Handbook of Meat Processing

Novel Technologies for Microbial Spoilage Prevention 277

summary of investigated antimicrobial active

packaging is presented in Table 14.8.

Other NonThermal Technologies

We are aware of a few other novel food

processing technologies, but meat industry

applications might be technically or econ-

omically challenging. Some equipment -

intensive applications may have future

potential if the cost of production becomes

economically viable. For example, pulsed

electric fi elds use bursts of high - intensity

electric pulses to inactivate microorganisms.

The main problem with this method for meat

applications is the requirement for the food

to be liquid (Marth 1998 ). Pulsed high - inten-

sity light treatment consists of xenon fl ash-

lamps capable of producing brief ( < 2 ms)

fl ashes of wide - spectrum (200 to 1,100 nm)

light to kill bacteria. Pulsed high - intensity

light has been approved for treatment of

foods and food contact surfaces (FDA 1996 ).

Its potential for meat industry applications is

yet to be determined. Marth (1998) men-

tioned low penetration power and the possi-

bility of lipid oxidation as drawbacks of this

technology. Cold plasma technology has

reported antimicrobial effects but has not yet

been applied to meat products (Critzer et al.

2007 ; Niemira and Sites 2008 ).

Novel Thermal Technologies

High - frequency heating is considered a

thermal process where the meat product is

heated through microwave or radiofrequency

energy, which causes oscillation of water

molecules, friction, and resultant heat genera-

tion (Hugas et al. 2002 ). The permitted fre-

quency bands include 13.56, 27.12, and

40.68 MHz for radiofrequency heating and

433, 915, 2,450, and 5,800 MHz for micro-

wave usage (Aymerich et al. 2008 ). All

microwave ovens share a similar design that

includes a magnetron device as a power

source and a waveguide to bring radiation to

within 60 days of storage at 4 ° C. Similar
antimicrobial effects may be seen with lactic
acid spoilage bacteria, since the behavior of
L. monocytogenes is similar to this group;
however, confi rmation studies are needed.
Siragusa et al. (1999) incorporated nisin
in a polyethylene - based plastic fi lm and
observed its activity against inoculated B.
thermosphacta on vacuum - packaged beef
surface tissue sections. An initial reduction
of 2.0 log 10 CFU/cm^2 of B. thermosphacta
was observed within 2 days of refrigerated
storage at 4 ° C. After 20 days of storage,
samples with nisin - containing plastic showed
signifi cantly fewer bacterial numbers com-
pared with control, 5.8 vs. 7.2 log 10 CFU/cm^2 ,
respectively.
Edible antimicrobial coatings, besides
their main function, also hold meat juices,
reduce rancidity and myoglobin oxidation
(oxygen barrier), restrict volatile compound
loss, and reduce off - odor absorption during
the storage of refrigerated meats (Kerry et al.
2006 ). A calcium alginate edible fi lm
containing nisin, citric acid, EDTA, and
Tween - 80 was effective against Salmonella
Typhimurium on chicken skin, with count
reductions ranging from 2 to 3 log 10 CFU/ml
after 72 - hour exposure at 4 ° C (Natrajan and
Sheldon 2000b ). Dipping of uninoculated
chicken drumsticks in the same solution fol-
lowed by overwrap packaging in foam tray
packs containing nisin - treated fi lm/absorbent
tray pads and storage at 4 ° C caused projected
shelf life extension up to 2.2 days based on
initial psychrotrophic plate count reduction
of up to 2.3 log 10 CFU/g (Natrajan and
Sheldon 2000b ). Marcos et al. (2007) dem-
onstrated the effectiveness of enterocin - con-
taining biodegradable fi lms (alginate, zein,
and polyvinyl alcohol) to control L. monocy-
togenes on air - packed and vacuum - packed
sliced cooked ham. Millette et al. (2007)
incorporated nisin in alginate fi lm and beads
through covalent links and were able to
reduce S. aureus numbers on beef muscle
slices (fi lm) or ground beef (beads) at 4 ° C. A