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Properties of cast films made from different ratios of whey protein isolate, hydrolysed whey protein isolate and glycerol

: Schmid, Markus

Fulltext urn:nbn:de:0011-n-2582011 (1018 KByte PDF)
MD5 Fingerprint: f5d140bde174a28f751a7743982160c6
Created on: 17.9.2013

Materials 6 (2013), No.8, pp.3245-3269
ISSN: 1996-1944
Journal Article, Electronic Publication
Fraunhofer IVV ()

Whey protein isolate (WPI)-based cast films are very brittle, due to several chain interactions caused by a large amount of different functional groups. In order to overcome film brittleness, plasticizers, like glycerol, are commonly used. As a result of adding plasticizers, the free volume between the polymer chains increases, leading to higher permeability values. The objective of this study was to investigate the effect of partially substituting glycerol by hydrolysed whey protein isolate (h-WPI) in WPI-based cast films on their mechanical, optical and barrier properties. As recently published by the author, it is proven that increasing the h-WPI content in WPI-based films at constant glycerol concentrations significantly increases film flexibility, while maintaining the barrier properties. The present study considered these facts in order to increase the barrier performance, while maintaining film flexibility. Therefore glycerol was partially replaced by h-WPI in WPI-based cast films. The results clearly indicate that partially replacing glycerol by h-WPI reduces the oxygen permeability and the water vapor transmission rate, while the mechanical properties did not change significantly. Thus, film flexibility was maintained, even though the plasticizer concentration was decreased.