C.Z. Alvarado2
1Poultry Science Department, Texas A&M University, College Station, Texas, USA
2Animal and Food Science Department, Texas Tech University, Lubbock, Texas, USA
Processors utilize in-line injection and tumble marination to decrease labour and handling. Stimulating pre-rigor muscle may cause increased toughness. This study compared marination of early post mortem (PM) breast meat using injection, vacuum tumbling, or both. From 45 broiler carcasses at 3 hours PM, breast fillets were deboned and injected (10% w/w, 0.54% NaCl + 0.42% PO4), tumbled (30 min, 635 mmHg, 14 RPM), or injected + tumbled.
Non-marinated controls deboned at 3h and 6h post mortem were included. Tumbled and control 3h fillets had higher shear value and cooking losses than the injected or tumbled+injected treatments. Sarcomere lengths were not different among 3-hr treatments. Tumble marination at 3h PM without injection produced tougher meat than injection, possibly due to stimulation, less brine distribution, or decreased fiber disruption as in the injected fillets.
To test the brine penetration throughout the fillet, breast fillets from 60 broilers were deboned at 3hrPM and vacuum tumbled (30 min, 635 mmHg, 14 RPM) with 15%w/w solution of 0.54% NaCl and 0.42% PO4. Although there were no differences in shear value due to marination, cooked meat moisture and sodium were higher in the brined fillets. Sodium ion concentration was higher on the surface and on the epimysium side, suggesting some uneven distribution.
Introduction
Marination of broiler breast meat has become an integral part of the poultry industry and production efficiencies have made in-line injection of fillets common, sometimes with detrimental tenderness effects. Dispersion of ions into the muscle provides a tenderizing effect due to the repulsion caused by association of the ions with the proteins. This repulsion also increases water uptake and therefore increases moisture content of the cooked meat and tenderness. However, incomplete dispersion of the ions through the meat can possibly affect the water holding capacity and tenderization potential of the marinades.
Xiong and Kupski (1999) used a dye tracing method to determine penetration of the marinade into tumbled broiler breast fillets; however, the water soluble dye may migrate at a different rate from the ions which are responsible for increased tenderization. Also, these methods did not use a vacuum when tumbling the fillets, possibly affecting marinade penetration into the meat. Since there have been few studies relating early post mortem marination and tenderness, the objectives of these studies were to determine tenderness differences with several in-line marination techniques and to determine sodium ion migration through vacuum tumbled fillets to determine if complete dispersion occurs.
Materials and methods
Experiment 1
Broiler breast fillets were deboned at 3 or 6 hours post mortem (PM) from 45 carcasses in each of two trials. Treatments included injected (0.172 MPa, 10%), vacuum + tumbled (635 mm Hg, 14 RPM, 10%), injected + tumbled, and non-marinated controls for fillets deboned at 3 h PM. A post-rigor, non-marinated control deboned at 6 h PM was also included. The fillets were marinated with a 10% solution at a final concentration of 0.54% NaCl and 0.42% PO4. All fillets were then stored at 4°C for 16 hours to allow for marinade equilibration. The fillets were then cooked and analyzed for Allo-Kramer shear, cook loss (%), and sarcomere length using the laser diffraction method. Data was analyzed by ANOVA and Duncan (P≤0.05).
Experiment 2
At 3 hours post mortem, fillets from 30 broiler in each of two trials were either untreated controls or were marinated with vacuum tumbling (635 mm Hg, 14 RPM) using a 15% solution of 0.54% NaCl and 0.42% PO4. All fillets were allowed to equilibrate for 16 hours at 4°C. The fillets were then cooked and measured for Allo-Kramer shear and cooked meat moisture (%) by the oven-dry method. Two cores (2.54 cm diameter) were cut from the center of the fillets, sliced in 2 mm thick slices, homogenized in deionized water and analyzed for sodium ion concentration using an ion selective sodium probe. Percent sodium ion was calculated for each slice based on the weight of each slice. Data were analyzed by ANOVA and Duncan (P ≤ 0.05).
Results and discussion
Experiment 1
The vacuum + tumbled and control 3h fillets had the highest shear value followed by injected + tumbled and injected which were not significantly different (Table 1). The injected fillets were significantly more tender than the tumbled fillets, possibly due to greater fiber disruption from fluid pressure, more extensive brine penetration and distribution, and the actual injector needles decreasing the integrity of the fiber network.
Even though both tumbling and pre-rigor injection act as stimulation to the muscle, the fiber disruption maybe greater in the injected fillets, decreasing toughness associated with pre-rigor muscle stimulation. Tumbling fillets in the pre-rigor state may increase the physical stimulation of the muscle and cause increased toughening. Also, the penetration and distribution of the marinade may be less in the tumble-only fillets when compared to the fillets that had the brine injected into them.
The longer sarcomeres observed in the control 6h fillets were expected since rigor mortis had developed before the muscle was removed from its skeletal restraint. The lack of differences between the injected and tumbled fillets is inconsistent with the shear value results but suggests that sarcomere length is just one factor influencing tenderness. Other factors such as hydration and protein interaction may also be involved. There were no significant differences in cooking loss between any of the 3 h treatments. The numerical distinctions between these means may simply reflect the variable nature of measuring small weight changes in individual fillets. Although the magnitude of these mean differences may be large enough to be practically important, statistical conclusions from this data set may not be possible.
Experiment 2
There were no significant differences in shear value between control and marinated fillets (Table 2). Even though sodium ions have a tenderizing effect in post rigor broiler breast meat, the early post mortem stimulation caused by early deboning and tumbling in the present experiment may have masked this effect.
Tumbled fillets had higher cooked meat moisture than control fillets (Table 2). Sodium ion concentration was greater in the treated than the control fillets and was greater on the surfaces of the treated fillets than in their center (Figure 1). These differences indicate that sodium ions migrate from both the lateral and medial surfaces to the center of the fillet. The significantly higher sodium ion concentration on the lateral side of the treated fillets compared to the medial side of the fillet may be due to the presence of the epimysium on the lateral surface of the fillet.
The results of these studies indicate that in-line tumble marination at 3 hours post mortem without injection produces significantly tougher meat than the injection treatments, possibly due to decreased disruption of fibers and decreased penetration and distribution of the marinade as occurs in the injected fillets. Also, vacuum tumbling pre-rigor broiler breast meat allows for sodium ion penetration to the center of the fillet but with increased concentrations on the surfaces of the fillet.
References
Xiong, Y.L. and D.R. Kupski, 1999. Poultry Sci. 78:1048.
From Proceedings of the "XVI European Symposium on the Quality of Poultry Meat" and the "X European Symposium on the Quality of Eggs and Egg Products", Saint-Brieuc Ploufragan, France.
