Novel Technologies for Microbial Spoilage Prevention 265have no visual, aroma, or taste indicators that
the product is toxic. We believe further
research is needed to address this concern.
The use of time - temperature indicators, such
as 3M ™ brand MonitorMark ™ Time
Temperature Indicators, may be useful for
consumers to predict whether a product has
been exposed to temperature abuse during
transport, storage, or retail display (Shimoni
et al. 2001 ).Ionizing Irradiation
Irradiation is a safe and effective method to
improve food safety and quality. Ionizing
irradiation employs gamma rays (cobalt - 60
and cesium - 137 as radioactive sources),
x - rays (machine - generated), and e beam
(high - energy electrons, machine - generated)
as treatments to successfully kill microbes in
foods. Irradiation damages microbial DNA,
resulting in cell death. According to Aymerich
et al. (2008) , viruses are most resistant to
irradiation, followed by bacterial spores,
yeasts, molds, Gram - positive bacteria, and
Gram - negative bacteria. This technology has
excellent penetration power. For example,
x - rays and gamma rays can penetrate 80 to
100 cm while e beams have less penetrating
power, ranging from 8 to 10 cm. None of
these ionizing treatments make food radioac-
tive, making questionable negative consumer
fears about the technology. Irradiated foods
should bear the internationally recognized
radura symbol (Fig. 14.1 ) together with a
“ treated with irradiation ” statement on the
label to inform consumers.
Two levels of irradiation processes are
recognized based on absorbed dose: raduriza-
tion (1 to 10 kGy) and radapperdization
(20 kGy and up) (Murano 2003 ). Reviews of
irradiation treatment of meats and meat prod-
ucts are available elsewhere (Thayer et al.
1986 ; Newsome 1987 ; Monk et al. 1995 ;
Farkas 1998 ). A summary of most recent
meat gamma irradiation studies is presented
in Table 14.2.Biological O 2 scavenging systems contain
viable respiring innocuous microorganisms
entrapped in alginate, gelatin, or agar
(Tramper et al. 1983 ; Doran and Bailey 1986 ;
Gosmann and Rehem 1986 ), or incorporated
into hydroxyethyl cellulose or polyvinyl
alcohol fi lms (Altieri et al. 2004 ). Several
reviews are available that provide more
detailed scavenger and emitter information
(Floros et al. 1997 ; Suppakul et al. 2003 ;
Kerry et al. 2006 ; Coma 2008 ).
Payne et al. (1998) examined the effect of
packs fl ushed with CO 2 , packs fl ushed with
CO 2 and containing Ageless ® oxygen scav-
enger, and packs containing oxygen scaven-
ger alone on microbial counts of beef stored
for up to 20 weeks at − 1.5 ° C. Although packs
with the scavenger system had the greatest
microbial counts at the end of week 16, all
three treatments were acceptable to consum-
ers, with fl ush - scavenger and scavenger
alone having lowest oxygen levels ( < 0.1%
v/v) compared with fl ush alone (0.9%). Ellis
et al. (2006) studied the quality of refriger-
ated chicken breast stored under MAP (100%
N 2 or 75 : 25 N 2 : CO 2 ), with or without
slow - and fast - release sachets containing
antimicrobial chlorine dioxide (ClO 2 ).
Samples containing ClO 2 sachets had 1.0 to
1.5 log 10 CFU/g lower total plate count on day
6 and day 9 of storage compared to MAP
controls alone. Tewari et al. (2001) showed
that commercial oxygen scavenger (Ageless ®
or FreshPax ® ) combined with N 2 CAP slowed
discoloration and metmyoglobin formation
of beef stored at 1 ° C compared to N 2 CAP
alone.
A potential major drawback of complete
oxygen removal from packaging by oxygen
scavengers or other means is the possibility
of nonproteolytic Clostridium botulinum
growth and neurotoxin production during
temperature abuse storage conditions (Coma
2008 ). The threat of nonproteolytic strains is
that outgrowth and toxin production by the
bacterium may occur despite the absence of
sensory defects. Thus, a consumer could