Effect of a Simulated Kilning Regime on the Profile and Antioxidant Activity
of the Free Phenolic Acids Extracted from Green Malt
MBAA TQ vol. 42, no. 3, 2005, pp.
204-208 |
VIEW ARTICLE
Elizabeth L. Inns (1), Lesley A. Buggey (2), Harry E. Nursten (1), and
Jennifer M. Ames (1). 1. School of Food Biosciences, The University of Reading,
Whiteknights, Reading, RG6 6AP, U.K. 2. Brewing Research International, Lyttel
Hall, Nutfield, Surrey, RH1 4HY, U.K.
Abstract
Free phenolic acids were extracted from a laboratory-produced sample of green
malt. Aliquots of the phenolic acid extract were heated from 25 to 110�C over
27 h, representative of a commercial kilning regime. Samples were taken at
regular intervals throughout heating and were assessed for changes in
antioxidant activity by both the
2,2(prime)-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical-cation
scavenging (ABTS(^•+)) and the ferric-reducing antioxidant potential (FRAP)
assays. Changes in the profile of the phenolic acids of the extracts were
determined by HPLC. Overall, there was a decrease in both antioxidant activity
level and the level of phenolic acids, but as the temperature increased from 80
to 100�C, there was an increase in both the antioxidant activity level and the
level of detected phenolic acids.
Keywords: antioxidant activity, kilning, malt, phenolic acids
S�ntesis
Se extrajeron �cidos fen�licos libres de una muestra de malta verde
producida en el laboratorio. Al�cuotas del extracto fueron calentadas de 25�C
a 110�C en 27 horas, semejante al calentamiento en un horno de malteado. Se
tomaron muestras a intervalos regulares durante el calentamiento y se le midi�
el cambio en la actividad antioxidante, tanto mediante el ensayo del contenido
de reductores (�scavengers�) de radicales de cationes (ABTS(^•+))
2,2�-azino-bis (�cido 3-etilbenzotiazolina-6-sulfonico) como por el ensayo de
la potencial antioxidante reductor del ion f�rrico (FRAP, por sus siglas en
ingl�s). Cambios en el perfil de loa �cidos fen�licos de los extractos fueron
determinados por HPLC. Al final del calentamiento hubo una reducci�n total
tanto en la actividad antioxidante como en el nivel de los �cidos fen�licos,
pero en la etapa de 80�C a 100�C aument� tanto la actividad antioxidante como
el nivel de los �cido fen�licos detectados.
Palabras claves: actividad antioxidante, horneado, malta, �cidos
fen�licos
