Optimization Of Drying Process For Marine Biocontrol Yeast Rhodosporidium Paludigenum

The marine yeast Rhodosporidium paludigenum Fell & Tallman was separated by our laboratory. Previous study found that it was new biocontrol antagonist yeast and had good inhibitory effect on a variety of fruits and vegetables such as apples, pears, winter jujubes and tomatoes. The preparation of dry yeast with high activity is one of the key technologies in its commercialization. The paper mainly investigated the preparation method and the optimized the spray drying process of R. paludigenum. Then the biocontrol effect of yeast powder prepared by spray drying was proved. The main research results were as follows.1. The spray drying process of R. paludigenum was given, including the yeast activation, seed cultivation, fermentation cultivation, pretreatment of fermentation liquid, spray drying and collection of yeast powder.2. The factors such as heat shock temperature and time, salt concentration of culture medium, import temperature of spray drying, feed rate and protectants concentration whose effect on cell survival of R. paludigenum was researched. Orthogonal test was used to optimize spray drying process. The best spray drying conditions was as follows:heat shock temperature was 39℃, heat shock time was 5 minutes, skim milk concentration was 20% and salt concentration of culture medium was 0.5%.3. Rehydration method's influence on the biocontrol effect of R. paludigenum in apples and pears was investigated. The results showed that the yeast powder suspension with sterile water was centrifuged then resuspended by sterile water or sterile saline water. The suspension has good biocontrol effect.4. Two storage temperatures' effect on activity of freeze-dried R. paludigenum was studied. The results showed that cold storage was suitable to store active dry yeast. Stored at 4℃for 3 months, the yeast could be used for restraining the decay of fruits, although the living cells dropt a litter.