1. The effect of Marbling on Palatability Buenos Aires September 2008

2. Meat Standards Australia Conception Consumption Genetics Nutrition/environment Pre-slaughter factors Post-slaughter factors Chilling Processing/value adding Cooking Consumer Feedback Critical Control Points

3. AUS-Meat Marbling scores

5. Tenderness/Marbling Relationship between marbling and tenderness is low and variable –Marbling accounts for 5-15% of variation in tenderness –Shackelford et al (1994) 1602 carcasses –Wheeler et al (1994) 1337 carcasses –Marbling does provide some assurance and so is used in a number of grading schemes

6. How does marbling impact on sensory? Tenderness Dilution of myofibre structure –Low density fat dilutes higher density denatured protein Dilution of connective tissue structure –IM fat is laid down in the peri- vascular cells

7. How does marbling impact on sensory? Juiciness Lubrication –IM fat stimulates salivation –High IM fat will give a sustained impression of juiciness

8. How does marbling impact on sensory? Flavour –Lean has a meat flavour which is similar across most species –Species flavour components held in the fat

9. Does marbling protect against overcooking? As fat conducts heat at a slower rate, high IM fat steaks thought to provide insurance against overcooking?? Beef CRC results show no interaction evident between doneness and IM Fat% for sensory traits Concluded that doneness was more important than IM fat% in producing tender, juicy steaks

10. Relationships between sensory and IM fat % RelationshipR 2 Tenderness/IM fat%12.7 Flavour/ IM fat% 17.4 Juiciness/ IM fat% 16.3

11. Differences in flavour scores between finish systems At the same shear force IM fat% At the same shear force IM fat% age At the same shear force

12. The effect of marbling in different muscles IM Fat % Tenderness scores 1% increase in IM Fat% resulted in a 1 unit increase in tenderness Striploin Blade Topside

13. How does IM Fat% grow Classical longitudinal growth study Age liveweight Growing 1.5% Conc Growing + Finishing 1.7-1.8% Conc Finishing Both treatments ad libitum Conc 6121830

14. Experimental design Groups of 8 animals from –ad libitum –restricted treatments slaughtered at 2 month intervals from 6 to 30 months Initial slaughter group 6 12 slaughters each of 8 animals by 2 treatments = 192 animals

15. LD thorax Chuck Tenderloin LD lumber Rump Rib Sirloinbutt Brisket Hindshin Foreshin Carcass jointing

16. Analysis Y = AX b If “b” > 1 the component (Y) has a high growth impetus relative to the total (X) Y X

17. Y = AX b If “b” < 1 the component (Y) has a low growth impetus relative to the total (X) Y X Analysis

18. Y = AX b If “b” = 1 the component (Y) has an average growth impetus relative to the total (X) Y X Analysis

19. LD thorax b=1.09 Chuck b=1.02 Fillet b=0.88 LD lumber b=0.99 Rump b=0.95 Rib b=1.01 Sirloinbutt b=1.03 Brisket b=0.99 Hindshin b=0.99 Foreshin b=1.00 IMFat% distribution high impetus average impetus low impetus

20. Correlations between joints in IMFat% Joint 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 Ad libiutm r=0.85 Restricted r=0.87

21. Correlations between joints in IMFat% Joint 1 2 3 4 5 6 7 8 9 10 MS 1 2 3 4 5 6 7 8 9 10 MS Ad libiutm r=0.85 Restricted r=0.87 0.73 0.80

22. Conclusion IM Fat does have a small impact on palatability (tenderness, juiciness and flavour) Difference in flavour between grain and grass feed animals is that grass fed have less IM Fat % and are older IM Fat % does not exhibit differential growth across the musculature IM Fat % in any cut can predict IM Fat % in other cuts