254 Chapter 13
The consumer has been shown to reject those
myoglobin forms that are not acceptable
meat colors from their perspective (Parry
1993 ; Allen et al. 1996 ). Consumers have
demonstrated a bias against the purchase of
vacuum packaged beef, which displays the
purple color of deoxymyoglobin (Meischen
et al. 1987 ). Also, prolonged storage of meat
in vacuum packs results in the accumulation
of drip, which is also unappealing to consum-
ers (Jeremiah et al. 1992 ; Parry 1993 ; Payne
et al. 1997 ).
VP continues to be used in numerous
ways for effi cient meatpacking and is still the
most cost - effective packaging strategy
employed for the packing of meat. A recent
innovation in VP has been the evolution
of shrinkable fi lms in use with horizontal
form - fi ll - seal machinery (Salvage and Lipsky
2004 ).Vacuum Skin Packaging of Meat
Drip formation in vacuum packed meat, as
discussed above, can partly be overcome by
vacuum skin packaging (VSP), using a fi lm
that fi ts very tightly to the meat surface,
leaving little space for the accumulation of(Gill and Gill 2005 ). The objective is that any
residual O 2 in the remaining atmosphere,
including O 2 dissolved in the product, will be
removed by enzymatic reactions within the
muscle tissue, or through other chemical
reactions with tissue components (Gill and
Gill 2005 ). Respiration of the meat in vacuum
packs will also quickly consume the vast
majority of residual O 2 , replacing it with
CO 2 , which eventually increases to 10 – 20%
within the package (Taylor 1985 ; Parry 1993 ;
Gill 1996 ). However, the amount of O 2
remaining in the pack at the time of closure
must be very small if the product is to be
effectively preserved, as the capacity of the
muscle tissue for removing O 2 is limited (Gill
and Gill 2005 ). The oxygen level is generally
reduced to less than 1% under good vacuum
conditions. Due to the barrier properties of
the fi lm used, entry of oxygen from the
outside is restricted (Parry 1993 ; Robertson
2006 ).
Vacuum - packaged meat is unsuitable for
the retail market because depletion of O 2 ,
coupled with low O 2 permeability of the
packaging fi lm, causes a change in meat
color from red to purple, due to the conver-
sion of oxymyoglobin to deoxymyoglobin.
Figure 13.4. Vacuum - packed meat products, chorizo and salami.