Abstract: Static liquid-state Bacillus licheniformis fermentation was used for pepper decortication and compared with traditional water retting. Meanwhile, the dynamic changes of pectinases, xylanase, cellulase and pH during pepper decortication by the two methods were explored. The results showed that the changes of polygalacturonase (PG) and pectin lyase (PL) revealed a similar pattern with two activity peaks during both decortication processes. However, cellulase activity was low and the pectin esterase (PE) activity remained high. Similar pH changes were observed during both decortication processes pH was between 5 and 5.5 at the end of decortication. Xylanase activity showed two peaks in traditional water retting method and a gradual increase in the late stage of Bacillus licheniformis fermentation. Therefore, pectinase might play an important role during pepper decortication. In the early stage of decortication, PG and PL first acted on pectin substances and damaged the pectin complex structure, and then PE hydrolyzed pectin molecules to form pectic acid accompanied with pH decrease. Further, xylanase activity increased gradually in the late stage of decortication and as a result, hemicellulose was rapidly depolymerized. Therefore, pepper decortication was completed under the synergistic action of multiple enzymes.

Key words: Piper nigrum L., decortication, water retting method, Bacillus licheniformis, pectinase, xylanase, cellulase