title: Wettability, surface microstructure and mechanical properties of films based on phosphorus oxychloride-treated zein.
abstract: BACKGROUND
  Zein, the predominant protein in corn, has been extensively studied as an alternative packaging material in edible and biodegradable films. However, films made from 100% zein are brittle under normal conditions. The aim of this investigation was to improve the film-forming properties of zein by chemical phosphorylation. The surface hydrophobicity, surface microstructure and mechanical properties of films based on untreated and phosphorus oxychloride (POCl(3))-treated zein were evaluated and compared. The effect of POCl(3) treatment on the rheological properties of zein solutions was also studied.
  
  
  RESULTS
  POCl(3) treatment, especially at pH 7 and 9, led to an increase in the apparent viscosity of zein solutions. Atomic force microscopy (AFM) analysis showed that the film based on POCl(3) -treated zein at pH 7 had a stone-like surface microstructure with a higher roughness (R(q)) than the untreated zein film. The AFM data may partially account for the phenomenon that this film exhibited high surface hydrophobicity (H(0) ). POCl(3) treatment diminished the tensile strength (TS) of zein films from 4.83-6.67 to 1.3-2.29 MPa. However, the elongation at break (EAB) of the films at pH 7 and 9 increased from 3.0-4.5% (control film) to 150.1-122.7% (POCl(3) -treated film), indicating the potential application of zein films in wrapping foods or in non-food industries such as sugar, fruit or troche that need good extension packing materials.
  
  
  CONCLUSIONS
  The data presented suggest that the properties of zein films could be modulated by chemical phosphorylation treatment with POCl(3) at an appropriate pH value.
authors.affiliation: College of Food Science and Engineering, JiangXi Agricultural University, Nanchang 330045, China.
authors.forename: Lei-Yan
authors.initials: LY
authors.lastname: Wu
authors.forename: Qi-Biao
authors.initials: QB
authors.lastname: Wen
authors.forename: Xiao-Quan
authors.initials: XQ
authors.lastname: Yang
authors.forename: Ming-Sheng
authors.initials: MS
authors.lastname: Xu
authors.forename: Shou-Wei
authors.initials: SW
authors.lastname: Yin
mesh_terms: D001673:Biodegradation, Environmental; D002476:Cellophane / Q000737:chemistry*; D005511:Food Handling / Q000379:methods*; D057927:Hydrophobic and Hydrophilic Interactions; D055595:Mechanical Phenomena; D018625:Microscopy, Atomic Force; D017553:Phosphorus Compounds / Q000737:chemistry*; D010766:Phosphorylation; D012212:Rheology; D013499:Surface Properties; D013718:Tensile Strength; D014783:Viscosity; D017155:Wettability; D003313:Zea mays / Q000737:chemistry*; D015028:Zein / Q000737:chemistry*
chemical_list: D017553:Phosphorus Compounds; D002476:Cellophane; D015028:Zein; C013196:phosphoryl chloride