Stratification of toughness in beef roasts.

Most meat scientists adopt a reductionist approach to the study of meat toughness, taking a few intramuscular cores from one or more muscles to simplify the enormous complexity of toughness in all the retail cuts derived from a whole carcass. This is a valid approach to a complex problem, but we should also start to consider how consumers respond to bulk meat such as steaks and roasts. Probing whole roasts reveals a complex internal structure, detectable by both connective tissue fluorescence and resistance to penetration. The dorsal aponeurosis of the Longissimus thoracis is a major connective tissue stratum in beef rib roasts and its properties are correlated with those of adjacent intramuscular connective tissues. When the aponeurosis is cooked, its reflectance first increases with protein denaturation, then decreases with gelatinisation. Heat-induced contraction is concurrent with the increase in reflectance. Gelatinisation is reduced if the aponeurosis is mechanically restrained to resist contraction. Thus, mechanical restraint interacts with heat penetration in explaining stratification of toughness in bulk meat.