Number 99 November 1996
MAFF UK - SURVEY OF BIOLOGICALLY ACTIVE PRINCIPLES IN MINT PRODUCTS AND
HERBAL TEAS
Index to MAFF UK Food Surveillance Information
Sheets, 1996
See also:
30: MAFF UK - Biologically
Active Principles in Natural Flavouring Source Materials and Preparations
(June 1994)
79: MAFF UK - Survey of Pulegone and
Menthol in Peppermint Oils (January 1996)
Summary
MAFF has completed a survey of four biologically active principles (BAPs)
(coumarin, safrole, isosafrole and pulegone) and menthol in a range of mint
products and herbal teas. Pulegone was not detected in mint sauces and jellies,
while levels in mint-flavoured sugar, chocolate and gum-based confectionery
products (range, <1-119 mg/kg) and in the one mint liqueur analysed (5 mg/kg)
were all significantly lower than the statutory limits for these products (350
and 250 mg/kg, respectively). Neither safrole nor isosafrole was detected in
any of the herbal teas analysed, while pulegone and menthol were only found in
peppermint and peppermint-containing teas (at levels of <1-27 mg/kg and <1-2602
mg/kg respectively). Although most of the herbal teas (54 samples) did not
contain coumarin, relatively high levels of up to 157 mg/kg (dry teas) were
found in a few of the imported cinnamon-based teas containing flavourings.
Investigations are currently underway to ascertain the source of the coumarin in
these products as the direct addition of BAPs to foods is not permitted.
Coumarin levels in infusions of these teas as consumed ranged from <0.01 to
5.8 mg/kg.
Background
Flavourings are materials which are used to impart taste (excluding
saltiness, sweetness or sourness) or odour, or both, to a food but which are not
intended to be consumed as such. Traditionally, herbs and spices are not
regarded as flavourings. The four main types of flavourings in use in the UK
are:
(i)natural flavouring preparations which are complex mixtures of
aromatic products obtained from plant or animal source materials (e.g. essential
oils);
(ii) chemically-defined flavouring substances comprising single
flavouring substances which are either derived from natural materials or are
produced synthetically;
(iii) process flavourings such as thermal process flavourings,
enzymatically or microbiologically derived flavourings and flavourings obtained
as products of biotechnology which are not covered by (i) and (ii) above; and;
(iv) smoke flavourings derived from smoke extracts and condensates
which are used to mimic the effects of traditional smoking.
Some natural flavouring preparations, derived from certain plant source
materials, have been shown to contain natural toxicants known as biologically
active principles (BAPs). The use of BAPs as flavouring substances, either
alone or in a mixture of flavouring substances, is not permitted in the UKor in
other EU Member States. Limits on the levels of 13 BAPs in foods and beverages
to which natural flavourings are added are set under the Flavourings in Food
Regulations 1992, as amended,1,2
which implement the EC flavourings framework directive (88/388/EEC).3
Based on information from MAFF's 1989-1991 inventory of natural flavouring
source materials and preparations,4 a survey of
the concentrations of four BAPs (coumarin, safrole, isosafrole and pulegone),
together with myristicin and menthol, in natural flavouring preparations was
carried out by MAFF Food Science Laboratory, Norwich (now part of MAFF Central
Science Laboratory [CSL]), between 1993 and 1994. The survey was intended to
provide current data on the levels of these substances in flavouring
preparations used by the UK flavourings industry, together with information on
the levels of use of these preparations, thereby allowing an estimate of the
resulting concentrations in foods and beverages to be determined. As reported
previously,4-6 the survey confirmed reports
from the scientific literature that peppermint and cornmint oils contain
pulegone and menthol, that cinnamon and its preparations contain safrole and
that coumarin is found in flouve (sweet vernal grass) oils and cassia. However,
little information was received on the levels of use of these preparations in
food.
As a follow-up to this work, an analytical survey was carried out to
determine the concentrations of pulegone and menthol in manufactured foods such
as mint confectionery, sauces, jellies and liqueurs and, together with levels of
coumarin, safrole and isosafrole, in a range of peppermint, cinnamon-containing
and other assorted herbal teas. The analysis of herbal teas for coumarin was
also intended to follow up some earlier work carried out by MAFF in 1990 which
indicated that detectable levels of coumarin could be found in a few brands of
herbal teas. By determining the concentrations of BAPs in foods directly rather
than estimating them from data on the concentrations of BAPs in flavourings and
the reported levels of use of these flavourings in foods, it would therefore be
possible to compare the BAP concentrations found in the survey with the limits
set by EC and UK legislation.
Methodology
A total of 118 products, comprising 51 samples of sugar, chocolate and
gum-based mint confectionery and various mint products (mint sauces, jellies and
liqueurs) and 67 herbal and peppermint teas, were purchased from retail outlets
in the London area in August 1994. Details of the ingredients listed on the
product label (including the presence of any flavourings) and, in the case of
herbal teas, the manufacturers' instructions for preparing the teas, were
recorded on receipt.
Samples were analysed by CSL Food Science Laboratory, Torry, using gas
chromatography-mass spectrometry (GC-MS) in the scanning mode with propyl
benzoate as an internal standard. Samples of mint confectionery and the other
mint products were analysed for pulegone and menthol, while the herbal teas were
analysed for all four BAPs (pulegone, coumarin, safrole and isosafrole) and
menthol. In the case of herbal teas, both dry teas and infusions, prepared
according to the manufacturers' instructions, were analysed. Additional
procedures for sample preparation, extraction and concentration of the BAPs were
developed by CSL.7
The accuracy and precision of the method were determined by "spiking"
around 10 percent of the samples and procedural blanks with the BAPs of
interest. Recoveries of the BAPs in the four herbal teas and infusions ranged
from 83 percent to 117 percent and from 88 percent to 175 percent, respectively,
with coefficients of variance (CVs) of 0-2.4 percent and 0-12.7 percent. The
range of recoveries (and CVs) for the sugar (n=3), chocolate (n=2) and gum-based
confectionery (n=2) were 92-119 percent (0-5.8 percent), 97-109 percent (0-12
percent) and 106-118 percent (0-2 percent), respectively. Results were not
adjusted for recovery. The limit of detection for the method was 1 mg/kg dry
matter.
Results
A summary of the concentrations of pulegone and menthol found in mint
confectionery and other mint products is given in Table 1.
As shown, pulegone levels of <1-32 mg/kg dry matter (mean, 13.9 mg/kg) were
found in mint-flavoured sugar-based confectionery products, with the highest
concentration being found in a sample of "extra strong mints". These
levels are similar to those found in a range of boiled and fondant sweets,
jellies, gums and pastilles by Bossi et al.8
(1.3-31.3 mg/kg) and by Chaveron et al.9 (2-21 mg/kg). The
concentration of 32 mg/kg found in the sample of extra strong mints is also
similar to that reported by a major manufacturer of these products.
Lower pulegone levels of <1-12 mg/kg (mean, 4.3 mg/kg) were found in
samples of mint-flavoured chocolate-based confectionery (Table
1), although analytical problems were encountered with some of these samples
due to their high fat content. Of the five samples of chewing gum analysed,
three were found to contain pulegone concentrations in the range, 35-119 mg/kg,
while pulegone could not be quantified in the remainder due to matrix problems.
These levels are higher than those reported by Chaveron et al.9 (5-31 mg/kg) but are lower than an estimated 240
mg/kg derived from level of use data for the USA10
and assuming a maximum pulegone concentration of 2.9 percent in the peppermint
oil, the highest level found in MAFF's repeat survey of mint oils.6
A pulegone concentration of 5 mg/kg was found in the one sample of crème
de menthe liqueur analysed (Table 1) which is at the
lower end of the range of values reported by Bossi et al.8 for five peppermint liqueurs (5-40 mg/kg). Pulegone
was not detected in any of the mint sauces and jellies analysed.
As in the case of pulegone, the highest levels of menthol were generally
found in samples of chewing gum (mean, 3546 mg/kg) and sugar-based confectionery
(mean, 476 mg/kg) (Table 1). Of the sugar-based
confectionery, extra strong mints contained the highest menthol level, at 1224
mg/kg, which is slightly lower than the concentration estimated11 by Linforth and Taylor for the same product (1690
mg/kg). Like pulegone, menthol was not detected in any samples of mint sauce
and mint jelly, while a menthol concentration of 219 mg/kg was found in the mint
liqueur sample.
A summary of the levels of pulegone, menthol, coumarin, safrole and
isosafrole found in peppermint, cinnamon-containing and other herbal teas,
analysed on a dry weight basis, is given in Table 2.
As expected, pulegone was found only in teas containing peppermint leaves and/or
peppermint flavourings, with pulegone being detected in 8 out of the 17
peppermint teas (range, 7-25 mg/kg dry matter) and one of the 12
peppermint-containing teas (27 mg/kg). Menthol was also found in these teas,
although the concentrations varied widely in both the peppermint teas (15-2602
mg/kg) and the peppermint-containing teas (<1-2591 mg/kg). Coumarin was
found mainly in cinnamon-containing teas, being detected in 11 out of 27 samples
of dry tea at concentrations of up to 157 mg/kg, although two other samples, one
of which contained peppermint in addition to cinnamon, also had detectable
levels of coumarin (28 and 31 mg/kg). It is interesting to note that in MAFF's
earlier survey of BAPs in natural flavouring source materials and preparations,4,5 coumarin was not detected in cinnamon powder but was
found in cassia, which is often traded commercially as cinnamon, at
concentrations of up to 2000 mg/kg (0.2 percent). None of the teas analysed in
the current survey contained safrole or isosafrole.
A summary of the levels of pulegone, menthol, coumarin, safrole and
isosafrole found in infusions of the various teas is given in
Table 3. As in the case of the dry teas, pulegone was
found only in peppermint infusions, with detectable concentrations of 0.03-0.45
mg/kg being found in 16 of the peppermint teas and levels of 0.04-0.13 mg/kg
being found in 6 of the peppermint-containing teas. Menthol was also detected
in all but one of these infusions at concentrations of 0.3-32.3 mg/kg and
0.04-9.7 mg/kg, respectively. A total of 22 infusions contained coumarin, with
the highest concentrations being found in the cinnamon-containing teas (0.04-5.6
mg/kg). As for the dry teas, neither safrole nor isosafrole was detected in any
of the infusions analysed.
Interpretation
The levels of pulegone found in the mint confectionery products (<1-119
mg/kg) and in the mint liqueur (5 mg/kg) analysed give no cause for concern, all
being significantly lower than the statutory limits for mint confectionery (350
mg/kg) and mint or peppermint flavoured drinks (250 mg/kg) as specified in the
Flavourings in Food Regulations 1992, as amended.1,2
Neither safrole nor isosafrole was detected in any of the herbal teas analysed,
while pulegone and menthol were found only in peppermint and
peppermint-containing teas, with most at low levels. While the majority of the
herbal teas (54 samples) did not contain coumarin, relatively high
concentrations of up to 157 mg/kg (dry teas) were found in a small number of
imported cinnamon-based teas containing flavourings. Investigations are
currently underway to ascertain the source of the coumarin in these products and
to determine whether or not they comply with UK Regulations. Coumarin levels in
infusions of these teas as consumed ranged from <0.01 to 5.8 mg/kg and
coumarin intakes from these infusions are unlikely to pose any significant risk
to health.
References
- The Flavourings in Food Regulations 1992 (S.I.
[1992] No. 1971). HMSO.
- The Flavourings in Food (Amendment) Regulations 1994
(S.I. [1994] No. 1486). HMSO.
- European Community (1988). Council Directive on the
approximation of the laws of the Member States relating to flavourings for use
in foodstuffs and to source materials for their production (88/388/EEC).
Official Journal of the European Communities L184/61-66.
- Ministry of Agriculture, Fisheries and Food (1995).
Flavourings in Food.
Food Surveillance Paper No. 48. HMSO.
- Ministry of Agriculture, Fisheries and Food and Department of Health
(1994). Food Safety Information Bulletin. Bulletin No. 50.
June 1994.
- Ministry of Agriculture, Fisheries and Food and Department
of Health (1996). Food Safety Information Bulletin. Bulletin No.
69. January 1996.
- Ministry of Agriculture, Fisheries and Food (1995).
Biologically active principles in herbal teas, mint teas and mint products.
Final Report submitted by MAFF Central Science Laboratory, Torry, December 1995.
- Bossi, G., Chialva, F. and Parato, P. (1978). The gas
chromatographic determination of mint essential oils, liqueurs, syrups and
confectionery products. Industrie Alimentari, November 1978,
835-836.
- Chaveron, H., Ollivon, M., Meili, M. and Libert, J-C.
(1980). Determination of pulegone by mass fragmentometry. Ann. Fals.
Exp. Chim.,
73, 33-40.
- Fenaroli's Handbook of Flavor Ingredients
(1995). Volume I. Third Edition. (Ed. Burdock, G.A.). CRC Press.
- Linforth, R.S.T. and Taylor, A.J. (1993). Measurement of
volatile release in the mouth. Food Chemistry 48,
115-120.
Contact Point
For further information please contact:
Dr A M Davies
MAFF, Food Safety and Science 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 6263
Return to Index to Surveillance Information Sheets, 1996 page
Go to top of page
These pages were last updated on 1 October 1996
