The results show that whiteness values of dried sample
at drying temperature of 70 and 100°C were not
significantly lower than that of dried sample at drying
temperature of 80 and 90°C and fresh sample. Moreover, it
was no visible to the naked eye. This can be concluded
that drying temperature was not influenced by whiteness
values. This could be explained that the times which differed from each other up to only 490 sec which could
not affect the whiteness values of dried coconut residue.
Oil content of the dried sample using fluidized bed drying
was up to 0.255±0.007, while all of results from fluidized
bed drying were higher than 0.250 g oil/g dry solids. The
highest oil content was 0.263±0.001 g oil/g dry solids achieved
from the dried sample by fluidized bed drying at 100°C
and significantly different from others as indicated in
Table 2. The results indicated that maximum drying
temperature of 100°C made the highest oil content of dried
sample, and it was the most suitable time for coconut
residue using fluidized bed dryer. It is possible that using
the higher drying temperature can obtain the higher oil
content (Sopannttayanon et al., 2011). On the contrary,
when whiteness values were considered, it was inversely
proportional to drying temperature. Thus, the drying
temperature should not be increased. Niamnuy and
Devahastin (2005) explained that because the fluidized
bed drying promotes intense particle movement, a higher
air velocity causes the collision between the dryer and
coconut pieces. Thus, it causes the squeezing action and
consequently contributed to an excretion of the oil.
Table 2: The whiteness values and oil content of dried
coconut residue under different fluidized bed drying