meat colour in fighting bulls

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Meat colour of fighting bulls. B. Hernández, G. Lisazo, A- Horcada, M.J Berian and A. Purroy Escuela Técnica superior de Ingenieros Agrónomos, Universidad Publica de Navarra. .

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Page 1: Meat colour in fighting bulls

Meat colour of fighting bulls.B. Hernández, G. Lisazo, A- Horcada, M.J Berian and A. Purroy

Escuela Técnica superior de Ingenieros Agrónomos, Universidad Publica de Navarra.

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Page 2: Meat colour in fighting bulls

Fighting bulls are subjected toboth physical and emotionalstress before theirdeath, conditions know toaffect quality of meat.

Meat from stressed orexcessively fatigued animalshas a high pH (>6.0 as oposedto 5.4 – 5.8 in normal meat)and a dark colour.

The aim of this work is tocharacterise the meat offighting bull, study howageing changes meat colourand investigate the stability ofcolour or shelf life of this kindof meat in comparison withother typical commercial beef

breed.

Page 3: Meat colour in fighting bulls

Material and Methods

AnimalsFourteen 4 yr old running bulls selected from The Fiesta of San Fermin werestudied. They were slaughtered by a sword wound in the bullring.These animals were compared with 15 bulls of Pirenaica breed slaugtheredat 12 – 13 months of age.

Page 4: Meat colour in fighting bulls

MethodsLongissimus dorsi muscle was removed from theleft half of he carcass 24 hours post-mortem.• The pH of Longissimus dorsi muscle was

Measured at 24 hours post-mortem with a pHmeter with a penetration probe.

• Reflectance spectra and CIE L*a*b coordinates, hue and chroma(C*) were determined using a MINOLTA CM-2002 with a D65illuminant and 10⁰ observed at three different periods of time: after24 hours of oxigenation, 5 days post mortem and 7 days postmortem

• Colour was also determined through chemical parameters, i.e.content of myoglobin derivates (deoxymioglobin, oxymioglobin, andmetmyoglobin)

• Total content of myoglobin was determined using a SHIMAZU UV-2001 PC spectophotometer

• Analysis of variance was performed using the SPSS 6.1.2 statisticalpackage.

Longissimuss dorsi

Page 5: Meat colour in fighting bulls

Results and Discussion

Page 6: Meat colour in fighting bulls

Table 1. Values of live weight, myoglobin content and pH in Longissimus dorsi muscle of Fighting bulls and

Pirenaica breed bulls

Colour of meat from fighting bulls was darker, redder and more purple than that of beef from Pirenaica breed (P<o.oo1).pH values in fighting bulls correspond, in theory, to DFD (Dark-Firm-Dry) meat (6.37±0.28) versus a normal meat (5.47±0.04).This fact is in agreement with what could be expected in meat that has suffered such a stressing treatment.

Page 7: Meat colour in fighting bulls

Table 2. Evolution of colour coordinates CIE L*, a*, b*, hue h* and Chroma C* (± standard deviation), in fighting bulls and

Pirenaica breed bulls (n=15) after 24 hours of oxigenation (Day 1) five days post mortem and seven days post mortem.

Meat of fighting bulls has L* values lower than those of beef from Pirenaica group at different periodos of time (P<0.001) due to its greater content of pigment and high pH. Thishigh content of myoglobin is due to the production system, the breed itself and their olderage at slaughter.Violent excitement inmediately before slaughter influences ultimate pH in rumiant animalsand the muscle fibers of dark cutters are swollen and tightly packed together forming a barrier to the difussion of oxygen and the absorption of light (Seideman et al, 1984)

Page 8: Meat colour in fighting bulls

Figure 1. a* versus b* values in fighting bulls and beef bulls (Pirenaica) in the three days of study

These two coordinates show that fighting bulls meat is more purple red orsatured and less red than Pirenaica beef.Different authors suggest that DFD meat causes problems of health securityduring packaing and is linked to a decrease in the price.

Page 9: Meat colour in fighting bulls

Figure 2ª. Time evolution of a coordinate in fighting bulls and beef bulls

Fighting bulls, meat with high pHvalues has a normal behaviour.This fact can be seen in a decrease ofthe a*coordinate as well as anincrease of the (MMb) content withtime (figure 2b.)In normal meat the a* coordinatedecreases and the proportion ofMMb increases with time.In DFD meat a* increases with timedue to the slow oxygenation ofpigments

Page 10: Meat colour in fighting bulls

Figure 2b. Time evolution of %MMb in fighting bulls and beef bulls

The proportion of MMb infighting bulls is higher than inbeef bulls.If the value of 20% of MMb(Renerre and Mazuel, 1985) isa criterion of rejection byconsumers, or shelf-life isconsidered, meat fromfighting bulls reached thislevels in three days versusseven days for normal meat ofthe Pirenaica breed.

Page 11: Meat colour in fighting bulls

Figure 3а y 3b. Time evolution of reflectancespectra in three days of study for normal and DFD

meat.

Colour evolution in DFD meat is quite different from the evolution in normal meat.The reflectance spectra of fighting bulls have shown changes in DFD meat practicallyimperceptible, whereas in normal meat the characteristic depresssion of MMb is marked in a progressive manner.

Page 12: Meat colour in fighting bulls

Surprinsingly…….

Meat from only two fighting bulls withIndividual pH values of 6.1 and 6.6 were considerated ashaving a DFD behaviour. All the animals cataloguesas DFD in the breed group have meat with pH>6 while allthose catalogued as normal have pH<6, whereas in thefighting bulls group the normal also animal have meat pHvalues comprised between 5.8 and 6.3. Then, there areanimals with high pH values and normal behaviourdespite the special pre-slaughter treatment.

Page 13: Meat colour in fighting bulls

Conclusion

Despite the Bull Run earlier in the day and thespecial conditions of slaughter resulting inhigh pH, meat from fihting bulls can not beregarded as DFD meat. The muscular tissue ofthese animals seems to resist well this kind ofstress tretment, maybe due to genetic causes.This breed deserves further careful study as ameat-producing animals.