LAUSR

Dimensional changes and water migration of individual muscle fibers and meat blocks of pectoralis major muscle obtained from commercial broilers (CB) and yellow-feathered chicken (YFC) were affected by early cooking temperatures (30, 40, 50 and 60 °C). At early heating temperatures (30–60 °C), the maximum shrinkage in the volume of meat blocks was higher (10–29%) than the individual extracted fiber fragments (7–19%). Changes in the width and cross sectional area were significantly ( p  < 0.05) higher than the length at each heating temperature in muscle fiber fragments and meat blocks of both breeds. However, most changes in the dimensions were recorded in CB than YFC during heating. Taken together, these all shrinkages in the muscle fibers and meat blocks are governed by the denaturation of myosin and actin with the rising heating temperature. The results of low field-nuclear magnetic resonance and proton density images demonstrated that CB has a higher tendency to loss water than YFC during heat treatments. SEM (scanning electron microscopy) results showed more damages in CB muscles than YFC by formation of cracks which act as drip channels in the muscle structural architectures. Additionally, CB muscles were significantly ( p  < 0.05) harder (52–64 N) than YFC (37–52 N) as affected by heat treatments (30–60 °C). Hence, it is plausible that CB has a lower tendency of water holding capacity due to its higher structural deformations than YFC.