Abstract:In order to prepare a collagen film with improved performance and make it more suitable for food packaging, dialdehyde hydroxypropyl methylcellulose (DHPMC) with different oxidation degrees were blended with collagen at a mass ratio of 1:1.25 to form films. The effects of the oxidation degree of DHPMC on the physico-chemical properties of collagen composite films were investigated. The results indicated that the triple helical structure of the collagen composite film was not damaged, and compared with the pure collagen film, the mechanical properties, thermal stability, resistance to enzymatic degradation and hydrophilicity of composite films were improved, with the structures of the composite films being more homogeneous and compact. When the oxidation degree of DHPMC was low (oxidation degree: 17.78%), the aldehyde groups of DHPMC molecules formed covalent bonds with the amino groups of collagen to enhance the interaction of the system. In addition, the low oxidation degree of DHPMC had little effect on the film’s properties, resulting in improved tensile strength (115.74 MPa) and thermal denaturation temperature (76.24 ℃) of the composite films compared with collagen/ hydroxypropyl methylcellulose (HPMC) composite film (104.69 MPa, 69.67 ℃). When the oxidation degree of DHPMC was higher (45.12%), DHPMC contained more aldehyde groups, whilst the degree of cellulose degradation also increased, causing the decreases in the tensile strength (93.56 MPa) and thermal denaturation temperature (71.13 ℃) of the composite film. Thus, the composite films prepared by blending DHPMC with a low oxidation degree and collagen showed better overall film-forming properties, which would expand their applications in food packaging.
