Influence of lipid content on pork sensory quality within pH classification

¹ Department of Animal Science, Iowa State University, Ames, IA, 50011
² Goodwin Family Farms, Ames, IA 50010
³ Department of Food Science and Nutrition, Iowa State University, Ames, IA 50011; Department of Animal Science, Iowa State University, Ames, IA, 50011

^* To whom correspondence should be addressed. E-mail: slonerga{at}iastate.edu.

	Abstract

The objective of this project was to determine the contribution of lipid content to textural and sensory properties of fresh pork within defined pH classifications. Pigs (n=1535; from 248 sires and 836 dams) from the 1991, 1992 and 1994 National Barrow Show^TM Sire Progeny Test were used in this study. The test included purebred Berkshire (107), Chester White (113), Duroc (249), Hampshire (220), Landrace (165), Poland China (101), Spotted (181), and Yorkshire (399) barrows (901) and gilts (634). Diets were uniform across breeds within test. The halothane (Hal 1843^TM) genotype (1346 NN and 189 Nn) was determined. Pigs were slaughtered at 105 kg body weight, and samples of the longissimus muscle were obtained from each carcass at the 10th rib. Star probe, sensory traits, and lipid content were determined on the longissimus muscle from each pig. A pH classification was assigned as follows: Class A, >5.95, n= 186; Class B, 5.80-5.95, n= 236; class C, 5.65-5.80, n= 467; class D, 5.50-5.65, n= 441; class E, <5.50, n=205. Data were analyzed using a mixed linear model including pH classification, test, gender, halothane genotype, breed, and breed-by-gender interaction as fixed effects, with sire and dam within breed included as random effects. Correlations were determined within pH class. Lipid content was a significant source of variation for models predicting star probe values in class C and D and for chewiness in class B, C and D. Increasing lipid content tended to increase sensory tenderness in pH class D. Sensory tenderness was not affected by lipid content in pH class A, B or E. Lipid content was not a significant source of variation for juiciness scores within any pH class. Intramuscular lipid is correlated with sensory texture traits primarily in classes C and D. Within class C and D, correlations indicate that increasing lipid content is associated with high sensory tenderness, low sensory chewiness, and low star probe values. It is concluded that lipid content is a small source of variation in texture and tenderness of pork loin with pH between 5.80 and 5.50, but not at high or low pH.

Key Words: Lipid, pH, Pork quality, Fatty acid, Sensory, Tenderness

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