Branimir Pavlić

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).

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.

Modeling and optimization of red currants vacuum drying process by response surface methodology (RSM).

Fresh red currants were dried by vacuum drying process under different drying conditions. Box-Behnken experimental design with response surface methodology was used for optimization of drying process in terms of physical (moisture content, water activity, total color change, firmness and rehydratation power) and chemical (total phenols, total flavonoids, monomeric anthocyanins and ascorbic acid content and antioxidant activity) properties of dried samples. Temperature (48-78 °C), pressure (30-330 mbar) and drying time (8-16 h) were investigated as independent variables. Experimental results were fitted to a second-order polynomial model where regression analysis and analysis of variance were used to determine model fitness and optimal drying conditions. The optimal conditions of simultaneously optimized responses were temperature of 70.2 °C, pressure of 39 mbar and drying time of 8 h. It could be concluded that vacuum drying provides samples with good physico-chemical properties, similar to lyophilized sample and better than conventionally dried sample.

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.

Recovery of antioxidant compounds from aronia filter tea factory by –product: novel versus conventional extraction approaches

Black chokeberry (Aronia melanocarpa L.) by-product from filter tea factory underwent subcritical water extraction (SWE) in order to recover polyphenolics and determine its antioxidant potential. In the current study Box-Behnken design was applied for optimization. Independent variables used in experimental design were temperature (T, 120-200 °C), extraction time (t, 15-35 min) and hydrochloride concentration (c, 0-1.5%). 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. The optimized SWE conditions for maximum responses of total phenols (TP), total flavonoids (TF) and monomeric anthocyanins (MA) contents, and minimum response of IC50 were temperature of 120.4 °C, extraction time of 15.2 min and absence of acidifier. The predicted values of TP, TF, MA and IC50 at these conditions were: 32.8863 mg GAE/g, 23.5164 mg CE/g, 0.5124 mg C3G/g and 0.0055 mg/mL, respectively.

Optimization: Microwave irradiation effect on polyphenolic compounds extraction from winter savory (Satureja montana L.)

ABSTRACT Microwave-assisted extraction of polyphenols with elevated antioxidant activity from winter savory was optimized by simultaneous maximization of total phenolics, total flavonoids yields, and antioxidant activity (measured by two assays—DPPH and reducing power assay). For optimization of microwave assisted extraction, Box–Behnken experimental design coupled with response surface methodology was applied. Independent variables were extraction time, ethanol concentration, and irradiation power. Analysis of variance was used to evaluate model fitness and determine optimal conditions.

Variation of bioactive compounds content in fermented cabbage: influence of fermentation temperature

The aim of this study was to analyze the effect of different fermentation temperature on bioactive compounds content of cabbage heads (Brassica oleracea var. capitata). Fermentation process was carried out at the temperature intervals 16-18 °C, 18-20 °C and 20-22 °C for 40 days. Dry weight, soluble dry weight, pH value, water activity, salt and sugar concentration, total acidity, penetration force, total color change, total phenolic compounds and organic acidswere investigated as the most important quality parameters. The highest content of total phenol compounds, as well as the highest contents of oxalic and acetic acidswas obtained in cabbage and brine sample fermented at 16-18 °C. The highest content of lactic acid in the cabbage sample fermented at 20-22 °C was obtained. In the case of brine samples, the highest contents of oxalic and lactic acids in samples fermented at 16-18 °C were observed, while the highest content of acetic acid in the sample fermented at 20-22 °C was obtained. Formic acid in cabbage and brine samples only in samples fermented at 20-22 °C was detected.

The effect of essential oil from sage (Salvia officinalis L.) herbal dust (food industry by-product) on the microbiological stability of fresh pork sausages

The effect of essential oil obtained from sage (Salvia officinalis L.) herbal dust (a food industry by-product) (SEO), on the pH value, microbiological stability and sensory properties of fresh pork sausages prepared without chemical additives was evaluated during 8 days of aerobic storage at 3±1°C. The addition of SEO significantly (p<0.05) reduced the microbial growth in fresh pork sausages. Moreover, SEO added at a level of 0.05 µL/g had no negative effect on sensory properties of this meat product. Hence, the results of this study showed significant antimicrobial activity of SEO obtained from sage filter tea processing byproducts and the potential for utilising SEO in fresh pork sausages in order to enhance their stability and safety.