Effects of Different Yeasts on Texture and Flavor of Sweet Potato Bread

In order to investigate the effects of different yeasts on the quality and flavor of sweet potato bread, the rheological properties, color, texture and flavor of sweet potato bread were compared and analyzed. The results showed that different yeasts had significant effects on the color, texture and flavor of sweet potato bread. The results of dynamic rheology showed that the G' and G" of yeast No.4 fermented dough were significantly higher than other groups(P<0.05). The hardness, chewiness, elasticity, cohesion and resilience of commercial yeast fermented bread were significantly lower than those of old yeast fermented bread(P<0.05). The L^* value and W value of No.4 old dough yeast fermented bread were significantly higher than others(P<0.05). The results of electronic nose test showed that the main flavor substance of sweet potato bread fermented by 7 different yeasts was inorganic sulfide. A total of 61 volatile compounds were detected by GC-IMS, which were mainly alcohols, ketones and acids, followed by aldehydes, ethers, esters and pyridines. Principal component analysis showed that there were significant differences in volatile flavor compounds of 7 kinds of yeast fermented breads, two principal component contribution rate of 85%, indicating GC-IMS technology could distinguish bread fermented by different yeasts. To sum up, this paper made a detailed comparative analysis of the nature and flavor differences of bread fermented by different yeasts, and would provide a scientific basis for yeast selection in bread production.