Next Article in Journal
Comparison of in Situ and ex Situ Methods for Synthesis of Two-Photon Polymerization Polymer Nanocomposites
Next Article in Special Issue
Influence of Surface Treatment on Tensile Properties of Low-Density Polyethylene/Cellulose Woven Biocomposites: A Preliminary Study
Previous Article in Journal
Lipid Monolayers with Adsorbed Oppositely Charged Polyelectrolytes: Influence of Reduced Charge Densities
Previous Article in Special Issue
Low Molecular Weight Chitosan (LMWC)-based Polyplexes for pDNA Delivery: From Bench to Bedside
Polymers 2014, 6(7), 2018-2036; doi:10.3390/polym6072018

Casein Films: The Effects of Formulation, Environmental Conditions and the Addition of Citric Pectin on the Structure and Mechanical Properties

1,* , 2
1 Dairy & Functional Foods Research Unit, Eastern Regional Research Center, Agricultural Research Service, United States Department of Agriculture, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA 2 Department of Food Science, Rutgers School of Environmental and Biological Sciences, 65 Dudley Road, New Brunswick, NJ 08901, USA
* Author to whom correspondence should be addressed.
Received: 1 October 2013 / Revised: 12 June 2014 / Accepted: 30 June 2014 / Published: 14 July 2014
(This article belongs to the Special Issue Natural Polymers 2014)
View Full-Text   |   Download PDF [2628 KB, uploaded 14 July 2014]   |  


Thin casein films for food packaging applications reportedly possess good strength and low oxygen permeability, but low elasticity and high sensitivity to moisture. Modifying the films to target specific behaviors depending on environmental conditions can enable a variety of commercial applications for casein-based films. The mechanical properties of solvent-cast (15% solids) calcium-caseinate/glycerol films (CaCas:Gly ratio of 3:1) were characterized as a function of processing and environmental conditions, including film thickness, solution formulation and ambient humidity (from 22% to 70% relative humidity (RH) at ~20 °C). At constant RH, the elongation at break (EAB) had a strong positive dependence on the film thickness. When RH increased, the tensile strength (TS) and modulus (E) decreased approximately linearly, while EAB increased. From 0.05% to 1% (w/w) of citric pectin (CP) was then incorporated into CaCas/Gly films following seven different formulations (mixing sequences), to alter the protein network and to evaluate the effects of CP on the tensile properties of CaCas/Gly/CP films. At constant film thickness and ~60% RH, the addition of 0.1% or 1.0% CP to the films considerably increased or decreased EAB, TS and E in different directions and to different extents, depending on the formulation, while optical micrographs also showed vastly differing network configurations, suggesting complex formulation- and stoichiometry-dependent casein-pectin interactions within the dried films. Depending on the desired film properties and utilization conditions, pectin may be a useful addition to casein film formulations for food packaging applications.
Keywords: high-methoxyl pectin; milk protein; edible film; food packaging high-methoxyl pectin; milk protein; edible film; food packaging
This is an open access article distributed under the Creative Commons Attribution License (CC BY 3.0).

Share & Cite This Article

Further Mendeley | CiteULike
Export to BibTeX |
EndNote |
MDPI and ACS Style

Bonnaillie, L.M.; Zhang, H.; Akkurt, S.; Yam, K.L.; Tomasula, P.M. Casein Films: The Effects of Formulation, Environmental Conditions and the Addition of Citric Pectin on the Structure and Mechanical Properties. Polymers 2014, 6, 2018-2036.

View more citation formats

Related Articles

Article Metrics

For more information on the journal, click here


[Return to top]
Polymers EISSN 2073-4360 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert