73D-29 |
Improvement of paperboard packaging performance with whey protein concentrate coating |
S. Y. LIN and J. M. Krochta. Dept. of Food Science & Technology, Univ. of California, Davis, 1 Shields Ave., Davis, CA 95616 Glycerol-plasticized whey protein isolate (WPI) coated on paperboard imparts excellent grease and oxygen resistance. However, possible plasticizer migration from WPI coating into paperboard during storage increases coating brittleness and cracking which impairs grease and oxygen barrier properties. The objective of this research is to substitute 80% whey protein concentrate (WPC-80) for WPI to reduce the coating cost. Additionally, lactose in WPC may provide plasticizing effect and reduce required plasticizer addition and resulting migration. Aqueous solutions of 10% (w/w) WPCs (80% protein content) with or without hydrolysis of lactose or proteins were prepared with glycerol, sorbitol, polyethylene glycol (PEG 200) or sucrose as plasticizer at 0.34 and 0.64M and heat denatured 30 min at 90°C. Films were cast on rimmed, smooth, HDPE plates. Films were also formed as coatings on paperboard to achieve a dry coating of 20-25 g/m2 by drying with forced air at 2-3 m/s and 80±5°C. Scotchban paper protector test was performed to detect existence of pin holes in coatings. WPC-80 solutions must be adjusted to pH 8.0 to remain fluid without gelation contributed by the ionic protein-protein interactions. Only paperboards coated with WPC-80s without added plasticizers exhibited pin holes. WPC-80 plasticized with 0.64M glycerol or sucrose, or with 0.34 or 0.64M sorbitol or PEG 200, produced flexible films. WPC-80 with hydrolyzed lactose required addition of less sucrose to produce flexible films. WPC-80 with hydrolyzed proteins also required addition of less sucrose to produce flexible film. These results suggest usefulness of hydrolyzed WPC-80 with addition of less and larger Mw plasticizer and less resulting plasticizer migration. WPC-80 coatings allow addition of less and larger Mw plasticizer with less plasticizer migration anticipates. Substitution of WPI with WPC-80 for paperboard coating will substantially lower the cost to produce paperboard coatings.
Session 73D, Food Packaging
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