agar and 1-1-diphenyl-2-picrylhydrazyl

Carboxymethyl cellulose/agar-based functional halochromic films were fabricated by adding alizarin and grapefruit seed extract (GSE). The fillers were evenly dispersed in the polymer matrix to form compatible composite films. The addition of alizarin has improved the film's mechanical strength (20%) and water resistance (40%) with potent antioxidant and excellent color indicating properties. In contrast, GSE has imparted strong antibacterial and antioxidant activities to the film. Also, the addition of alizarin and GSE slightly improved the water vapor barrier properties but did not affect the thermal stability of the film. The composite film also exhibited UV blocking properties with adequate transparency. The composite film showed an excellent pH-dependent color change with color reversibility and color stability and a volatile gas detection function. The film also showed potent antimicrobial activity against foodborne pathogenic bacteria,

Topics: Agar; Anthraquinones; Anti-Bacterial Agents; Antioxidants; Benzothiazoles; Biocompatible Materials; Biphenyl Compounds; Cellulose; Citrus paradisi; Escherichia coli; Listeria monocytogenes; Materials Testing; Microbial Sensitivity Tests; Molecular Structure; Particle Size; Picrates; Plant Extracts; Sulfonic Acids

The objectives of this study were to evaluate the effect of different functional groups of sulfate, amine, and hydroxyl and/or their ionized groups on in vitro antioxidant capacities of low-molecular-weight polysaccharides (LMPS) prepared from agar (LMAG), chitosan (LMCH), and starch (LMST), respectively, and to elucidate their structure-activity relationship. Ascorbic acid and ethylenediaminetetraacetic acid (EDTA) were used as positive controls. The in vitro antioxidant capacities of LMAG and LMCH were higher than that of LMST in the DPPH radical, superoxide radical, hydrogen peroxide, and nitric oxide radical scavenging and ferrous metal-chelating capacities. The different scavenging capacities may be due to the combined effects of the different sizes of the electron-cloud density and the different accessibility between free radical and LMPS, which, in turn, depends upon the different hydrophobicities of the constituent sugars.

Topics: Agar; Antioxidants; Biphenyl Compounds; Chitosan; Ferrous Compounds; Free Radical Scavengers; Hydrophobic and Hydrophilic Interactions; Iron Chelating Agents; Molecular Weight; Picrates; Polysaccharides; Starch; Structure-Activity Relationship