Biomedical Engineering Reference
In-Depth Information
The product had a longer storage life at refrigeration than at ambient temperature and
in paper-foil-polyethylene pouch than in polypropylene pouches.
A reduction in the nitrite content in hot dogs using hurdle technology without
sacrifi cing product safety and quality was reported (Jafari and Emam-Djomeh
2007
). The water activity and pH of the hot dog were adjusted to 0.95 and 5.4 and
the sausages were kept at chilled temperature (>3 °C but
10 °C) throughout their
shelf life. There was a decrease in total aerobic counts in hurdle treated hot dogs
(with 50 ppm nitrite), compared to the control (with 120 ppm nitrite), whereas
C. perfringens
counts and
C. botulinum
detection were the same in both hurdle
treated and control samples. Sensory characteristics of control and treated product
remained similar.
Shelf stable pork sausages were developed using hurdle technology and their
quality was evaluated during ambient temperature (37 ± 1 °C) storage (Thomas et al.
2008a
). Various hurdles incorporated were low pH, low water activity, vacuum
packaging and post package reheating. Dipping in potassium sorbate solution prior
to vacuum packaging was also studied. Hurdle treatment reduced oxidative and
microbiological quality deterioration during storage as indicated by pH, TBARS,
tyrosine values and microbial counts. The pH, a
w
and reheating hurdles inhibited
yeast and mould growth up to day 3, while additional dipping in 1 % potassium
sorbate solution inhibited their growth throughout the 9 days storage. Despite low
initial sensory appeal, the hurdle treated sausages had an overall acceptability in the
range 'very good' to 'good' up to day 6. The suitability of hot-boned pork and pork
fat for processing shelf-stable pork sausages using hurdle technology was also eval-
uated by the same workers (Thomas et al.
2008b
). Hot-processed sausage received
higher total plate counts while lactobacillus counts were high in cold-processed
product throughout the storage period. Sensory evaluation revealed that hurdle-
treated pork sausages from hot-boned pork were equally suitable as those from
cold-boned pork up to day 6 at ambient temperature.
The effectiveness of various hurdles such as irradiation, reduced water activity,
and vacuum packing in preventing the growth of
C. sporogenes
,
S. aureus
and
B. cereus
in ready-to-use shelf stable meat products was tested (Chawla and Chander
2004
). Radiation treatment (2.5 kGy) resulted in complete elimination of inoculated
10
6
cfu of
S. aureus
and
B. cereus
but not of
C. sporogenes
. The water activity of
0.85 and vacuum packaging of products prevented the growth of all three organisms
inoculated into these samples during 3 months of storage at room temperature.
Irradiation also successfully inactivated yeast and moulds which otherwise grow in
the kababs after 2 months of storage. Kanatt et al. (
2006b
) developed a process for
the preparation of shelfstable, ready-to-eat shrimps using a combination of reduced
water activity (0.85 ± 0.02), packaging and
≤
-irradiation (2.5 kGy). Microbiological
analysis of the product revealed a dose dependent reduction in total viable count and
Staphylococcus
species. In non-irradiated samples a visible mould growth was seen
within 15 days of storage at ambient temperature (25 ± 3 °C). No signifi cant changes
in textural properties and sensory qualities of the product were observed on radia-
tion treatment and they were microbiologically safe and sensorially acceptable even
after 2 months of storage at ambient temperature.
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