Abstract: Alcalase protease was used to hydrolyze the protein extracts of Spirulina to produce polypeptides. The effects of pH, enzyme dosage, hydrolysis time and temperature on degree of hydrolysis were investigated by single factor test respectively, and these factors were optimized by response surface methodology (RSM) which was designed based on Box-Behnken central combination. The optimum hydrolysis conditions were as follows: pH=7, enzyme dosage (ratio of enzyme to substrate) 4 300 U·g^-1, hydrolysis temperature 55℃ and time 160 min.The hydrolysates of Spirulina protein were ultrafiltrated by 5 kD hollow fiber ultrafiltration membrane and purified by SephadexG-25 column chromatography with PBS (pH=7) as eluent. Low-molecular-weight peptides were collected, and the molecular weight was from 307 D to 1 450 D．

Key words: Spirulina, peptides, response surface methodology, enzymatic hydrolysate