Abstract SCHIRACK, ANDRIANA VAIS. The Effect of Microwave ...

(w.b.) within 3 days, large quality losses result from biological activity (Young et al.,
1982). Fungus growth due to high moisture content can lead to high free fatty acid
concentrations, caused by fungal lipase activity (Sanders et al., 1993).
In wagon drying, a balance is needed in air flow, air humidity, and drying time
so that the bottom layers of peanuts are not over-dried, but the top layer of peanuts
will not spoil before drying is completed (Young et al., 1982). Deep-bed drying of
peanuts can be envisioned as the drying of successive single layers. For each
layer, the temperature and humidity of the air is changed as it passes through the
peanuts (Troeger, 1982).
The rate of moisture removal during peanut drying is proportional to the
difference in vapor pressure of the peanut interior and that of the surrounding air. As
the moisture content of the peanut decreases, the time needed to remove a certain
amount of moisture increases because the vapor pressure difference is not as great.
When the humidity of the air becomes equal to that of the peanuts, drying ceases
(Troeger, 1982).
The heat used for drying also promotes reactions of the concentrated peanut
components (Sanders et al., 1993). The step of curing in peanut processing initiates
catabolic processes, such as degradation of carotenoids. Enzymatic and
nonenzymatic reactions also occur, which have been only minimally investigated
(Sanders et al., 1995).
Troeger (1982) conducted drying simulations to determine effects of varying
parameters on drying time and energy use. Simulations showed that drying peanuts
with a higher airflow rate (4.72 m 3 /s versus 3.05 m 3 /s) decreased drying time about
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