61 research outputs found
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Effects of drying methods and conditions on antimicrobial activity of edible chitosan films enriched with galangal extract
The aim of this work was to study the effects of drying methods and conditions (i.e., ambient drying, hot air drying at 40 degrees C, vacuum drying and low-pressure superheated steam drying within the temperature range of 70-90 degrees C at an absolute pressure of 10 kPa) as well as the concentration of galangal extract on the antimicrobial activity of edible chitosan films against Staphylococcus aureus. Galangal extract was added to the film forming solution as a natural antimicrobial agent in the concentration range of 0.3-0.9 g/100 g. Fourier transform infrared (FTIR) spectra and swelling of the films were also evaluated to investigate interaction between chitosan and the galangal extract. The antimicrobial activity of the films was evaluated by the disc diffusion and viable cell count method, while the morphology of bacteria treated with the antimicrobial films was observed via transmission electron microscopy (TEM). The antimicrobial activity, swelling and functional group interaction of the antimicrobial films were found to be affected by the drying methods and conditions as well as the concentration of the galangal extract. The electron microscopic observations revealed that cell wall and cell membrane of S. aureus treated by the antimicrobial films were significantly damaged. (C) 2009 Elsevier Ltd. All rights reserved
Electrospun Cellulose Acetate Fiber Mats as Carriers for Crude Extracts From Phyllanthus Emblica Linn. Fruits
Fruit of Phyllanthus emblica Linn (PE) was extracted with methanol and then partitioned into diethyl ether, ethyl acetate, butanol, and water fractions. The diethyl ether fraction showed the highest antibacterial activity against two pathogenic bacteria including Escherichia coli (ATCC 25922) and Staphylococcus aureus (ATCC 25923). The PE extract from diethyl ether fraction was then loaded into 17%w/v cellulose acetate (CA) solution prepared in 2:1 v/v acetone/N, N-dimethylacetamide at concentrations of 1, 3, and 5% w/w (based on the weight of CA). The PE extract-loaded electrospun CA fiber mats were fabricated by electrospinning. The morphological appearance of both the neat and the PE extract-loaded electrospun CA fibers were smooth with the average diameters in a range of 335-694 nm. The amounts of water retention and release characteristics of PE extract from fiber mats in an acetate buffer (pH 5.5) were studied and compared with the corresponding cast-films fabricated by the solvent casting method. The amount of water retention of the PE extract-loaded fiber mats was about 112-205% which was higher than that of the cast films (i.e. 25-35%). The study of release characteristics of PE extract from fiber mats and films was carried out by total immersion method in an acetate buffer at 32°C for 72 h. The PE extract-loaded fiber mats exhibited greater amount of extract released than those of the cast films. The maximum amounts of PE extract released from fiber mats and films were about 40-80% and 18-23%, respectively
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