Effects of an anionic surfactant (FFD-6) on the energy and information flow between a primary producer (Scenedesmus obliquus) and a consumer (Daphnia magna)

The effects of a commercially available anionic surfactant solution (FFD-6) on growth and morphology of a common green alga (Scenedesmus obliquus) and on survival and clearance rates of the water flea Daphnia magna were studied. The surfactant-solution elicited a morphological response (formation of colonies) in Scenedesmus at concentrations of 10–100 μl l−1 that were far below the No Observed Effect Concentration (NOEC) value of 1,000 μl l−1 for growth inhibition. The NOEC-value of FFD-6 for colony-induction was 3 μl l−1. Daphnia survival was strongly affected by FFD-6, yielding LC50–24h and LC50–48h of 148 and 26 μl l−1, respectively. In addition, clearance rates of Daphnia feeding on unicellular Scenedesmus were inhibited by FFD-6, yielding a 50% inhibition (EC50–1.5h) at 5.2 μl l−1 with a NOEC of 0.5 μl l−1. When Daphnia were offered FFD-6-induced food in which eight-celled colonies (43 × 29 μm) were most abundant, clearance rates (~0.14 ml ind.−1 h−1) were only 25% the rates of animals that were offered non-induced unicellular (15 × 5 μm) Scenedesmus (~0.56 ml ind.−1 h−1). As FFD-6 concentrations in the treated food used in the experiments were far below the NOEC for clearance rate inhibition, it is concluded that the feeding rate depression was caused by the altered morphology of the Scenedesmus moving them out of the feeding window of the daphnids. The surfactant evoked a response in Scenedesmus that is similar to the natural chemically induced defensive reaction against grazers and could disrupt the natural information conveyance between these plankton organisms

Optimization of ultrasound-assisted extraction of polyphenolic compounds from coriander seeds using response surface methodology

Coriandrum sativum L. (coriander) seeds (CS) were used for preparation of extracts with high content of biologically active compounds. In order to optimize ultrasoundassisted extraction process, three levels and three variables of Box-Behnken experimental design (BBD) in combination with response surface methodology (RSM) were applied, yielding maximized total phenolics (TP) and flavonoids (TF) content and antioxidant activity (IC50 and EC50 values). Independent variables were temperature (40-80oC), extraction time (40-80 min) and ultrasonic power (96-216 W). Experimental results were fitted to a second-order polynomial model with multiple regression, while the analysis of variance (ANOVA) was employed to assess the model fitness and determine optimal conditions for TP (79.60oC, 49.20 min, 96.69 W), TF (79.40oC, 43.60 min, 216.00 W), IC50 (80.00oC, 60.40 min, 216.00 W) and EC50 (78.40oC, 68.60 min, 214.80 W). On the basis of the obtained mathematical models, three-dimensional surface plots were generated. The predicted values for TP, TF, IC50 and EC50 were: 382.68 mg GAE/100 g CS, 216 mg CE/100 g CS, 0.03764 mg/mL and 0.1425 mg/mL, respectively. [Projekat Ministarstva nauke Republike Srbije, br. TR31013

Determination of optimal parameters of basil supercritical fluid extraction by response surface methodology

The supercritical fluid extraction of aroma compounds from basil (Ocimum basilicum L.) was studied. Response surface methodology was used to optimize the parameters of the process. Full factorial design was applied to evaluate the effects of two independent variables (pressure and temperature) on the extraction yield and linalool yield. From the response surface plots, pressure and temperature exhibited independent and interactive effect on the extraction yield. The optimal conditions to obtain the highest extraction yield (1.91%) of O. basilicum were the pressure of 29.7 MPa and temperature of 59.2oC, whereas the highest yield of linalool (1.998 g•kg-1) was obtained at the pressure of 20 MPa and temperature of 40oC. The experimental values agreed with the predicted ones, indicating suitability of the response surface methodology for optimizing the extraction process. [Projekat Ministarstva nauke Republike Srbije, br. TR 31013

Monitoring the physico-chemical parameters of cabbage heads during fermentation: the impact of fermentation conditions and cabbage varieties

The influence of different fermentation conditions and cabbage hybrids and variety, “Tenacity“, “Bravo” and “Futoški“, on physico-chemical properties of cabbage heads was studied in this research. Experiment was set up in industrial conditions. Samples 1T, 4B and 7F were obtained by spontaneous fermentation with 3.3% NaCl solution, samples 2T, 5B and 8F were obtained with brine from previous cabbage fermentation and samples 3T, 6B and 9F were treated with 100 mL of lactic-acid starter culture onto 3.3% NaCl solution. Previous cabbage fermentation was done with 3.3% of salt solution and final percentage of salt in brine used for investigation was 2.57%. Cabbage samples were taken after 0, 3, 6, 12, 24 days and at the end of fermentation process (44th day for one group of samples and 55th day for the other) in order to determine total color and texture changes. Temperature and pH value were analyzed during the fermentation process, while water activity (aw) and total sugars content were analyzed for raw cabbage samples and on the last fermentation day. 44th day was determined as the end of fermentation for six samples, and 55th day for three samples, by measuring remaining sugar content. Considering into account all obtained results and fermentation conditions, sample 9F shown the best properties at the last fermentation day in terms of investigated physico-chemical parameters. aw value, shear force, total color change, pH value and total sugar content of this sample on the last fermentation day were 0.958, 14672 g, 8.46, 3.45 and 0.92%, respectively