Abstract
An automated method for the determination of pectinesterase (PE) activity in food based on the absorbance decrease of a Bromothymol Blue (BTB) solution due to the α-D-polygalacturonate residues formed in the pectin demethoxylation catalysed by pectinesterase is presented. The approach used is a semiautomatic flow injection (FI) approach. The method exhibits a linear range between 0.1–1.5 U/mL, with a precision, expressed as RSD, of 4.3% and a sampling frequency of 8h−1. The usefulness of the method was tested by determining PE activity in natural and manufactured juices and also applying the standard addition method, with recoveries between 84.8 and 102.6 %.
ACKNOWLEDGMENT
The Comisión Interministerial de Ciencia y Tecnología (CICyT) is thanked for financial support (Project No. PB97/0505). F.D.R expresses her gratitude to the Leonardo da Vinci Programme (UE project) for a grant.