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

when the air is distributed from above (Cammarn et al., 1990). A recirculation fan is
used to remove exhaust gas. Peanuts are roasted at an internal temperature of 265
to 300 °F, and the moisture content is lowered from 4-6% moisture to 1% moisture
(Hoffpauir, 1953). As a result, reactions such as the Maillard reaction occur which
are key to the formation of typical roasted peanut flavor and color.
The predominant reactions occurring during roasting include the Maillard
reaction, Strecker degradation, and sugar caramelization. The Maillard reaction
involves a reducing sugar, such as glucose from the hydrolysis of sucrose, and an
amino acid under specific conditions of pH, water activity, and temperature. The
reaction intermediate loses a water molecule to form glycosylamine. After the
subsequent Amadori rearrangement, an amino keto sugar is formed, which can lead
to further decomposition products (Cammarn et al., 1990).
The Strecker degradation involves the decomposition of glucose to a dione,
which reacts with an amino acid and loses water molecule, and eventually
polymerizes to form pyrazines or other products. At high temperatures,
caramelization of sugars can also occur. Caramelization involves the dehydration
and decomposition of sugar molecules to form a variety of products such as
aldehydes, ketones, sugar fragments, and unsaturated rings. These unsaturated
molecules can absorb light to make brown pigments (Cammarn et al., 1990).
In addition to protein and carbohydrate reactions, after the peanuts are
roasted, the oil is more susceptible to oxidation. This occurs despite the fact that
lipoxygenase and polyphenoloxidase have been denatured, because of the
presence of nonenzymatic catalysts (Ory et al., 1992).
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