Biomedical Engineering Reference
In-Depth Information
Table 2.1
Control of spores: product treated to control vegetative cells and protected from
recontamination
Critical pH Values
pH ≤ 4.6
Critical
a
w
Values
4.6 < pH < 5.6
pH 5.6
a
w
≤ 0.92
Non-TCS
Non-TCS
?
0.92 <
a
w
< 0.95
Non-TCS
Non-TCS
?
a
w
> 0.95
Non-TCS
?
?
Note: ? means stability is question, thus number of measures need to be taken
Table 2.2
Control of vegetative cells and spores: product not treated or treated but not protected
from recontamination
Critical pH Value
s
pH < 4.2
Critical
a
w
Values
4.2 < pH < 4.6
4.6 < pH < 5.0
pH > 5.0
a
w
< 0.88
Non-TCS
Non-TCS
Non-TCS
Non-TCS
0.88 <
a
w
< 0.90
Non-TCS
Non-TCS
Non-TCS
?
0.90 <
a
w
< 0.92
Non-TCS
Non-TCS
?
?
a
w
> 0.92
Non-TCS
?
?
?
Note: ? means stability is question, thus number of measures need to be taken
must be kept cold or hot, because the food (i.e. temperature controlled for safety,
TCS) has the necessary intrinsic factors to support the growth of pathogens. The
TCS foods require time/temperature control to limit pathogen growth or toxin for-
mation that constitutes a threat to public health. A science-based framework was
proposed by the IFT/FDA panel (IFT/FDA Report
2003
). The framework contains
two steps:
• Step 1: Was the food treated to destroy vegetative cells of potentially pathogens
and packaged to avoid recontamination? If yes, position your product in Table
2.1
according to its pH and water activity (
a
w
). If not, position your product in
Table
2.2
according to its pH and
a
w
.
• Step 2: If the food is classified as a non-TCS food according to Step 1 above, it
may be stored and held safely without regard to time or temperature. If the need
for time/temperature control is questionable, the food should be held either hot
or cold for safety or subjected to a product assessment as the next step in deter-
mining the appropriate classification.
The product assessment was performed based on the factors, such as ingredients,
processing, change of acids used to lower pH, preservatives, and formulation. The
final decision on the hurdles could be based on challenge testing and available pre-
dictive models. The panel used their proposed framework to determine its
applicability to a specific example(s) from selected class of food product catego-
ries. Additional examples of the determination of TCS are provided in the report
developed by Texas Department of State Health Services (TCS Guidance
2006
).
They also identified the pathogens of concern for different classes of food products
and potential hurdles alone or combination to be used. Scientific sound criteria for
