Update on PSE in Poultry Meat

Christine Z. Alvarado, Ph.D. Department of Animal and Food Sciences Texas Tech University Meat Quality

Attributes influenced by postmortem muscle :

¾ Color

¾ Water Holding Capacity

¾ Texture

Ferket and Foegeding, 1994; Pearson, 1994 Meat Quality

Pale, Soft, Exudative

¾ accelerated postmortem

¾ denaturation

Hedrick et al., 1989; Lawrie, 1998 Meat Quality

Combination of events:

¾ Rapid postmortem decline in muscle pH

¾ High carcass temperatures (early postmortem)

Bendall and Wismer-Pederson, 1962; Penny, 1969 Meat Quality

Pale, Soft, Exudative Meat

¾ Pale color ¾ Soft texture ¾ Low water holding capacity

= reduced yields and poor quality Protein Denaturation

Myofibrillar

Water holding capacity / gel strength

Sarcomplasmic proteins

Color

Bendall and Wismer-Pederson, 1962; Penny, 1969 Protein Denaturation

Protein denaturation can cause low strength (poor) gels to form resulting in softer (mushy) texture.

Example: Pale, SOFT, Exudative meat Protein Denaturation

Poor slice ability

PSE meat Deli Loaves and Rolls Made with PSE Turkey Meat

Excessive Purge Pale color Low WHC Problems with PSE Broiler Meat

¾ Lost yield (sometimes hidden)

¾ Problems in further processing equipment (e.g. automatic breast deboner)

¾ Variation in color Economic Implications

4The use of PSE meat in cooked products can cost a processing plant $2-4 million/year in lost meat yield alone.

4Estimate does not factor in: hpackaging costs hrework labor hmultiplier effect PSE Incidence in Poultry

Ranges from 5-40%

20-25% is “background” (genetic?)

Remainder varies with day, week, or season (environment?)

Genetic and environmental factors not distinctly separated Factors Influencing PSE Meat

Genetic PSE Environmental

Ryanodine Antemortem Receptor (RyR) Postmortem Porcine Stress Syndrome

¾ genetic disorder (autosomal recessive)

¾ linked to the ryanodine receptor gene

¾ single point mutation

¾ induced by halothane and succinylcholine

¾ induced by stress

¾ Malignant Hyperthermia in other species

Hall et al., 1966; Harrison et al., 1968; Webb and Jordan, 1978; Fujii et al., 1991 The Ryanodine Receptor

Single Point Mutation

¾ Cytosine (C) to thymine (T) at nucleotide 1843

¾ Substitution of cysteine for arginine in position 615

¾ Abnormal calcium release

¾ Observed in swine and humans – PSS/MH

¾ No evidence to support or refute mutation in avian species Fujii et al., 1991 Halothane Screening -

+ The Ryanodine Receptor

Isoforms

¾ Mammalian

hα located in hβ located in cardiac muscle and brain

¾ Avian

hα and β located in skeletal muscle hGenetic difference found but currently being studied

Percival et al., 1994 Antemortem Stress Factors

¾ Stresses associated with PSE meat in swine

hRapid Growth hPreslaughter handling practices hTransportation hEnvironmental temperatures

¾ Poultry are subjected to similar conditions

Cassens et al., 1975; Backstrom and Kaufmann, 1995; D’Souza et al., 1998; Maribo et al., 1998 Rapid Growth

Fast growing/heavier birds

¾ More susceptible to heat stress

hhigher body temperature hgreater metabolic heat production hhigher mortality

¾ Greater incidence of muscle abnormalities

¾ Muscles may outgrow life support system

Bohren et al., 1982; Sosnicki and Wilson, 1991; Hunt et al., 1999; Mahon, 1999; Mills et al., 1999 Antemortem Stress Factors

Transportation

¾ Physiologically stresses poultry

¾ No increase in PSE incidence associated with 3 h of transportation prior to slaughter

¾ May be dependent on duration and other conditions

Kannan et al., 1997; Freeman et al., 1984; Kannan et al., 1998 Gregory, 1994; Cashman et al., 1989; Owens and Sams, 1999 Antemortem Stress Factors

Chronic heat stress

¾ Higher incidence of PSE meat in turkeys

¾ Heat stressed turkeys exhibited: hlower muscle pH hhigher L* values hhigher drip loss hhigher cook loss

McCurdy et al., 1996; McKee and Sams, 1997 Postmortem Factors

Chilling Rates

¾ Slow or inadequate chilling increases PSE

¾ Problem in turkeys due to size

¾ Postmortem temperature is the most important factor influencing overall meat quality

McKee and Sams, 1998; Alvarado and Sams, 2002; Alvarado and Sams, 2003 Objectives

¾ To evaluate the relationships between muscle chilling rates, pH decline, color, water holding capacity, and texture, in turkey carcasses

¾ To develop a time and temperature range for chilling turkey carcasses to decrease meat quality problems associated with PSE meat. Materials and Methods

¾ 48 Male Nicholas Turkeys processed in 2 trials

¾ Bled, scalded, picked, eviscerated

¾ Chilled at 0, 10, 20, 30 C

¾ Deboned Materials and Methods

• Sample Analyses • Temperature of the fillets • pH • L* Value • Gel Strength • % CL • Expressible Moisture Temperatures of Turkey Pectoralis from Various Chilling Times and Temperatures

42 a 0 C 40 a 10 C 20 C 38 30 C b 36 a 34 32 b 30 c 28 Carcass Temperature (C) Carcass Temperature Pooled SEM = 0.43 d 26 0 20406080100 Time Postmortem (min) pH of Turkey Pectoralis Chilled at Various Rates 6.3 a 0 C 6.2 10 C 20 C 30 C 6.1

6.0 pH a 5.9 ab a b 5.8 ab Pooled SEM = 0.02 b 5.7 0 20406080100 Time Postmortem (min) Muscle Temperature and pH Decline from Turkey Lobes 5.96

5.92 aa Pooled SEM = 0.02 5.88

5.84 pH 5.8 b

5.76 b 5.72 24 26 28 30 32 Carcass Temperature (C) Relationship of Muscle Temperature and L* Value from Turkey Lobes

58 Pooled SEM = 0.31 57 aa a 56

55 L* Value 54 b

53

52 26 28 30 32 34 36 38 Carcass Temperature (C) Means of Meat Quality Parameters for deboned turkey breast fillets

Temperature ( C )

Parameter 0 10 20 30 Pooled SEM L* Value 51.85 51.47 51.50 51.45 0.20 (24 h)

Drip Loss 0.23 b 0.24b 0.27b 0.40a 0.02

Cook 14.72b 15.08b 14.61b 18.82a 0.60 Loss Exp. 27.15 25.4 25.01 25.58 0.51 Moist.

Gel 17.31 16.01 15.67 15.65 0.69 Strength abMeans with different superscripts are significantly different (P<0.05) Conclusion

¾There is a chilling time and temperature relationship which can be a factor in the development of PSE meat.

¾Therefore, processors should implement a proper chilling regime in order to maintain acceptable meat quality.

Carcass Temperature recommendations

¾ < 35 - 36 C at 0.75 h PM

¾ < 28 - 30 C at 1.5 h PM Alvarado and Sams, 2003,2003 Strategies to Improve PSE Meat

¾ Adjustment of pH or ionic strength • use ingredients to restore protein function

• High pH phosphates (Pre-rigor and PM) • Increased pH • Decreased Cook loss • Improved color by 24 h PM3 Objectives

To determine the effects of pre-rigor marination with sodium phosphates on pH, color, and WHC in both normal and pale broiler breast fillets Materials and Methods

¾ Poultry Research Center (3h PM): • Injected (15% solution, 25 PSI) pH 9 (0.9% NaCl, 0.45% PO4) pH 11 (0.9% NaCl, 0.45% PO4) • Vacuum tumbled (25 mm Hg, 30 min, 14 RPM) • pH • Lab* value • Marinade pick-up/ retention • Cook Loss • Expressible moisture • Sensory • TBARS Measurements from Normal and Pale Fillets Marinated with a pH 9 Solution

pH pH L* L* EM CL (2h) (24h) (2h) (24h) (%) (%)

a,x a,y b,x b,x b a Normal 6.30 6.12 49.57 49.19 18.58 22.38

Pale 6.09b,x 6.00b,x 53.79a,x 51.38a,y 22.65a 24.09a

Pooled 0.03 0.02 0.40 0.27 1.34 0.60 SEM

a, bMeans in a column differ ( P < 0.05) x, yMeans in a row and within the same parameter differ (P < 0.05) Measurements from Normal and Pale Fillets Marinated with a pH 11 Solution

pH pH L* L* EM CL (2h) (24h) (2h) (24h) (%) (%)

a,x a,x b,x b,x b a Normal 6.30 6.28 49.87 48.63 17.94 20.29

Pale 5.95b,x 6.22a,y 53.86a,x 50.39a,y 24.47a 20.99a

Pooled 0.04 0.02 0.48 0.21 1.19 0.97 SEM

a, bMeans in a column differ ( P < 0.05) x, yMeans in a row and within the same parameter differ (P < 0.05) Sensory Measurements from Marinated Fillets

Treatment Hedonic Scale Value pH 9 3.44 pH 11 3.42 TBARS Measurements from Marinated Fillets

Pale TBARS TBARS TBARS (Day 0) (Day 2) (Day 4)

pH 9 2.17 3.22 4.78

pH 11 2.07 4.06 3.93

Normal TBARS TBARS TBARS (Day 0) (Day 2) (Day 4) pH 9 1.76 3.92 3.7

pH 11 1.99 4.17 4.46 Shelf-life Measurements from Marinated Normal Fillets

8 7 6 5 4

Log CFU/ml 3 2 Day 0Day 3Day 6Day 9

1 4 Shelf-life Measurements from Marinated Pale Fillets

8 7 6 5 4

Log CFU/ml 3 2 Day 0 Day 3 Day 6 Day 9

pH 9 pH 11 Conclusion

High pH phosphates ¾ Increased pH ¾ Decreased Cook loss ¾ Improved color by 24 h PM

Impacts to industry: higher yield, increased consumer acceptability Strategies to Improve PSE Meat

¾ Sort meat based on color or meat pH

• direct PSE meat to “non-problem” products

• away from products with no or low amounts of salts and phosphates Sorting Breast Fillets

¾ Based on Color

• easy and rapid • human eye • optical scanning equipment

¾ Based on Meat pH • more complicated • currently used in pork and beef industry Conclusions

¾ Long-term strategies

• genetic typing • screening tests • selective breeding

¾ Short-term strategies • reduce environmental stress • sort meat • control flow/distribution of PSE meat Questions?

Christine Alvarado, Ph.D. International Center for Food Industry Excellence Animal and Food Sciences Texas Tech University