Abstract:

Food colloids were incorporated to the sweet potato starch film, and their effects on the tensile strength, tensile strain at break, water vapor permeability and oxygen permeability of the film were studied. Results showed that adding food colloids increased the tensile strength of the film significantly, with the maxium at 36.22MPa through adding 5% HPCMC, 1.4 times higher than the control film. Addition of CMC-Na and KGM increased significantly the water vapor permeability of the film, while other food colloids did not. At the same time, water vapor permeability was not influenced significantly by HPCMC content. Oxygen permeability increased with addition of HPCMC, xanthan and chitosan (5g/100g starch), decreased with addition of KGM, but no with addition of CMC-Na and MC. High content of HPCMC (＞7 g/100g starch) decreased the oxygen permeability. When the content of HPCMC reached 10g/100g starch, the oxygen permeability of starch film decreased to 0.749 × 10-6cm3·m/(m2·d·kPa), which decreased by 67% when compared with control film.

Key words: food colloids, sweet potato starch film, mechanical properties, permeabilities