Research On Quality Control Technology Of Freeze-dried Strawberries

With the development of freeze-drying technology,freeze-dried strawberry is deeply loved by the majority of consumers.Frozen strawberry is widely used in processing enterprises because of its annual supply.But strawberry happens Browning during processing and storage,organization,collapse and microbes increased,etc.,to solve these problems,this experiment adopts the clothing technology for strawberry ice armor plating color,bacteriostasis and solidification processing,and explore the comprehensive treatment of freeze-dried strawberries resulted in different storage temperatures condition changes,dynamic model and the shelf life prediction model was set up,It provides basis for theoretical research and practical production in this field.The results are as follows:1.The quality of freeze-dried strawberry processed by strawberry raw materials in different frozen states is different.The sensory quality of freeze-dried strawberry slices processed by sub-frozen strawberry raw materials is the best,and can improve the texture properties of freeze-dried products,such as hardness,so that the taste of products is more crisp and easy to rehydrate.Therefore,when frozen strawberry is used as raw material for industrial production,it can be slowed to sub-frozen state before processing,which can not only reduce the difficulty of segmentation,but also improve the product quality.Under different conditions,1.00%citric acid,1.50%D-isoascorbate sodium and 1.00%trehalose had the best effect on the color protection of strawberry anthocyanins.The combination of 1.00%citric acid and 1.00%trehalose had the best color preserving effect on strawberry,and the absorbance value was 1.17 when the light time was 6 h,which was 1.19 times that of the control group.2.The ice coating treatments of potassium sorbate,dehydroacetic acid and glucose oxidase（GOD）had certain bacteriostatic effect on freeze-dried strawberry,and 0.15%GOD had the best bacteriostatic effect.The total number of bacteria in freeze-dried strawberry was 3.60Ig CFU/g when the storage time was 30 days.Compared with the control,the deformation rate of freeze-dried strawberry decreased and the yield rate increased,indicating that 1.50%Ca Cl₂had a good supporting effect on the tissue structure of freeze-dried strawberry and effectively slowed down the tissue collapse.3.Considering the raw materials,color protection,antibacterial and curing techniques of freeze-dried strawberry,1.00%citric acid,1.00%trehalose,1.50%Cacl₂and 0.15%GOD were used as complex ice coating solution to carry out comprehensive quality control technology on strawberry.When the freeze-dried strawberry was prepared for 90 days,compared with the control,The absorbance value was 0.34 higher,the yield was 5.30%higher,the rehydration ratio was 2.87 higher and the deformation rate was 4.80%lower.4.The study of freeze-dried strawberry dynamic model showed that the zero-order dynamic model was established based on the color difference value and the absorbance value.After verification,the average relative errors of the color difference value and the absorbance value were 7.90%and 5.20%respectively,both less than 10.00%,indicating that the model has high prediction accuracy.The shelf life prediction model shows that the color difference value has the highest correlation with sensory evaluation.The shelf life prediction model with color difference value as the end point was established,which could effectively monitor and predict the shelf life of freeze-dried strawberry stored at 15-45℃.