Potential of polysaccharides for food packaging applications. Part 2/2: An experimental review of the effect of aging conditions on the functional properties of polysaccharide films

In recent years, polysaccharides have attracted interest for their potential use in food packaging due to their functional properties, such as film-forming ability and oxygen barrier property. However, when considering polymers extracted from natural resources for packaging applications, one of the most critical issues is their stability over time. Accordingly, this study conducted a comprehensive evaluation of the effect of storage on the functional properties of films made from the most popular polysaccharides (hydroxypropylmethylcellulose, methylcellulose, hydroxypropylcellulose, low methoxyl pectin, cationic starch, sodium alginate, kappa-carrageenan, chitosan, and pullulan) to be potentially used in packaging or coating applications. The optical, mechanical and barrier (to oxygen and water vapor) properties of these polysaccharide films were measured after 6 and 12 months of storage at 50% relative humidity (RH) and 25 °C. The values obtained were compared with those initially determined for starting materials just after their production (0 month). The functional properties of almost all of the polysaccharide films showed remarkable stability during the 12 months of storage. However, small changes were observed in some of the properties, especially in the optical ones. This was the case for the chitosan films which exhibited a color change indicative of Maillard reaction, as also evidenced by changes in the UV visible spectrum (especially in the 280–350 nm range) with a sharp decrease in the transmittance. Furthermore, after 12 months of storage, all polysaccharide films lost 4–60% of their initial glycerol content. Surprisingly, this did not significantly affect either the mechanical or barrier properties of the films.