Liquid and vapour water transfer through whey protein/lipid emulsion films.
BACKGROUND
Edible films and coatings based on protein/lipid combinations are among the new products being developed in order to reduce the use of plastic packaging polymers for food applications. This study was conducted to determine the effect of rapeseed oil on selected physicochemical properties of cast whey protein films.


RESULTS
Films were cast from heated (80 degrees C for 30 min) aqueous solutions of whey protein isolate (WPI, 100 g kg(-1) of water) containing glycerol (50 g kg(-1) of WPI) as a plasticiser and different levels of added rapeseed oil (0, 1, 2, 3 and 4% w/w of WPI). Measurements of film microstructure, laser light-scattering granulometry, differential scanning calorimetry, wetting properties and water vapour permeability (WVP) were made. The emulsion structure in the film suspension changed significantly during drying, with oil creaming and coalescence occurring. Increasing oil concentration led to a 2.5-fold increase in surface hydrophobicity and decreases in WVP and denaturation temperature (T(max)).


CONCLUSIONS
Film structure and surface properties explain the moisture absorption and film swelling as a function of moisture level and time and consequently the WVP behaviour. Small amounts of rapeseed oil favourably affect the WVP of WPI films, particularly at higher humidities.
Kokoszka
Sabina
S
Department of Food Engineering and Process Management, Faculty of Food Sciences, Warsaw University of Life Sciences-SGGW, 159c Nowoursynowska Street, Warsaw, Poland.
Debeaufort
Frederic
F
Lenart
Andrzej
A
Voilley
Andree
A
D003890:Desiccation; D004655:Emulsions / Q000737:chemistry*; D005229:Fatty Acids, Monounsaturated; D018857:Food Packaging / Q000379:methods*; D005990:Glycerol; D057927:Hydrophobic and Hydrophilic Interactions; D008894:Milk Proteins; D010539:Permeability; D010938:Plant Oils / Q000737:chemistry*; D000074262:Rapeseed Oil; D013227:Steam; D013499:Surface Properties; D013696:Temperature; D014867:Water / Q000737:chemistry*; D000067816:Whey Proteins
D004655:Emulsions; D005229:Fatty Acids, Monounsaturated; D008894:Milk Proteins; D010938:Plant Oils; D000074262:Rapeseed Oil; D013227:Steam; D000067816:Whey Proteins; D014867:Water; D005990:Glycerol