Enzymatic hydrolysis of flavonoids and pectic oligosaccharides from bergamot (Citrus bergamia Risso) peel

Pectinolytic and cellulolytic enzymes (Pectinase 62L, Pectinase 690L, and Cellulase CO13P) were
used to evaluate the solubilization of carbohydrates and low molecular weight flavonoids from bergamot
peel, a major byproduct of the essential oil industry. The enzymes were characterized for main-chain
and side-chain polysaccharide hydrolyzing activities and also against pure samples of various
flavonoids previously identified in bergamot peel to determine various glycosidase activities. The
addition of Pectinase 62L or 690L alone, or the combination of Pectinase 62L and Cellulase CO13P,
was capable of solubilizing between 70 and 80% of the bergamot peel, and up to 90% of the flavonoid
glycosides present were cleaved to their aglycones. Cellulase CO13P alone solubilized 62% of the
peel but had no deglycosylating effect on the flavonoid glycosides. Over a 24-h time course, a rapid
release of cell wall carbohydrates was observed after treatment with Pectinase 62L, with a concurrent
gradual hydrolysis of the flavonoid glycosides. Size-exclusion chromatography of the solubilized extract
showed that after 24-h incubation, the majority of the solubilized carbohydrates were present as
monosaccharides with a smaller proportion of oligosaccharides.