Abstract:  From the curve of the spin-spin relaxation time(T2)against the fermentation time,we discovered that the addition of yeast in dough and the fermentation time had little influences on T21 and T22,while T23 was exceptional. Namely,they mainly changed the distribution and mobility of free water in dough. The curve of T23 and fermentation time undulated in the all course of fermentation. The more the added yeast the higher the T23 constant of dough . We also found dough with 1.5% yeast had many uneven holes and broken network of wheat gluten in the period of fermentation from the MRI images obtained. While dough with 0.5%yeast content and 1.0%yeast content were more appropriate to produce steamed bread because of their slower speed of fermentation,smooth CO2 generation and better network structure.

Key words:  , NMR； MRI； dough； ferment process； moisture transfer