Influences of four pretreatments on anthocyanins content, color and flavor characteristics of hot-air dried rose flower

Anthocyanins, which could be extracted from red rose, are water-soluble natural pigment of higher value. Anthocyanins are, however, known to suffer significant degradation and losses during drying, which is sometimes required prior to pigment extraction. Various pretreatments are here proposed and were tested as means to help preserve anthocyanins during subsequent hot air drying. Fresh rose flowers were dipped in four different solutions (citric acid, CA; ascorbic acid, AA; tartaric acid, TTA; and sucrose, Suc) of different concentrations viz. 0.1%, 1% and 2% w/v). The pretreated flowers were dried at 50 degrees C. Monomeric anthocyanins and polymeric color percentage of fresh and hot air dried rose were evaluated; color measurement and electronic nose analysis were also conducted. The results showed that 2% TTA resulted in the largest amount of anthocyanins (14.78 +/- 0.19 mg/g, dry mass cyanidin 3-glucoside equivalent), which was equivalent to 3.2% loss compared with the amount in the fresh sample. However, the color of the 2%-TTA treated sample was not as bright as those treated by 0.1% TTA, 0.1% Suc and 1% Suc. All dried samples exhibited flavor that is related to biosynthesis compounds such as those produced during Maillard reaction and baking.