Low Water Activity; Samples Not At Room Temperature - Decagon Devices AquaLab 4TE Operator's Manual

AquaLab
8. Sample Preparation

Low Water Activity

When a sample's water activity value is below the cooling capacity of
the Series 4, your AquaLab will display an error message indicating
the lowest reading it attained on that particular sample. See Chapter 12's
troubleshooting problem #5 for possible solutions.
If your sample is not below 0.03 a but is still getting the error mes-
w
sage, refer to Chapter 12 for other possible explanations.

Samples Not at Room Temperature

Samples that are 4°C colder or warmer than the instrument (cham-
ber) temperature will need to equilibrate to instrument tempera-
ture before a fast, accurate reading can be made. Rapid changes in
temperature over short periods of time will cause the water activ-
ity readings to rise or fall until the temperature stabilizes. When
the temperature stabilizes within one or two degrees of the chamber
temperature, you can proceed with normal measurements.
High-water activity samples that are warmer than the chamber tem-
perature can cause condensation inside the measuring chamber, which
will adversely aff ect subsequent readings. A warning message appears
(Sample too hot) if the sample temperature is more than 4°C above
chamber temperature. If this message appears, immediately remove
the sample from the instrument, place a lid on the cup, and allow the
sample to cool to within 4°C of the instrument before measuring.
Samples that are lower than 4°C of the instrument's temperature
will cause long read times. Th e sample temperature must be within
one or two degrees of the chamber temperature before fast, accurate
readings can be made.
50