Investigated samples were titanium-aluminum bilayers, deposited on a silicon substrate, with the top titanium or aluminum layer of variable thickness on the surface. Irradiation was done in ambient air with single femtosecond laser pulses under standard laboratory conditions. The samples were analyzed by complementary methods of optical and scanning electron microscopy and optical profilometry, exhibiting laser-fluence-dependent ablative removal either of the top layer or the entire bilayer or even partial ablation of the underlying silicon substrate. The removal (spallation) threshold fluences for the topmost layer are scalable versus its thickness almost irrespectively of its material, being rather selective for the Ti-coated samples and much less selective for the Al-coated samples. The removal of the entire bilayers was found to be strongly influenced by electronic properties of the underlying metallic layer, dictating the NLTF-Si adhesion, heat conduction, and capacity in the NLTFs toward the NLTF-Si interface and beyond, as well as by their thermophysical characteristics, e.g., almost twice higher melting temperature and enthalpy for Ti. As a result, precise fs-laser machining of the entire NLTFs is pronounced and selective for the samples with the fusible Al at the low-adhesion Al-Si interfaces, compared with the incomplete NLTF removal from the high-adhesion and refractory Ti-Si interfaces
Artificial neural network model in predicting the quality of fresh tomato genotypes
No full textSenzorska analiza predstavlja najbolje sredstvo za precizno opisivanje kvaliteta svežih namirnica. Međutim, to je skupa i dugotrajna metoda koja se ne može koristiti za merenje pokazatelja kvaliteta u realnom vremenu. Cilj ovog rada bio je da doprinese proučavanju odnosa između podataka dobijenih primenom senzorske analize i instrumentalnih metoda i da definiše odgovarajući model za predviđanje senzorskih svojstava svežeg paradajza pomoću određivanja fizičko-hemijskih svojstava. Analiza glavnih komponenti (RSA) primenjena je na eksperimentalne podatke da bi se okarakterisali i diferencirali posmatrani genotipovi, objašnjavajući 73,52% od ukupne varijanse, koristeći prve tri glavne komponente. Model veštačke neuronske mreže (ANN) korišćen je za predviđanje senzorskih svojstava na osnovu rezultata dobijenih osnovnim hemijskim i instrumentalnim određivanjima. Razvijeni ANN model predviđa senzorska svojstva sa visokom adekvatnošću, sa ukupnim koeficijentom determinacije od 0,859.Sensory analysis is the best mean to precisely describe the eating quality of fresh foods. However, it is expensive and time-consuming method which cannot be used for measuring quality properties in real time. The aim of this paper was to contribute to the study of the relationship between sensory and instrumental data, and to define a proper model for predicting sensory properties of fresh tomato through the determination of the physicochemical properties. Principal Component Analysis (PCA) was applied to the experimental data to characterize and differentiate among the observed genotypes, explaining 73.52% of the total variance, using the first three principal components. Artificial neural network (ANN) model was used for the prediction of sensory properties based on the results obtained by basic chemical and instrumental determinations. The developed ANN model predicts the sensory properties with high adequacy, with the overall coefficient of determination of 0.859
Chemical composition and antimicrobial activity of Osage orange (Maclura pomifera) leaf extracts
No full textThe main goal of this study was to establish the chemical profile of Osage orange (Maclura pomifera) leaf extracts, obtained by conventional maceration technique, and to examine its antimicrobial activity. The identification and quantification of the extract compounds were done using ultra-high-performance liquid chromatography, with a diode array detector coupled with triple-quadrupole mass spectrometer and gas chromatography-mass spectrometry techniques. Thirty-one polyphenolic compounds were detected and identified in the ethanolic extracts, whereby 5-O-caffeoylquinic acid was found to be the dominant compound. Among other compounds, pentacosane and palmitic acid were the most abundant compounds in the dichloromethane extract. The preliminary antimicrobial activity screening shows that Gram-positive bacteria tend to be more sensitive to the investigated extracts. The highest antimicrobial activity was determined against Enterococcus faecalis ATCC 19433 and Listeria monocytogenes ATCC 35152. From these results, Osage orange leaves can be considered as plant material with significant antimicrobial properties
Isothermal kinetics of ethanolic extraction of total hypericin from pre-extracted Hypericum perforatum flowers
No full textIntroduction Hypericum perforatum L., Hypericaceae (St John's wort) is a highly familiar plant in the medicinal community which recently showed good antiviral activities including against some types of coronavirus. Objective Establishing the kinetics of isothermal extraction of total hypericin (TH) from the pre-extracted flowers of H. perforatum flowers. Methods The solvent extraction of TH from the remaining solid residue after the pre-extraction procedure was performed providing isothermal conditions at the temperature of 313 K, 323 K, and 328 K (+/- 1 K) using ethanol as a solvent. The feasibility of mathematical modelling of the isothermal kinetics of TH extraction was explored applying some of the frequently used kinetic models of solvent extraction: first-order reaction model, film theory model, unsteady-state diffusion model, parabolic diffusion model, Elovich's equation. The kinetic complexity was examined using the differential isoconversional method. Results The kinetics of isothermal solvent extraction of TH is a kinetic elementary process with the unique rate-determining step. It was found that the kinetics of isothermal extraction of TH can be best described employing the theoretical Jander three-dimensional (3D) diffusional model and its suitability for modelling the investigated extraction was confirmed with statistical parameters [adjusted linear correlation coefficient (R-adj(2)) = 0.998-0.999 and the standard error (SE) = 0.005-0.006]. The values of the model kinetic parameters (rate constant (k(M)/min(-1)), activation energy (E-a = 21.0 +/- 4.9 kJ/mol) and pre-exponential factor (lnA = 3.1 +/- 2.2 min(-1)) were calculated. Conclusions Based on the model mechanism of the kinetics of the investigated extraction a new mathematical model is suggested and the controlling step of the overall process was found
The influence of grape pomace substrate on quality characterization of Pleurotus ostreatus-Total quality index approach
No full textTotal quality index approach was used to reflect the quality of Pleurotus ostreatus mushroom, cultivated on grape pomace (P) as food waste substrate and wheat straw (S), in four different combined ratios: 100P; 80P20S; 50P50S; and 20P80S, with 100S, serving as control substrate. This approach involved two directions of mushroom analysis. The whole mushroom fruiting bodies analysis introduced a single total quality index (TQI(M)) based on 11 quality parameters. The mushroom water extracts analysis was presented by another single total quality index (TQI(E)), with seven quality parameters. This mathematical model revealed that the mushroom extracts have a better overall quality score with higher pomace content in substrate mixture, compared to the whole mushroom quality changes throughout the observed shelf life period. Future research may pay attention to the phytotoxicity of grape pomace as a food waste, as well as the influence of grape pomace on glucan content, as a health-beneficial compounds. Practical applications From the sustainable part of view, advantage of this type of production is its belonging to the sustainable food waste management strategy. The main importance of food waste use is their exploitation through bioconversion process into the new value-added products, generating near zero waste. Also, the type and chemical composition of plant waste used as mushroom substrate affects the nutritional profile and quantity of the produced mushroom. Therefore, the application of this principle of production benefits winemakers on the one hand, eliminating the generation of toxic waste and protecting the environment. From a quality point of view, approach outlined in this research shows practical application of using quality index as a tool for overall quality evaluation. Finally, combining food waste for producing mushrooms evaluated through a quality index perspective paves the way for increasing mushroom in the mushroom values chain
Evaluation of novel green walnut liqueur as a source of antioxidants: Multi-method approach
No full textIn this study, a novel green walnut liqueur (GWL) based on green walnuts, as the main ingredient, with the addition of fruits, aromatic plants, chocolate and honey, was produced at the pilot-scale. Antioxidant activity (AO) of the obtained GWL was determined using multiple AO assays in parallel, standard spectrophotometric (FC, DPPH and FRAP) and recently developed electrochemical ones, HydroxoPerhydroxoMercury(II) Complex and Mercury Reduction Antioxidant Power, and compared to similar commercial alcoholic beverages. Characterization of the GWL in terms of volatile and polyphenolic components was performed using SPE-GC-MS and HPLC-DAD-MS/MS, respectively. Sensory quality assessment was performed by experts in the field of sensory analysis of alcoholic beverages, using a scoring method. According to all AO assays applied, AO activity and total phenolics content of GWL were superior in comparison to commercial spirits considered. The volatile fraction of GWL was mainly composed of eugenol,alpha-terpineol and vanillin, while the most prevalent phenolic compounds were gallic (5.054 mg/L) and chlorogenic acid (1.307 mg/L) and flavonoids such as catechine (0.882 mg/L), quercetin (0.499 mg/L) and its sugar-conjugated derivatives, quercetin 3-O-glucoside (0.774 mg/L) and quercetin-3-O-rhamnoside (0.614 mg/L). Gallic acid is the major contributor to total AO activity, especially determined by DPPH and FRAP, followed by catechine, quercetin and chlorogenic acid. Among the terpenoids, contribution of eugenol to total AO activity is estimated as the highest. Excellent sensory quality (18.52 of maximum 20 scores) was ascribed to GWL. Consequently, the presence of bioactive compounds and high AO activity of GWL, in addition to high sensory quality score, indicates a high market potential for this high-value product
Analysis of the estimated remaining service life of gas rectification columns
No full textGas rectification columns are process apparatuses which are very important part of each onshore plant. Sudden failure of these types of columns causes huge daily losses, while fluid leakage can be very dangerous for the people and hazardous for the environment. For that reason, a regular and correct examination of the column is of great importance for the continual process of leading. Together with the detailed examination of the column, a risk-based inspection was applied to maximize savings, both material, time, and costs. The expected remaining service life of rectification columns was also analyzed, while the corrosion rates were calculated according to the various international standards. The minimum required column wall thickness was calculated according to the most commonly used international standard and the obtained difference was analyzed. Detailed analysis of the total risks of the column due to potential failure is presented