Senka Vidović

Modeling and optimization of ultrasound-assisted extraction of polyphenolic compounds from Aronia melanocarpa by-products from filter-tea factory

Aronia melanocarpa by-product from filter-tea factory was used for the preparation of extracts with high content of bioactive compounds. Extraction process was accelerated using sonication. Three level, three variable face-centered cubic experimental design (FCD) with response surface methodology (RSM) was used for optimization of extraction in terms of maximized yields for total phenolics (TP), flavonoids (TF), anthocyanins (MA) and proanthocyanidins (TPA) contents. Ultrasonic power (X₁: 72-216 W), temperature (X₂: 30-70 °C) and extraction time (X₃: 30-90 min) were investigated as independent variables. Experimental results were fitted to a second-order polynomial model where multiple regression analysis and analysis of variance were used to determine fitness of the model and optimal conditions for investigated responses. Three-dimensional surface plots were generated from the mathematical models. The optimal conditions for ultrasound-assisted extraction of TP, TF, MA and TPA were: X₁=206.64 W, X₂=70 °C, X₃=80.1 min; X₁=210.24 W, X₂=70 °C, X₃=75 min; X₁=216 W, X₂=70 °C, X₃=45.6 min and X₁=199.44 W, X₂=70 °C, X₃=89.7 min, respectively. Generated model predicted values of the TP, TF, MA and TPA to be 15.41 mg GAE/ml, 9.86 mg CE/ml, 2.26 mg C3G/ml and 20.67 mg CE/ml, respectively. Experimental validation was performed and close agreement between experimental and predicted values was found (within 95% confidence interval).

Free radical scavenging activity, total phenolic and flavonoid contents of mulberry (Morus spp. L., Moraceae) extracts

Mulberry (Morus spp. L., Moraceae) fruits, leaves, bark and branch have been used in traditional medicine as diuretic, hypoglycemic and hypotensive. The mechanism of their effects is correlated with the content of active components. Objective of this work was to evaluate and compare antioxidant properties of different extracts of two Morus species growing in Serbia: Morus alba L. (white mulberry) and Morus nigra L. (black mulberry). Potential antioxidant activity, content of antioxidant compounds (phenolics and flavonoids) and radical scavenging capacity, tested by DPPH method, were evaluated. The phenolic and flavonoid composition of different Morus extracts was determined by the HPLC method. The extracts prepared from fruits, leaves and roots of M. alba and M. nigra exhibited different characteristics. The highest extraction yield was achieved by M. alba leaves extraction (23.40%). M. nigra roots extract shown the highest total phenolics (186.30 mg CAE/g), while highest total flavonoids content (67.37 mg RE/g) was determined for M. nigra leaves extracts. In addition, black mulberry leaves extracts with the highest antioxidant activity had the highest phenolic acids contents. The dominant phenolic components in the samples were rutin and chlorogenic acid. All investigated mulberry dry extracts shown high content of phenolic compounds and significant antioxidant activity. This work contributes to knowledge of the antioxidant properties of Morus species. The obtained results may be useful in the evaluation of new dietary supplements and food products.

Optimization of frozen sour cherries vacuum drying process.

The objective of this research was to optimize the vacuum-drying of frozen sour cherries in order to preserve health-beneficial phytochemicals, as well as textural characteristics. Investigated range of temperature was 46-74°C and, of pressure, 17-583mbar, in a new design of vacuum-dryer equipment. The total solids, a(w) value, total phenolics, vitamin C, antioxidant activity, anthocyanin content, total colour change and firmness were used as quality indicators of dried sour cherry. Within the experimental range of studied variables, the optimum conditions of 54.03°C and 148.16mbar were established for vacuum drying of sour cherry. Separate validation experiments were conducted, under optimum conditions, to verify predictions and adequacy of the second-order polynomial models. Under these optimal conditions, the predicted amount of total phenolics was 744mg CAE/100 dw, vitamin C 1.44mg/100g per dry weight (g dw), anthocyanin content 125mg/100g dw, IC(50) 3.23mg/ml, total solids 70.72%, a(w) value 0.646, total colour change 52.61 and firmness 3395.4g. The investigated parameters had a significant effect on the quality of the dried sour cherries.

Optimization of ultrasound-assisted extraction of bioactive compounds from wild garlic (Allium ursinum L.).

Ultrasound-assisted extraction was used for extraction of bioactive compounds and for production of Allium ursinum liquid extract. The experiments were carried out according to tree level, four variables, face-centered cubic experimental design (FDC) combined with response surface methodology (RSM). Temperature (from 40 to 80 °C), ethanol concentration (from 30% to 70%), extraction time (from 40 to 80 min) and ultrasonic power (from 19.2 to 38.4 W/L) were investigated as independent variables in order to obtain the optimal conditions for extraction and to maximize the yield of total phenols (TP), flavonoids (TF) and antioxidant activity of obtained extracts. Experimental results were fitted to the second order polynomial model where multiple regression and analysis of variance were used to determine the fitness of the model and optimal condition for investigated responses. The predicted values of the TP (1.60 g GAE/100 g DW), TF (0.35 g CE/100 g DW), antioxidant activity, IC50 (0.71 mg/ml) and EY (38.1%) were determined at the optimal conditions for ultrasound assisted extraction: 80 °C temperature, 70% ethanol, 79.8 min and 20.06 W/L ultrasonic power. The predicted results matched well with the experimental results obtained using optimal extraction conditions which validated the RSM model with a good correlation.

Cold Pressing and Supercritical CO2 Extraction of Hemp (Cannabis sativa) Seed Oil

In a past few decades the variety of hemp Cannabis sativa L. was unfairly neglected because of the similarity with the kind of hemp that is illegal and is used as a narcotic. The objective of this study was to evaluate the oil extraction process from Cannabis sativa seeds by cold pressing followed by extraction with supercritical CO2. In pressing experiments, the response surface methodology was conducted in order to study the effects of temperature, frequency and nozzle size on oil recovery and quality parameters. The optimal condition to obtain the highest oil recovery and the best oil quality within the experimental range of the variables studied was at temperature of 60 °C, frequency of 20 Hz and using nozzle of ID 6 mm. The residual oil in the press cake was totally extracted by supercritical CO2 in newly designed and built supercritical fluid extraction system. The oregano essential oil was the most effective in protecting the oil from oxidative deterioration.

Characterisation of volatiles in dried white varieties figs (Ficus Carica L.)

The aromatic profile of volatiles in dried figs varieties Bružetka Bijela and Zimnica were characterised by headspace solid-phase (HS-SPME) procedure with gas chromatography–mass spectrometry analysis (GC-MS). The volatile compounds were distributed by distinct chemical classes, including alcohols, aldehydes, esters, terpenic compounds, and other compounds. The figs were dried in a pilot plant cabinet dryer. Prior to drying process, figs were pre-treated by sulphur dioxide, immersed in solution of citric acid and ascorbic acid, respectively. Several mathematical thin-layer drying models, available in the literature, were fitted to experimental data of figs, implementing non-linear regression analysis techniques. The results showed that pre-treatments of figs decrease significantly the drying time. The best thin-layer drying model in terms of fitting performance was Wang and Singh model. The major volatile compound in dried figs was benzaldehyde. After benzaldehyde, the most abundant aldehyde in dried figs was hexanal. The comparison among dried figs showed the highest abundance of aldehydes, in general, in non-treated (control) dried figs compared to pre-treated samples. Furthermore, ascorbic acid was the most efficient in preserving esters and alcohols in case of Bružetka Bijela, whereas in case of Zimnica, sulphur dioxide was in advance compared to ascorbic acid. Ethyl acetate was the most abundant ester found in dried figs. Among other compounds, 2-butanone,3-hydroxy was the most abundant identified volatiles. Linalool, as the only identified terpen, was in case of both dried fig varieties, preserved by immersion into ascorbic acid. The immersion into citric acid has not been so successful in volatiles conservation.

Optimization of microwave‐assisted extraction (MAE) of coriander phenolic antioxidants ‐ Response surface methodology approach

BACKGROUND Microwave-assisted extraction (MAE) of polyphenols from coriander seeds was optimized by simultaneous maximization of total phenolic (TP) and total flavonoid (TF) yields, as well as maximized antioxidant activity determined by 1,1-diphenyl-2-picrylhydrazyl and reducing power assays. Box-Behnken experimental design with response surface methodology (RSM) was used for optimization of MAE. Extraction time (X1 , 15-35 min), ethanol concentration (X2 , 50-90% w/w) and irradiation power (X3 , 400-800 W) were investigated as independent variables. Experimentally obtained values of investigated responses were fitted to a second-order polynomial model, and multiple regression analysis and analysis of variance were used to determine fitness of the model and optimal conditions. RESULTS The optimal MAE conditions for simultaneous maximization of polyphenol yield and increased antioxidant activity were an extraction time of 19 min, an ethanol concentration of 63% and an irradiation power of 570 W, while predicted values of TP, TF, IC50 and EC50 at optimal MAE conditions were 311.23 mg gallic acid equivalent per 100 g dry weight (DW), 213.66 mg catechin equivalent per 100 g DW, 0.0315 mg mL(-1) and 0.1311 mg mL(-1) respectively. CONCLUSION RSM was successfully used for multi-response optimization of coriander seed polyphenols. Comparison of optimized MAE with conventional extraction techniques confirmed that MAE provides significantly higher polyphenol yields and extracts with increased antioxidant activity.

The protective effect of a mix of Lactarius deterrimus and Castanea sativa extracts on streptozotocin-induced oxidative stress and pancreatic β-cell death

Pancreatic β-cell death or dysfunction mediated by oxidative stress underlies the development and progression of diabetes mellitus. In the present study, we tested extracts from the edible mushroom Lactarius deterrimus and the chestnut Castanea sativa, as well as their mixture (MIX Ld/Cs), for potential beneficial effects on streptozotocin (STZ)-induced pancreatic β-cell death. Analysis of chelating effects, reducing power and radical-scavenging assays revealed strong antioxidant effects of the C. sativa extract and MIX Ld/Cs, while the L. deterrimus extract displayed a weak to moderate effect. The antioxidative effect of the chestnut extract corresponds with the high content of phenolics and flavonoids identified by HPLC analysis. In contrast, the mushroom extract contains relatively small amounts of phenols and flavonoids. However, both extracts, and especially their combination MIX Ld/Cs, increased cell viability after the STZ treatment as a result of a significant reduction of DNA damage and improved redox status. The chestnut extract and MIX Ld/Cs significantly lowered the STZ-induced increases in superoxide dismutase and catalase activities, while the mushroom extract had no impact on the activities of these antioxidant enzymes. However, the L. deterrimus extract exhibited good NO-scavenging activity. Different mechanisms that underlie antioxidant effects of the mushroom and chestnut extracts were discussed. When combined as in the MIX Ld/Cs, the extracts exhibited diverse but synergistic actions that ultimately exerted beneficial and protective effects against STZ-induced pancreatic β-cell death.

Chemometric guidelines for selection of cultivation conditions influencing the antioxidant potential of beetroot extracts

Display Omitted 64 beetroot samples were cultivated under different conditions.Novel approach to samples similarity analysis was applied.The differences between the samples were detected.ANN-R model best predicts antioxidant activity of beetroot extracts. The estimation of influences of different cultivation conditions on chemical composition of crops can be quite complex task. Usually, the classical statistic approach (comparison of statistical characteristics of different populations) is applied. However, this study presents the analysis of the influence of different cultivation conditions (cultivation with or without foil cover, different preceding crops and fertilization) on the contents of dry matter, betalains and phenolic compounds in 64 beetroot (Beta vulgaris L. ssp. vulgaris) samples and their antioxidant potential (IC50) by using powerful chemometric tools, such as Wald-Wolfowitz run test, cluster analysis and sum of ranking differences, in order to obtain groupings of the samples which share similar properties or to test if the samples come from the same population. Besides the aforementioned classification or pattern recognition analysis, the regression methods (linear, multiple linear and artificial neural network regressions) were carried out in order to establish reliable linear and non-linear relationships between IC50 and contents of betalains, phenolic compounds and dry matter. The results reveal certain influence of foil cover, used during the cultivation, on beetroot antioxidant potential and content of the determined betalains and phenolic compounds, as well as the strong non-linear relationship between the analyzed variables. Certain influence of preceding crops on phenolic compounds content is detected by Wald-Wolfowitz run test.

Fatty Acid Profiles of Four Wild Mushrooms and Their Potential Benefits for Hypertension Treatment

Mushrooms are useful in balancing human diet and treating different health problems. The main determinant of the fluidity of erythrocyte membranes and rheologic properties of blood is the lipid composition of the membrane, which directly depends on lipids present in the diet. Lipid profiles of 4 European wild edible mushrooms, as well as the ability of mushroom lipids to modify the fluidity of erythrocyte membrane, were examined by using gas chromatography-mass spectometry, gas chromatography-flame ionization detector, and electron paramagnetic resonance spin probing technique. Lipids from 2 species--Macrolepiota procera and Collybia platyphylla--provoked an increase in erythrocyte membrane fluidity. Therefore, introduction of these and other wild mushrooms with similar lipid profiles to the human diet could be very beneficial in the treatment of hypertension and other cardiovascular diseases related to decreased fluidity of erythrocyte membranes.