Determination of synthetic phenolic antioxidants in food items using HPLC and total antioxidants using FIA approaches
Loading...
Date
2007
Authors
Yong, Yek Sing
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
Synthetic phenolic antioxidants (SPAs) are food additives that are added to food
to extend their shelf life. While there is a growing trend towards using natural
antioxidants, synthetic antioxidants continue to be widely used. The use of
synthetic antioxidants is regulated by the Food Act and Regulations of Malaysia,
which stipulates that the maximum level permitted for the combination of the
synthetic antioxidants in a few food items is 200 ppm. Due to the toxicity of
these SPAs, analytical techniques for their determination is required.
Two analytical methods for the determination of: (i) SPAs (propyl gallate (PG),
tert-butyl hydroquinone (TBHQ), butylated hydroxyanisole (BHA) and butylated
hydroxytoluene (BHT), and (ii) total antioxidants in cooking oil, bread spread
and cheese samples are described.
Liquid-liquid extraction was used to isolate the SPAs from the food items. The
effect of extracting solvents and extraction conditions were investigated for their
recoveries using HPLC. Under the optimized HPLC conditions, baseline
separation of the four SPAs in less than 8 minutes was achieved, and
recoveries in the range of 93.0-108.0% for PG and TBHQ meanwhile 96.0-
101.0% and 74.0-94.0% for BHA and BHT, respectively when spiked with 50
ppm and 200 ppm SPAs to cooking oil, bread spread and cheese were found.
The levels of SPAs in all food items analysed were below the legal limits.
Two approaches were developed for the flow injection analysis (FIA)
determination of total antioxidants based on spectrophotometric detection. In
the first assay, the Fe(III)-phen system that was based on the reduction of
Fe(III) to Fe(II) by the phenolic antioxidant followed by addition of 1,10-
phenanthroline (phen) to form a red-orange Fe(II)-(phen)3 complex was
developed. The second method (ABTS radical scavenging system) was based
on the bleaching of the green coloured ABTS radical (ABTS.+) in the presence
of antioxidants. The optimized FIA procedure is linear over 1.0-80.0 ppm and
1.0-50.0 ppm for Fe(III)-phen and ABTS radical system, respectively with
detection limits of 0.2 and 0.5 ppm. Sampling rate of 30-40 samples h-1 was
achieved. Good correlation (r2= 0.905) between the proposed methods and the
manual spectrophotometric methods were found when applied to the
determination of total antioxidants in 38 food items.
Description
Master
Keywords
Chemical science , Synthetic phenolic antioxidants , Food item