Open AccessMoisture Sensitivity, Optical, Mechanical and Structural Properties of Whey Protein-Based Edible Films Incorporated with Rapeseed Oil
Author(s) -
Sabina Galus,
Justyna Kadzińska
Publication year - 2016
Publication title -
food technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.744
H-Index - 67
eISSN - 1334-2606
pISSN - 1330-9862
DOI - 10.17113/ftb.54.01.16.3889
Subject(s) - rapeseed , whey protein isolate , whey protein , emulsion , plasticizer , ultimate tensile strength , chemistry , water activity , oil droplet , materials science , food science , chemical engineering , water content , volume fraction , chromatography , composite material , organic chemistry , geotechnical engineering , engineering
The objective of this work is to study the effect of the rapeseed oil content on the physical properties of whey protein emulsion films. For this purpose, whey protein films with the addition of 0, 1, 2 and 3% of rapeseed oil, and glycerol as a plasticizer were obtained by the casting method. Film-forming emulsions were evaluated and compared using light scattering granulometry. The Sauter mean diameters ( d 32 ) of lipid droplets in film-forming solutions showed an increasing trend when increasing the oil volume fractions. The inclusion of rapeseed oil enhanced the hydrophobic character of whey protein films, reducing moisture content and film solubility in water. All emulsified films showed high lightness ( L* ≈90). Parameter a * decreased and parameter b* and total colour difference (∆ E ) increased with the increase of the volume fractions of oil. These results were consistent with visual observations; control films were transparent and those containing oil opaque. Water vapour sorption experimental data at the full range of water activity values from 0.11 to 0.93 were well described with Peleg's equation (R 2 ≥0.99). The tensile strength, Young's modulus and elongation at break increased with the increase of rapeseed oil volume fraction, which could be explained by interactions between lipids and the protein matrix. These results revealed that rapeseed oil has enormous potential to be incorporated into whey protein to make edible film or coating for some food products. The mechanical resistance decreased with the addition of the lipids, and the opacity and soluble matter content increased.