Ontario Pork Carcass Appraisal Project Symposium
Background
Although the period immediately prior to
slaughter and the following 24 hours post-mortem are viewed as
the most critical period in the life of pigs in determining the
eating quality of pork other factors have also been implicated.
Significant breed differences in sensory characteristics of pork,
for instance, have been consistently reported, particularly when
the Duroc and Hampshire breeds are included in the comparison.
On the other hand, studies in the UK and Europe have found few
differences between sexes in the eating quality of pork.
Increased consumer demand for quality products
and competition from other food commodities are forcing the Canadian
pork industry to pay stricter attention to the eating quality
of pork. Although the producer, packer, retailer and consumer
can all affect the eating quality of pork through handling, storage
and cooking, it is important for the Canadian pork industry to
start with a raw product of top quality.
Methods
The taste panel analyses of the longissimus
dorsi muscle (loin) were conducted in two different laboratories:
University of Guelph (225 animals), and Agriculture and Agri-Food
Canada Lacombe Research Centre (626 animals). Because of the
differences in methodology and definition of sensory characteristics,
the two data sets were analyzed separately and are presented separately.
Details of analyses are given in Appendix 3.
Results and Discussion
Results are presented in Tables for both
locations (Lacombe and Guelph) but discussion is limited to the
Lacombe results, given their substantially greater scope and accuracy.
Effect of Breed
With the exception of small differences
in cooking loss, there were no significant differences between
Yorkshires and Landrace in any physical or sensory attributes
(Tables 1 and 2). For all intents, the eating quality of pork
from these two breeds was indistinguishable.
Hampshires scored highest, followed by
Durocs and then Landrace and Yorkshire, on taste panel assessments
of tenderness, connective tissue (a high score indicates low amounts
of connective tissue), juiciness, flavour intensity and overall
palatability. Only for flavour desirability did Durocs score
as high as Hampshires, though both breeds still scored higher
than Landrace and Yorkshires. The only physical attribute of
the meat that followed the same pattern of breed differences as
the sensory assessments was shear force. Durocs had the lowest
cooking loss, while Hampshires had the highest. Durocs had the
highest marbling, but there were no distinguishable differences
among Hampshires, Landrace and Yorkshires. Differences in colour,
structure and retail appearance were fairly small, but Durocs
scored highest and Hampshires lowest for all three. Overall,
the breed differences in physical properties of the meat for cooking
matched those observed for the carcass loin measurements (see
article by Ball et al. in these proceedings). In particular,
breed differences in loin drip loss were relatively accurate predictions
of breed differences in cooking loss.
Effect of Sex
Overall, differences among sexes in physical
and sensory attributes of the meat were fairly small (Tables 3
and 4). Boars scored a little higher than barrows and gilts for
initial and overall tenderness. Interestingly, the sex differences
in tenderness did not match the differences in shear force, where
gilts had a significantly higher value than both barrows and boars.
Barrows also had slightly higher marbling and slightly lower
colour scores than gilts and boars. Again, given how small the
differences observed were, there was remarkable consistency of
sex differences in the physical attributes of the meat samples
prior to cooking with corresponding measures taken on the carcass.
Effect of PSS Genotype
Meat from carriers of the PSS gene was inferior
to that from normal pigs for every aspect of physical and sensory
quality assessed at Lacombe, though differences were statistically
significant for only seven of the 13 attributes. The only puzzling
result was the barely significant higher flavour intensity of
meat from carriers in the Guelph, but not the Lacombe assessments.
This might be a chance event given the large sampling errors
involved. Again, the genotype differences for physical attributes
of meat prior to cooking matched those found for corresponding
measurements on the carcass.
Implications
Hampshires were better than Durocs which
were better than Landrace and Yorkshires for virtually all aspects
of meat quality. The differences were more than large enough
to affect decisions on breed usage where meat quality is an important
consideration.
Differences among the sexes in the eating
attributes of pork were minimal and were probably insufficient
to be of practical significance. The PSS gene appeared to have
a small negative impact on eating quality in heterozygotes, consistent
with producing paler and softer loins and hams with higher drip
loss (see article on PSS genotype by Gibson et al. in these proceedings).
These negative effects add weight to the argument that the PSS
gene should be eliminated in most breeding and production systems.
Table 1.
Least square means and standard errors for physical and sensory
attributes of loins from four breeds (Lacombe Research Centre
data).
| No. of animals | ||||||||
| Cooking loss (%) | ||||||||
| Shear force (N) | ||||||||
| Marbling score | ||||||||
| Colour score | ||||||||
| Structure score | ||||||||
| Retail appearance | ||||||||
| Initial tenderness | ||||||||
| Overall tenderness | ||||||||
| Perceptible
connective tissue | ||||||||
| Juiciness | ||||||||
| Flavour intensity | ||||||||
| Flavour desirability | ||||||||
| Overall palatability | ||||||||
Table 2.
Least square means and standard errors for the sensory attributes
of loins from four breeds (University of Guelph data).
| No. of animals | ||||||||
| Tenderness | ||||||||
| Juiciness | ||||||||
| Flavour intensity | ||||||||
Table 3.
Least square means and standard errors for physical and sensory
attributes of loins from barrows, gilts and boars (Lacombe Research
Centre data).
| No. of animals | ||||||
| Cooking loss (%) | ||||||
| Shear force (N) | ||||||
| Marbling score | ||||||
| Colour score | ||||||
| Structure score | ||||||
| Retail appearance | ||||||
| Initial tenderness | ||||||
| Overall tenderness | ||||||
| Perceptible connective tissue | ||||||
| Juiciness | ||||||
| Flavour intensity | ||||||
| Flavour desirability | ||||||
| Overall palatability | ||||||
Table 4.
Least square means and standard errors for the sensory attributes
of loins from barrows, gilts and boars (University of Guelph data).
| No. of animals | ||||||
| Tenderness | ||||||
| Juiciness | ||||||
| Flavour intensity | ||||||
Table 5.
Least squares means and s.e. for the effect of PSS genotype on
physical and sensory attributes of loins (Lacombe data).
| Cooking loss (%) | ||||
| Shear force (N) | ||||
| Marbling score | ||||
| Colour score | ||||
| Structure score | ||||
| Retail appearance | ||||
| Initial tenderness | ||||
| Overall tenderness | ||||
| Perceptible connective tissue | ||||
| Juiciness | ||||
| Flavour intensity | ||||
| Flavour desirability | ||||
| Overall palatability | ||||
Table 6.
Least squares means and s.e. for the effect of PSS genotype on
sensory attributes of loins (Guelph data).
| Tenderness | ||||
| Juiciness | ||||
| Flavour intensity | ||||