Study On The Effect Of Grain Raw And Auxiliary Ingredients On The Quality Characteristics Of Hot-packed Steamed Bread

Thermal-vacuum package is a new type of Chinese steamed bread(CSB)preservation technology that can extend the shelf life of CSB to more than 90 days at room temperature.However,there is no systematic study on the effects of wheat starch,protein and polysaccharides on the staling of thermal-vacuum package CSB starch.Therefore,this study analyzed the effects of wheat starch(0%,10%,30%),gluten(0%,1%,2%)and oat ?-glucan(0%,1%,3%,5%)on starch retrogradation mechanism,protein structure and quality of CSB during storage at room temperature,aiming to provide theoretical support for food processing enterprises to develop special flour for CSB,which has important practical significance for the health care and industrialization of staple food CSB in China.(1)During storage at room temperature,the total moisture content of the thermalvacuum package CSB firstly increased then decreased,and the moisture migration of CSB was from the crust to the core.The mixed crystals of B and V-type was observed during storage,forming a typical diffraction peak at 17°.The hardness,?H value,relative crystallinity and long-range ordering of CSB were increased,while the springiness,cohesiveness and resilience were decreased.(2)The total moisture content,specific volume,and springiness of CSB with different wheat starch substitution firstly decreased then increased,while hardness,chewiness,?H value,relative crystallinity and long-range ordering firstly increased then decreased.The content of strongly bound water decreased,but the content of weakly bound water and free water increased.CSB slices with 10%wheat starch substitution had clear pores and dense structure,which could maintain the network structure of gluten and improve the gas and water holding capacity of CSB.Appropriate amount of wheat starch substitution can delay the staling and improve the quality of CSB by improving the elasticity of thermal-vacuum packed CSB,maintaining the structure of gluten network and preventing water loss during storage.(3)The specific volume of CSB with different gluten substitution firstly increased then decreased.,the secondary structure of protein changed from helix and irregular curl to corner and fold.The color of steamed bread becomes darker,and the water molecules gradually migrated from strong bound water to weak bound water and free water.CSB with 1%gluten had good texture properties,significantly increased springiness,decreased hardness,gumminess,cohesiveness and resilience,and the sensory evaluation score was the highest.Appropriate addition of gluten is conducive to the formation of hydrogen bonds between macromolecules,and promote the maintenance and extension of starch protein network structure,so as to improve the quality of steamed bread.(4)With the increase of oat ?-glucan,the total moisture content and specific volume of CSB firstly increased then decreased,the hardness and cohesiveness firstly decreased then increased;the free sulfhydryl content,weakly bound water and free water content increased,while,the content of strongly bound water,relative crystallinity and long-range ordering decreased.Oat ?-glucan can bind to starch molecules through hydrogen bonds or compete with protein to absorb water,thus inhibiting the recrystallization of CSB starch and delaying retrogradation.Changing the composition of gluten,starch and polysaccharide of wheat flour can delay the staling of CSB starch and improve the quality of CSB to a certain extent.