Novel Technologies for Microbial Spoilage Prevention 275could be protective for antimicrobials, allow-
ing them to slowly migrate to the product
surface over extended periods of time without
deactivating them. Siragusa and Dickson
(1992) investigated the possibility of organic
acid use in bioactive edible packaging in the
form of calcium alginate gels. On lean beef
tissues inoculated with L. monocytogenes ,
they showed that lactic acid (1.7% v/v)
immobilized in alginate reduced pathogen
counts by 1.3 log 10 CFU/g compared to a
0.03 log decrease from the acid treatment
alone. Similarly, acetic acid (2% v/v) reduced
counts by 1.5 (alginate) and 0.25 log 10 CFU/g,
respectively. Cutter and Siragusa (1996,
1997) investigated the impact of nisin alone
and nisin in calcium alginate gels as a surface
treatment antimicrobial on refrigerated beef
lean and adipose tissues inoculated with the
spoiler B. thermosphacta. Untreated, algi-
nate - treated, or nisin alone did not suppress
bacterial growth ( > 6 log 10 CFU/cm^2 by day
7), while treatment with nisin - alginate did
suppress growth (2.4 log 10 CFU/cm^2 by day
7). Bacteriocin titers from both tissues
were greater in nisin - alginate vs. nisin - only
samples after day 7 of incubation. Active
packaging in the form of edible fi lms is
advantageous because it retains antimicrobial
activity and steadily delivers the antimicro-
bial to the contaminated meat surface.drawbacks coupled with worker safety issues
related to ozone inhalation hazards limit
widespread adoption of ozone technology.
Electrolyzed water is produced by passing
12% NaCl solution across a bipolar mem-
brane with an electrode on each side, result-
ing in an acidic solution called electrolyzed
oxidizing water and an alkaline solution
(Fabrizio and Cutter 2004 ). Electrolyzed
oxidizing water has a low pH (2.3 to 2.7),
high oxidation - reduction potential (ORP,
1000 mV), and free chlorine (25 to 80 ppm)
(Huang et al. 2008 ). Thus, electrolyzed oxi-
dizing water antimicrobial effect is due to the
combined action of low pH, high ORP, and
free chlorine. Fabrizio and Cutter (2005)
investigated the infl uence of electrolyzed
oxidizing water (pH 2.3 to 2.7, 1150 mV
ORP, ∼ 50 ppm free chlorine) on L. monocy-
togenes inoculated on beef frankfurters
stored for 7 days at 4 ° C. Electrolyzed oxidiz-
ing water caused only a slight reduction
( < 0.5 log 10 CFU/g) in pathogen numbers, but
was more effective than 2% acetic acid
and 10% trisodium phosphate. Similarly,
Fabrizio and Cutter (2004) showed no sig-
nifi cant infl uence of electrolyzed oxidizing
water applied to fresh pork inoculated
with L. monocytogenes and Salmonella
Typhimurium. As with most antimicrobials,
complex organic composition of meat tends
to lessen the ability to inactivate bacteria.
Novel approaches are needed to retain the
antimicrobial activity of these agents in meat
matrices.
Active Antimicrobial Packaging
Antimicrobial packaging can involve utiliza-
tion of several concepts (Table 14.6 ).
Quintavalla and Vicini (2002) noticed that
microbial contamination of intact fresh
muscle occurs mostly at the surface and anti-
microbials applied directly on the surface
could be easily inactivated by meat compo-
nents. Therefore, antimicrobial packaging
Table 14.6. Types of active antimicrobial
packaging- Addition of sachets/pads containing volatile
antimicrobial agents (contact with product
through headspace) - Incorporation of volatile/non - volatile compounds
directly into packaging - Coating or absorbing antimicrobials onto polymer
surfaces - Chemical bonds (ion or covalent linkages)
between antimicrobials and packaging material - Using polymers that are inherently antimicrobial
- Edible packaging containing antimicrobials
From Appendini and Hotchkiss (2002)