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Covalent Attachment of Lactase to Low‐Density Polyethylene Films
Author(s) -
Goddard J.M.,
Talbert J.N.,
Hotchkiss J.H.
Publication year - 2006
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1750-3841.2006.00203.x
Subject(s) - covalent bond , lactase , glutaraldehyde , chemistry , polyethylene , surface modification , polymer , polymer chemistry , immobilized enzyme , x ray photoelectron spectroscopy , amination , enzyme , chemical engineering , organic chemistry , catalysis , engineering
Polymer films to which bioactive compounds such as enzymes are covalently attached offer potential for in‐package processing of food. β‐galactosidase (lactase) was covalently attached to surface‐functionalized low‐density polyethylene films. A two‐step wet chemical functionalization introduced 15.7 nmol/cm 2 primary amines to the film surface. Contact angle, dye assays, X‐ray photoelectron spectroscopy, and appropriate protein assays were used to characterize changes in film surface chemistry after each step in the process of attachment. Glutaraldehyde was used to covalently attach lactase to the surface at a density of 6.0 μg protein per cm 2 via reductive amination. The bond between the covalently attached lactase and the functionalized polyethylene withstood heat treatment in the presence of an ionic denaturant with 74% enzyme retention, suggesting that migration of the enzyme into the food product would be unlikely. The resulting polyethylene had an enzyme activity of 0.020 lactase units (LU)/cm 2 (approximately 4500 LU/g). These data suggest that enzymes that may have applications in foods can be covalently attached to inert polymer surfaces, retain significant activity, and thus have potential as a nonmigratory active packaging materials.