Extraction, enzymatic properties and application of laccase from Pleurotus citrinopileatus residue.

[Objective] Explore a low-cost laccase preparation method that can be used for juice clarification. [Methods] The extraction method, optimal reaction conditions and preparation conditions of enzyme powder were optimized, and the prepared laccase powder was applied to blueberry juice clarification. [Results] The optimal extraction conditions for laccase were as follows: citric acid buffer with pH 4.8, solid-liquid ratio of 1:5 (g/mL), extraction temperature of 50 °C, and extraction time of 4 h. The optimal conditions for laccase reaction were as follows: reaction temperature 30 °C, pH 4.8, Cu²⁺ concentration 10 mmol/L, Mn2+ concentration 5 mmol/L. The optimal conditions for the preparation of enzyme powder were as follows: maltodextrin and skimmed milk powder were mixed as drying aids according to the mass ratio of 1:1, the air inlet temperature was 140 ?, and the feed flow rate was 160 mL/h. The degradation rate of total phenols of blueberry was as high as 63.5% under the conditions of laccase dosage of 6 U/10 mL, enzymatic hydrolysis temperature of 55 °C and enzymatic hydrolysis time of 120 min. [Conclusion] Laccase extracted from the residue of Ulmus lum mushroom using an optimal process can be used for the clarification of blueberry juice. [ABSTRACT FROM AUTHOR]