Pork Quality Prepared By: Dr. Elisabeth Huff Lonergan Iowa State University

What is Pork Quality? Summation of those attributes that make pork desirable as a human food.

Pork Quality Processing Characteristics Sensory Characteristics Safety Nutritional Value Animal Welfare Sustainability

Processing Characteristics Water-Binding Capacity Uniformity Structure Texture

Sensory Characteristics Appearance Color Tenderness Aroma Juiciness Flavor

Pork Quality Attributes Color Marbling Drip Loss

Marbling Evaluated on the cut surface of the loin eye Subjective score of the amount of visible fat in the loin eye Can affect flavor and juiciness

Marbling scores correspond to intramuscular lipid content Marbling Standards

Ideal Pork Color Measured or evaluated on the cut surface of the loin eye or ham ideal –Reddish-pink –Range Pale-pinkish gray Dark red

Objective Color Measurement

1.0 Pale pinkish gray to white 61* 2.0 Grayish pink 55* 3.0 Reddish pink 49* 4.0 Dark reddish pink 43* 5.0 Purplish red 37* 6.0 Dark purplish red 31* Color Standards Minolta L* values use D65 daylight light source & measured on day one.

Firmness Evaluated on the cut surface of the loin eye Firm chops retain shape Soft chops deform easily and sag Better eating quality and processing characteristics are associated with firmer chops

Drip Loss (Water Holding Capacity) Ability of meat to retain its water during the application of external forces –Affects Appearance Juiciness Brine retention –Typical Range (24 hours) < 0.5% to 10% 0.5-1% average

PSE Pale pinkish gray, very Soft and Exudative. Undesirable appearance and excessive shrinkage. RFN Reddish pink, Firm and Non-exudative. This ideal quality has desirable color,firmness and water- holding capacity. DFD Dark purplish red, very Firm and Dry. Firm and sticky surface, high water- holding capacity. PSE, RFN & DFD

Color & Drip Loss Relationship PSERFNDFD Color & Drip Loss Relationship

pH Measure of the relative acidity of meat Related to: –Color –Drip loss –Firmness

Postmortem Conversion of Muscle to Meat Postmortem pH decline pH 7.2 Living Muscle hours postmortem pH pH of Meat

Glucose Glycogen 2 Pyruvate 3 ATP glycolysis 10 reactions Lactic Acid anaerobic pathway Circulatory System aerobic pathway Aerobic Metabolism O2O2 Sarcolemma Cell O2O2

Glucose Glycogen 2 Pyruvate 3 ATP glycolysis 10 reactions Lactic Acid anaerobic pathway Circulatory System Sarcolemma Cell pH drops

Postmortem pH decline Extent and rate of pH decline affects quality Slow steady decline to an ultimate pH of 5.8 or greater may predict higher quality pork

pH pH decline - limited extent –Slow, limited pH decline –Darker colored pork –Higher water-holding capacity –Caused by a limited amount of glycogen at exsanguination Time After Exsanguination pH

Normal rate of pH decline Low Ultimate pH - extended pH decline –Lower water-holding capacity –Greater “glycolytic potential” –“RN” Gene (Napole gene)

pH pH decline-rapid rate –Rapid, early pH decline can cause Pale, Soft, and Exudative (PSE) pork Genetics and Handling (both live animal and carcass) are the most common causes of PSE

Economic Value of HAL Gene

pH Decline and Pork Color DARK NORMAL PALE

Improving Meat Quality Genetics set the foundation and the limit for meat quality improvement –genetics account for 10 to 50% of the variation in meat quality traits

Genetic Variability in Meat Quality Differences between breeds or genetic lines Variation within breeds or genetic lines Major gene effects –Halothane gene, Napole gene, etc.

Trait Characteristics

Genetic Correlations ADGBF.14 Color pH Drip, % IMF Drip, %

Meat Quality and Production Traits Increase IMF –more BF, less LMA –no effect on pH and color Higher pH –Limited effects on growth and BF –usually darker color

Differences Between Genetic Lines Based on producer Checkoff funded research –NBS Sire Progeny Tests –Terminal Line Evaluation –Quality Lean Growth Modeling –Maternal Line Evaluation

NBS Progeny Test, BreedSiresProgeny Berkshire81619 Chester White43315 Duroc93696 Hampshire65465 Landrace62478 Poland China40283 Spotted40280 Yorkshire Total

Breed Differences: Summary Berkshire and Duroc - best pH, color, marbling Yorkshire - average on most, low marbling Landrace - below average on most traits Hampshire - poorest on pH, color, drip and cook loss

Animal Differences Within a Breed NameBreed EPD for IMF Great DaneDuroc0.25 (%) ChangerDuroc-0.16 Difference in progeny0.41% CambridgeYork0.11 InterstateYork-0.02 Difference in progeny0.13%

Genetics Nutrition On-Farm Handling Transportation Pre-Slaughter Handling Carcass Handling Stunning

Ideal Pork Quality Color –Reddish-pink Drip Loss –< 0.5% Ultimate pH – Marbling –Equivalent to % intramuscular fat