Principles of Cheese Technology 261over a wide pH range of 2.0 to 8.5. Many
molds can grow well at normal refrigeration
temperatures, although the optimum tempera-
ture for growth is generally from 25 ° C to
30 ° C (77 ° F to 86 ° F). Cheese packaged in
plastic fi lm does not develop a rind around the
periphery, so ample surface moisture and
nutrients are available to support mold growth,
provided suffi cient oxygen is available.
Several popular cheeses are ripened by
molds and require oxygen for proper devel-
opment. Internal mold - ripened varieties
(for example, blue, Gorgonzola, Stilton,
Roquefort) lose their blue marbling effect
after storage in vacuum packages. Nonethe-
less, many Roquefort - type cheeses are tight -
wrapped in aluminum foil or plastic laminates.
Hard, thermoformed trays with aluminum
foil lids have been used to package crumbled
blue cheese varieties.
Internal mold - ripened cheeses (Brie,
Camembert) can develop off - fl avors if
allowed to ripen anaerobically. Different
fi lms and foils have been used for packaging
these varieties. For example, aluminum foil
laminates with certain perforations are used
to allow a controlled amount of oxygen gain
and yet prevent dehydration. Plastic - lined
metal cans also have been used, with cheeses
being autoclaved at 2 to 3 psi for several
minutes to gain better shelf stability. However,
fl avor changes may be noticed, depending on
the type of metal can used.
For most cheese varieties, undesirable
mold growth is the major cause of product
deterioration. Vacuum packaging, gas fl ush-
ing, and tight shrink - wrapping techniques
are designed to exclude oxygen in the fi lm
package and thus prevent mold develop-
ment. An oxygen balance sheet involves the
balance between oxygen - gain and oxygen -
loss factors. Oxygen gain factors are:- Enclosed oxygen under the fi lm in
wrapping - Leakage through defective seals, in over-
laps, or at end folds
cation of a calico or cheesecloth bandage,
followed by treatment of the cheese with
greased muslin. The structure was either
sewn or glued on with fl our paste. Dressing
the cheese involved the application of wax,
oil, or fat. Cheese treated in this manner
developed a protective rind as a result of
surface dehydration.
Practically all of the cheese for ripening
now is packaged in fi lms and foils. Tight -
wrapping with certain fi lms has been used
for large ripening blocks. Shrink fi lms also
can be used. In the case of Swiss type cheese
in which gas formation during ripening is
considerable, fi lms that absorb CO 2 or have
lower barrier properties can be used. Expand-
able materials also can be employed, but
space must be provided to allow for package
expansion. Blue cheeses also can be ripened
in shrink fi lm bags. However, the cheese
wheels must be perforated after packaging to
allow access to oxygen, which is necessary
for the blue mold development.
Impact of Packaging on the Shelf Life
of Cheese
The shelf life of packaged cheese in retail
channels depends on several factors. Cheese
deterioration at this stage may be related to
milk quality, plant sanitation, manufacturing,
and packaging procedures including han-
dling and storage conditions. Natural cheeses
generally do not contain added preservatives
nor are they heat treated to control mold
development.
In the case of process cheese, imitation
cheese, and cheese analogs, extended shelf
life is obtained from pasteurizing heat treat-
ments and application of permissible antimy-
cotic agents. In both natural and process
cheese, a suitable package must minimize
oxidative deterioration of cheese color and
fl avor, and protect the cheese from moisture
loss as well as from mold growth.
Contrary to the nature of bacteria, most
molds thrive in acidic conditions and grow