engleski

Characterisation of chitosan films with Vitamin C

The concept of having the additional value in edible packaging is an important tool in enhancing the nutritional aspect and the process of creation of novel food products beyond the existing traditional technology for shelf-life prolongation. Antioxidant compounds such as vitamin C, could be applied to produce novel functional products thus improving their quality. This research is aimed to optimize the formulation of edible films made from chitosan (CS) and Vitamin C enriched chitosan (CSC). Films are aimed to be furtherly used as antioxidant coatings, thus Vitamin C was chosen for its known antioxidant properties. Influence of chitosan concentration (2 % w/v) and presence of Vitamin C (0.2, 0.4 and 0.6 % w/v) on structural, optical and barrier properties of films was tested. Knowledge on these parameters is important to tailor good coating design. By increasing Vitamin C concentration, lightness L* and b* decreased indicating green film taint. Additionally, the light transmittance of CSC films were further reduced with the increasing concentration of ascorbate. Formulations with Vitamin C were significantly different from the control (CS film as control). In addition, they were more soluble in water but also had decreased water content and water vapor permeability. Fourier Transform Infrared (FTIR) Spectroscopy showed that characteristic CS bands were weak and new peaks were detected, which can be attributed to the -NH3+ bending vibration an -COO- symmetrical stretching vibration resulting from the electrostatic interaction. Thermal degradation showed much lower degradation temperature and higher weight loss in the decomposition process of the CSC. Reduced thermal stability might be related to lower crystallinity of chitosan films. Those changes in physical properties were due to the stronger destructive capacity of ascorbic acid to the crystalline structure of the chitosan matrix as well as related to intermolecular chitosan chains bonding.

edible films, chitosan, vitamin C, barrier properties

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