2 ABOUT AQUALAB AquaLab TDL
2.4 AquaLab and Temperature
Samples not read at room temperature during the read cycle equi-
librate with the TDL temperature before the water activity is dis-
played. Large temperature differences cause longer reading times,
since TDL cannot make a complete and accurate reading until the
sample and the instrument equilibrate to within ±4
◦
C. There are
several advantages in having a temperature-controlled water activity
meter. A few major reasons are:
1. Research purposes. Researchers can use temperature con-
trol to study the effects of temperature on the water activity of
a sample, make a comparison of the water activity of different
samples independent of temperature, and conduct accelerated
shelf-life studies or other water activity studies where temper-
ature control is critical. There are many shelf-life, packaging,
and isotherm studies in which temperature control would be
very beneficial. (See Section 14. Further Reading for more
information)
2. Compliance with government or internal regulations for
specific products. Though the water activity of most products
varies by less than ±0.002 per
◦
C, some regulations require
measurement at a specific temperature. The most common
specification is 25
◦
C, though 20
◦
C is sometimes indicated.
3. Minimization of extreme ambient temperature fluctu-
ations. If the environmental and AquaLab temperatures fluc-
tuate by as much as ±5
◦
C daily, water activity readings vary
by ±0.01 a
w
. Temperature control eliminates variations due to
changes in ambient conditions.
6
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