3. Results and discussion
3.1. The different pressure–temperature treatments
3.1.1. Air blast freezing and high pressure treatment of fresh
samples
Overall air blast freezing took 40 min, nearly 17 min
corresponding to phase transition (liquid water to ice I).
Freezing point was 1.6 C for raw and 2.7 C for saltadded
samples.
The pressure–temperature paths followed by a typical
raw sample and the pressure-transmitting medium during
HPP at 20 C is drawn over the (P,T)-phase diagram of
water on Fig. 1. The path followed by a salt-added sample
exhibits a similar aspect (data not shown). All the process
took place in the liquid region, without phase changes
occurring. The temperature increase during pressurisation
(18–22 C) and the decrease (20 C) on pressure release
were due to adiabatic heating and cooling, respectively,
of both sample and pressure-transmitting medium (Otero,Molina-Garcı´a, & Sanz, 2000). In spite of the control by
the thermostatic bath, the sample temperature varies from
43 C at the beginning of pressure holding at 650MPa to
27 C at the end.