TITLE:
Pectinmethylesterase extraction from orange solid wastes: Optimization and comparison between conventional and ultrasound-assisted treatments
AUTHORS:
Antonio D. Rodriguez-Lopez, Luis Mayor, María M. Galfarsoro, Jorge Martinez-Otalo, Esperanza M. Garcia-Castello
KEYWORDS:
Orange Peel; Solid-Liquid Extraction; Ultrasound-Assisted Extraction; Pectinmethylesterase; Press Liquor
JOURNAL NAME:
Agricultural Sciences,
Vol.4 No.9B,
November
6,
2013
ABSTRACT: During orange juice
production, a half of fresh oranges weight is considered as production waste
(peels, pulp, seeds, orange leaves and damaged orange fruits). An alternative
for the management of these wastes is their treatment by addition of lime and a
latter pressing, obtaining a press cake and a press liquor rich in sugars (10° Brix)
and citric acid, protein, pectin and ethanol. For non-thermal concentration of
press liquor to obtain citruss molasses (65°-70° Brix), the removal of pectin
is necessary. Traditionally, depectinization of juices has been done by using
pectinmethylesterase (PME) enzymes from external sources. In this work it performed
the extraction of PME enzymes from orange peels to obtain the optimum
extraction conditions. Two different methods of solventextraction were compared (conventional andultrasound-assisted
methods). For the conventional extraction experiments, a central composite design
with three variables ([NaCl], pH and time) and five replicates of the center
point was used. For ultrasound-assisted extraction, experiments were done at pH
= 5.5 and [NaCl] = 1.25M), varying
extraction time (1-30 min). Response variables were PME activity,
protein content and a ratio between them, named PME effectiveness (ηPME). At the same experimental
conditions (pH =5.5, [NaCl] = 1.25 M, t = 15 min) it was found that conventional extractions led to slightly better results in terms of ηPME than ultrasound-assisted extraction method.