Extraction of pectins with different degrees of esterification from mulberry branch bark.

Pectins were extracted from mulberry branch bark, a byproduct of the sericulture industry. A single-factor experiment was used to optimize the production conditions. Under optimal conditions, the galacturonic acid yields from bark with and without epidermis were 61.73 + or - 1.39% and 35.12 + or - 0.24%, respectively. The extracted pectins mainly consisted of galacturonic acid with a trace amount of neutral sugars, and the total galacturonic acid content in the pectins extracted from the bark without epidermis reached 85.46 + or - 2.76%. Pectins extracted from bark without epidermis had a higher degree of esterification (71.13 + or - 1.67%) than those extracted from bark with epidermis (24.27 + or - 2.89%). Pectin solution from bark without epidermis showed higher apparent viscosity, suggesting its higher gelation ability. Thus, the mulberry branch bark is a potential source of pectin with different degrees of esterification.