Physical and functional characterization of active fish gelatin films incorporated with lignin

Abstract

a b s t r a c tIn order to provide gelatin films with antioxidant capacity, two sulphur-free water-insoluble lignin powders (L 1000 and L 2400 ) were blended with a commercial fish-skin gelatin from warm water species at a rate of 85% gelatin: 15% lignin (w/w) (GeL 1000 and GeL 2400 ), using a mixture of glycerol and sorbitol as plasticizers. The water soluble fractions of GeL 1000 and GeL 2400 films were 39.38 AE 1.73% and 46.52 AE 1.66% respectively, rendering radical scavenging capacity (2,2 0 -azino-bis(3-ethylbenzothiazoline-6-sulphonic acid, ABTS assay)) of 27.82 AE 2.19 and 15.31 AE 0.88 mg vitamin C equivalents/g film, and ferric ion reducing ability (FRAP assay) of 258.97 AE 8.83 and 180.20 AE 5.71 mmol Fe 2þ equivalents/g film, respectively. Dynamic oscillatory test on film-forming solutions and Attenuated Total Reflectance (ATR)-FTIR spectroscopy study on films revealed strong lignin-induced protein conformational changes, producing a noticeable plasticizing effect on composite films, as deduced from the study of mechanical (traction and puncture tests) and thermal properties (Differential Scanning Calorimetry, DSC). The gelatin films lose their typical transparent and colourless appearance by blending with lignin; however, the resulting composite films gained in light barrier properties, which could be of interest in certain food applications for preventing ultraviolet-induced lipid oxidation. Lignin proved to be an efficient antioxidant at non-cytotoxic concentrations, however, no remarkable antimicrobial capacity was found.

Synthesis and characterization of Acacia lignin-gelatin film for its possible application in food packaging

“…Water solubility (WS) of films was determined according to the method described by Nunez-Flores et al (2013). WS was calculated by the equation:…”

“…To overcome this problem, the addition of plasticizers and natural fillers having antioxidant and antibacterial properties, such as polyphenols would be significant to improve their physico-chemical and functional properties (Pena et al 2010;Nunez-Flores et al 2013). The incorporation of fillers aids, to reduce the intrinsic brittleness of the films by decreasing intermolecular forces, increasing the mobility of polymeric chains and improving their flexibility, and thus, will extend the functional properties of the film and provide an active packaging biomaterial (Nunez-Flores et al 2013).…”

“…The complex polyphenolic structure and numerous functional groups of lignin are useful in their effective utilization for the development of polymers, adhesives, coating, additives, carbon fibers, activated carbon, foams and metal nanoparticles (Park et al 2008;Wang et al 2009;Aadil et al 2016). The effective use of lignin in blends with different biopolymers, such as starch (Bhat et al 2013), gelatin (Nunez-Flores et al 2013) and synthetic polymers like poly(vinyl alcohol), poly(ethylene), poly(lactic acid), poly(vinyl chloride) have also been reported in the literature (Gordobil et al 2014;Sahoo, et al 2011). Being a natural and potent antioxidant, Acacia wood lignin is better suited for the development of safe, biodegradable and functional edible film as compared to other biopolymers (Aadil et al 2014;Barapatre et al 2015).…”

Retardation of lipid oxidation using gelatin film incorporated with longan seed extract compared with BHT

“…These light barrier attributes are probably due to the formation of more compact structure between phenolic compounds in the extract and functional groups of gelatin molecule. Núñez-Flores et al (2013) said that lose of transparency the gelatin film blending with lignin gained in light barrier properties. The background to support this finding may by the chromophoric nature of lignin which highly capable of protecting against UV radiation.…”

Gelatin-Based Films and Coatings for Food Packaging Applications

“…Other biopolymers have been blended with gelatin with an improvement in gelatin film properties such as chitosan [72,73], lignin [74], lignosulphonates isolated from spent sulphite liquors [75] or fish protein isolate [76].…”