Change search
ReferencesLink to record
Permanent link

Direct link
Influence of citric acid and curing on moisture sorption, diffusion and permeability of starch films
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.
Fibre and Polymer Technology, Royal Institute of Technology.
Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Engineering and Chemical Sciences.ORCID iD: 0000-0001-7368-7227
Karlstad University, Faculty of Technology and Science, Department of Chemical Engineering. Karlstad University, Faculty of Technology and Science, Paper Surface Centre.ORCID iD: 0000-0002-1256-1708
2013 (English)In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 94, no 2, 765-772 p.Article in journal (Refereed) Published
Abstract [en]

Starch films with different amounts of citric acid produced by solution casting were subjected to differ-ent curing temperatures and compared with films plasticized with glycerol. The films were tested in a controlled moisture generator, which enabled the moisture sorption to be measured and the diffusion coefficient and water vapor permeability to be calculated. It was shown that increasing the amount of citric acid added led to a reduction in the equilibrium moisture content, diffusion coefficient and water vapor permeability of the films, the values of which were all considerably lower than the values obtained for the films plasticized by glycerol. It was also seen that curing the film with 30 pph citric acid at 150

◦C led to a significant reduction in the equilibrium moisture content, the diffusion coefficient and the water vapor permeability at high relative humidity which suggests that crosslinking occurred. The calculated water vapor permeability data were comparable with the value obtained with direct measurements.

Place, publisher, year, edition, pages
Amsterdam: Elsevier, 2013. Vol. 94, no 2, 765-772 p.
Keyword [en]
starch, citric acid, cross-linking, diffusion
National Category
Polymer Technologies
Research subject
Chemical Engineering
Identifiers
URN: urn:nbn:se:kau:diva-27071DOI: 10.1016/j.carbpol.2013.02.006ISI: 000317946200007PubMedID: 23544631OAI: oai:DiVA.org:kau-27071DiVA: diva2:618199
Projects
Renewable functional barriers
Funder
VINNOVA
Available from: 2013-04-26 Created: 2013-04-26 Last updated: 2015-12-15Bibliographically approved
In thesis
1. Effects of Citric Acid on Starch-Based Barrier Coatings
Open this publication in new window or tab >>Effects of Citric Acid on Starch-Based Barrier Coatings
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

With growing environmental concerns, efforts are made to replace petroleum based products with renewable alternatives. This is particularly evident in the packaging industry, where replacing synthetic polymers with renewable materials is of considerable interest. Materials for food packaging need to give protection, acting as a barrier against substances that can adversely affect the food quality such as water and oxygen.

In this work, barrier dispersion coatings based on starch were used to produce coated papers which act as barrier against water and oxygen. However, since starch is both a hydrophilic and hygroscopic material, this barrier material becomes problematic to use at high relative humidity. In order to reduce this problem and improve the barrier properties enabling starch based barrier materials to be used in food packaging applications, two approaches were studied.

Citric acid was utilized as a cross-linker of the starch and it was found to reduce the moisture sorption, the molecular movement and swelling at high relative humidity. It was seen that cross-linking and hydrolysis due to the low pH both affected the barrier properties significantly, but in opposing directions. By controlling these two reactions it was seen that this could lead to reduced gas permeability. It was also seen that cross-linking of starch by citric acid occurs at low temperatures, 70 °C at pH as high as 6.5.

Starch nano-composites were produced by incorporating montmorillonite, to the barrier dispersion to improve the barrier properties. It was seen that the suspension viscosity was reduced by poly(ethylene glycol) and citric acid adsorption on the montmorillonite particles. Also, a tendency for improved barrier properties with reduced aggregate volume fraction and reduced swelling was observed. It was also seen that up scaling this formulation to pilot scale was possible and that promising results were achieved.

Abstract [en]

Baksidestext

With growing environmental concerns, efforts are made to replace petroleum based materials with renewable alternatives such as starch. In this work, dispersions based on starch were used to produce coated papers which act as barrier against substances that can adversely affect the food quality such as water and oxygen. However, since starch is both a hydrophilic and hygroscopic material, this barrier material becomes problematic to use at high relative humidity.

Citric acid was utilized as cross-linker for starch and it was found to reduce the moisture sorption, diffusion and swelling at high relative humidity. Both cross-linking and hydrolysis due to the low pH affected the barrier properties significantly, but in opposing directions. By controlling these two reactions it was possible to achieve reduced gas permeability.

Starch nano-composites were produced by incorporating montmorillonite clay, to the barrier dispersion. It was seen that the suspension viscosity was reduced by poly(ethylene glycol) and citric acid adsorption on the clay. Also, a tendency for improved barrier properties with reduced aggregate volume fraction and reduced swelling was observed. It was also seen that up scaling this formulation to pilot scale was possible and promising results were achieved.

Place, publisher, year, edition, pages
Karlstad: Karlstads universitet, 2013. 80 p.
Series
Karlstad University Studies, ISSN 1403-8099 ; 2013:25
Keyword
Starch, Citric acid, Cross-linking, hydrolysis, Montmorillonite, WVTR, OTR, Barrier properties
National Category
Polymer Technologies
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kau:diva-27127 (URN)978-91-7063-502-1 (ISBN)
Public defence
2013-06-13, 9C203, Nyquistsalen, Karlstads universitet, 10:15 (English)
Opponent
Supervisors
Projects
Renewable Functional Barriers
Funder
Vinnova
Available from: 2013-05-23 Created: 2013-04-29 Last updated: 2013-05-23Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textPubMedhttp://www.sciencedirect.com/science/article/pii/S0144861713001446

Search in DiVA

By author/editor
Olsson, ErikJohansson, CaisaJärnström, Lars
By organisation
Department of Engineering and Chemical SciencesDepartment of Chemical EngineeringPaper Surface Centre
In the same journal
Carbohydrate Polymers
Polymer Technologies

Search outside of DiVA

GoogleGoogle Scholar

Altmetric score

Total: 86 hits
ReferencesLink to record
Permanent link

Direct link