Preparation and characterization of composite hydrocolloid films from sodium alginate and high methoxyl pectin

A technology for obtaining of a composite biodegradable film on the basis of sodium alginate and apple high methoxyl (HM) pectin has been developed. Good mechanical characteristics have been established when using the two polysaccharides in proportion 1:1. For them the ultimate tensile strenght (TS) was 53,53 MPa, the elongation at ultimate strenght (E) was 34,48%, Young's modulus (YM)- 202,84 MPa. The composite film showed very poor solubility at low pH, including in a simulated gastric juice. At pH values above 4,0 the alginate films showed slower and the composite films faster and complete disintegration in the medium. Due to the good mechanical characteristics and selective solubility depending on pH, the composite sodium alginate-HM pectin films are appropriate as material for encapsulating of biologically active substances or microorganisms with low activity or survival, under conditions of low pH.