Physical properties of whey protein--hydroxypropylmethylcellulose blend edible films.
The formations of glycerol (Gly)-plasticized whey protein isolate (WPI)-hydroxypropylmethylcellulose (HPMC) films, blended using different combinations and at different conditions, were investigated. The resulting WPI: Gly-HPMC films were analyzed for mechanical properties, oxygen permeability (OP), and water solubility. Differences due to HPMC quantity and blend method were determined via SAS software. While WPI: Gly and HPMC films were transparent, blend films were translucent, indicating some degree of immiscibility and/or WPI-HPMC aggregated domains in the blend films. WPI: Gly-HPMC films were stronger than WPI: Gly films and more flexible and stretchable than HPMC films, with films becoming stiffer, stronger, and less stretchable as the concentration of HPMC increased. However, WPI: Gly-HPMC blended films maintained the same low OP of WPI: Gly films, significantly lower than the OP of HPMC films. Comparison of mechanical properties and OP of films made by heat-denaturing WPI before and after blending with HPMC did not indicate any difference in degree of cross-linking between the methods, while solubility data indicated otherwise. Overall, while adding HPMC to WPI: Gly films had a large effect on the flexibility, strength, stretchability, and water solubility of the film polymeric network, results indicated that HPMC had no effect on OP through the polymer network. WPI-HPMC blend films had a desirable combination of mechanical and oxygen barrier properties, reflecting the combination of hydrogen-bonding, hydrophobic interactions, and disulfide bond cross-linking in the blended polymer network.
Brindle
L P
LP
Department of Food Science and Technology, University of Georgia, Athens, GA 30602, USA.
Krochta
J M
JM
D018441:Biofilms; D005503:Food Additives; D018857:Food Packaging / Q000379:methods; D005990:Glycerol; D006860:Hydrogen Bonding; D065347:Hypromellose Derivatives; D008747:Methylcellulose / Q000031:analogs & derivatives* / Q000032:analysis / Q000737:chemistry; D008894:Milk Proteins / Q000032:analysis / Q000737:chemistry* / Q000302:isolation & purification; D010100:Oxygen / Q000032:analysis; D010539:Permeability; D010968:Plasticizers; D011134:Polysaccharides / Q000032:analysis / Q000737:chemistry; D012996:Solutions; D000067816:Whey Proteins
D005503:Food Additives; D008894:Milk Proteins; D010968:Plasticizers; D011134:Polysaccharides; D012996:Solutions; D000067816:Whey Proteins; D065347:Hypromellose Derivatives; D008747:Methylcellulose; D005990:Glycerol; D010100:Oxygen