Texture profile analysis (TPA) was performed in raw and cooked
samples at 4 ± 1 C with a Texture Analyzer TA-XT2 (Stable Micro
Systems, Surrey, UK) following American Meat Science Association
(AMSA) procedures (Claus, 1995). Cubic samples (1 1 1 cm)
were cut from burgers and subjected to a two-cycle compression
test. Samples were compressed to 70% of their original height with
a cylindrical probe of 10 cm diameter at a compression load of
25 kg, and a cross-head speed of 20 cm/min. Texture profile parameters
were determined following descriptions by Bourne (1978)
and interpreted as follows. Hardness (kg) is the maximum force required
to compress the sample; cohesiveness is the extent to which
sample could be deformed prior to rupture (A2/A1), A1 being the
total energy required for the first compression and A2 the total energy
required for the second compression; springiness (cm) is the
ability of the sample to recover its original shape after the deforming
force is removed; gumminess (kg) is the force to disintegrate a
semisolid meat sample for swallowing (hardness cohesiveness)
and chewiness (kg cm) is the work needed to masticate the sample
for swallowing (springiness gumminess).