3. Results
3.1. Total viable count (TVC)
The average TVC, considering as a whole all samples analyzed,
was equal to 1.2 1.2 log CFU cm2
. The prevalent TVC was
detected on the bottom of the refrigerator (1.5 1.2 log CFU cm2
).
The value of the greatest count is always detected on the bottom of
the refrigerator (3.6 log CFU cm2
).
The inner surface of our domestic refrigerators can be likened to
a work surface in the food industry. In the European Union, specific
microbiological criteria for assessing the hygienic conditions of
work surfaces in the food industry have never been fixed.
We could, however, take a cue from the criteria set by the
Directive 2001/471/EC on the norms on general hygiene in
slaughterhouses and laboratories for cutting fresh meat (CD, 2001).
This provision was repealed by EC Regulation no. 2073/05 (EU,
2005), but the criteria that Directive 2001/471/EC called for may
be useful in assessing the cleanliness of the refrigerator in relation
to the total microbial count. The EU provision stated that an area of
work could be considered “hygienically acceptable” if it had a TVC
between 0 and 10 CFU cm2 (see Table 1). In support of this
interpretation, there are also the recommendations of the U.S.
Public Health Service reported by Favero, Gabis, and Vesley (1984),
while the Public Health Laboratory Service (PHLS) in the UK
(Herbert, Donovan, & Manger, 1990) advised fixing a more practical
target of acceptability pinpointed at 80 CFU cm2
.
Based on the criteria listed in Table 1, we can judge the surfaces
of the household refrigerators sampled as summarized in Table 2.
Separating the “unacceptable” class, which represents 50.3% of
the total samples analyzed, the values in Table 3 are shown.
It can be noted that 21% and 43% of the total samples for the wall
and the bottom respectively have counts greater than
100 CFU cm2
.
In Fig. 1 we show a graphical representation of the values of TVC
obtained in Tables 2 and 3; the graph relates the number of samples
and the grouping based on logarithmic classes.
Note that the brown bar (TVC from the bottom) prevails in
classes with greater values while it is lower with respect to the wall
in the classes with smaller values.