pectins and 2-2--azino-di-(3-ethylbenzothiazoline)-6-sulfonic-acid

A pectin/chitosan matrix-loaded curcumin film (PCCF) with a deep eutectic solvent (DES) as the solvent and plasticizer was prepared in this study. Different quantities of curcumin (identified as PCCF-0, PCCF-1, PCCF-2. PCCF-3) were loaded on the pectin/chitosan film in order to evaluate their effects on the film properties. Results showed that curcumin could interact with the pectin/chitosan matrix and form a complex three-dimensional network structure. PCCF could promote the thickness, tensile strength, thermal properties, antioxidant and antiseptic capacities, but deteriorate the light transmission and elongation at the same time. The addition of curcumin would change the color of the film, without significantly affecting the moisture content. The tensile strength of PCCF-3 reached the maximum value of 3.75 MPa, while the elongation decreased to 10%. Meanwhile, the water-resistance properties of PCCF-3 were significantly promoted by 8.6% compared with that of PCCF-0. Furthermore, PCCF showed remarkable sustained antioxidant activities in a dose-dependent manner. PCCF-3 could inhibit DPPH and ABTS free radicals by 58.66% and 29.07%, respectively. It also showed antiseptic capacity on fresh pork during storage. Therefore, curcumin addition could improve the barrier, mechanical, antioxidant and antiseptic properties of the polysaccharide-based film and PCCF has the potential to be used as a new kind of food packaging material in the food industry.

Topics: Anti-Infective Agents, Local; Antioxidants; Benzothiazoles; Biocompatible Materials; Biphenyl Compounds; Chitosan; Curcumin; Food; Free Radical Scavengers; Humidity; Pectins; Picrates; Solubility; Spectroscopy, Fourier Transform Infrared; Sulfonic Acids; Water; X-Ray Diffraction

Topics: Anions; Antioxidants; Arabinose; Benzothiazoles; Biological Availability; Biphenyl Compounds; Cations; Coumaric Acids; Dietary Fiber; Flavonoids; Fruit; Galactose; Glucose; Hydroxybenzoates; Mannose; Micronutrients; Minerals; Opuntia; Pectins; Picrates; Plant Mucilage; Polyphenols; Polysaccharides; Rhamnose; Sulfonic Acids; Xylose

This work investigates the effect of drying okra pods by different techniques [freeze-drying (FD), sun-drying (SD), oven-drying (OD) and microwave-drying (MD)] on the molecular structure, physicochemical and antioxidant properties of the subsequently extracted OP. Remarkably, although the degree of methyl esterification (∼41.1 %) remained similar among samples, the content of galacturonic acid (62.67-68.77 %), average number molecular weight (MnI: 758.8-808.5 kDa, MnII: 20.9-24.2 kDa), and to a greater extent the apparent viscosity of an aqueous solution of pectin molecules, water holding capacity (0.21-10.71 g/g) and emulsifying activity (42.3-72.7 %) and stability (38.6-53.5 %), decreased with the drying temperature in the order of FD-OP > SD-OP > OD-OP > MD-OP. On the other hand, only FD-OP presented a higher proportion of galactan and/or arabinan side chains [(Ara + Gal) / Rha = 12.37%] compared to the rest of the samples, with values ranging from 7.79 to 9.17%. FD-OP and SD-OP resulted in lower DPPH and ABTS radical scavenging activities.

Topics: Abelmoschus; Antioxidants; Benzothiazoles; Biphenyl Compounds; Desiccation; Freeze Drying; Fruit; Hot Temperature; Microwaves; Pectins; Picrates; Sulfonic Acids; Sunlight

A rapid spectrophotometric method for the determination of pectinesterase activity is presented. In this assay, methanol released from pectin by pectinesterase is oxidized with alcohol oxidase to form hydrogen peroxide and formaldehyde. Hydrogen peroxide is then quantitated with peroxidase and the chromogen 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid). Since both reactions exhibit the same pH optimum it was possible to couple the methanol assay directly to the action of pectinesterase for the real-time determination of this enzyme. The assay is reliable and sensitive, being capable of quantitating a minimum pectinesterase activity of 0.0625 unit (1 unit = 1 microM methanol released per minute). It is also capable of detecting the enzymatic demethoxylation of galactopyranosyl uronic acid methyl esters of pectin down to a minimum concentration of 1.56 nM of methanol per milliliter using a pectin substrate with a methoxy content of 10% (w/w) at a concentration of 0.5 microgram/ml.

Topics: Alcohol Oxidoreductases; Benzothiazoles; Carboxylic Ester Hydrolases; Chromatography, Ion Exchange; Formaldehyde; Hydrogen Peroxide; Indicators and Reagents; Pectins; Peroxidase; Spectrophotometry; Sulfonic Acids