Scale-Up Extraction Of Functional Substances From Microalgae And Biological Activity Evaluation

With the rapid development of economy and society, more and more people are concerned about reasonable and balanced diet, demands for functional foods and health products containing bioactive substances are increasing. Microalgae are rich in nutrients and various bioactive substances, scale-up extraction of the bioactive ingredients from microalgae and processing into cost-effective health products will be of great value and application prospect. This paper takes Spirulina platensis, Chlorella pyrenoidosa and Haematococcus pluvialis as research objects, using Ultrasonic circulating countercurrent extraction equipment and supercritical fluid extraction device to extract active ingredients from these three microalgae respectively in a scale-up degree in order to get optimum extraction conditions for different functional components. Effects of different extraction conditions on the extraction rate of the active ingredient extraction will be investigated. This paper also studies whether water extracts of Spirulina have immunoregulatory effects on animals as well,The main experimental results were as follows:1. Ultrasonic circulating countercurrent extraction equipment to extract water-soluble substances from Spirulina, the effects of different extraction methods on the yield of water-soluble polysaccharide and phycobiliprotein were studied. The results showed that optimal extraction conditions from small test can’t be directly amplified because phycobiliprotein content was too low in this alcohol extraction first then water extraction method. After improving scale-up process, the target extract(phycobiliproteins and spirulina polysaccharide) in the powder were spray dryied, it tunred out that the concentration of phycobiliprotein and water-soluble polysaccharide was 31.81%,4.24% respectively, the yield of phycobiliprotein and water-soluble polysaccharide was 11.24%,2.21% respectively. The optimum conditions for extracting water-soluble substances from Spirulina were: 45 ℃,3 h, solid-liquid ratio(algae residue: phosphate buffer, g/m L) 1: 6, water extraction twice, temperature was raised to 70 ℃ at the third time.2. Select immunocompromised animal model, the effects of water extracts from spirulina on the immune function of mice were investigated in terms of body weight, organ coefficient of spleen and thymus, spleen lymphocyte proliferation and NK cell activity. The results showed that different doses of aqueous extract of Spirulina were of no significant difference in body weight in immunosuppressed mice; high dose group of Spirulina aqueous extract was significantly increased(p<0.05)compared with the model group in terms of thymus coefficient; middle and high dose group of Spirulina aqueous extract were significantly increased compared with the control group in terms of stimulation index(p<0.05~0.01); middle and high dose group of Spirulina aqueous extract were significantly increased compared with the control group in terms of NK cell kill rate(p<0.01). It turned out that aqueous extract of Spirulina could increase body weight of of immunocompromised mice, promote lymphocyte transformation, enhance NK cell activity and its effects were not much different with positive control group(gypenosides). Spirulina aqueous extract can enhance immune function and show dose-effect relationship.3. Use circulating countercurrent extraction equipment to extract functional components from chlorella, a comparative study of scale-up extraction of water-soluble and alcohol-soluble substance under different extraction conditions was perfromed. The results showed that, contents of the bioactive substances extracted from Chlorella by no-freezing fixed-solvent extraction method were significantly higher than other two methods. Total extraction rate of Chlorophyll, carotenoids and fatty acids were 73.87%, 93.29% and 91.59% respectively. The optimum conditions for extracting alcohol-soluble substances from Chlorella were: 40 ℃, ultrasonic 30 min, solid-liquid ratio(algae powder: ethanol, g/m L) 1:6, alcohol extract three times. Fixed solvent enlarge Chlorella prepared aqueous composition of water-soluble proteins and polysaccharides in high yield on reducing solvent, 14.85% and 4.55% respectively. The optimum conditions for extracting water-soluble substances from Chlorella were: 45 ℃, 3 h, solid-liquid ratio(algae residue: phosphate buffer, g/m L) 1: 6, water extraction three times, temperature was raised to 70 ℃ at the third time.4. The ultra-pressure cell disruption method was applied to breaking thick-walled spores in order to optimizating the rate of cell disruption and extraction of astaxanthin. Cell disruption rate of Haematococcus pluvialis was 98.21%. After vacuum drying and granulation, supercritical CO2 extraction of was optimized by orthogonal experiments. It turned out that the best condition for astaxanthin extraction was 30 MPa, 50 ℃, entrainer(95% ethanol, V/V) 300 m L, the highest rate of astaxanthin extraction was 83.79%.