title: Sorption isotherm and plasticization effect of moisture and plasticizers in pea starch film.
abstract: Pea starch films were produced with various plasticizers (glucose, fructose, mannose, sorbitol, and glycerol). Effects of plasticizer content (4.34 to 10.87 mmol/g of dry starch) and storage relative humidity (RH) (11.3% to 75.4%) on moisture content (MC), tensile strength (TS), elongation (E), modulus of elasticity (EM), and water vapor permeability (WVP) were evaluated using response surface methodology. MC was influenced strongly by RH. Glycerol-plasticized films had the highest MC, indicating that water molecules played a more important role in plasticizing starch films. Monosaccharide-plasticized films and polyol-plasticized films had similar TS values. However, monosaccharide-plasticized films had higher E values and lower EM values than polyol-plasticized films, meaning monosaccharides had better efficiency in plasticizing starch films. Recrystallization happened in glucose- and sorbitol-plasticized films when they were stored in high RH. Sorption isotherm studies showed the similar adsorption and desorption profiles for all 3 monosaccharide-plasticized films and a hysteresis. The Flory-Huggius model fitted experimental data best for starch films, while the BET model fitted the data marginally.
authors.affiliation: Dept of Food Science, Univ of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: J H
authors.initials: JH
authors.lastname: Han
mesh_terms: D055119:Elastic Modulus; D005990:Glycerol / Q000737:chemistry; D006813:Humidity; D008956:Models, Chemical; D009005:Monosaccharides / Q000737:chemistry; D018532:Pisum sativum / Q000737:chemistry*; D010968:Plasticizers / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D013012:Sorbitol / Q000737:chemistry; D013213:Starch / Q000737:chemistry*; D013499:Surface Properties; D013718:Tensile Strength; D014867:Water
chemical_list: D009005:Monosaccharides; D010968:Plasticizers; D011108:Polymers; C024617:polyol; D014867:Water; D013012:Sorbitol; D013213:Starch; D005990:Glycerol