Abstract:

The effect of different roasting degrees on the quality of germinated brown rice was examined by investigating
the changes in major components, color and flavor volatile compounds in germinated brown rice with mild, moderate
and intensive roasting. Results showed that the contents of reducing sugar and soluble protein in germinated brown rice
roasted to three different degrees were significantly lower than in those without roasting (P ＜ 0.05), but there was no
significant difference among the roasting degrees (P ＞ 0.05). Meanwhile, γ-aminobutyric acid (GABA) content significantly
reduced with an increase in roasting degree (P ＜ 0.05). Total phenolic content in highly roasted germinated brown rice
was significantly higher than that observed at lower roasting levels (P ＜ 0.05). After roasting, the contents of amylose
and resistant starch increased, but no significant difference was found among the three degrees (P ＞ 0.05). Roasting had
little effect on the total starch content. With increasing roasting degree, a*, b* and ΔE values increased, whereas L* value
decreased. By using headspace solid-phase micro-extraction (HS-SPME) coupled with gas chromatography and mass
spectrometry (GC-MS), the flavor volatile compounds of germinated brown rice without roasting and with different
roasting degrees were analyzed. It was found that the kinds and contents of pyrazines and furans significantly
increased. The loss of GABA content in germinated brown rice with mild roasting was the least, and it had the highest
relative content of pyrazines that could be a major factor contributing to baked fragrance. Therefore, mild roasting is more
appropriate for germinated brown rice.

Key words: germinated brown rice, roasting, nutritional ingredients, flavor volatile compounds