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

Conclusions
This research investigated the impact of different microwave blanching
parameters on the properties of roasted peanuts, and characterized the changes in
flavor which occur in peanuts during microwave blanching at high temperatures.
The microwave processing parameters best suited for blanching peanuts were first
identified. Processing treatments were differentiated by energy absorbed during
processing, average and maximum internal temperatures, loss in moisture content,
and blanchability. The best blanchability resulted from higher process temperatures
and greater loss in moisture content. Treatments exceeding 110 °C resulting in a
final moisture content of 5.5 % or less yielded blanchability values greater than the
85 % industry standard.
The effect of this alternative blanching technique on flavor was evaluated
using descriptive sensory analysis. A sensory panel determined that peanuts
reaching the highest internal temperatures (~ 128 °C) and resulting in the lowest
moisture content (4.5%) during blanching had the most total offnote flavor.
However, temperatures as high as 113 °C did not produce significant off-flavor. The
microwave-associated off-flavor was related to stale/floral and burnt/ashy flavors,
and was related inversely to positive flavor attributes such as roasted peanutty,
sweet aromatic, and sweet taste.
Analysis of the peanut flavor volatiles using GC/O, GC/MS, and threshold
testing revealed an increased formation of guaiacol, phenylacetaldehyde, and 2,6-
dimethylpyrazine in the off-flavored peanuts compared to that in a process control.
Model system work confirmed that increased concentrations of these compounds
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