Four methods for drying oyster soft tissues were compared: oven-drying
at 105, 100 and 80-degrees-C and freeze-drying. Weights were recorded
every 12 h for 5 days, and after sample treatments were switched, eve
ry 24 h for another 3 days. The time required for all the oysters in a
treatment to reach constant weight was 36, 36 and 60 h for 105, 100,
80-degrees-C over-dried treatments and 120 h for the freeze-dried trea
tment. Within a treatment, the time required to reach constant weight
was not weight-related. The average ratio of wet to 5-day dry weight r
anged from 9.07 to 9.47 for oven-drying but was only 7.35 for freeze-d
rying. After 3 additional days at 105-degrees-C, the 105, 100, 80-degr
ees-C oven-dried and freeze-dried groups lost an additional < 1, 1, 1
and 8% of their mean weights, respectively. All oven-dried groups pine
d 1% over the 5-day weight in the freeze drier, while the freeze-dried
group lost an additional 2% in 3 days. The temperature for oven-dryin
g, at least between 80 and 105-degrees-C, affected final dry weights b
y 1% or less, but the drying times required to achieve constant weight
were different. Freeze-drying required more time than oven-drying. Ov
en-drying should be continued to constant weight whatever the drying t
emperature employed and however long that takes.