Objective To improve the development and application value of resourcos of Auricularia auricula (L. ex Hook) Underw, extraction process of uronic acid from Auricularia auricula (L. ex Hook) Underw was optimized.
Method By comparing the uronic acid yield, applications of ultrasound, microwave, light, neutral protease, cellulase, and/or pectinase were incorporated in the extraction to maximize the production. Critical processing conditions including substrate particle size, pectinase dosage, solvent to substrate ratio, temperature, time, pH, ultrasonic power, and ultrasound application time were evaluated in a single factor test. The ultrasound-assisted process with added pectinase was selected for the process optimization using the response surface method with 4 factors and 3 levels.
Result The optium method for extracting uronic acid from A.auricula were ultrasound and pectinase. The optimum extraction conditions were determined to include the substrate particle size of 58 μm, pectinase addition at 0.25%, solvent to substrate ratio at 100 mL·g-1, temperature at 50℃, 2 h process duration, pH at 5.50, and 540 W ultrasonic treatment for 30 min. The response surface experiment indicated that a solvent to substrate ratio of 110 mL·g-1, pH at 5.60, ultrasonic power of 540 W, and temperature at 49℃ would maximize the uronic acid yield at 7.95‰, which was 201% of what a traditional hot water method delivered.
Conclusion The newly established highly efficient process to extract uronic acid from ultra-fine A. auricula powder applied 540 W ultrasound, added pectinase, used 110 mL per gram of substrate, adjusted pH to 5.60, and maintained a temperature at 49℃ throughout the process, which optimized the extration process of uronic acid of A.auricula, improved the economic value and provided reference for exploiting resources of A.auricula.
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