Effects of isolated soybean protein (ISP) and ascorbic acid on volatiles formed from fructose solution were investigated by selected ion flow tube-mass spectrometry (SIFT-MS). Model system were prepared by 5% fructose solution with pH 6 phosphate buffer and heated at 100°C for 2 h. The results show that fructose forms furan (114 PPB), ormic acid (59 PPB), and acetic acid (40 PPB) in the headspace of 500ml bottle containing 80 mL solution. 0.5% ascorbic solution also form furan, formic and acetic acid which are less than the yields of 5% fructose does. ISP stimulates the formation of furan from fructose. Fructose and ascorbic acid form formic and acetic compounds independently, but form the furan dependently. It could be concluded that the degradation mechanism is multiple and complicated for the formation of furan, formic and acetic acids from ISP, fructose and ascorbic acid, which need further researching.