title: Extrusion and characterization of thermoplastic starch sheets from "macho" banana.
abstract: Starch isolated from macho banana was oxidized by using 2.5% and 3.5% (w/w) of sodium hypochlorite. Native and oxidized starches with glycerol were processed using a conical twin screw extruder to obtain thermoplastic laminates or sheets, which were partially characterized. Oxidized banana starches presented higher moisture and total starch but lower ash, protein, lipids, and apparent amylose content than the native starch. Micrographs of sheets from oxidized starches showed wrinkles and cavities presumably caused by the plasticizer, but with less free glycerol and unplasticized starch granules than those from native starch. Sheets from oxidized starch showed a notorious increase in all thermal parameters (To, Tp, and ΔH), mechanical properties (tensile strength, elongation at break, and elasticity), and solubility. Banana starch X-ray diffraction patterns corresponded to a mixture of the A- and B-type polymorphs, with apparently slightly higher crystallinity in oxidized specimens than in native starch. A similar trend was observed in the corresponding sheets.
  
  
  CONCLUSIONS
  Due to the pollution problem caused by the conventional plastics, there has been a renewed interest in biodegradable sheets, because they may have the potential to replace conventional packaging materials. Banana starch might be an interesting raw material to be used as edible sheet, coating or in food packaging, and preservation, because it is biodegradable, cheap, innocuous, and abundant.
authors.affiliation: Centro de Desarrollo de Productos Bióticos, Inst. Politécnico Nacional, Km 6 Carretera Yautepec-Jojutla, Calle Ceprobi 8, Col. San Isidro, C.P.62731 Yautepec, Morelos, México.
authors.forename: P
authors.initials: P
authors.lastname: Alanís-López
authors.forename: J
authors.initials: J
authors.lastname: Pérez-González
authors.forename: R
authors.initials: R
authors.lastname: Rendón-Villalobos
authors.forename: A
authors.initials: A
authors.lastname: Jiménez-Pérez
authors.forename: J
authors.initials: J
authors.lastname: Solorza-Feria
mesh_terms: D002152:Calorimetry, Differential Scanning; D055598:Chemical Phenomena; D004548:Elasticity; D018857:Food Packaging; D005638:Fruit / Q000737:chemistry* / Q000254:growth & development; D005990:Glycerol / Q000032:analysis / Q000737:chemistry; D055595:Mechanical Phenomena; D008800:Mexico; D008855:Microscopy, Electron, Scanning; D028521:Musa / Q000737:chemistry*; D016877:Oxidants / Q000737:chemistry; D010084:Oxidation-Reduction; D010539:Permeability; D012973:Sodium Hypochlorite / Q000737:chemistry; D012995:Solubility; D013213:Starch / Q000032:analysis / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure; D013227:Steam / Q000032:analysis; D013718:Tensile Strength; D014867:Water / Q000032:analysis; D014961:X-Ray Diffraction
chemical_list: D016877:Oxidants; D013227:Steam; D014867:Water; D013213:Starch; D012973:Sodium Hypochlorite; D005990:Glycerol