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

2. Fighting bulls are subjected to both physical and emotional stress before their death, conditions know to affect quality of meat. Meat from stressed or excessively fatigued animals has a high pH (>6.0 as oposed to 5.4 – 5.8 in normal meat) and a dark colour. The aim of thiswork is to characterise the meat of fighting bull, studyhowageingchanges meat colour and investigate the stability of colour or shelflife of thiskind of meat in comparisonwithothertypicalcommercial beef breed.

3. Material and Methods Animals Fourteen 4 yroldrunning bulls selected from The Fiesta of San Ferminwere studied. Theywereslaughteredby a swordwound in the bullring. Theseanimalswerecomparedwith 15 bulls of Pirenaica breedslaugthered at 12 – 13 months of age.

4. Methods Longissimusdorsimusclewas removed from the lefthalf of he carcass 24 hourspost-mortem. The pH of Longissimusdorsimusclewas Measured at 24 hours post-mortem with a pH meter with a penetrationprobe. Reflectancespectra and CIE L*a*b coordinates, hue and chroma (C*) weredeterminedusing a MINOLTA CM-2002 with a D65 illuminant and 10⁰ observed at three different periods of time: after 24 hours of oxigenation, 5 days post mortem and 7 days post mortem Colour wasalsodeterminedthroughchemicalparameters, i.e.content of myoglobinderivates (deoxymioglobin, oxymioglobin, and metmyoglobin) Total content of myoglobinwasdeterminedusing a SHIMAZU UV-2001 PC spectophotometer Analysis of variancewasperformedusing the SPSS 6.1.2 statisticalpackage. Longissimussdorsi

5. Results and Discussion

7. 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).Thisfact is in agreementwithwhatcouldbeexpected in meat that has sufferedsuch a stressingtreatment.

9. Figure 1. a* versus b* values in fighting bulls and beef bulls (Pirenaica) in the threedays of study Thesetwocoordinates show that fighting bulls meat is more purple red orsatured and less red than Pirenaica beef. Different authorssuggestthat DFD meat causes problems of healthsecurityduringpackaing and is linkedto a decrease in the price.

11. Figure 2b. Time evolution of %MMb in fighting bulls and beef bulls The proportion of MMb in fighting bulls is higher than in beef bulls. If the value of 20% of MMb (Renerre and Mazuel, 1985) is a criterion of rejectionbyconsumers, orshelf-life is considered, meat from fighting bulls reachedthislevels in threedays versus sevendaysfor normal meat of the Pirenaica breed.

12. Figure 3а y 3b. Time evolution of reflectancespectra in threedays of studyfor normal and DFD meat. Colour evolution in DFD meat is quite different from the evolution in normal meat. The reflectancespectra of fighting bulls haveshownchanges in DFD meat practically imperceptible, whereas in normal meat the characteristicdepresssion of MMb is marked in a progressivemanner.

13. Surprinsingly……. Meat from onlytwo fighting bulls with Individual pH values of 6.1 and 6.6 wereconsiderated as having a DFD behaviour. All the animals catalogues as DFD in the breedgrouphave meat with pH>6 whileall thosecatalogued as normal have pH<6, whereas in the fighting bulls group the normal also animal have meat pH valuescomprisedbetween 5.8 and 6.3. Then, there are animalswithhigh pH values and normal behaviour despite the special pre-slaughtertreatment.

14. Conclusion Despite the Bull Runearlier in the day and the specialconditions of slaughterresulting in high pH, meat from fihting bulls can notberegarded as DFD meat. The muscular tissue of theseanimalsseemstoresistwellthiskind of stress tretment, maybeduetogenetic causes. Thisbreeddeservesfurthercarefulstudy as a meat-producinganimals.