The shrimps frozen by air-blast had the freezing rate of
6.8–7.4 cm/h while those frozen by the cryogenic freezing
had the freezing rate of 11.8–21.9 cm/h (Table 1). The samples
frozen with air-blast freezing at the air velocity of 4
and 6 m/s had the %freezing loss significantly lower than
those at 8 m/s (p 6 0.05). This may be due to the higher
air velocity causing an excessive dehydration of the samples
(Fennema et al., 1975). The samples frozen at the air velocity
of 4 m/s had the cutting force lower while those at the
8 m/s had the cutting force higher than the fresh samples.
The shrimps frozen at the air velocity of 6 m/s had the cutting
force similar to the fresh samples (p > 0.05). This may
be due to the higher water removal at the surface during
freezing at the higher air velocity. Therefore, the air-blast
freezing at the air velocity of 6 m/s was selected for further
studies of thawing and freeze–thaw cycle effects.