Impact of PayleanTM on Pork Quality
Scott N. Carr & Dr. Floyd K. McKeith, University of Illinois
David Gerrard, Purdue University
Ractopamine hydrochloride (RAC or PayleanTM) is a phenethanolamine with beta-adrenergic agonist properties. The FDA approved the use of Ractopamine, up to 18g/T for finishing swine weighing up to 240 pounds (109 kilograms). The recommended usage today is at a level of 4.5 to 9g/T for the last four weeks of the finishing period. The effects of RAC on carcass composition and pork quality have been characterized in the literature. The majority of the research in the literature was conducted prior to 1990. There have been numerous production changes in the last decade. Those changes include genetics and management practices. The emphasis on quality and the techniques used to evaluate quality have also changed drastically during this time period. The importance of pork quality is major issue to the industry. Pork quality is not clearly defined and may describe a wide range of characteristics. For the purpose of this review, it will be defined as the visual characteristics (color, water-holding capacity and marbling) and eating quality (tenderness, juiciness and flavor). The objective of this paper is to provide a broad overview of pork quality measurements, examine past research addressing the impact of PayleanTM on fresh pork quality and the current status of knowledge relating to the impact of PayleanTM on pork quality.
Fresh Pork Color
Pork color is an important characteristic that impacts the consumer’s perception of fresh pork (Brewer & McKeith, 1999). It is typically characterized objectively using colorimeters, described using the L*, a* and b* described by AMSA (1991) and subjectively using a set of pork color standards such as NPPC 1991, NPPC 1999 or the Japanese color standards.
Fresh pork color from PayleanTM fed pigs has been evaluated both objectively and subjectively. In an early study, Uttaro et al. (1993) objectively compared pork from pigs fed 18g/T of PayleanTM to controls and did not observe any differences in fresh loin L* values. However, differences (P<0.05) were found in a* values and b* values with the pork from the controls being more red and yellow in color compared to the pigs fed 18 g/T PayleanTM. Furthermore, Uttaro et al.
(1993) also evaluated cured ham color and demonstrated that PayleanTM treated pigs had lower (P<0.05) L* values than controls, while no differences were observed in a* and b* color values. Stites et al. (1994) observed no differences (P>0.05) in subjective lean color scores for pigs fed 0, 4.5, 9 and 18g/T of PayleanTM.
In more recent studies, Ivers et al. (2000), Stoller et al. (2002) and Ivers et al. (2002) reported no differences (P>0.05) in L* Minolta values or subjective color scores of the cut fresh loin. There were differences (P<0.01) in a* and b* values as the controls yielded higher values compared to the PayleanTM treated pigs. Herr et al. (2000) reported no differences (P>0.05) in Hunter Miniscan L, a or b color measures of the cut fresh loin.
Table 1. Post-mortem pH measurements on pork carcasses. Treatment means within a row with different superscripts are different (P<0.05) 1Measured on the loin of 180 carcasses. 2Measured on the loin of 30 carcasses 3Measured on the loin chop of 180 carcasses at approximately 30h post mortem.
|Variable||Paylean Treatment (g/ton)|
|pH 45 min1||6.12||6.09||6.26||0.042|
|pH 1.5 h2||5.88||5.79||5.96||0.080|
|pH 3.0 h2||5.65||5.72||5.82||0.066|
|pH 4.5 h2||5.70||5.65||5.92||0.076|
|pH 8.0 h2||5.51||5.57||5.59||0.034|
|pH 24 h1||5.52||5.55||5.55||0.011|
|Loin chop pH3||5.46a||5.53b||5.53b||0.015|
Marbling or intramuscular fat (IMF) has long been associated with eating quality of meat. Marbling or IMF can be measured visually and objectively. Visually using a one (1) to five (5) scale (NPPC, 1991) or the recent standards (NPPC, 1999) are on a continuous scale, which actually represents the amount of chemically determined lipid in the muscle. Objective measurements are based on chemical analysis of muscle tissue.
Stites et al. (1991) and Crome et al. (1996) reported no differences (P<0.05) in subjective marbling scores between control pigs and pigs that were fed PayleanTM. Watkins et al. (1990) reported the results of two studies. In study 1 with 888 pigs, no differences (P>0.05) were observed. In study 2 with 360 pigs, PayleanTM fed pigs had higher (P<0.05) subjective levels of marbling compared to control pigs. Whereas, Stites et al. (1994) observed no differences (P>0.05) in extractable lipid content between control and PayleanTM fed pigs. More recent studies have reported no differences in subjective marbling scores between control and PayleanTM fed pigs (Ivers et al., 2000; Herr et al., 2000; Stoller et al., 2002 and Ivers et al., 2002). Stoller et al. (2002) reported a breed by diet interaction for chemically separated loin lipid content as Berkshire pigs fed PayleanTM had lower (P<0.05) lipid values than control pigs while Duroc pigs were unaffected. Ivers et al. (2002) reported pigs fed 9g/T PayleanTM have lower chemically separated loin lipid content compared to pigs fed 18g/T PayleanTM/.
Table 2. Summary of PayleanTM affects on pork quality. Treatment means within column per experiment with different superscripts are different (P<0.05). 2Study 1. 3Study 2.
|grams/Ton||pH-45m||pH-24h||L* Loin||a* Loin||b* Loin||L* Cured Ham||a* Cured Ham||b* Cured Ham||C||F||M||Shear value (kg)||Drip%||Tend||Juice||Flavor|
|Zimmerman et al. 1989||0||3.0|
|Aalhaus et al. 1990||0||6.23a||5.49||5.86a||3.76|
|Watkins et al. 19902||0||2.1|
|Watkins et al. 19903||0||1.8a|
|Stites et al. 1991||0||2.8||2.9|
|Dunshea et al. 1993 (gilts)||0||5.43||6.59|
|Dunshea et al. 1993 (barrows)||0||5.41||5.83|
|Uttaro et al. 1993||0||46.32||7.59a||3.14a||62.40a||11.00||8.51||4.23a||6.45|
|Stites et al. 1994||0||5.41||2.85||2.84||5.72||4.82||6.42|
Firmness and wetness are two variables of pork quality that have often been evaluated together. This is conducted by visually appraising the cut loin surface and comparing it to a three- (NPPC, 1999) or a five- (NPPC, 1991) point scale. An evaluator is trained from these reference scales before beginning these subjective measures.
Stites et al. (1991) compared control pigs to pigs fed 4.5, 9 and 18g/T PayleanTM and reported no differences (P>0.05) in firmness between any of the treatments. Zimmerman et al. (1989) compared 0 and 18g/T PayleanTM and also observed no differences (P>0.05) in firmness.
Herr et al. (2000), Stoller et al. (2002) and Ivers et al. (2002) all reported no differences (P>0.05) in firmness between control and PayleanTM fed animals.
pH is a measure to determine the level of acidity or the alkaline level in any given substance and is correlated with meat quality traits. As a result, it is one of the most commonly used measurements in the industry today to help determine the quality of meat. Meat color, firmness and water holding capacity are affected by the pH of the muscle. An optimum ultimate pH for fresh pork would be in the range of 5.7-5.9.
Aalhus et al. (1990) and Dunshea et al. (1993) reported no differences (P>0.05) in ultimate pH values for pigs fed PayleanTM compared to controls. However, Aalhaus et al. (1990) showed a numerically higher ultimate pH values for PayleanTM fed pigs. In addition, Dushea et al. (1993) reported numerically higher ultimate pH values for barrows but numerically lower pH values for gilts at the 18g/T level of PayleanTM. Stites et al. (1994) observed no statistical differences (P>0.05) in pH values for loin chops from pigs fed diets containing with 4.5, 9 and 18g/T PayleanTM/ compared to the control pigs.
Ivers et al. (2002) found no differences (P>0.05) in 45 min, 1.5, 3.0, 4.5, 8.0 & 24hr post-mortem pH measurements between control pigs and PayleanTM fed pigs (table 1). However, pigs fed the 18g/T level have numerically higher muscle pH values at all six post-mortem measurements. In addition, Ivers et al. (2000) reported greater (P<0.05) ultimate loin chop pH values for pigs fed PayleanTM compared to the control pigs. Herr et al. (2000) reported no differences (P>0.05) in 45-min post-mortem pH values between control and PayleanTM fed pigs. Stoller et al. (2002) observed no differences (P>0.05) in 24 and 48-hr post-mortem ultimate pH between PayleanTM fed and control pigs.
Water Holding Capacity
The ability of meat to bind water and retain moisture during storage can accurately define water capacity. Drip loss refers to the percentage of moisture that is lost during the storage period, usually 24 or 48hr, of a chop. Purge loss refers to the percentage of moisture that is lost during the storage period, usually 7 to 21d, of a section of loin.
Aalhaus et al. (1990) and Dunshea et al. (1993) reported no differences (P>0.05) in loin chop drip loss for pigs fed PayleanTM compared to control pigs.Ivers et al. (2002) reported pigs fed 18g/T PayleanTM level had less (P<0.05) loin chop drip loss than controls. Carr et al. (2002) also reported that pigs fed 18g/T PayleanTM tended to have less purge loss from unenhanced loins compared to the controls. However, pigs fed diets containing 18g/T PayleanTM tended to have higher purge loss values in enhanced loins than the control treatment. Herr et al. (2000) and Stoller et al. (2002) reported no differences in water holding capacity between any control and PayleanTM fed pigs.
Sensory properties of meat can include juiciness, tenderness and off-flavor/flavor intensity. Trained sensory panelists using a linear scale can measure these properties. Mechanical measurements of tenderness can also be applied. The most common mechanical device is the Warner-Bratzler shear force machine for the objective determination of muscle tenderness.
Stites et al. (1994) reported no differences (P>0.05) between control pigs and PayleanTM fed pigs for juiciness, tenderness and off-flavor. Carr et al. (2002) reported no differences (P>0.05) between control and PayleanTM fed pigs for enhanced chops. However, they observed that treated pigs (9 or 18g/T PayleanTM) had lower (P<0.05) sensory tenderness scores than controls (7.91 vs. 7.96 vs. 9.06, respectively) for non-enhanced chops from the same pigs.
Aalhaus et al. (1990) observed higher (P<0.05) shear values indicating less tender pork, for PayleanTM fed pigs compared to controls. Uttaro et al. (1993) also reported higher (P<0.05) shear values for 18g/T PayleanTM fed pigs compared to the controls. However, Stites et al. (1994) observed no differences (P>0.05) in tenderness between control and PayleanTM fed pigs. Carr et al. (2002) reported no differences (P>0.05) in shear values of enhanced chops, but observed higher (P<0.05) shear values for PayleanTM treated non-enhanced loins compared to the non-enhanced control loins.
Table 3. Summary of Paylean affects on pork quality1 1Treatment means within column per experiment with different superscripts are different (P<0.05)
|grams/Ton||Crome et al. 1996||Ivers et al, 2000||Herr et al. 2000||Ivers et al. 2002||Carr et al. 2002|
|0||9||18||0||9||18||16% CP||16% + PayleanTM||18% CP + PayleanTM||Phase + PayleanTM||0||9||18||0||9||18|
|L* Cured Ham||48.71||49.4||49.05|
|a* Cured Ham||9.88a||8.60ab||8.12b|
|b* Cured Ham||4.51a||3.60b||3.22b|
|Shear value (kg)||3.76a||4.29b||4.42b|
Recent and past research shows that feeding PayleanTM to late finishing swine does not have an adverse effect on pH, visual color or objective L color value. Furthermore, feeding PayleanTM does not impact waterholding capacity, Warner Bratzler shear force and has been associated with reduced tenderness when fed at a high level for prolonged time periods.
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