Changes in nutritional constituents, anthocyanins, and volatile compounds during the processing of black rice tea.

The present study was undertaken to assess the changes in nutritional composition, anthocyanins, and volatile compounds during 3 successive processes (soaking, steaming, and roasting) for black rice tea production. Significant ( p<0.05) decreases of cyanidin-3-glucoside and peonidin-3-glucosidetotal content were presented in black rice grains during soaking, steaming, and roasting. However, only steaming and roasting caused significant ( p<0.05) decreases in the contents of total starch and crude fat, whereas accompanied with a stable level of total starch during all the processes. Furthermore, 94 of volatile compounds were identified in the raw and processed black rice. Nonanal, butylated hydroxytoluene, 1-hexanol, naphthalene, and 1-octen-3-ol were the main volatile compounds. These volative compounds extracted from raw black rice grain varied widely compared to the processed materials. The study indicated that processing could significantly affect the profiles of nutritional compositions, anthocyanins, and volatile compounds during the production of black rice tea. [ABSTRACT FROM AUTHOR]