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

asic pH, and higher concentrations of certain sugars such as fructose. The specific
type of pyrazine formed is influenced by the nitrogen source (Koehler and Odell,
1970).
Time and temperature conditions of roasting have perhaps the most
significant impact on compound formation. Leunissen et al. (1996) found that the
concentrations of pyrazine compounds and hexanol, hexanal, and methylpyrrole
were related to the severity of the roasting conditions. In a model system study,
Koehler and Odell (1970) found that no pyrazine compounds were formed at
temperatures less than 100 °C, but above this temperature pyrazine yield rapidly
increased. Roasting at temperatures above 120 °C produces a wide range of
compounds in peanuts due to Maillard reactions (Leunissen et al., 1996). In the
early stages of a heating reaction at 120 °C, methylpyrazine was the major product,
while the ratio of dimethylpyrazine to methylpyrazine steadily increased thereafter.
At temperatures above 150 °C, some pyrazine degradation may occur (Koehler and
Odell, 1970). By direct chromatography, Vercellotti et al. (1992) found
methylpropanal, methylbutanal, methylbutanol, methylpyrazine, dimethylpyrazine,
methylethylpyrazine, and vinylphenol to vary with degree of roast. Other factors will
affect roasting temperature, as seen in Chiou et al. (1991), where the internal
temperature of low-moisture seeds (3.4%) was higher than high moisture seeds
(10.4%).
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