| Nowadays, people's consciousness of environmental protection gradually strengthens, the tradition plastic package materials can not satisfy people's request in food packaging. Starch, a kind of natural polysaccharides obtained from a great variety of crops, is environment-friendly material. Because of its good biodegradability, starch has been a major focus of interest in packaging materials in the world.In this paper, glycerol plasticized corn starch, potato starch and pea starch films were studied. Sodium alginate (Al-Na) was used as reinforcing reagent, to modify the properties of edible films.At first, this paper explored the technology of film preparation by casting method, to identify the best technological parameters: corn starch: 5g starch in 100ml solution, glycerol/starch mass ratio 1/4, the maximum addition amount of Al-Na 3g, stirring velocity 120 r/min, degassing time 10 min at 0.09MPa, drying temperature 50℃; potato starch and pea starch: 5g starch in 200ml solution, stirring velocity 180 r/min, degassing time 15 min at 0.09MPa, other factors are the same as corn starch.FT-IR and SEM were used to study the structure of films. The effect of Al-Na on the starch films were also studied through measuring mechanical properties, water uptake, water vapor permeability, oil permeability etc. The result showed that: There was strong interaction between Al-Na and starch molecules, which could form films of uniform structure. After adding Al-Na 3g, the stress of starch films would raise more than 100%. Addition of Al-Na could restrain water absorption better in potato and pea starch films. After films were stored in environment of RH=75% for 7 days, the films containing Al-Na showed better mechanical properties. And starch films with Al-Na could reduce water vapor permeability and oil permeability. |
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