Research On Storage Technology Of Spirulina

The Spirulina is widely studied and used due to its high protein content and its fighting against radiation damage, cancer, enhancing immunity, lowering cholesterol and other effects. In order to make the excellent Spirulina play an important role in scientific research and production as long as possible, it is necessary to adopt the appropriate methods to keep the activity of the algal, avoid pollution and degrading, keep the effects of genetic stability. To obtain more secure and effective preservation methods, four preservation methods of Spirulina including immobilization storage, succeeding preservation, cryopreservation and freeze-drying method based on 8 Spirulina strains were researched in this paper.The study contents and results are as follows: 1、The immobilized preservation methodTaking F-971 Spirulina for example, firstly, the best preservation solutions of three kinds of immobilized carrier were determined by the orthogonal experiment design. Agar immobilized method is 1% agar concentration, cell density of 1.0 ×104 cfu/ m L and no glucose; Immobilized method for k- carrageenan is 2% carrageenan concentration, cell density of 1.0 ×104 cfu/ m L and no glucose; Immobilized method for Na-alginate is 2% sodium alginate concentration, 0.3 M Ca Cl2 concentration, diameter of 2.8 mm, cell density of 1.0 ×105 cfu/ m L. Then explored the influence of the number of Spirulina cells fixed on unit carrier and the Spirulina’s shape on three kinds of immobilized preservation effect. The results indicated that the preservation effect decreased obviously while the number of Spirulina cells fixed on unit carrier increased gradually for the three methods of immobilized preservation of spirulina; Agar and k-carrageenan immobilized methods are suitable for long linear Spirulina preservation, and sodium alginate immobilized method is not suitable for the preservation of short linear Spirulina. Four months later, the algal species of three methods of immobilization storage preservation were activated culture and measured their relative growth rate. The results show that the method of carrageenan immobilized algae strains of high survival(7 strains) and the relative growth rate is higher(0.062-0.143), so carrageenan is the preferable material for Spirulina immobilized preservation. 2、The succeeding preservation methodThe algae strains with liquid succeeding preservation method and solid succeeding preservation method under the condition of different illumination and temperature preservation for four months. By determinating and comparing the content of chlorophyll and the relative growth rate we found the best preservation conditions for liquid succeeding preservation method is 20 ℃, 500 lx. By comparing the relative growth rate of solid-preserved algae storaged under different preservation conditions we found the best condition of solid medium succeeding preservation method of optimal is 6% agar concentration, natural light, 4 ℃. 3、The cryopreservation methodThe optimal conditions of the TTC–dehydrogenase assay on Spirulina viability was firstly determined by single factor and orthogonal test and the results are as follows : TTC concentration is 0.1%, p H value of buffer solution is 8.0 to 8.5, the concentration of ethanol is 60%, the incubation time is 5 h and the incubation temperature is 35 ℃. Then the F-351 which was the most low temperature resistance algal of 8 experimental algae that was selected by iodometric method was used as experimental material to explore the optimal conditions of cryopreservation. Eventually determined the Spirulina crypreservation method, the algal cell density is 1.0×107 cfu/m L and domesticated in 4 ℃ refrigerator for 72 h, with 10% sucrose solution do cryoprotectant, after blending in 0 ℃for 3 h, then preserved in liquid nitrogen.8 strains were storaged by the optimized cryopreservation method, the results showed that in addition to F-350, F-1070, F-902 which are no-resistant to low temperature lost cell activity in the preservation for four months. The other 5 kinds of Spirulina can resurrection during a certain period of time for the growth of normal. So the cryopreservation method can be applied to preservation of good low temperature resistance algal. 4、The freeze-drying preservation methodTaking F-351 Spirulina for example, ascorbic acid was selected as the best cryoprotectant for vacuum freeze-drying. By studying the influence of freeze-drying time to the growth of Spirulina, we found that the algal is unable to restore growth when the loss rate of water for algal cells was 78.94%. So the drought resistance of Spirulina is poorer, and the freeze-drying method is not suitable for Spirulina’s storage. 5、The comparison of different storage methods of SpirulinaIn conclusion, we found that the succeeding preservation method is suitable for all algals due to its easy operation and high survival. Using the cryopreservation method to long-term preserve good low temperature resistance algal is better and can extend storage period. Immobilized method for carrageenan carrier has the best storage effect and can be used in some algals’ long-term preservation.