Identification of volatile flavor compounds in fermented glutinous rice (Tapai) using gas chromatography

Abstract

Fermented glutinous rice or tapai is a popular fermented snack in Asian countries such as Indonesia and Malaysia. Tapai is made from cooked glutinous rice and mix with powdered ragi which acts as the fermentation starter. In this study, three samples of fresh tapai were analyzed for their chemical properties (pH and salt content) for duration of 4 weeks. For identification of volatile compounds in homemade tapai using GC-FID, four compounds have been detected namely ethanol, 1-propanol, isobutanol and isoamyl alcohol. The percentage of ethanol was increased from 1.80608% in week 1 and drastically increased to 10.8004% in week 4. The three other alcoholic compounds were detected with a very small percentage from week 1 to week 4. The pH of three samples were decreased every week where the pH ranged from 5.15 - 3.04 for Tapai A, 4.81 - 2.41 for Tapai B and 5.06 - 2.99 for Tapai C. Meanwhile, salt (NaCl) content for three samples of tapai were almost similar which range from 28.093% - 28.453% (w/v).