Extension of Shelf Life and Control of Human Pathogens in Produce by Antimicrobial Edible Films and Coatings - Microbial Safety of Fresh Produce - page 230

accounted for the remainder of the inhibition. It was found that for oils containing
alcohol, ketone, ester, oxide, and hydrocarbons the major inhibition came from the
vapors whereas for oils containing greater volumes of aldehydes inhibition came from
diffusion (Inouye and others 2006).
Minimum inhibitory concentrations (MICs) of antimicrobial edible fi lms can be
assessed by the agar diffusion assay and observing the zone of inhibition, or the agar
dilution method with visible growth observed, or broth dilution with visible growth,
optical density, absorbance, or viable counts measured (Burt 2004). The MIC is deter-
mined as the lowest concentration at which growth is inhibited. The major problem
with the method of determining the strength of antimicrobial activity of edible fi lms
is their hydrophobic nature, which makes them insoluble in water-based media (Fisher
and Phillips 2008). Recently applied methods to evaluate the effect of antimicrobial
edible fi lms on the inhibition of human pathogens are shown in Table 12.1.

Table 12.1. Effects of edible antimicrobial fi lms on the inhibition of human pathogens

MIC a Base Material

for Films

Target Pathogens
Antimicrobial

Antimicrobial
Agent

References

Whey protein
isolate (WPI)

E. coli O157 : H7 Oregano oil 2 %w/v Seydim and

Sarikus 2006

Staph. aureus Garlic oil 3

S. enteritidis Rosemary oil > 4

L. monocytogenes

Alginate - apple
puree

E. coli O157 : H7 Oregano oil 0.1 %w/v Rojas - Gra ü and

others 2007a

Carvacrol 0.1

Lemongrass oil 0.5

Citral 0.5

Cinnamon oil 0.5

Cinnamaldehyde 0.5

Pectin - apple
puree

E. coli O157 : H7 Oregano oil 0.08 %w/v Rojas - Gra ü and

others 2006

Lemongrass oil 0.5

Cinnamon oil 0.5

Alginate E. coli Garlic oil > 0.4 %v/v Pranoto and

others 2005

S . typhimurium Garlic oil > 0.4

Staph. aureus Garlic oil 0.2

B. cereus Garlic oil 0.1

Yam starch b S. enteritidis Chitosan 3 Durango and

others 2006

Alginate - apple E. coli O157 : H7 Citral oil 0.5 %w/w Rojas - Gra ü and

others (2007b)

Lemongrass oil 0.5

Chitosan L. monocytogenes Chitosan > 1 %w/v Coma and others

2001

Chitosan E. coli O157 : H7 L.

monocytogenes

Zivanovic and
others 2005

Anise oil 4 %w/w

Basil oil 4

Coriander oil 4

Oregano oil 1

a Concentration in fi lm solution.
b Method for testing inhibition was growth curve; all other tests were by zone of inhibition assay.