Effect of Na2CO3 on quality and volatile compounds of steamed bread fermented with yeast or sourdough

Abstract The effects of Na2CO3 on the quality, change of protein subunits and volatile compounds of sourdough leavened Chinese steamed bread (sourdough-CSB) and yeast leavened CSB (yeast-CSB) were investigated. Results suggested that, low Na2CO3 level endowed both CSB with softer crumb and little change of surface color. Besides, Na2CO3 addition improved the overall aroma profile by inhibiting the production of aroma-negative compounds (butanoic acid, 1-octen-3-ol, hexanal and heptanal). Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis showed an obvious increase in intensity of protein bands with low molecular weight, consistent with the result of size-exclusion high-performance liquid chromatography analysis and free sulfhydryl group (SH) content, indicating the hydrolysis of glutenin macropolymer (GMP) under alkaline condition in yeast-CSB. While in sourdough-CSB, GMP and SH content firstly decreased at low Na2CO3 level (0-0.2%) and then increased at high Na2CO3 level (0.3%-0.5%).