Steamed breads were prepared according to sponge dough
method described by He, Liu, and Zhuo (2004) with some
modification. Dry yeast, 1 g (Mauripan, Harbing Mauripan Yeast
Co., Ltd., Harbing) was dispersed in water (30 C). Whole wheat
flour 100 g was mixed with yeast/water (85% of Farinograph
water absorption) in a flour mixer (JHMZ200, East Fude Technology
Development Center, Beijing). Mixing time, water addition
and proof time were adjusted based on the performance of
the dough and results of a large number of experiments. The
mixing time was 10 min. After pressing pieces 20 times using a
rolling pin, the dough was divided into three pieces and shaped
by hand to a round, long and straight dough piece with a smooth
surface. Dough pieces were proofed for 50 min at 38 C and 85%
RH. Flour and dough were remixed by hand until the dough
became cohesive. The breads were steamed for 20 min in a
steamer.