Comparative physical, antioxidant, and antimicrobial properties of films prepared by dissolving chitosan in bioactive vinegar varieties.

Solvent casting following the dissolution of chitosan in aqueous acetic acid is the most widely used method for preparing chitosan films. In this study, an economical and practical way is proposed to improve the physicochemical properties of chitosan films by using vinegar varieties both as solvents and as bioactive additives to improve the properties of the films. Chitosan films were prepared by dissolving chitosan in pomegranate, grape, apple, and hawthorn vinegar. Vinegar contains bioactive phenolics and different organic acids together with acetic acid, depending on the main raw material from which it is obtained. The films' mechanical, optical properties, antioxidant and antimicrobial activities were compared with each other and with the chitosan film prepared by dissolving chitosan in acetic acid. The antioxidant and antimicrobial properties of chitosan films prepared with vinegar increased. The use of vinegar as a solvent increased the UV light barrier properties of the films. Improved antimicrobial, antioxidant, optical, and elastic properties of films prepared by dissolving chitosan in vinegar varieties are promising in applications of these films as potential and economic food packaging materials.

Antioxidant and antimicrobial chitosan films enriched with aqueous sage and rosemary extracts as food coating materials: Characterization of the films and detection of rosmarinic acid release.

Chitosan films containing aqueous extracts of sage and rosemary were prepared as a potential food coating material with antioxidant and antibacterial properties. The effect of adding extracts at different concentrations on the mechanical, physical, and optical properties of the films was investigated. The addition of the extracts significantly increased Young's modulus values of the films compared to the chitosan film, and a significant decrease was observed in the swelling percentage and water vapor permeability of the films. Since all the prepared films were ionically cross-linked, the increase in water solubility of the films with the addition of the extract was at a low level. The release of rosmarinic acid, which is found in significant amounts in both plants, from the films was monitored by the capillary electrophoresis. The antioxidant properties imparted to the films by the addition of plant extracts were determined by DPPH and FRAP methods. The addition of plant extracts increased the antimicrobial property of chitosan films against Staphylococcus aureus and Escherichia coli. Films containing sage and rosemary extracts showed potential for use as food coating materials.

Antimicrobial cerium ion-chitosan crosslinked alginate biopolymer films: A novel and potential wound dressing.

Wound dressings require good antiseptic properties, mechanical strength and, more trustably, natural material ingredients. Antimicrobial properties of cerium ions and chitosan are known and alginate based wound dressings are commercially available. In this study, the advantages of these materials were combined and alginate films were crosslinked with cerium(III) solution and chitosan added cerium(III) solution. Films were characterized by Fourier transform infrared spectroscopy (FTIR), light transmittance, scanning electron microscopy (SEM), swelling experiments, water vapor transmittance tests, and mechanical stretching tests. The antibacterial and physical properties of the films were compared with those of conventional calcium alginate films. Both cerium ion crosslinked and cerium ion-chitosan crosslinked alginate films gained antibacterial activity against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. Cerium alginate-chitosan films showed high resistance to being deformed elastically. Results show that cerium alginate-chitosan films can be flexible, ultraviolet-protecting, and antibacterial wound dressings.

Antimicrobial and physical properties of chitosan films incorporated with turmeric extract.

In this study, the effects of turmeric extract incorporation on the antibacterial and physical properties of the chitosan films were evaluated. Turmeric containing chitosan-based film was produced with casting procedure and cross-linked with sodium sulfate. Mechanical, optical, thermal properties, and water vapor permeability of the films were studied. The addition of turmeric to chitosan film significantly increased the tensile strength of the film and improved the ultraviolet-visible light barrier of the film. Infrared spectroscopy analysis suggested an interaction between the phenolic compounds of the extract and amin group of chitosan. Antimicrobial activity of the chitosan films was studied against Salmonella and Staphylococcus aureus by plate count agar technique and a better antimicrobial activity was observed with turmeric incorporation. Turmeric incorporated chitosan films with enhanced antimicrobial activity and film stiffness can be suggested as a promising application for food packaging.

Cation effect on slow release from alginate beads: a fluorescence study.

In this study, spherical alginate beads containing pyranine (P y ) as a fluorescence probe were prepared by ionotropic gelation of a sodium alginate solution. The steady state fluorescence technique was used to study pyranine release from the alginate beads crosslinked with calcium, barium and aluminum ions, respectively. The slow release of P y was observed with the time drive mode of the spectrophotometer at 512 nm. Fluorescence emission intensity (I p ) from P y was monitored during the release process, and the encapsulation efficiency (EE) of pyranine from the alginate beads was calculated. The Fickian Diffusion model was used to measure the release coefficients, D sl . It was seen that the slow release coefficients of pyranine from the alginate beads crosslinked with Ca(2+), Ba(2+), and Al(3+) ions increased in the following order: D sl (Al(3+))> D sl (Ca(2+))> D sl (Ba(2+)). In contrast, the initial amount of pyranine and EE into the beads showed the reverse behavior.