Number 187 September 1999
MAFF UK - SURVEY OF 3-MONOCHLOROPROPANE-1,2-DIOL (3-MCPD) IN SOY
SAUCE AND SIMILAR PRODUCTS
Index to MAFF UK Food Surveillance Information
Sheets, 1999
See also:
181: MAFF, UK - Survey of
3-monochloropropane-1,2-diol (3-MCPD) in acid-hydrolysed vegetable
protein (June 1999)
Summary
A survey of 3-monochloropropane-1,2-diol (3-MCPD) in soy sauce
and other similar products available in the UK, which was announced
in a JFSSG Press Release on 31 August,1
has been completed. Forty samples of soy, mushroom soy, oyster sauce
and other sauces were purchased from retail outlets during August
and September 1999 and analysed using a validated method of analysis
with a detection limit of 0.01 mg/kg. The survey was carried out
to check for compliance with the Food Advisory Committee's (FAC's)
recommended limit for 3-MCPD of 0.01 mg/kg following reports that
significantly higher levels had been detected in some brands of
soy sauce in other European countries.
3-MCPD was undetectable in 21of the 40 samples analysed in the
survey, with a further 5 samples (13%) containing very low levels
of between 0.01 and 0.02 mg/kg. However, 9 samples (22%) contained
3-MCPD levels above 1 mg/kg, the highest being 30 mg/kg. The Department
of Health has advised that there is no immediate concern for health,
but officials have contacted the companies concerned to urge them
to take action to reduce levels in line with the FAC's advice. A
follow-up survey will be conducted in one year's time to confirm
that this action has been taken.
Background
3-MCPD is one of a group of chemical contaminants known as chloropropanols.
Originally identified as a contaminant of the savoury ingredient,
acid-hydrolysed vegetable protein (acid-HVP), it has since been
found to occur at low levels in several other foods and food ingredients
as a result of processing, storage conditions or migration from
certain food contact materials.
In 1994, following a review of the available data, the EC Scientific
Committee for Food (SCF) advised2
that "residues of 3-MCPD in food products should be undetectable
by the most sensitive analytical method" and "that all
efforts should be undertaken to develop methods leading to products
not containing chlorinated propanols". The SCF subsequently
reaffirmed this advice in June 1997. In line with the SCF's advice,
the UK's Food Advisory Committee (FAC) has recommended3
that industry take steps to ensure that 3-MCPD is undetectable (i.e.
less than 0.01 mg/kg) in food and, where technologically feasible,
in food ingredients as well.
Officials in the Joint Food Safety and Standards Group (JFSSG)
have recently been notified that the authorities in Denmark, Germany,
the Netherlands and Sweden have found high levels of 3-MCPD (6-124
mg/kg) in several brands of soy sauce. Limited published information
is currently available on the levels of 3-MCPD in soy sauce sold
in the UK, with the only data relating to a survey of five samples
carried out in 1997 which showed that 3-MCPD was undetectable in
all samples. The JFSSG therefore commissioned this survey to determine
the levels of 3-MCPD in soy sauce available in the UK and to check
for compliance with the FAC’s advice.
Methodology
The survey
A total of 40 samples was purchased from major retailers and specialist
supermarkets in London and Leeds during August and September 1999.
Of these samples, 27 were soy sauces and the remainder comprised
mushroom soy, oyster, teriyaki and various other similar sauces.
Most of the products had been imported from the Far East (mainly
China, Hong Kong and Singapore), although a small number had been
manufactured in Europe. This exercise was conducted to collect information
on the broad range of products on the UK market and the sampling
regime was designed to cover as many different products as possible,
not necessarily reflecting the market share of the various brands.
The samples included all the major brands as well as the more minor
brands which were only available from specialist outlets. For each
sample, the batch details, best before date, country of origin and
list of ingredients were recorded on receipt. Two samples (with
different batch codes) were taken for three products to check on
inter-batch variability.
Method of analysis
The sample analysis was carried out at the Central Science Laboratory,
York. Samples were analysed by a validated gas chromatographic-mass
spectrometric (GC-MS) method, using deuterated 3-MCPD as an internal
standard.4 To extract 3-MCPD, saline
solution was added. After sonication, diatomaceous earth was added
and mixed thoroughly. The sample plus diatomaceous earth was transferred
to a glass chromatography column and the non-polar components eluted
using a mixture of hexane and diethyl ether. The 3-MCPD was eluted
using diethyl ether and the sample extract concentrated to a small
volume. A portion of the concentrated sample extract was then taken
for derivatisation with heptafluorobutyrylimidazole (HFBI) prior
to injection onto the GC-MS. Identification of 3-MCPD was based
on the comparison of the full scan mass spectrum of the sample chromatographic
peak with a mass spectrum of HFBI-derivatised 3-MCPD. Quantification
was based on comparison of chromatographic peak areas for 3-MCPD
at m/z 253 and for the deuterated 3-MCPD at m/z 257.
Calibration standard solutions containing 3-MCPD at concentrations
equivalent to 0.006-1.88 mg/kg in an 8 g sample were run with each
batch of samples. The results for samples found to contain over
1.88 mg/kg were confirmed by re-analysis using a reduced sample
size in order to bring the response well within the calibration
range. The limit of detection for this work was assessed as being
0.01 mg/kg.
For quality assurance purposes samples were analysed in batches
comprising: 10 samples; a reagent blank in which sodium chloride
solution was substituted for soy sauce; a sample spiked at 0.01
mg/kg; (or 1 mg/kg for batches consisting of repeat analyses of
samples found to contain more than 1.88 mg/kg 3-MCPD). Quality criteria
were set such that: reagent blanks should not show a 3-MCPD response
greater than that equivalent to 0.006 mg/kg in a 8 g sample; and
the recovery of 3-MCPD added to a sample in each batch at 0.01 mg/kg
(or 1 mg/kg for batches consisting of repeat analyses of samples
found to contain more than 1.88 mg/kg 3-MCPD) should fall within
the range 80-120%.
The analytical data showed that the analyses met the quality criteria
set. Recoveries ranged between 86% and 118%; and reagent blank samples
gave responses equivalent to no higher than 0.005 mg/kg in a 8 g
sample.
Results
The results of the survey are summarised in Table
1. A full list of results, including details of the brand names
for each product, is given in Table 2. The
results show that levels of 3-MCPD were below the FAC’s recommended
limit in 21 of the 40 samples analysed. Levels were between 0.01
mg/kg and 0.02 mg/kg in 5 samples (13%), between 0.02 and 1 mg/kg
in 5 samples (13%) and above 1 mg/kg in 9 samples (22%). Three of
these samples contained more than 10 mg/kg, the highest being 30
mg/kg.
Three products were sampled twice in the survey and the results
are given in Table 3. Levels for one product
were consistently low (i.e. not detectable), but there was considerable
inter-batch variation for the other two products.
Interpretation
The results show that two-thirds (26 samples) of the 40 samples
analysed contained 3-MCPD at levels very close to or below the FAC's
recommended limit of 0.01 mg/kg (Figure 1).
This is a significantly higher proportion than has been so far been
found in other European countries, although most of these surveys
have concentrated on a smaller number of brands. For example, of
the 41 samples that have been analysed so far in Germany, 12 contained
less than 1 mg/kg, four contained 1-10 mg/kg and 25 had levels in
excess of 10 mg/kg, the highest being 124 mg/kg. Similarly, in the
Netherlands, where only three brands have been analysed, four out
of 12 samples were reported to contain undetectable levels of 3-MCPD,
with 6 containing between 0.02 and 1 mg/kg and two between 1 and
10 mg/kg.
A significant number of samples in the UK survey (22%) contained
levels above 1 mg/kg. Of these, six samples were soy sauces, two
were oyster sauces and one was a mushroom soy sauce, indicating
that 3-MCPD contamination is not restricted to soy sauces. The nine
products had been imported from China and Hong Kong, Taiwan and
the Philippines and had best before dates ranging from 1999 to 2002.
Thus, higher levels were not restricted to any one country of origin
or to older batches.
Three of these samples also declared HVP as an ingredient on the
label. Several grades of soy sauce are manufactured in the Far East,
including the traditional fermented product as well as lower grades
which contain varying proportions of acid-HVP. It is possible that
the 3-MCPD which was detected in these products could have resulted
from the acid hydrolysis used to manufacture HVP. Surveys carried
out by MAFF in 1990 and 1992 showed that 3-MCPD levels of up to
100 mg/kg were quite common in acid-HVP until about 10 years ago
(Figure 1).5,6 Since then, levels
in European products have declined markedly, as was shown by the
results of a recent JFSSG survey of acid-HVP in which 3-MCPD was
undetectable (less than 0.01 mg/kg) or was found at low levels in
38 (76%) of the 50 samples analysed.7
However, this survey did not include any products used in the manufacture
of foodstuffs outside Europe. Therefore, it is possible that the
elevated levels of 3-MCPD which were found in some samples of soy
sauce in the current survey could have been due to the presence
of acid-HVP which had not undergone a similar reduction in levels.
The Department of Health has advised that the levels of 3-MCPD
found in the survey do not represent an immediate hazard to health
but has confirmed that it would be prudent for manufacturers and
suppliers to take action to reduce the concentrations of 3-MCPD
in their products, in line with the FAC's advice. A follow-up survey
will be conducted in one year's time to confirm that the necessary
action has been taken.
Comments from industry
In line with the JFSSG guidelines for planning and reporting surveys,
manufacturers and suppliers of those samples which yielded results
in excess of 0.01 mg/kg were sent their own results and asked to
comment. In replying, they were asked to indicate what action they
intended to take regarding the high levels of 3-MCPD found in some
of their products. The responses received are shown in Annex
1.
References
-
MAFF/DH Joint Food Safety and Standards Group (1999) Press Release
FSA 18/99 Industry alerted to contaminant levels in soy sauce.
- European Commission (1997) Opinion on 3-monochloropropanediol
(3-MCPD), expressed on 16 December 1994. pp. 31-33 in Reports
of the Scientific Committee for Food. Food Science and Techniques,
Thirty-sixth Series. Office for Official Publications of the European
Community, Luxembourg.
- Food Advisory Committee (1999) Press Release
5/99 Recent developments on 3-MCPD in food and food ingredients.
- Kelly, J., Crews, C. and Brereton, P. (1998)
Determination of 3-monochloropropane-1,2-diol in food and food
ingredients using mass spectrometric detection: collaborative
trial. CSL Report FD 97/75
- MAFF (1991) Survey of hydrolysed vegetable
proteins for chlorinated propanols. CSL Report FD 91/6.
- MAFF (1993) Survey of chlorinated propanols
in hydrolysed vegetable protein 1992. CSL Report FD 93/17.
-
JFSSG (1999) Survey of 3-monochloropropane-1,2-diol (3-MCPD) in
acid-hydrolysed vegetable protein. Food Surveillance Information
Sheet No. 181.
Further Information
The full report of this survey is held in the MAFF Library, Nobel
House, 17 Smith Square, London, SW1P 3JR; Tel: +44 (0)171 238 6575.
If you would like to consult a copy, please contact the Library
giving at least 24 hours notice or, alternatively, copies can be
obtained from the Library; a charge will be made to cover photocopying
and postage.
For further information please contact:
Dr A M Davies
MAFF, Joint Food Safety and Standards Group
Additives and Novel Foods Division
Room 232 Ergon House
c/o Nobel House
17 Smith Square
LONDON SW1P 3JR
Tel: +44 (0) 171-238-6217
Fax: +44 (0) 171-238-2
E-mail: a.davies@fsci.maff.gov.uk
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These pages were last updated on 29th September 1999.
