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There is currently increased interest in the use of alternatives to autoclaved culture media, in order to maintain the properties of the media, while saving energy and time. In this study, we assess a new system for culture media preparation, using a conventional microwave with a water bath and a glass bottle with a rubber cap that allows depressurization. Sterilization, using the proposed system (1000 W, 3 to 20 min), was compared with autoclaving for the preparation of tryptone soy agar (TSA), tryptone soy broth (TSB), Sabouraud 4% dextrose agar (SDA), and violet red bile glucose agar (VRBG). Microwave exposure for 7 min yielded sterile TSA plates. The productivity of both sterilization methods was assessed using the pour plate method, and significant increases in the growth of certain micro-organisms after using a microwave were observed for every culture medium, especially those that were sterilized by boiling (VRBG). The kinetics of microbial destruction showed that Escherichia coli and Bacillus subtilis spores were destroyed after 3 and 7 min in a microwave, respectively, while three decimal reductions were obtained for Geobacillus stearothermophilus spores after 15 min in an autoclave. This new sterilization method could be a feasible, rapid, and economical method to prepare microbiological media, with a quality similar to that obtained through autoclaving. [ABSTRACT FROM AUTHOR]

In the analysis of water samples, the type of filtration membrane material can influence the recovery of Legionella species, although this issue has been poorly investigated. Filtration membranes (0.45 µm) from different materials and manufacturers (numbered as 1, 2, 3, 4, and 5) were compared: mixed cellulose esters (MCEs), nitrocellulose (NC), and polyethersulfone (PES). After membrane filtration of samples, filters were placed directly onto GVPC agar and incubated at 36 ± 2 °C. The highest mean counts of colony-forming units and colony sizes for Legionella pneumophila and Legionella anisa were obtained with PES filters (p < 0.001). All membranes placed on GVPC agar totally inhibited Escherichia coli and Enterococcus faecalis ATCC 19443 and ATCC 29212, whereas only the PES filter from manufacturer 3 (3-PES) totally inhibited Pseudomonas aeruginosa. PES membrane performance also differed according to the manufacturer, with 3-PES providing the best productivity and selectivity. In real water samples, 3-PES also produced a higher Legionella recovery and better inhibition of interfering microorganisms. These results support the use of PES membranes in methods where the filter is placed directly on the culture media and not only in procedures where membrane filtration is followed by a washing step (according to ISO 11731:2017). [ABSTRACT FROM AUTHOR]

BACKGROUND The successful replacement of some synthetic food antioxidants by safe natural antioxidants has fostered intensive search for new vegetable sources of antioxidants. In our study the phenol and flavonoid content of extracts of tara pods was determined. The antioxidant activity was also studied by three different analytical assays: the measurement of scavenging capacity against a radical ABTS+, the oxygen radical absorbance capacity ( ORAC) and the ferric reducing antioxidant power ( FRAP). RESULTS All analyzed samples showed a good antioxidant capacity, but the use of a solution of ethanol 75% in a 1 h ultrasonic process allowed achieving the greatest quantity of phenolics (0.464 mg gallic acid equivalent ( GAE) g−1 dry weight ( DW) ) and the highest antioxidant activity measured by the ABTS+ and ORAC methods (10.17 and 4.29 mmol L−1 Trolox equivalents ( TE) g−1 DW, respectively). The best method for efficient extraction of flavonoids (3.08 mg catechin equivalent ( CE) g−1 DW) was a 24 h maceration in cold water. Two extracts obtained with ethanol 75% and water were added to a model food system (oil-in-water emulsion) and the oxidative stability was studied during storage at 38 °C. Oxidation was monitored by determination of the peroxide value. The addition of 48 µg mL−1 ethanol extract to the emulsion delayed oxidation to the same extent as 17.8 µg mL−1 of Trolox, while water extract was only effective in the early stages of the oxidation process. CONCLUSION The results of this study indicate that ethanolic tara extracts may be suitable for use in food, cosmetic and nutraceutical applications. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND Hypercholesterolaemia plays a key role in the development and progression of coronary artery disease. There are numerous drugs available to treat this condition but they are often expensive and can have unwanted side effects. Therefore, a screening of lactic acid bacteria to select candidate probiotic strains to reduce cholesterol levels was carried out. Three Lactobacillus plantarum strains (CECT 7527, 7528 and 7529) were selected as potential probiotics to reduce cholesterol levels after conducting several in vitro tests for demonstrating the functionalities of the strains according to international guidelines. RESULTS The three strains showed a high ability to survive under gastrointestinal tract conditions and to adhere to intestinal cells. Regarding lipid metabolism, the strains showed a great production of bile salt hydrolase, especially when combined. Moreover, the strains assimilated cholesterol directly from the medium. Part of the cholesterol present in the medium was removed via binding onto the bacterial cellular surface. Finally, the three strains, especially CECT 7529, produce large quantities of propionic and butyric acids. CONCLUSION Combined, these characteristics suggest that these strains could be excellent candidates for reducing high blood cholesterol levels. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]