Abstract:With the koji enzyme activity and crude soy sauce quality as indicators，the effects of ultrafine and conventional grinding pretreatments on the brewing of laver soy sauce were explored. The koji preparation process was optimized by single factor tests and response surface methodology. The results showed that the protease activity in the koji followed the order of no addition of laver > addition with conventionally grinded laver >addition with ultrafine grinded laver. Moreover，the protease activity was higher in the koji with Porphyra yezoensis than in the koji with Porphyra haitanensis in the case of ultrafine grinding. After 180 days of fermentation，the viscosity of the soy sauce produced with ultrafine grinded laver was higher than that in the soy sauce produced with conventionally grinded laver，and both were higher than that of ordinary soy sauce. The optimal koji preparation parameters of laver soy sauce were fermentation with the inoculation amount of 0.50% at 32 °C for 48 h. Under these conditions，the protease activity reached up to 2 109.00 U/g. The verification test with the optimized koji preparation process showed that ultrafine grinding pretreatment increased the utilization rates of proteins in P. yezoensis and P. haitanensis soy sauce by 5.91% and 6.05%，respectively，compared with the conventional grinding pretreatment.