until getting an internal temperature
of 71 °C, taken in the geometrical center of each burger through a hypodermic
type thermometer (Model HVP-2-21-V2-TG-48-OCT-M Omega,
Stanford, CT). After cooking, they were cooled to 21 °C for 1 h before
weighting. The weight, thickness and diameter of five burgers from
each batchweremeasured before and after cooking. To estimate dimensional
changes, reductions in diameter and thickness increase were calculated
from the following equations:
%Diameter reduction ¼ ðrawdiameter–cookeddiameterÞ
100=ðrawdiameterÞ
%Thickness increase ¼ ðcookedthickness–rawthicknessÞ
100=ðcookedthicknessÞ:
To estimate the cooking yield, the amount of fat and moisture
retained in the samples was calculated from the following equations:
%Cookingyield ¼ ðcookedweightÞ 100=ðrawweightÞ
%Fat retention ¼ ðcookedweight %fat incookedburgerÞ=ðrawweight
%fat inrawburgerÞ
%Moistureretention ¼ ðcookedweight %moistureincookedburgerÞ
ðrawweight %moistureinrawburgerÞ: