Crystallization of high-amylose starch by the addition of plasticizers at low and intermediate concentrations.

The antiplasticization effect of plasticizers (that is, polyols and monosaccharides) in starch films was investigated. Pea starch films were plasticized by various polyols and monosaccharides at the levels of 0% to 25% (w/w, plasticizer/starch). After 14 d of storage at 50% relative humidity, the crystallinity of pea starch films increased with increasing concentration of plasticizers from 0% to 20%. Accordingly, moisture content, water vapor permeability, oxygen permeability, and elongation decreased with increasing plasticizer concentration from 0% to 20%, showing the antiplasticization effect. The addition of plasticizers above 20% reduced the crystallinity of starch films, consequently showing the plasticization effect. The results showed that the addition of the plasticizers facilitated the crystallization of the polymer chains through the antiplasticization phenomenon at the concentration range below 15%. Above 20%, plasticizers performed the conventional plasticization effect. Each plasticizer had different critical concentration where the antiplasticization was converted to plasticization.