Mulberry is the flower fruit of the deciduous tree mulberry of Moraceae. Mulberry is also known as mulberry fruit and mulberry jujube. Studies have found that mulberries contain a large amount of anthocyanins, which have antioxidant, anti-inflammatory, antithrombotic and other activities. Due to the thin skin and juicy characteristics of fresh mulberry fruit, it is especially intolerant to storage and is easily corrupted, which affects the edible quality and commodity value. It is usually processed into fruit juice, jam, jelly, fruit wine, fruit vinegar and other products, and also processed into powder by drying.

The processing of fresh mulberries into mulberry fruit powder not only prolongs the storage period of mulberries, reduces the costs of storage, transportation and packaging, but also broadens the scope of application. At present, there are two important problems in the study of dried fruit powder, such as loss of active ingredients, easy drying, and easy agglomeration and adhesion. The drying methods used in fruit powder processing mainly include spray drying, hot air drying, vacuum freeze drying, microwave drying, variable temperature and pressure difference puffing drying, etc. Spray drying is used more, but the temperature is high, heat-sensitive substances are easily destroyed, and nutrients are easily lost, and spray drying often uses fruit juice for drying, and the utilization rate of the filter residue is low. Hot air drying is relatively cheap and easy to obtain, but it has a large loss of nutrients. Vacuum freeze-drying can effectively preserve the active substances in the material, which is a better drying method. Ye Lei et al. reported that the retention rate of Vc, total phenols and anthocyanins in fruit powder by vacuum freeze-drying can reach more than 95%. Sablani et al. showed that after freeze-drying, the anthocyanin content of red raspberries was increased by 7% to 26%, and that of blueberries was increased by 6% to 32% compared with fresh samples. The anthocyanins in mulberries are unstable and can be degraded by enzymes, sugars and other phenolic acids in their own cells, and freeze-drying can solve this problem better than other drying methods. Because fruits and vegetables are rich in organic acid components such as glucose, fructose, sucrose, malic acid, these substances have low glass transition temperature (Tg) and good water absorption, which will cause dry fruit and vegetable powder to easily agglomerate and cause cohesion. For substances with higher Tg such as dextrin and starch, the agglomeration phenomenon and cohesive state can be effectively improved.

Commonly used freeze-drying auxiliaries include macromolecular substances such as maltodextrin, cyclodextrin, gum arabic, pectin, etc. These substances have high Tg, and can increase the Tg of fruit and vegetable powder after being added, and prevent them from freezing during freeze-drying and storage. Block and bond.

The whole fruit is made into pulp by wet pulverization process, and then the pulp is vacuum freeze-dried to obtain mulberry fruit powder, and the preparation process of mulberry powder is optimized by orthogonal test, in order to prepare mulberry fruit powder with high anthocyanin content and good water solubility ; And study the effects of pH, temperature, sugar, sodium chloride, preservatives and other external conditions on the stability of anthocyanins in mulberry fruit powder, which is the basis for the later use of mulberry fruit powder in pasta products, puffed foods, meat products, dairy products, candy products, cultured products, etc. The application in the field of food processing such as baked products provides a theoretical basis.