Although　Spirulina　protein　can　be　effectively　extracted　by　ultrasonic　treatment,　the　subsequent　ultrafiltration　for　protein　purification　is　always　inefficient.　Several　carbohydrases　and/or　ethanol　were　tested　to　improve　the　efficiency　of　ultrafiltration,　and　the　key　components　that　influence　the　purification　were　analyzed.　The　results　showed　that　Viscozyme®　L　treatment　enhanced　the　Spirulina　protein　extraction　yield　from　89　%　to　99　%.　Treated　by　Viscozyme®　L,　protein-polysaccharide　complexes　with　a　molecular　weight　of　approximately　175　kDa　had　reduced　leading　to　a　reduction　of　particle　size　from　4800nm　to　460nm.　In　comparison,　individual　carbohydrase　had　little　effect　on　the　crude　extracts.　In　the　subsequent　ultrafiltration　(100kDa　MWCO),　the　Viscozyme®　L　treated　crude　extract　had　a　purity　of　74　%　in　the　retentate　only　10　%　higher　than　that　without　enzyme.　When　alcohol-soluble　components,　including　97　%　of　chlorophyll,　were　removed　by　ethanol,　the　complex　of　the　protein-polysaccharide　complex　(156　kDa)　in　Viscozyme®　L　treated　crude　extract　was　depolymerized　to　two　fractions　(protein　of　132　kDa　and　polysaccharide　of　99　kDa).　This　depolymerization　facilitated　the　follow-up　ultrafiltration,　yielding　a　Spirulina　protein　fraction　with　a　purity　exceeding　96　%.　The　high-purified　spirulina　protein　contained　more　than　45　%　essential　amino　acids,　which　can　be　applied　to　functional　foods　and　nutritional　supplements.　©　2025