Thermal treatment
Freeze-dried pellet was stored in glass tube for accelerated storage
test at 60 and 37°C. At 60°C, sample was removed at 2 h intervals
for 10 h of exposure; at 37°C, sample was removed at seven days
intervals for 28 days of exposure. Freeze-dried sample was also
stored at 4°C to determine the number of viable cells each 15 days
during two months. Kinetics parameters (z-value, activation energy,
decimal reduction time and the rate constant of temperature) were
determined by the method as described by (Mottar, 1984; Yao et
al., 2008; Hernandez et al., 2009).