Handbook of Meat Processing

Technological Quality of Meat for Processing 27

while that from Duroc and Duroc/Hampshire

was lower in fat. Pork from Danish Landrace

Duroc pigs was more tender than that from

Landrace, Duroc, and various crosses with

Yorkshire pigs. Blanchard et al. (1999)

reported that meat from crossbred pigs that

were at least half Duroc were more tender

than that from Large White and British

Landrace crosses. Brewer et al. (2002) also

reported that pork from Duroc - sired pigs is

more tender than that from Duroc/Landrace -

and Pietrain - sired pigs.

Wood et al. (2004) reported that breed

affected the fatty acid composition of intra-

muscular neutral lipid. Pork from Berkshire

and Tamworth pigs (fatter carcasses) had

more 14:0 and 16:0, while that from Duroc

and Large White (leaner) contained more

polyunsaturated fatty acids. Meat from Duroc

pigs had high concentrations of 20:5n - 3 and

22:6n - 3.

Genetic markers for tenderness have been

identifi ed for Duroc - Landrace pigs (Rohrer et

al. 2006 ). Chromosome 2 region 60 – 66 cM

appears to be associated with all measures of

pork tenderness and the region on chromo-

some 17 (32 – 39 cM) was associated with

measures of intramuscular fat and loineye

area.

Diet Effects on Meat Quality

Diet can contribute to meat quality directly

(compounds from the feed source deposit in

the meat) or indirectly (primarily by increas-

ing fatness). Feeding fi sh byproducts, raw

soybeans, canola oil, and meal can result in

undesirable fl avors in meat (Melton 1990 ).

Pork fat is more likely to be affected by alter-

ation of dietary fat source than is beef fat

because pigs have little capacity to biohydro-

genate unsaturated fats, depositing them in

tissues in much the same form as they were

consumed. Feeding pigs high levels of PUFA

decreases saturation of carcass fat and has

detrimental effects on pork quality (Whitney

et al. 2006 ). Unsaturated fatty acids result in

in fat, 10% lower in cholesterol and 17%
lower in calories (USDA 2007 ). However,
genetic selection for leanness has not been
without unintended consequences. Pigs
homozygous for the Halothane gene (nn)
have higher gain: feed ratios, and their car-
casses are leaner than those from Halothane
negative (NN) and heterozygotic (Nn) pigs
(Leach et al. 1996 ). While pigs carrying one
or two copies of the Halothane gene have
higher lean content, they are likely to produce
pale, soft, and exudative (PSE) meat that has
excessive drip loss because of rapid pH
decline while the carcass is still hot (Sather
et al. 1990 ). Fernandez et al. (2004) reported
that NN and Nn pigs exhibited postmortem
changes at the same rate, as evidenced by
similar glycogen, lactate, creatine phosphate
and ATP levels, and pH values at 40 minutes
postmortem. Raw meat (longissimus lumbo-
rum) from nn pigs had lower visual color
intensity and homogeneity scores than meat
from NN and Nn pigs. Meat from nn pigs was
less tender than that from NN pigs; the Nn
pigs were intermediate.
Meat from pigs (Swedish Hampshire x
Finnish Landrace) that are homozygous
and heterozygous for the rendement napole
(RN - ; acid meat) allele has been shown to be
juicier than that from noncarriers. The RN -
allele also contributes to tenderness (Josell et
al. 2003 ). Emnett (1999) reported that
Berkshire and Chester White pigs had lower
glycolytic potential (thought to be an indica-
tor of the RN - allele) than Hampshire or
Hampshire crossbred pigs. High glycolytic
potential values were associated with lower
pH, poorer WHC, higher cooking loss, and
paler color.
Meat derived from pigs of these very dif-
ferent genetic backgrounds does differ in
quality characteristics (Brewer et al. 2002 ).
Ellis et al. (1996) reported that Duroc pigs
produce meat that is highly marbled and has
good eating quality. Brewer et al. (2004)
reported that meat from Duroc/Landrace - and
Large White - sired pigs was higher in fat,