Natural convection is phenomenon frequently encountered
during the shelf life of a foodstuff, for example,
during transport in a container, storage in a
domestic refrigerator and in an unventilated cold room.
This is also the case when food pallets are placed on a
dock during loading and unloading operations, during
which heat exchange takes place between the product
and ambient air. If the cold chain is improved due to
good design, efficient logistics, rigorous supervision and
adequate staff training, the last step in the cold chain,
the ‘‘domestic refrigerator’’, is still a source of concern.
Consumers sometimes store sensitive foods in refrigerators
running at temperatures that are too high for long
periods. A consumer survey in France showed that 26%
of refrigerators run at an average temperature above 8
C (Laguerre, Derens, & Palagos, 2002), whereas the
temperature specified in standards is 4 C.
All temperature abuse accelerates microbial growth
in foods to some extent: a 5 C rise for about 10 min can