Preparation And Recoverability Research Of Instant Tremella Fuciformis Soup

Instant Tremella Fuciformis(T.Fuciformis)soup is a block product formed by drying fresh soup.It could rehydrate to a similar state to fresh soup by adding an appropriate amount of water directly when eating.It is widely welcomed by consumers for its easy portability and convenience in eating,thus showing broad market prospects.In order to ensure good appearance and recovery of the final product,the drying of the product is usually treated by freeze drying.However,the freeze-drying method has the problems of long time,high energy consumption and high cost.Based on the above problems,starting from the preparation of instant T.Fuciformis soup,this paper firstly explored the effect of the cooking process on the quality of instant T.Fuciformis soup.Afterwards,dehydration and concentration pretreatment and combined drying were adopted in order to reduce the time required for drying,reduce the energy consumption of preparation,and reduce the production cost on the basis of ensuring a good appearance and recoverability of the instant T.Fuciformis soup.The main contents and results were as follows:1、Effects of the cooking process(material-to-liquid ratio and cooking time)on the quality of instant T.Fuciformis soup were explored.The results showed that the cooking process affected the textural properties and recoverability of instant T.Fuciformis soup.In the range of material-to-liquid ratio of 1:6～1:14 and cooking time of 30～90 min,with the decrease of the material-to-liquid ratio and the prolongation of the cooking time,viscosity of soup increased,the hardness and fracturability of instant T.Fuciformis soup increased and the debris decreased.However,the rehydration capacity of the product decreased.After rehydration,the rheological properties of the product were closely related to the polysaccharide content in the soup.The rehydrated soup showed frequency and temperature dependence and was thermally reversible.Therefore,based on the convenience of product transportation and packaging,and the recovery results of freeze-dried products,suitable conditions were selected: the ratio material-to-liquid for 1:10 and cooking time for 60 min was applied in the follow-up research.2、The drying time was reduced by concentrating T.Fuciformis soup before drying.Effects of removing moisture content(10%～50%)on the quality of the instant T.Fuciformis soup was explored.Compared with the sample without pretreatment,when the water content of the soup was removed within 40%,rehydration capacity,rheological properties and tribology properties of instant T.Fuciformis soup showed no significant difference.In addition,drying time could be reduced by up to 9.5 h per batch.When 50% of the water in the soup was removed,the tremella pieces were seriously agglomerated during the initial rehydration time,the water absorption rate and the rehydration rate of the product was slow.The rehydration capacity decreased significantly compared with other samples.Therefore,drying time of instant T.Fuciformis soup could be reduced by removing less than 40% of the water in the soup through pretreatment.3、The drying time was reduced by employing combined drying.The influence of moisture transfer point and combined drying methods on the quality of instant T.Fuciformis soup was explored.Based on comprehensive product quality(appearance,volume shrinkage,textural properties,rehydration capacity)and drying time,the moisture transfer point of 15 ± 2% was selected for the follow-up combined drying method.The results showed in freeze-vacuum combined drying(FD-VD),freeze-hot air combined drying(FD-HAD)and freeze-far-infrared combined drying(FD-FIRD),the inherent morphology and porous structure of FD-VD dried products was preserved,and the rehydration capacity was best.The retention of volatile substances in FD-VD rehydration soup was the largest,and the rheological properties did not change greatly.At the same time,the friction coefficient was the lowest,and the product taste was the best.In addition,FD-VD could save more than 10 h per batch on the basis of ensuring certain appearance quality and recoverability.Therefore,FD-VD could be used to replace single FD to prepare instant T.Fuciformis soup to a certain extent.