ldi

wa

ood &

apor

orm 1

dient to soy sauces or the use of acid treatment in the

manufacturing of soy sauces possibly leads to the con-

3-MCPD was always higher than that of 1,3-DCP

(FSA, 2001).

3-MCPD was originally regarded by the European

Commissions Scientic Committee for Food (EC,1997) as a genotoxic carcinogen and the UK Food

.

* Corresponding author. Fax: +65 6324 4563.

E-mail address: wong_kwok_onn@ava.gov.sg (K.O. Wong).

Food Control 17 (2006)0956-7135/$ - see front matter 2005 Elsevier Ltd. All rights reserved1. Introduction

3-Monochloropropane-1,2-diol (3-MCPD) is one of

the chloropropanol group of chemical contaminants

and is a well-known contaminant of acid-hydrolysed

vegetable protein (acid-HVP) (MAFF, 1999). In the tra-

ditional production of acid-HVP where defatted vegeta-

ble proteins are hydrolysed by hydrochloric acid,

3-MCPD is formed by high temperature chlorinationof residual lipids that are associated with the vegetable

proteins. The inclusion of acid-HVP as a savoury ingre-

tamination of the sauces with 3-MCPD. The contami-nant has been reported in sauces (Macarthur et al.,

2000; Nyman, Diachenko, & Perfetti, 2003) as well as

in many other foods and food ingredients such as

breads, cheeses, salami, burgers and modied starches

(Crews, Brereton, & Davies, 2001; Crews et al., 2002a;

Hamlet, 1998; Hamlet, Jayaratne, & Matthews, 2002).

1,3-Dichloropropan-2-ol (1,3-DCP), another chloropro-

panol, can be formed from 3-MCPD and has beenfound in soy sauce and related sauces. When 3-MCPD

and 1,3-DCP co-occurred in sauces, the level ofAbstract

A continuous national monitoring program is performed to monitor the levels of 3-monochloropropane-1,2-diol (3-MCPD) in

both soy and oyster sauces and to assess the dietary intake of 3-MCPD by the general Singapore consumers from sauces. The pro-

gram involved the requisition of laboratory reports on the 3-MCPD levels in the sauces from importers before importation as well as

sampling of sauces at the point of import and at domestic manufacturers for the analysis of 3-MCPD. Out of the 421 soy and oyster

sauce samples monitored between January 2000 and April 2002, 376 samples (89.3%) contained 3-MCPD levels at or below the

national maximum limit of 0.02 mg/kg. The upper bound average 3-MCPD concentration of all the sauces was 0.45 mg/kg. The

estimated average daily dietary intake of 3-MCPD from sauces based on the national maximum limit and based on the upper bound

average 3-MCPD level found in the monitoring program were calculated and compared with the Tolerable Daily Intake (TDI) of

2 lg/kg body weight. The average daily intake of 3-MCPD by Singapore consumers from sauces was below the TDI and this indi-cates that there is no health risk associated with the intake of 3-MCPD from sauces. However, consideration has to be taken into

account the total 3-MCPD intakes from all food sources in the diet.

2005 Elsevier Ltd. All rights reserved.

Keywords: 3-Monochloropropane-1,2-diol; Sauces; Dietary intake3-Monochloropropane-1,2-diosauces: Occurrence and

Kwok Onn Wong *, Yock H

Food Control Division, Food & Veterinary Administration, Agri-F

MND Complex, Sing

Received 23 May 2004; received in revised fdoi:10.1016/j.foodcont.2005.01.010(3-MCPD) in soy and oysteretary intake assessment

Cheong, Huay Leng Seah

Veterinary Authority, 5 Maxwell Road, #18-00, Tower Block,

e 069110, Singapore

9 January 2005; accepted 20 January 2005

www.elsevier.com/locate/foodcont

408413

tially genotoxic in vivo and its level in food should also

be reduced to a level as low as technologically achievable

spectrometry (GC/MS) method previously validated by

an inter-laboratory collaboration trial (Brereton, Kelly,

Crews, Honour, & Wood, 2001). This method has been

accepted for Ocial First Action status by the Associa-

tion of Ocial Analytical Chemists (AOAC Ocial

Method 2000.01).Sauce samples that were collected at the point of im-

port and at the domestic sauce manufacturers were sent

to Setsco Services Pte Ltd, Singapore, for the analysis of

3-MCPD levels. Both the laboratory and the AOAC

Ocial Method 2000.01 that was employed by the lab-

oratory for determining 3-MCPD levels in sauces have

been accredited under the Singapore Accreditation

CouncilSingapore Laboratory Accreditation Scheme(SAC-SINGLAS). The laboratory has also routinely

Control 17 (2006) 408413 409(COC, 2001; COM, 2001).

In May 2001, the European Commissions ScienticCommittee for Food derived a Tolerable Daily Intake(TDI) of 2 lg/kg body weight for 3-MCPD (SCF,2001). The gure of 2 lg/kg body weight is the sameas the Provisional Maximum Tolerable Daily Intake

(PMTDI) established by the Joint Food and Agriculture

Organisation/World Health Organisation Expert Com-

mittee on Food Additives in June 2001 (JECFA,

2002). This study reports the results from the January

2000 to April 2002 period of an on-going monitoringprogram to monitor the 3-MPCD levels in soy and oys-

ter sauces. The results were used to evaluate whether the

level of 3-MCPD intakes from soy and oyster sauces is a

cause for health concern in Singapore by comparing the

estimated dietary intake of 3-MCPD with the TDI of

2 lg/kg body weight.

2. Materials and methods

2.1. Samples

A national monitoring program was instituted to

monitor the levels of 3-MCPD in both imported and

domestically manufactured soy and oyster sauces. The

program was conducted via requesting laboratory ana-lytical reports on the 3-MCPD levels in the sauces from

the importers before the products were imported. Sam-

pling of sauces at the point of import and at the domes-

tic sauce manufacturers for laboratory analysis of

3-MCPD was also conducted.

2.2. Determination of 3-MCPD levels

3-MCPD levels were all reported based on determina-Advisory Committee has recommended that 3-MCPD

should be reduced in foods and food ingredients to the

minimum detectable using an analytical method capable

of detecting levels down to 0.01 mg/kg (FAC, 1999). The

UKs Committee on Mutagenicity of Chemicals inFood, Consumer Products and the Environment(COM, 2000) and Committee on Carcinogenicity of

Chemicals in Food, Consumer Products and the Envi-

ronment (COC, 2000) have later reviewed new toxico-

logical data and concluded that 3-MCPD does not

have signicant genotoxic potential in vivo. However,

in view that 3-MCPD is still considered by COC as car-

cinogenic in animals (COC, 2000), the UKs Food Advi-sory Committee has advised the industry to reduce3-MCPD levels in all foods and food ingredients to

the lowest technologically possible (FAC, 2000). The

UKs COC and COM have regarded 1,3-DCP as poten-

K.O. Wong et al. / Foodtions made according to a gas chromatography/massparticipated in prociency testing program on the anal-

ysis of 3-MCPD in sauces run by the UK Central

Science Laboratory under the Food Analysis Perfor-

mance Assessment Scheme (FAPAS) and the labora-

tory has been obtaining satisfactory results.

Deuterated 3-MCPD (d5-3-MCPD) as an internal

standard was added to a known amount of sample fol-lowed by saline solution to extract 3-MCPD and the

mixture was blended to a homogenous consistency.

After sonication or centrifugation, diatomaceous earth

(Celite 545) was added to the 3-MCPD extract and

mixed thoroughly. The mixture was transferred to a

manually compacted glass chromatography column

and non-polar compounds were eluted using a mixture

of hexane and diethyl ether. 3-MCPD was eluted usingdiethyl ether and the 3-MCPD extract was concentrated

to a small volume on a water bath at 5070 C. A vol-ume of the concentrated extract was subsequently deri-

vatised using N-heptauorobutyrylimidazole (HFBI).

The derivatised sample was analysed by GC/MS using

the conditions summarised in Table 1.

Identication of 3-MCPD was based on the compar-

ison of the full scan mass spectrum of the samplechromatographic peak with a mass spectrum of HFBI-

derivatised 3-MCPD. Quantication was based on

Table 1

Conditions and instrument settings for determination of 3-MCPD by

GC/MS

Gas chromatograph Agilent GCMSD

Column DB-5MS (30 m 0.25 mm 0.25 lm)Injector temperature 270 COven temperature 50 C for 1 min, 2 C/min to 90 C,

40 C/min to 270 C, 270 C for 10 minCarrier gas Helium

Flow rate 1 mL/min

Injection method Split 20:1

Injection volume 1 lL

Mass spectrometer Agilent

Interface temperature 250 CSan range m/z 50500

Monitoring ion d5-3-MCPDm/z 257, 4563-MCPDm/z 291, 289, 275, 253, 453

sauces and 17 oyster sauces. As these products do not

Concomparison of chromatographic peak areas for

3-MCPD at m/z 253 and for d5-3-MCPD at m/z 257.

The reporting limit was 0.010 mg/kg. The lowest calibra-

tion point was set at 0.005 mg/kg, at this point of detec-

tion the S/N ratio was above 3.

For quality assurance purposes, samples were ana-lysed in batches comprising: 10 samples; a reagent

blank; a sample spiked at 0.010 mg/kg. 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

0.010 mg/kg should fall within the range 80120%. The

results of recovery experiments that were routinelycarried out on each batch of samples always fell within

the acceptable range of 80120% and the data were

not corrected for recovery. The measurement uncer-

tainty was assessed as 0.0065 mg/kg at 0.01654 mg/kg

3-MCPD. The measurement uncertainty was taken into

account only when a product was assessed for regula-

tory compliance with the national maximum limit for

3-MCPD. Since the 3-MCPD levels were used toestimate the dietary intake of the contaminant, the data

presented in this paper did not take the measurement

uncertainty into consideration.

2.3. Food consumption data

The food consumption data was obtained from the

National Nutrition Survey 1998 conducted by theSingapore Ministry of Health (MOH, 2001). Dietary

practices, food frequency, and 24-h food intake ques-

tionnaires were used in the survey. Approximately

2400 individuals aged between 18 and 69 years partici-

pated in the survey to provide information on their

dietary patterns and food intakes. The average amounts

of soy and oyster sauces consumed per day (g/day) by

the average respondents, average consumers and highconsumers (dened as the 95th percentile) were obtained

based on the food consumption data. The amount of soy

and oyster sauces consumed was contributed by both

domestic and non-domestic uses and included those that

were consumed as table top sauces as well as those that

were used as ingredients in the preparation of dishes.

2.4. Estimation of dietary intake

The average dietary intake of 3-MCPD from soy and

oyster sauces was estimated for the average respondents,

average consumers and high consumers by multiplying

the average 3-MCPD level by the average amount of

sauces consumed per day by each of the corresponding

population group. The analytical 3-MCPD concentra-

tions in the sauce samples were used to calculate theaverage contaminant level. For samples with 3-MCPD

410 K.O. Wong et al. / Foodlevels below the reporting limit, the reporting limit ofcontain added HVP, the most likely source of contami-

nation of these samples could be the use of acid hydro-

lysed soy bean and/or wheat ingredients.

Three of the 58 domestically manufactured sauces

(5.2%) and 42 of the 363 imported sauces (11.6%) con-

tained 3-MCPD above the national maximum limit of

0.02 mg/kg. A considerable number of samples, 25 outof the 45 samples (55.6%) that contained 3-MCPD0.010 mg/kg was used in the calculation. The estimates

of 3-MCPD intakes were thus based on the upper bound

average level of contamination in sauces and were there-

fore an overestimate of the true intakes. The calculated

average daily intake of 3-MCPD per unit body weight

was then compared with the TDI/PMTDI of 2 lg/kgbody weight established by SFC/JECFA.

3. Results and discussion

3.1. Occurrence of 3-MCPD in sauces

Following the conclusion that 3-MCPD is non-genotoxic (COC, 2000; COM, 2000) and the establish-

ment of a TDI for 3-MCPD (SCF, 2001), the Australia

New Zealand Food Standards Council (FSANZ, 2002)

and the European Commission (EC, 2001) have adopted

a regulatory limit for the contaminant based on a 40%

dry matter content, which came into force in November

2001 and April 2002, respectively. The requirement of

normalization of dry matter content is due to the vari-ability in the dry matter content of the sauces. Surveys

on 3-MCPD levels in sauces that were conducted before

the European Commission or Australia/New Zealand

limits came into force in which the results were not nor-

malized for dry matter have previously been published

(FSANZ, 2003; Macarthur et al., 2000; Nyman et al.,

2003). As the majority of sauces in this monitoring pro-

gram were sampled before the above regulatory limitswere implemented, the dry matter contents of the sauces

were not determined and the 3-MCPD levels were also

not normalized for dry matter content. In this paper,

comparison of the 3-MCPD levels can only be made

based on the wet weight of the samples.

Table 2 summarises the levels of 3-MCPD found in

421 samples of soy and oyster sauce. Only three domes-

tically manufactured sauces (one sample of soy sauceand two samples of oyster sauce) have declared the pres-

ence of HVP, two (one sample each of soy sauce and

oyster sauce) of which did not have quantiable levels

of 3-MCPD. This suggested that 3-MCPD was either

absent or present in very low amounts in the HVP used

in these two sauces. Of the remaining 418 sauces that did

not declare the presence of HVP, 61 sauces (14.6%) have

3-MCPD levels above 0.01 mg/kg. These included 44 soy

trol 17 (2006) 408413above the national maximum limit, have 3-MCPD levels

Table 2

Range of 3-MCPD levels in soy and oyster sauces

Product type Exporting/

producing

country

Number of

samples

without

declaration

of HVP

Number of

samples

with

declaration

of HVP

Number of samples in each range (mg/kg) of 3-MCPD Upper

bound

average

(mg/kg)

60.01a >0.010.02 >0.020.05 >0.050.2 >0.20.5 >0.53.0 >3.0

Soy sauce Australia 1 1

China 40 29 5 5 1 0.026

Hong Kong 13 11 2 0.012

Indonesia 4 3 1 0.133

Japan 28 23 5 0.017

Malaysia 162 151 4 2 5 0.026

Philippines 1 1

Singapore 1 1

Singapore 42 37 4 1 0.011

Taiwan 13 6 1 4 2 0.481

Thailand 10 8 2 17.01

USA 2 2

K.O. Wong et al. / Food Control 17 (2006) 408413 411Oyster sauce Australia 2 2

China 6 3

Hong Kong 10 9

Japan 4 4

Malaysia 58 50 1

Singapore 2 1

Singapore 13 10 2

Taiwan 3 2

Thailand 6 5

a 0.01 mg/kg is the reporting limit for 3-MCPD.falling between >0.02 and 0.05 mg/kg. The upper bound

average 3-MCPD concentration for all the soy and

oyster sauces was 0.45 mg/kg. The highest 3-MCPD

level of 110.8 mg/kg was found in an imported soy

sauce; the highest 3-MCPD level found in soy sauces

in surveys conducted in UK, Australia and USA was

respectively, 30.5 mg/kg, 150 mg/kg and 876 mg/kg (all

published levels were based on wet weight of thesamples) (FSANZ, 2003; Macarthur et al., 2000; Nyman

et al., 2003).

Table 3

Estimated dietary intake of 3-MCPD from soy and oyster sauces

Population group Intake of

sauce (g/day)

Level of 3-MC

0.02 mg/kg

Dietary intake

(mg/kg body w

Average respondents (1869 years) 0.43 0.14

Average consumers (1869 years) 8.90 2.97

High consumers (1869 years) 19.80 6.59

Average consumers (18 to

vey on the 3-MCPD levels in savoury foods in Singa-

The diligent eorts of all the ocers in the Food

Control Division who were involved in the national

Control 17 (2006) 408413respondents who have actually consumed soy and/or

oyster sauces.

3-MCPD levels of 0.02 mg/kg and 0.45 mg/kg were

used in the estimation of dietary intake of 3-MCPD

from soy and oyster sauces. The former level is the

national maximum limit for 3-MCPD in sauces. The lat-ter level is the upper bound average 3-MCPD level from

the monitoring program and it was used in the dietary

intake assessment assuming that products with 3-MCPD

levels above the national maximum limit were available

in the market and have been consumed.

The dietary intakes of 3-MCPD by average respon-

dents, and by average consumers from various

age groups were considerably below the TDI at both3-MCPD levels of 0.02 mg/kg and 0.45 mg/kg (Table

3). For high consumers of any age group, dietary intakes

were

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3-Monochloropropane-1,2-diol (3-MCPD) in soy and oyster sauces: Occurrence and dietary intake assessmentIntroductionMaterials and methodsSamplesDetermination of 3-MCPD levelsFood consumption dataEstimation of dietary intake

Results and discussionOccurrence of 3-MCPD in saucesEstimation of dietary intake

AcknowledgmentsReferences