Abstract: The effect of the film-forming ratio, glycerol concentration and pH value on the thermal properties of the soy protein isolate (SPI) and chitosan (CS) blend film was studied by adopting the differential scanning calorimetry (DSC). The results show that the structure of the blend film is more stable than that of the SPI and CS single film at the same condition, the degree of cross linking of the blend film achieves the maximum when the film-forming ratio is SPI:CS=1:1,at which the thermal stability of the blend film is optimal. The increase of the glycerol concentration can lower the height of the blend film exothermic peak and expand the width of the peak, but the glass transition and melting temperatures decline correspondingly; the degree of crystallization of the blend film,glass transition temperature and degree of crystallinity all remain lower when the pH value is in the range of 1～3; the three values ascend and the thermal stability of the blend film is superior when the pH value is in the range of 4～6.

Key words: food packaging and storage, soy protein isolate, chitosan, edible film