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Inhibition of
Penicillium Commune by Edible Whey Protein Isolate Films Incorporating Lactoferrin,
Lactoferrin Hydrolysate, and Lactoperoxidase Systems
By,
S. Min and J. M. Krochta
Department of Food Science and Technology
University of California, Davis
Application of antimicrobial-containing edible films has advantages
over the direct application of antibacterial agents onto food because
edible films can be designed to slow antimicrobial diffusion from the
surface of food. Lactoferrin and lactoperoxidase are components of whey
protein that are separated and concentrated for their functional
properties, including antimicrobial properties. Thus, edible films based
on whey protein isolate (WPI) could be compatible matrices to hold these
antimicrobial compounds at the surface of food.
The first objective was to study effects of lactoferrin (LF),
lactoferrin hydrolysate (LFH) and lactoperoxidase systems (LPOS), both
directly and incorporated into WPI films, on the inhibition of P.
commune. The second objective was to compare the elastic modulus (EM),
tensile strength (TS), and percentage elongation at break (%E), oxygen
permeability (OP), and color of WPI films incorporating LPOS with those
of WPI films without LPOS.
The concentrations of LF,LFH and LPOS were in the range of 0.05-3,
0.05-3 and 0.01-1 % (w/w), respectively. Inhibition effects were
examined by measurement of inoculated suspension turbidity, inhibition
diameter on inoculated agar, and direct WPI film surface inoculation
tests. EM, TS, and %E and OP were measured by following ASTM standard
methods D882-01 and D3985, respectively. Hunter L, a, b, values were
measured for film color determination.
LF and LFH at 1% (w/w) or higher inhibited P. commune in 1% peptone
water, but not in potato dextrose broth. Only WPI films incorporating 1%
(w/w) LPOS inhibited growth of P. commune. The mechanical and physical
properties of WPI films were not significantly changed by incorporation
of LPOS (P>0.05).
WPI films incorporating LPOS may be applied to foods to control the
growth of P. commune with identical mechanical and physical properties
to those of regular WPI films.
For more information on Dr. Krochta’s work and the Food Science and Technology Department at UC Davis, please visit Dr. Krochta's Web site - http://foodscience.ucdavis.edu/fst/faculty/KrochtaWeb/index.htm.