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Author:
Cho, Sung-Woo (KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology)
Title:
Aging and heat-sealing properties of films based on wheat gluten
Department:
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology
Publication type:
Licentiate thesis, comprehensive summary (Other scientific)
Language:
English
Place of publ.: Stockholm Publisher: KTH
Pages:
59
Series:
Trita-CHE-Report, ISSN 1654-1081; 2007:58
Year of publ.:
2007
URI:
urn:nbn:se:kth:diva-4489
Permanent link:
http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-4489
ISBN:
978-91-7178-749-1
ISRN:
978-91-7178-748-4
Subject category:
Polymer Chemistry
SVEP category:
Polymer chemistry
Keywords(en) :
wheat gluten, aging, migration, opacity, heat sealability, shear strength
Abstract(en) :

Recently the research interest of the possibility of using wheat gluten (WG) as packaging material has greatly increased due to its combination of high gas barrier, attractive mechanical, film-forming and renewable properties. The source is also readily available and inexpensive on a worldwide basis. The glycerol-plasticized WG films cast from pH 4 and pH 11 solutions were investigated in order to understand the mechanisms behind the undesired aging. The film prepared from the pH 11 solution was mechanically more stable upon aging than the pH 4 film, which was initially very ductile but turning brittle with time. It was revealed that the protein structure of the pH 4 film was initially less polymerized/aggregated and the polymerization increased during storage but it did not reach the degree of aggregation of the pH 11 film, whereas deamidation was occurred and increased in the pH 11 film. During aging, the pH 4 film lost more mass than the pH 11 film mainly due to migration of glycerol but also due to some loss of volatile mass and the greater plasticizer loss of pH 4 film was presumably due to its initial lower degree of protein aggregation /polymerization. The glycerol migration of cast films exposed to a porous paper was further investigated with respect to pH of cast solution, glycerol content and film thickness since it was the main reason for deterioration of the properties. The opacity was also characterized. The glycerol migration was quantified using GC method in order to determine only glycerol content, but not other volatile substances. Glycerol content did not significantly change the opacity and pH 4 films showed good contact clarity because of less Maillard reaction. Glycerol was extensively migrating to the paper support and the migration seemed to be diffusion controlled. The heat sealability of WG films was investigated, using an impulse-hear sealer. It was observed that the WG films were readily sealable keeping up their integrity. The sealing temperature had a negligible effect on the lap-shear strength, but the peel strength increased with sealing temperature. The lap-shear strength increased with increasing mold temperature and the failure mode changed.

Note:
QC 20101103
Presentation:
2007-09-21, Sal K2, KTH, Teknikringen 28, Stockholm, 10:00
Supervisor:
Hedenqvist, Mikael (KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology)
Opponent:
Hakkarainen, Minna, Docent (Inst. för fiber- och polymerteknologi)
Lindström, Mikael, Docent
Available from:
2007-09-19
Created:
2007-09-19
Last updated:
2010-11-03
Statistics:
315 hits