Abstract
Kefiran is an exopolysaccharide classified as a heteropolysaccharide comprising glucose and galactose in equimolar quantities, and it is classified as a water-soluble glucogalactan. This work aimed to investigate the effect of different extraction conditions of kefiran on the structural and physical properties of the edible films obtained. Fourier-transform infrared spectroscopy and scanning electron microscopy were performed, together with a determinations of moisture content, solubility, water vapor permeability and degree of swelling. The kefiran films presented values of the water vapor permeability between 0.93 and 4.38 × 10−11 g/m.s.Pa. These results can be attributed to the development of a more compact structure, where glycerol had no power to increase the free volume and the water vapor diffusion through their structure. The possible conformational changes in the kefiran film structure, due to the interspersing of the plasticizers and water molecules that they absorb, could be the reason for producing flexible kefiran films in the case of using glycerol as a plasticizer at 7.5% w/w. Moreover, it was observed that the extraction conditions are a significant factor in the properties of these films and their food technology applications.
Highlights
Nowadays, there is a clear trend towards natural and environmentally friendly alternatives for food protection solutions, since aspects such as clean labeling, healthy or organic food concepts are demanded increasingly by the consumers [1,2]
Based on the results obtained in this study, the kefiran solution extracted at 80 ◦ C could be used as new film-forming material
Kefiran films plasticized with glycerol (7.5% (w/w))
Summary
There is a clear trend towards natural and environmentally friendly alternatives for food protection solutions, since aspects such as clean labeling, healthy or organic food concepts are demanded increasingly by the consumers [1,2]. Attention has been directed towards biopolymer-based packaging as a potential alternative to synthetic polymer-based food packaging materials These materials offer the possibility of creating a thin layer of edible films and coatings with many advantages [4] and functions (antioxidant, antibacterial, antifungal, prebiotic) [5]. In the food packaging industry, microbial activities are of great concern They can form protective layers (wrapping or coating) around fresh or processed foods, regulate their respiration rates, and protect them from loss of water, tissue softening, browning, and microbial contamination [6]. They can add commercial value to food products by enhancing their appearance, while acting as carriers of functional ingredients, such as antioxidants, antimicrobial agents and nutraceuticals [7]. These serve as a barrier to water and gas transfer and have multiple applications within the medical, pharmaceutical and food sectors [9]
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