Study On Comprehensive Utilization Of Spirulina Algae Residue

Spirulina is rich in nutrients,among which the extraction of phycocyanin is an important part of the deep processing of Spirulina.Water is used as a solvent for extracting phycocyanin at home and abroad,and its extraction rate is about 10%,and the remaining part（algae residue）accounts for about 40%of the original algae powder.The remaining algae residue is generally used as feed or fertilizer,and its utilization value is extremely low.In this study,algae residue was used as the raw material to study the content of its main active substances,and the supercritical CO₂ extraction process parameters for the active substances were optimized.The main bioactive components and part of the biological activities in supercritical extraction of algae residue and the feasibility of using the algae residue as a nutrient protein powder were studied.The main research results are as follows:（1）Through detection and analysis,the total protein content,total lipid content,polysaccharide content,and polyphenol content of the algae residue were 71.60%,4.02%,4.78%,and 225mg/100g,respectively.The chlorophyll content was 1.60%,the carotenoid content was 169mg/100g,and the heavy metal content all complied with national standards.（2）Taking the yield of algae residue as an indicator,the optimal extraction process parameters were obtained through single factor and orthogonal experiments:CO₂ flow rate was 0.3L/min,the pressure was30MPa,entrained flow rate was 0.83m L/min,the temperature was 40°C.The best extraction rate reached1.98%.（3）The content of the main active substances in the algae residue oil was studied,and every 100g of the algae residue oil contained 1.95gβ-carotene,9.84g polyphenols,and 18.56mgα-tocopherol.Algae oil contained 23 kinds of fatty acids,including 11 kinds of unsaturated fatty acids such as DHA,nervonic acid,γ-linolenic acid,accounting for 94.55%of total fat.（4）The results of the biological activity study of algae residue showed that the scavenging IC₅₀ value of the algae residue on DPPH free radicals was 1.10±0.08mg/m L,and the scavenging IC₅₀ value of superoxide anion free radicals was 43.20±1.30mg/m L.The IC₅₀ value ofα-glucosidase inhibition is252.02±2.70μg/m L,the IC₅₀ value of xanthine oxidase inhibition is 12.83±0.90mg/m L,and the IC₅₀ value of angiotensin-converting enzyme inhibition is 1.90±0.12mg/m L,proving that the algae residue oil has good biological activity.（5）The feasibility study of the residue of algae residue as a nutritional protein powder,the protein content of the residue of algae residue was 72.01%,the water content was 4.78%,and the crude polysaccharide content was 4.32%,the total amount of amino acids was as high as 65.46g/100g.when the addition of maltodextrin co-solvent was 6%,the solubility of the algae residue was the best,reaching61.08%,and the nitrogen soluble index value was 60.95%.When the residue of algae oil was digested by simulated gastric fluid for two hours,the digestibility reached 29.67%,and the final digestibility after digestion by simulated intestinal fluid was 64.32%.In summary,this study broadens the utilization of algae residues,improves the economic benefits of Spirulina deep processing and the full utilization of this resource,which promotes the virtuous circle and sustainable development of the Spirulina industry.