Physical properties of whey protein coating solutions and films containing antioxidants.
Antioxidants (ascorbyl palmitate and alpha-tocopherol) were incorporated into 10% (w/w) whey protein isolate (WPI) coating solution containing 6.67% (w/w) glycerol (WPI:glycerol = 6:4). Before incorporation, the antioxidants were mixed using either powder blending (Process 1) or ethanol solvent-mixing (Process 2). After the antioxidant mixtures were incorporated into heat-denatured WPI solution, viscosity and turbidity of the WPI solutions were determined. The WPI solutions were dried on a flat surface to produce WPI films. The WPI films were examined to determine transparency and oxygen-barrier properties (permeability, diffusivity, and solubility). WPI solution containing antioxidants produced by Process 1 and Process 2 did not show any difference in viscosity and turbidity, but viscosity was greater for the WPI solution with rather than without antioxidants. WPI films produced by Process 2 were more transparent than the films produced by Process 1. Oxygen permeability of Process 1 film was lower than Process 2 film. However, both the diffusivity and solubility of oxygen were statistically the same in Process 1 and Process 2 films. Both control WPI films and antioxidant-containing WPI films had very low oxygen solubility, comparable to polyethylene terephthalate films. Permeability of antioxidant-incorporated films was not enhanced compared to control WPI films.
Han
J H
JH
Dept. of Food Science, Univ. of Manitoba, Winnipeg, MB R3T 2N2, Canada. hanjh@ms.umanitoba.ca
Krochta
J M
JM
D000975:Antioxidants / Q000032:analysis* / Q000494:pharmacology; D001205:Ascorbic Acid / Q000031:analogs & derivatives / Q000032:analysis / Q000494:pharmacology; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D004058:Diffusion; D018857:Food Packaging / Q000295:instrumentation*; D005519:Food Preservation / Q000295:instrumentation* / Q000379:methods*; D005524:Food Technology; D005990:Glycerol; D015227:Lipid Peroxidation / Q000187:drug effects; D008894:Milk Proteins / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D010539:Permeability; D012995:Solubility; D014783:Viscosity; D000067816:Whey Proteins; D024502:alpha-Tocopherol / Q000032:analysis / Q000494:pharmacology
D000975:Antioxidants; D008894:Milk Proteins; D000067816:Whey Proteins; D024502:alpha-Tocopherol; D005990:Glycerol; D001205:Ascorbic Acid; C031226:6-O-palmitoylascorbic acid; D010100:Oxygen