Abstract:

This study investigated the changes in physicochemical and microbial properties during storage at 25 ℃ of bread
made with Jiaozi, a traditional starter culture for steamed bun in northern China, established the changing patterns of the
physical parameters related to bread staling, and revealed the anti-staling mechanism. Sensory evaluation indexes, hardness,
water activity, thermal characteristics, free water content, scanning electron micrograph, disruption ratio, swelling degree and
texture profile analysis (TPA) properties were determined as well as microbial indexes. The results showed that the water
content of bread declined, and hardness rose remarkably with extended storage time. Compared with sourdough bread, Jiaozi
bread contained higher levels of water, its texture was softer, and its starch granules were more prone to agglomeration.
The quantitative physical parameter range for bread staling was also established. TPA showed that starch retrogradation
and staling were effectively inhibited by applying the traditional starter culture in bread. This study can provide a beneficial
exploration for the transformation of the traditional qualitative analysis to quantitative analysis in bread production.

Key words: Jiaozi bread, staling, thermal characteristics, physical properties