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

The computer monitored power output, reflected power, and power at the exit of the
microwave tunnel through power diodes (JWF 50D-030+, JFW Industries, Inc.,
Indianapolis, IN). Immediately after blanching, peanuts were cooled to room
temperature using forced ambient air. Samples were taken for moisture content and
blanchability analysis. The remainder of each sample was sealed in plastic bags
and stored in opaque plastic tubs.
A random complete block design was used to evaluate the effect of
processing factors during microwave blanching. The experiments were split into two
sets (Table 1). Set 1 consisted of 7% moisture content peanuts heated using
varying microwave exposure times and both with (F) and without (NF) the use of
circulated 25 °C air in the conveyor tunnel. These peanuts were exposed to
microwave energy for 4, 5, 8, or 11 minutes. The control sample for this set was
peanuts undergoing the same storage procedures but which were not treated with
microwave energy. Peanuts in Set 2 had initial moisture contents of 5, 7, 9 and
11 % and were processed for the same exposure time (11 minutes, 5 kW) without
the use of a fan. The treatments in Set 2 were replicated three times, while
treatments in Set 1 were replicated four times.
The surface temperatures of the peanuts during processing were measured
using infrared probes installed along the length of the conveyor tunnel (model OS36-
T, OMEGA Engineering, Inc., Stamford, CN). Internal peanut temperatures were
measured using four fiber optic probes (FOT- L/10M, Fiso Technologies, Inc.,
Quebec, Canada) inserted into the center of individual peanuts which traveled the
length of the conveyor. The probes were connected to a multi-channel fiber optic
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