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Food Surveillance Information Sheet


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
  1. The Flavourings in Food Regulations 1992 (S.I. [1992] No. 1971). HMSO.
  2. The Flavourings in Food (Amendment) Regulations 1994 (S.I. [1994] No. 1486). HMSO.
  3. 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.
  4. Ministry of Agriculture, Fisheries and Food (1995). Flavourings in Food. Food Surveillance Paper No. 48. HMSO.
  5. Ministry of Agriculture, Fisheries and Food and Department of Health (1994). Food Safety Information Bulletin. Bulletin No. 50. June 1994.
  6. Ministry of Agriculture, Fisheries and Food and Department of Health (1996). Food Safety Information Bulletin. Bulletin No. 69. January 1996.
  7. 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.
  8. 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.
  9. Chaveron, H., Ollivon, M., Meili, M. and Libert, J-C. (1980). Determination of pulegone by mass fragmentometry. Ann. Fals. Exp. Chim., 73, 33-40.
  10. Fenaroli's Handbook of Flavor Ingredients (1995). Volume I. Third Edition. (Ed. Burdock, G.A.). CRC Press.
  11. 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


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These pages were last updated on 1 October 1996

 
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