Response surface methodology and central composite design were used to optimize a biosynthesis medium for the production of xylanases by Streptomyces sp. P12-137 in submerged fermentation culture at pH 5.0, with wheat bran as substrate. The three variables involved in this research were the wheat bran, potassium nitrate and xylose concentrations. Statistical analysis of the results showed that, in the range studied, xylose and potassium nitrate concentrations had a significant effect on xylanase production. The optimized biosynthesis medium contained (in %, w/v): wheat bran 1.0, KNO3 1.0, xylose 0.5. This medium resulted in a 3-fold increased level of the xylanase (27.77 UA/ml) production compared to the initial level (8.30 UA/ml) after 120 h of fermentation, whereas the value predicted by the quadratic model was 26.45 UA/ml.
Response surface methodology (RSM) based on the 2 3 factorial central composite design (CCD) was used to optimize the biotechnological conditions for growth and protein production by a selected fungal strain Geotrichum candidum MIUG 2.15, by solid-state cultivation on a semisolid medium based on a mixture of paper residues, i.e. office paper, newspaper, and cardboard, mixed in a ratio of 1:1:1(w/w), supplemented with cheese whey waste and complex manure. Three independent variables, the solid:liquid ratio, the concentration of complex manure, and cultivation time, were evaluated to determine their correlative effect on biomass production and protein biosynthesis. The optimal conditions for obtaining a maximum protein yield of 9.53% w/w dry mass were the following: the complex manure concentration of 0.5%, the solid:liquid ratio of 1:5, and the growth time of 10 days.
For the present study, whole coriander seeds harvested in Romania were screened (<4 mm) and minced in order to obtain ground powder with various particle sizes. Three types of ground powder with particle sizes of 500, 630 and 710 μm were subjected to extraction with supercritical CO2. The extraction conducted over a period of 210 min was carried out at 150 bar and temperatures of 40 and 50C. The best extraction yield (0.57% w/w) was achieved for the 630‐μm particle size ground at 40C; for this temperature, the density of CO2 is higher as well as its solvation power. The chemical composition of the coriander essential oil extracted at maximum yield was determined through gas chromatography; 10 compounds that make up nearly 97% of the extract thus being identified. The antibacterial activity of the coriander essential oil was investigated on three foodborne pathogens: Escherichia coli O157:H7, Salmonella spp. and Staphylococcus aureus. The growth of the three pathogens, stored for 10 days at 10C, in the presence of coriander essential oil was proved to be significantly inhibited. Practical Applications In contrast with the direct use of powdered spices, the addition of spice extracts in food products does not affect their texture. The supercritical CO2 extraction of coriander essential oils is an environmentally friendly technique that results in pure solvent‐free extracts with high biological potential. In addition, the extraction takes place at low temperatures that help prevent the degradation of the biological components. The pure coriander essential oil thus obtained can be processed further (e.g., microencapsulation) to increase its efficiency in food products. The coriander essential oil obtained using the supercritical CO2 extraction has demonstrated an antibacterial activity, which qualifies its use both as condiment and as preservative.
In this work, the optimization of two extraction methods, conventional CE and ultrasound-assisted UAE, to obtain extracts from cornelian cherry fruit with high antioxidant activity, which can be used to produce healthier jelly candies, is presented. In the CE process, the effects of temperature (30–50 °C), time (15–45 min), and hydroalcoholic mixtures (60–100% ethanol, v/v) were studied. The highest antioxidant activity (29.83 ± 0.85 mg TE/g dw) was found in the extracts obtained using 60% ethanol at 40 °C for 15 min. The UAE process led to comparable values of 26.60 ± 0.53 mg TE/g dw at 40% amplitude and pulsed sonication (5 s on and 5 s off) for 12.5 min. Under these experimental conditions, the specific energy consumed was 1.91 kJ/g. The vitamin C content and its inhibitory activity against metabolic enzymes were evaluated in extracts with different antioxidant activity. A significant inhibitory effect against carbohydrate-metabolism-associated enzymes was identified for all the tested extracts, with an inhibitory effect against α-glucosidase higher than 75%, but with a lower effect against α-amylase. The extract obtained by CE (60% ethanol, 40 °C, 15 min) provided the highest vitamin C content of 39.9 ± 1.2 mg ascorbic acid/100 g dw. Four variants of the healthier jelly candies were formulated, with a vitamin C content of 0.34 mg ascorbic acid/100 g dw in samples with agar-agar and 0.70 mg ascorbic acid/100 g dw in samples with gelatin.
Rich in vitamins, polyphenols, carotenoids, carbohydrates, with a high antioxidant activity, cornelian cherry (Cornus mas) is one of the 65 species of Cornaceae family, fruits that are used in food industry, cosmetic industry or homeopathic medicine. The valuable bioactive compounds and the high economical potential of this tree makes suitable to be considered as a raw material to study the optimum extraction conditions in order to maximize the bioactive compounds’ concentration. In this study, the main purpose was to investigate both the favourable and restrictive conditions for Cornus mas using the GIS technique. The Remote Sensing and Geographic Information Systems (GIS) technique indicated the favourability factors for Cornus mas trees in Romania country. The response surface methodology was employed to study the effect of temperature, time and solvent concentration on the flavonoids’ (TFC) and polyphenols (TPC) concentrations and the antioxidant activity values. The maximum concentration of TPC (24.70 mg GAE/g raw material) and TFC (1.36 mg QE/g raw material) were obtained with 60% ethanol concentration at different temperature and time values. The cube model with centred faces for the Box-Behnken central composition revealed the highest value of the concentration of TAA (101.31 mg TE/g raw material) at 100% ethanol concentration, 50 °C extraction temperature and the maximum extraction time of 30 min. The most relevant variable was the solvent concentration and the obtained results suggested that the central-face cube model (86% for TPC, 97% for TFC and 95% antioxidant activity) approximated the experimental data.
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