334 Chapter 18
quite different from those used today and at
a time when less was known about boar taint.
A French study on bacon lardons (bacon
cubes) prepared from gilts and boars at three
different combinations of skatole (S) and
androstenone (A) (low S/low A, low S/high
A and high S/high A) and assessed by 96
consumers demonstrated that the combina-
tion of high skatole and high androstenone
was signifi cantly worse for several odor
descriptors (Beague et al. 1997 ). This is to be
expected, since androstenone and skatole are
both volatile, particularly at the high tem-
peratures attained during frying (a common
method of cooking). Off - fl avors during con-
sumption may be less marked due to the
partial volatilization of the taint compounds
during cooking (Bonneau et al. 1992 ) and
any abnormal fl avors partially masked by the
curing ingredients, especially salt.
Immuno - castration appears to be an effec-
tive way to reduce the incidence of boar taint
in fresh pork (Prunier et al. 2006 ; Pearce
et al. 2008 ), and its adoption could have a
marked effect in reducing the volume of
tainted bacon. This reduces both taint com-
pounds because high levels of androstenone
act naturally to increase skatole in the liver.
The use of different fi ber sources in the diet
before slaughter (e.g., chicory) is effective in
reducing skatole.PSE and DFD
The incidence of the PSE condition in the UK
pork industry has risen from 6% in the 1970s,
to 13% in the 1980s, and 15% in the 1990s
(Table 18.2 ). This is probably due to changes
in abattoir operation (fewer plants with
higher throughputs and greater pre - slaughter
stress) and breeding programs that have
resulted in pork with a higher incidence of
white fi bers and a greater tendency to PSE.
The adverse effects of using PSE meat in
cured meats are well documented (Kauffman
et al. 1978 ; Honkavaara 1988 ; Clarke 1998 ;
Fisher et al. 2000 ; O ’ Neill et al. 2003 ). Usingmarks caused by the needles of a mechanical
injector during the curing process. Micro-
scopic investigations revealed that the dark
bands showed ordered myofi brillar structure
(i.e., myofi brils with overlapping thick and
thin fi laments and well - defi ned Z lines),
while the light bands exhibited a disordered
structure in which the usual structural fea-
tures were obscured by amorphous material
which the authors attributed to denatured sar-
coplasmic protein or denatured myofi brillar
material. The phenomenon was attributed to
localized variations in brine concentration
around the injection sites. At the time, some
affected batches of bacon were returned to
the manufacturer, but the condition now
appears to be accepted as a normal feature of
modern bacon production. A similar phe-
nomenon can also occur in moisture - enhanced
pork (Gooding et al. 2009 ), suggesting a
common mechanism in both types of product.
Boar Taint
The compounds responsible for boar taint,
androstenone and skatole, were identifi ed
many years ago, but boar taint remains a
persistent problem for the pork industry.
However, quantifying the occurrence of off -
odors or off - fl avors in cooked bacon is
diffi cult, partly because individuals are
highly variable in their sensitivity, particu-
larly in their response to the pheromone,
androstenone (Annor - Frempong et al. 1997 ).
Castration of entire male pigs is a common
method of preventing boar taint, but, even
here, taint could arise due to high levels of
skatole. The latter is produced by fermenta-
tion of the amino acid tryptophan in the hind
gut.
Most of the studies investigating boar
taint in bacon were carried out more than 25
years ago (Rhodes 1971 ; Lesser et al. 1977 ;
Mottram et al. 1982 ; Smith et al. 1983 ;
Lundstrom et al. 1983 , cited by Malmfors
and Lundstrom 1983 ), when slaughter
weights were lower and pig genetics were