Properties of chitosan-laminated collagen film

Abstract

The objective of this study is to determine physical, mechanical and barrier properties of chitosan-laminated collagen film. Commercial collagen film, which is used for making collagen casings for dry fermented sausage production, was laminated with chitosan film layer in order to improve the collagen film barrier properties. Different volumes of oregano essential oil per 100 mL of filmogenic solution were added to chitosan film layer: 0, 0.2, 0.4, 0.6 and 0.8 mL to optimize water vapour barrier properties. Chitosan layer with 0.6 or 0.8 % of oregano essential oil lowered the water vapour transmission rate to (1.85±0.10J-10-6 and (1.78±0.03)·10 -6 g/(m2·s·Pa) respectively, compared to collagen film ((2.51±0.05)·10-6 g/(m 2·s·Pa)). However, chitosan-laminated collagen film did not show improved mechanical properties compared to the collagen one. Tensile strength decreased from (54.0±3.8) MPa of the uncoated collagen film to (36.3±4.0) MPa when the film was laminated with 0.8 % oregano essential oil chitosan layer. Elongation at break values of laminated films did not differ from those of collagen film ((18.4±2.7) %). Oxygen barrier properties were considerably improved by lamination. Oxygen permeability of collagen film was (1806.8±628.0)·10-14 cm3/ (m·s·Pa) and values of laminated films were below 35·10-14 cmV(m·s·Pa). Regarding film appearance and colour, lamination with chitosan reduced lightness (L) and yellowness (+b) of collagen film, while film redness (+a) increased. These changes were not visible to the naked eye.