Intramuscular Myths: Fat has Little Influence on Eating Quality

Studies by PJ Rincker, J Killefer, M Ellis, MS Brewer and FK McKeith of the Department of Animal Science and Department of Food Science and Human Nutrition, University of Illinois, scotch claims that intramuscular fat content governs the taste, tenderness and juiciness of prime pork. Genetics and handling at slaughter probably have a greater influence, writes Jane Jordan, ThePigSite Editor.
calendar icon 29 February 2008
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The investigations looked at 290 Fresh pork loins, that were selected from a commercial packing facility. Selection was based on subjective marbling of the intact loin and 24-hour pH value to determine the influence of marbling on sensory attributes.

The study was designed using pigs from a similar genetic background, raised in similar production facilities, and slaughtered on a single kill day to minimize the effects of genetics, management, environment, and slaughter day.

Loins were vacuum-packaged, transported to the University of Illinois Meat Science Laboratory, and aged for seven days, after which a chop was removed from the area of the tenth rib for proximate analysis.

"Intramuscular fat content had limited effects on perceived tenderness, juiciness, pork flavor, and oiliness; although some significant differences were detectable..."

Pork quality study, University of Illinois

Quality measurements, including National Pork Producers Council colour, marbling, and firmness, ultimate pH, Minolta colour/quality values, and drip loss, were determined after aging.

After the proximate composition was completed, 150 loins were selected to provide a continuous and uniform distribution of extractable lipid, ranging from one to eight per cent, and a pH range from 5.5 to 5.8. Trained sensory panel analyses (end point cooking temperatures of 62, 71, or 80°C) as well as measurement of Warner-Bratzler shear force (cooked to 71°C) were performed on chops from the 150 loins.

Consumer evaluation was also conducted on a sub group of 40 these loins. They were broken down into five discrete levels of intramuscular lipid, with averages of 1.6, 2.5, 3.6, 4.5, and 5.7 per cent extractable lipid. Consumers were also asked to select the chops they would most prefer from a retail display case based on the amount of marbling present.


Results from the consumer portion of the study indicated that intramuscular fat content had limited effects on perceived tenderness, juiciness, pork flavor, and oiliness; some significant differences (P < 0.05) were detectable, but they were numerically small. Most consumers also selected lean chops from the retail case, with nearly 50 per cent selecting chops with less than 1.7 per cent extractable lipid.

Warner-Bratzler shear force was negatively related (P < 0.0001) to extractable lipid, with an R2 value of 0.10. Results from the trained panel sensory analysis indicate that the percentage of extractable lipid did not correlate strongly with perceived tenderness, juiciness, or pork flavor for this group of pork loins that was controlled for genetics, pH, management, and day of slaughter. Reference: J. Anim Sci. 2008. 86:730-737. doi:10.2527/jas.2007-0490

To access the full article visit: The Journal of Animal Science

February 2008
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