Paenibacillus polymyxa Z6 was screened as protopectinase (PPase) producing strain and its PPase activity was 44.4 U/mL. The factors influencing PPase production were identified by a two-level Plackett-Burman design with seven variables. The results indicated that Ca 21 concentration, fermentation time, and temperature were the most influential factors on the PPase production, which were applied in the Box-Behnken design. The predicted maximum PPase activity was 219 U/mL and the experimental maximum PPase activity was 221 U/mL, under the predicted optimum conditions, 170 mg/L Ca
21, 27 8C, and 29 hr of fermentation. The present PPase was composed of both type-A PPase, polygalacturonase; and type-B PPase, arabinanase, and rhamnogalacturonase. Finally, the PPase was applied for the pectin extraction from apple pomace and achieved an average yield of 11.9% with properties like 8.5% moisture content, 1.6% ash content, 3.8 mPaÁS viscosity, and pH 6.1 of 1% solution.
Practical applicationsProtopectinase (PPase) is a "green" way for pectin extraction with the advantages of low emission, rhamnogalacturonase. This PPase was used in pectin extraction from apple pomace and harvested pectin with lower moisture, lower ash, and higher viscosity compared with the chemically produced one, which indicates that this PPase has potential for application in food industry.