3.2. Humidity regulation
Experimental data based on TR was used to calculate the
amount of water produced per day in a typical package containing
250 g of mushrooms stored at different combinations of temperatures
and RH (Fig. 5). Thus, with the calculated value, it was
possible to compare the moisture sorption by humidity-regulating
trays. The amount of water produced per day at 96% RH and 4 C
was approximately 1.6
10 2mg s 1 this increased by at least
2–6 times for the temperature in the range of 12–20 C. However,
the amount of water produced at 100% RH was reduced to half
(0.8
10 2mg s 1 at 4 C) compared to 96% RH, but this rate of
water produced was still enough to form condensation inside the
package. Therefore, in order to avoid condensation and maintain an
optimal RH of 90–96% (Villaescusa and Gil, 2003), the humidityregulating
tray should have a capacity to absorb at least 8.4 g water
for storing 250 g of mushrooms for 6 days at 4 C. In the control-PP
trays, the RH rapidly increased and the headspace was saturated with water vapour (100% RH), while in the humidity-regulating
trays excess moisture from mushroom transpiration was absorbed
by the tray, thereby maintaining 93% RH throughout 6 days of
storage (Fig. 6). Furthermore, Bi et al. (2014) investigated the effect
of moisture absorbers inside MA-packaged mushrooms (Pleurotus
ostreastus). The authors reported that packages with the use of
moisture absorbers RH rapidly increased and was stable at 95%
after 36 h, while in packages without moisture absorbers the air
was saturated (100% RH) after 48 h. This was consistent with the
observation in this study.