116 Chapter 5
Packaging
Packaging has a large direct effect on storage
life, especially in fatty meats and meat prod-
ucts, and in extreme cases, indirectly due to
substantially increasing the freezing time. A
number of examples have occurred where
large pallet loads of warm boxed meat have
been frozen in storage rooms. In these cases,
freezing times can be so great that bacterial
and enzymic activity results in a reduction of
storage life.
In most cases, it is the material and type
of packaging that infl uence frozen storage
life. Without wrapping, freezer burn may
occur, causing extreme toughening and the
development of lipid oxidation as the surface
dries, allowing oxygen to reach subcutaneous
fat in the affected area. Wrapping in a tightly
fi tting pack having a low water and oxygen
permeability (such as a vacuum pack) can
more than double the storage life of a product.
Waterproof packing also helps to prevent
freezer burn, and tight packing helps to
prevent an ice buildup in the pack. When a
product is breaded, packaging appears to
have little effect, and in a trial where breaded
pork chops and breaded ground pork werethaw cycles during a product ’ s life cause
only small quality damage (Wirth 1979 ) or
possibly no damage at all. In fact, a slight but
signifi cant improvement in samples that had
been frozen and unfrozen several times was
found by one taste panel (Jul 1982 ).
Minor temperature fl uctuations in a stored
product are generally considered unimpor-
tant, especially if they are below − 18 ° C and
are only of the magnitude of 1 to 2 ° C. Well -
packed products and those that are tightly
packed in palletized cartons are also less
likely to show quality loss. However, poorly
packed samples are severely affected by the
temperature swings. There is disagreement
on how much effect larger temperature fl uc-
tuations have on a product. Some authors
consider temperature fl uctuations to have the
same effect on the quality of the product as
storage at an average constant temperature
(Dawson 1971 ); others consider that fl uctua-
tions may have an additive effect (Van Arsdel
1969 ; Bech - Jacobsen and B ø gh - S ø rensen
1984 ). There is evidence that exposure to
temperatures warmer than − 18 ° C rather than
temperature fl uctuations may be the major
factor infl uencing quality deterioration
(Gortner et al. 1948 ).
12001000800600400Storage life of lamb (days) 2000
–40 –30 –20
Temperature (°C)–10 0Figure 5.4. Experimental data on the frozen storage life of lamb at different temperatures.