Effects of glycerol and storage relative humidity on the properties of kudzu starch‐based edible films
2014
Zhong, Yu | Li, Yunfei
Kudzu (Pueraria lobata) starch films were prepared using glycerol as plasticizer. The effects of glycerol (0, 10, 20, 30, and 40% of dry starch) and storage relative humidity (RH, 53, 75, and 100%) on molecular interactions, crystalline structural characterizations, and thermal stabilities of the films were investigated using Fourier transform‐infrared (FT‐IR) spectra, XRD, and thermogravimetry and DTA (TG‐DTA). The results showed that kudzu starch could form intermolecular hydrogen bonds with glycerol and water molecules, and increasing RH could enhance the sensibility of CO bonds in COC groups to glycerol. The addition of glycerol promoted the formation of B‐type and V‐type crystal structure in plasticized film, whereas increasing RH impeded V‐type crystal structure. Thermal stability decreased slightly as glycerol content and RH increased. Moreover, anti‐plasticization was found from TG‐DTA spectra and water sorption isotherms at low water activities. Furthermore, water vapor permeability (WVP) and mechanical properties of the films were also studied. The WVP values increased with increasing glycerol content and RH, and the lowest value was about 3.15 × 10⁻¹¹ g m⁻¹ s⁻¹ Pa⁻¹ for 20% glycerol plasticized film at 50% RH. The puncture strength of kudzu starch film ranged from 1.31 to 10.86 N and deformation ranged from 4.10 to 5.15 mm.
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