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WHO FOOD ADDITIVES SERIES: 52

THE SAFETY EVALUATION OF NATURAL FLAVOURING COMPLEXES

First draft prepared by

Dr I. C. Munro
CANTOX Health Sciences International, Mississauga, Ontario, Canada

and

Dr A. Mattia
Division of Biotechnology and GRAS Notice Review, Office of Food Additive Safety, Center for Food Safety and Applied Nutrition, United States Food & Drug Administration, Maryland, USA

Introduction

Safety evaluation of natural flavouring complexes

Specifications for natural flavouring complexes

Estimates of daily intake

Proposed modification to the current Procedure for the Safety Evaluation of Flavouring Agents

Conclusions and recommendations

References

1. INTRODUCTION

For nearly 40 years, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) has played a leading role in the development of principles and procedures for the safety evaluation of flavouring agents. In 1996, the Committee began an ongoing programme to conduct safety evaluations and establish specifications for individual flavouring agents. On the basis of this experience, the Committee recognizes that the safety evaluation of flavouring agents presents unique challenges, principally owing to the fact that there are more than 2000 such agents used in commerce, the vast majority of which are added at extremely low levels in food. In view of the fact that the majority of individual flavouring agents occur naturally in food, the Committee has concluded that to evaluate each of these substances by traditional toxicological testing is simply not warranted in most cases (WHO, 1987).

In 1987, WHO classified flavouring agents into four groups:

  1. (a) Artificial substances that are unlikely to occur naturally in food;
  2. (b) Natural substances that are not normally consumed as food, their derived products, and the equivalent nature-identical flavourings;
  3. (c) Herbs and spices, their derived products, and the equivalent nature-identical flavourings, and
  4. (d) Natural flavouring substances obtained from vegetable and animal products and normally consumed as food whether processed or not, and their synthetic equivalents.

Since 1996, the Committee has evaluated the safety of approximately 1150 individual flavouring agents using the Procedure for the Safety Evaluation of Flavouring Agents (Annex 1, references 116 and 117 ). The Committe organized these agents into a number of well-defined chemical groups (i.e. congeneric groups) in order to effectively evaluate such a large number of substances. The evaluations conducted to date have demonstrated that flavouring agents within a congeneric group have a similar biochemical fate and toxicological potential. Most individual flavouring agents have been shown to be efficiently detoxicated to yield innocuous metabolites. Knowledge of their metabolic fate, coupled with low intake levels that are typically below thresholds of toxicological concern, has formed the basis for the majority of the Committees evaluations of individual flavouring agents. In instances where the metabolic fate of an individual flavouring agent was not well known or readily predictable, or where intake exceeded the threshold of toxicological concern for the relevant structural class, the Committee has relied on data on the toxicity of the agent itself or of a structurally related substance in order to perform a rigorous safety evaluation. The results of these evaluations comprise an extensive database, which has been published since 1996 in the WHO Food Additive Series as a series of monographs on congeneric groups.

A key development in the process by which the Committee evaluates the safety of flavouring agents has been the establishment of specifications, consistent with JECFA practice, for all flavouring agents. The criteria underpinning these specifications require that the chemical assay for individual flavouring agents be specified. The Committee has adopted the criterion of a minimum assay of 95% purity of the named flavouring agent. In some cases, flavouring agents have been reported to be of less than 95% purity. In such instances, the Committee has required the identification of the secondary components such that at least 95% of the chemical composition of the named flavouring agent can be accounted for. Key features of secondary components are that many are themselves flavouring agents that are likely have been evaluated previously by the Committee, as a member of a different congeneric group, or they are structurally related substances that belong to the same congeneric group as the named flavouring agent.

In order to provide for a rigorous safety evaluation when there are many secondary components, the Committee has collected and evaluated data on each of these components. This process has been facilitated by the fact that, since 1996, the Committee has reviewed and published monographs on most of the chemical groups of flavouring agents. Using these monographs on congeneric groups, the Committee now has the capacity to efficiently evaluate additional flavouring agents and numerous secondary components. An obvious extension of this process is that the Committee can begin to evaluate mixtures of flavouring agents, as found in natural flavouring complexes.

2. SAFETY EVALUATION OF NATURAL FLAVOURING COMPLEXES

Natural flavouring complexes fall into the following categories:

  1. Essential oils: the volatile flavouring constituents of plant sources (leaves, fruits, buds, bark, etc.) usually obtained by steam distillation, by expression or extraction, or some combination of these processes.
  2. Extracts: the volatile and non-volatile flavouring constituents of plant sources, as described in (1) above, obtained by extraction with a permitted polar or non-polar solvent, the choice of which depends on the botanical source and the constituents desired.
  3. Oleoresins, often called solid extracts: obtained by extraction as in (2) above, followed by removal of the solvent.

These categories fall into groups (b), (c), and (d) listed above (WHO, 1987). The agents that comprise these categories range from those that consist almost entirely of a single chemical entity, such as bitter almond oil (benzaldehyde), to those with a highly complex composition (e.g. rosemary oil). In some instances, dozens of constituents are essential to the technical flavour characteristics of the natural flavouring complex. Although the chemical composition of these complexes is variable, their constituents can be assigned to relevant congeneric groups.

Table 1 gives examples of natural flavouring complexes and individual flavouring agents and provides an indication of the number of these substances that are used in commerce in the United States. Tables 2 and 3 list the constituents of two natural flavouring complexes, bois de rose oil and lemongrass oil, organized by congeneric group. While each of these complexes has numerous constituents, these constituents fit readily into congeneric groups, most of which have already been evaluated by the Committee.

Table 1. Examples of individual flavouring agents and natural flavouring complexes

Type of flavouring agents (number of agents of this type)

Examples (No.)

Chemical assay

Individual flavouring agents with minimum assay value of >95% (1400)

Cinnamyl alcohol (No. 647)

Minimum assay of >95% (JECFA)

Individual flavouring agents with minimum assay value of <95% (230)

(E,R)-3,7-Dimethyl-1,5,7-octatrien-3-ol (No. 1154)

Minimum assay of 93%; 3-5% linalool, and lesser quantities of linalool oxide and nerol oxide

Natural flavouring complexes Essential oils (190)

Wintergreen oil (Group (b))a

FCC chemical assay: not less than 98% and not more than 100.5% methyl salicylate

 

Lemongrass oil (Group (c))a

FCC chemical assay: not less than 75%, by volume, of aldehyde as citral

 

Lemon oil, distilled (Group (d))a

FCC chemical assay: between 1% and 3.5% aldehydes, calculated as citral

Extracts (100)

Vanilla extract (Group (c))a

Oleoresins (30)

Black pepper oleoresin (Group (c))a

FCC chemical assay: piperine: not less than 36%; volatile oil content: between 15 ml and 35 ml/100 g.

a Group as classified by WHO (1987) (see Introduction)

FCC, Food Chemical Codex

This monograph proposes that the existing Procedure for the Safety Evaluation of Flavouring Agents (Annex 1, references 116 and 117), as refined by the Committee (Annex 1, references 122, 131), be further modified to accommodate the safety evaluation of natural flavouring complexes. After consideration of an approach to determining specifications that could be used to specify a chemical assay for a natural flavouring complex, details of the suggested modifications to the existing Procedure in order to provide for the evaluation of natural flavouring complexes are outlined herein.

2.1 Specifications for natural flavouring complexes

The Committee has always insisted upon specifications that define the substance being considered and, as previously noted, has typically required that a chemical assay for individual flavouring agents be at least 95%. In cases in which the named substance could not practically be freed from secondary components, the Committee has evaluated each secondary component individually. The emphasis throughout has been on assuring the identity and safety of the substance being evaluated.

In dealing with natural flavouring complexes, it may be useful to invoke compendia of specifications published by organizations that have previously considered these agents. The Food Chemicals Codex is one such organization, recognized by regulation in the United States and elsewhere. Food Chemicals Codex specifications typically list physiochemical properties, contaminants (including heavy metals and polynuclear aromatics) and microbiological parameters, to ensure that food ingredients, including flavouring agents, are safe for human consumption. For many natural flavouring complexes, Food Chemicals Codex also specifies a minimum chemical assay for key chemical constituents. For example, the chemical assay for caraway oil specifies that it should contain not less than 50%, by volume, of ketones calculated as carvone. The assay for peppermint oil is not less than 5% esters, calculated as menthyl acetate, and not less than 50% menthol. Clearly, flexibility is maintained in a chemical assay specified by Food Chemicals Codex in that a minimum level is specified for a chemical group that may be measured or calculated as a key chemical constituent in the natural flavouring complex. This approach could be used effectively to specify a chemical assay for natural flavouring complexes evaluated by the Committee.

To perform an evaluation, the Committee would organize the constituents of the natural flavouring complex into congeneric groups (e.g. phenols, tertiary alcohols, etc.) and perform a series of evaluations for the congeneric group. Within key congeneric groups (e.g. alicyclic secondary alcohols and ketones) selected constituents (e.g. menthol) will be associated with the technical flavouring characteristics of the natural flavouring complex (e.g. peppermint oil). In a manner entirely consistent with Food Chemicals Codex, the evaluation of congeneric groups within the complex could be linked by chemical assay to constituents that are fundamental to the flavouring characteristics of the natural flavouring complex.

An essential general principle is that the specification should be no more complex than is essential to assure the most critical aspects of safety, identity, and technical function. Determination of these key characteristics requires the use of methods shown to be reliable through collaborative studies. Existing relevant specifications from Food Chemicals Codex for bois de rose oil and lemongrass oil are provided in Tables 4 and 5 (Food Chemicals Codex, 1996).

2.2 Estimates of daily intake

The principles and procedures used by the Committee to estimate intake in the safety evaluation of individual flavouring agents are equally valid and appropriate for natural flavouring complexes, provided that the intended conditions of use are similar to those for individual flavouring agents. One obvious difference between individual flavouring agents and natural flavouring complexes is that some of the latter have much broader patterns of use in the food supply and much higher volumes of disappearance into the marketplace than do individual agents. Natural flavouring complexes such as vanilla extract and lemon oil are used in a wide variety of food categories that have high rates of consumption from products such as baked goods, beverages, soft and hard candy, and dairy products. Annual volumes of production for twelve natural flavouring complexes in use in the United States exceed 1 000 000 kg.

Table 2. Constituents of bois de rose oil, organized by congeneric groupa

Congeneric group (date of JECFA review)

DT class

FEMA No.

CAS No.

Constituent

3

I

2303

141-27-5

Geranial

3

I

2507

106-24-1

Geraniol

3

I

2509

105-87-3

Geranyl acetate

3

I

2303

106-26-3

Neral

3

I

2770

106-25-2

Nerol

3 (1997, 2003)

I

 

 

alpha,beta-Unsaturated aliphatic primary alcohol/ aldehyde/ acid/acetal/ ester

6

I

 

29171-20-8

trans-Dehydrolinalool

6

I

 

20053-88-7

3,7-Dimethyl-1,5,7-octatrien-3-ol

6

I

 

 

2,6-Dimethyl-3,7-octadien-2,6-diol

6

I

2635

78-70-6

Linalool

6

I

2772

7212-44-4

trans-Nerolidol

6

I

 

5986-38-9

Ocimenol

6

I

 

 

Spathulenol

6

I

2248

562-74-3

Terpinen-4-ol

6

I

3045

98-55-5

alpha-Terpineol

6

I

 

 

gamma-Terpineol

6 (1998)

I

 

 

Aliphatic, alicyclic and aromatic saturated and unsaturated tertiary alcohol and related ester

16

II

2465

470-82-6

1,8-Cineole

16

II

3746

5989-33-3

cis-Linalool oxide

16

II

3746

56752-50-2

trans-Linalool oxide

16

II

3746

68892-15-9

Linalool oxide (2 peaks)

16

II

3735

7392-19-0

2,2,6-Trimethyl-6-vinyltetrahydropyran

16 (2003)

II

 

 

Aliphatic and alicyclic ethers

31

I

 

29350-73-0

Cadinene

31

I

 

483-76-1

delta-Cadinene

31

I

 

39029-41-9

gamma-Cadinene

31

I

2229

79-92-5

Camphene

31

I

2252

87-44-5

beta-Caryophyllene

31

I

 

3856-25-5

alpha-Copaene

31

I

 

 

Cyclosativene

31

I

2356

99-87-6

para-Cymene

31

I

 

33880-83-0

beta-Elemene

31

I

 

 

Eremophilene

31

I

2633

138-86-3

Limonene

31

I

2762

123-35-3

Myrcene

31

I

3539

3338-55-4

(Z)-beta-Ocimene

31

I

3539

3779-61-1

(E)-beta-cimene

31

I

 

555-10-2

beta-Phellandrene

31

I

2902

127-91-3

beta-Pinene

31

I

2903

80-56-8

alpha-Pinene

31

I

 

17066-67-0

beta-Selenene

31

I

 

473-13-2

alpha-Selenene

31

I

 

 

gamma-Selenene

31

I

3046

586-62-9

Terpinolene

31 (2004)

I

 

 

Aliphatic and aromatic hydrocarbons

 

 

 

 

Total

FEMA, Flavour and Extract Manufacturers Association; CAS, Chemical abstracts service

Notes:

The composition data cited above are derived from industry and from published literature. The data are representative of the NFC in commerce (1, 2 and, in some cases, 4) and various analytical data for studies on the impact of various factors (geography, maturity, storage, etc.) on the composition of the NFC (mainly 3). Typically, four types of analyses are available:

1.

Target analyses from industry: routine quality control analysis for key constituents responsible for technical flavour function

2.

Complete analyses from industry: complete analysis for all constituents in the NFC intended for commerce

3.

Target analyses from the literature: published limited analysis for constituents in the NFC on the basis of the objective

4.

Complete analyses from the literature: published complete analysis for all constituents in the NFC

a

For bois de rose oil, constituents identified in complete analyses account for >95%

b

Only data available from complete analyses are used in the safety evaluation procedure for the NFC

c

All references for data from industry (Ind. 1-8): Industry (1999-2002) Private communication to the Flavour and Extract Manufacturers Association, Washington DC

d

References for data from the published literature:

1.

Formacek, K. & Kubeczka, K.H. (1982) The chemical composition of commercial bois-de-rose oil. In: Essential oils analysis by capillary chromatography and carbon-13 NMR spectroscopy. New York: John Wiley and Sons

2.

Buccallato, F. (1988) Bois-de-rose oil: A glimpse into the past. Perfumer Flavorist, 13, 35-36

3.

Lawrence, B. (1984) Bois-de-rose oil. Perfumer Flavorist 24, 63

Table 3. Constituents of lemongrass oil organized by congeneric groupa

Congeneric group (Date of JECFA review)

DT class

FEMA No.

CAS No.

Constituent

1

I

2362

112-31-2

Decanal

1

I

2792

124-13-0

Octanal

1 (1996, 1997)

I

   

Straight-chain primary aliphatic alcohol/aldehyde/acid/acetal/ester

3

I

2303

141-27-5

Geranial

3

I

2307

106-24-1

Geraniol

3

I

2509

105-87-3

Geranyl acetate

3

I

 

106-29-6

Geranyl butyrate

3

I

 

105-86-2

Geranyl formate

3

I

2303

106-26-3

Neral

3

I

2770

106-25-2

Nerol

3

I

2773

141-12-8

Neryl acetate

3 (1997, 2003)

I

   

alpha,beta-Unsaturated aliphatic primary alcohol/aldehyde/acid/acetal/ester

4

I

2307

 

Citronellal

4

I

2309

106-22-9

Citronellol

4

I

2311

150-84-5

Citronellyl acetate

4

I

 

106-72-9

2,6-Dimethyl-5-heptenal

4

I

   

(Z)-5-Decenal

4

I

 

141-27-5

3,7-Dimethyl-3(E),6-octadienal

4

I

   

3,7-Dimethyl-3(Z),6-octadienal

4

I

 

50705-16-3

3,3-Dimethylbicyclo[2.2.1]heptane-2-carbaldehyde

4

I

 

112-54-9

Dodecanal

4

I

2401

68820-34-8

(E)-5-Dodecenal

4

I

 

55050-40-3

exo-Isocitral

4

I

 

55722-59-3

Isocitral

4 (1998)

I

   

Nonconjugated unsaturated linear and branched chain aliphatic primary alcohol/aldehyde/acid/ acetal/ester

5

II

 

409-02-9

6-Methyl-5-hepten-2-one

5

II

 

4485-09-0

4-Nonanone

5

I

3388

593-08-8

2-Tridecanone

5

I

3093

112-12-9

2-Undecanone

5 (1998, 2002)

II

   

Aliphatic/alicyclic secondary alcohol/ketone/ketal/ester

6

I

   

epi-Cubebol

6

I

   

alpha-Cubenol

6

I

 

639-99-6

Elemol

6

I

 

473-16-5

alpha-Eudesmol

6

I

2635

78-70-6

Linalool

6

I

2772

40716-66-3

(E)-Nerolidol

6

I

2248

562-74-3

Terpinen-4-ol

6

I

3045

98-55-5

alpha-Terpineol

6 (1998)

I

   

Aliphatic/alicyclic/aromatic tertiary alcohols and esters

8

I

2125

507-70-0

Borneol

8

II

2159

76-49-3

Bornyl acetate

8

II

2230

76-22-2

Camphor

8

I

2247

1197-06-4

(Z)-Carveol

8

I

 

6753-98-6

alpha-Humulene

8

II

 

89-81-6

Piperitone

8

II

 

546-80-5

alpha-Thujone

8

II

 

473-67-6

Verbenol

8 (2004)

II

   

Secondary alicyclic/saturated/unsaturated/ alcohol/ketone/ketal/ester

31

I

3331

495-62-5

gamma-Bisabolene

31

I

 

483-76-1

delta-Cadinene

31

I

 

39029-41-9

gamma-Cadinene

31

I

2229

79-92-5

Camphene

31

I

2252

87-44-5

beta-Caryophyllene

31

I

 

3856-25-5u

Copaene

31

I

   

Cyclosativen

31

I

2356

99-87-6

para-Cymene

31

I

 

515-13-9

beta-Elemene

31

I

3839

18794-84-8

(E)-beta-Farnesene

31

I

 

23986-74-5

Germacrene D

31

I

 

1195-32-0

1-Isopropenyl-4-methylbenzene

31

I

2633

138-86-3

Limonene

31

I

2762

 

Myrcene

31

I

3539

3779-61-1

(Z)-beta-Ocimene

31

I

3539

3779-61-1

(E)-beta-Ocimene

31

I

2856

555-10-2

beta-Phellandrene

31

I

2903

80-56-8

alpha-Pinene

31

I

3046

586-62-9

Terpinolene

31

I

   

Tetradecane

31

I

 

508-32-7

Tricyclene

31

I

   

Cadina-1(10),5-diene

31

I

   

Cadina-3,5-diene

31 (2004)

I

   

Aliphatic and aromatic hydrocarbons

32

III

 

1139-30-6

Caryophyllene epoxide

32

III

   

6,7-Epoxy-3,7-dimethyl-2-octenal

32

III

   

Geraniol-6,7-epoxide

32

III

   

Humulene epoxide

32

III

   

Rosefuran epoxide

32 (2005)

III

   

Epoxides

       

Totals

Notes to Table 3

FEMA, Flavour and Extract Manufacturers Association; CAS, Chemical abstracts service

Notes:

The composition data cited above are derived from industry and from published literature. The data are representative of the NFC in commerce (1, 2 and, in some cases, 4) and various analytical data for studies on the impact of various factors (geography, maturity, storage, etc.) on the composition of the NFC (mainly 3). Typically, four types of analyses are available:

1.

Target analyses from industry: routine quality control analysis for key constituents responsible for technical flavour function;

2.

Complete analyses from industry: complete analysis for all constituents in the NFC intended for commerce;

3.

Target analyses from the literature: published limited analysis for constituents in the NFC on the basis of the objective;

4.

Complete analyses from the literature: published complete analysis for all constituents in the NFC.

   

a

For lemongrass oil, constituents identified in complete analyses account for >95%

b

Only data available from complete analyses are used in the safety evaluation procedure for the NFC (shaded columns)

c

References for data from industry (Ind. 14): Industry (19762003) Private communication to the Flavour and Extract Manufacturers Association, Washington D.C.

d

References for data from published literature:

1.

Chowdhury, J.U. et. al. (1998) Studies on the essential oil bearing plants of Bangladesh. Part IV. Composition of the leaf oils of three Cymbopogon species: C. flexuosus Wats. J. Essent. Oil Res., 10: 301306.

2.

Chalchat, J.C. et. al. (1997) Correlation between chemical composition and antimicrobial activity. VI. Activity of some African essential oils. J. Essent. Oil Res. 9, 6775.

Table 4. Food Chemicals Codex specifications for bois de rose oil

NFC cluster

Bois de rose

Common name

Rosewood

Botanical family

Lauraceae

Genus and species

Aniba rosaeodora Ducke
Aniba duckei Kostermans
Aniba rosaedora Ducke var amazonica Ducke
Aniba parviflora (Meissner) Mex

Synonyms

Aniba rosaeodora var. amazonica
Brazilian rosewood oil

Geographical source

Wood is collected in principally in Brazil and, to a lesser extent, in Peru

Description of botanical source

Tropical, medium-sized, wild-growing evergreen

Degree of maturity

Mature trunk wood

FEMA No(s).

2156

FDA citation(s)

182.20

COE No(s).

Not applicable

Other information

Use in formulations has become less attractive as environmental concerns have grown over the destructive nature of rosewood oil production in Brazil.

Plant parts used

Trunk wood

Derivatives used (e.g. absolute, oil, extract, etc.)

Essential oil (FEMA2156)

Yield, %, based on original botanical

Yields of oil vary according to wood feedstock quality and moisture content. Typical yields of oil are approximately 1% (w/w).

Method of isolation

Steam distillation of water soaked comminuted trunk wood. Distillation is carried out in mild or galvanized steel vessels that may vary in size from 200 to 1000 kg capacity of chips. Steam generation is by boiler fueled with spent chips. No further processing of the oil is carried out either by the primary distiller or by the end-user.

Solvents used

Not applicable

Appearance

Colourless or pale yellow liquid with a refreshing, sweet woody, linalool-like, somewhat floral-spicy odour.

Angular rotation

FCC: -4 to+6
Brazilian: -2 to +5
Cayenne: -10 to -17
Peruvian: -2 to +6

Heavy metals Specific gravity

FCC: passes test (as lead, Pb)
FCC: 0.868-0.889 at 25 C
Brazilian: 0.871-0.888 at 20 C
Cayenne: 0.866-0.877 at 20 C
Peruvian: 0.870-0.880 at 20C

Refractive index

FCC: 1.462-1.470 at 20 C
Brazilian: 1.4620-1.4685 at 20 C
Cayenne: 1.4610-1.4665 at 20 C
Peruvian: 1.4620-1.4700 at 20C

Distillation range Solubility in alcohol

FCC: Not less than 70% distills between 195 and 205C
FCC: 1 :6 in 60% alcohol
Brazilian: 1:3-5 in 60% alcohol
Cayenne: 1:4 in 60% alcohol
Peruvian: 1:6 in 60% alcohol

Solubility in water

Very soluble

Solubility in other solvents

FCC: Soluble in mineral oil, most fixed oils and propylene glycol Slightly soluble in glycerin

Moisture

Not applicable

Major components assay (if applicable)

FCC: Total alcohols 82-92%, calculated as linalool
ISO: Total alcohols 84-93%, calculated as linalool
Main constituent is linalool. The l-form of linalool is predominant in cayenne oil, whereas the d- and l-isomers are present in Brazilian and Peruvian oils.

Recommended JECFA specifications for chemical assay

Not less than 80% and not more than 95% tertiary terpenoid alcohols and related esters, calculated as linalool (decision-tree class I).

COE, Council of Europe; FCC, Food chemicals Codex; FEMA, Flavour and Extracts Manufacturers Association; ISO, International Organization for Standardization

Table 5. Food Chemicals Codex specifications for lemongrass oil

NFC cluster

Lemongrass

Common name

Lemongrass

Botanical family

Gramineae

Genus and species

Cymbopogon flexuosus (Nees.) Stapf ("East Indian type")
Cymbopogon citratus DC ("West Indian type")

Synonyms

Citral terpenes
Indian melissa oil
Indian oil of verbena
Oil of lemon grass

Geographical source

India, West Africa, Central America, West Indies, South America

Description of botanical source

Cultivated herbaceous grass

Degree of maturity

Mature fresh or partly dried leaves

FEMA No(s).

2624

FDA citations(s).

182.20

COE No(s).

CE38

Other information:

Lemongrass oil has one of the largest annual volumes of production of all essential oils in the world. Most of the volume produced is used for the production of citral.

Plant parts used

Leaves

Derivatives used (e.g. absolute, oil, extract, etc.)

Oil

Yield, %, based on original botanical

0.2-0.4%

Method of isolation

Steam distillation

Solvents class used

No solvents

Cymbopogon flexuosus

 

Appearance

ISO: Pale yellow to yellowish brown, mobile liquid with odour resembling that of citral

Optical rotation

ISO: -3 to+1 at 20 C
FCC: -3 to +1

Heavy metals

FCC: passes test

Specific gravity

ISO: 0.885-0.905 at 20/20 C
FCC: 0.894-0.904 at 25/25 C

Refractive index

ISO: 1.4830-1.4890 at 20 C
FCC: 1.483-1.489 at 20C

Distillation range

Not applicable

Solubility in alcohol

ISO: Miscible 1:3 in 70% (v/v) ethanol at 20 C
FCC: Passes test

Solubility in water

Not available

Solubility in other solvents

Not available

Moisture

Not available

Major components assay (if applicable)

ISO: Carbonyl content (as citral) 73% min
FCC: Aldehyde (as citral) 75.0% min.

Other

ISO: Residue from vacuum distillation: 10% (m/m) max.
FCC: Steam-volatile oil 93.0% min.

Cymbopogon citrates

 

Appearance

ISO: Pale yellow to orange-yellow, mobile liquid with characteristic strong note of citral.

Optical rotation

ISO: -3 to +1 at 20C
FCC: -3 to +1

Heavy metals

FCC: passes test

Specific gravity

ISO: 0.872-0.897 at 20/20C
FCC: 0.869-0.894 at 25/25C

Refractive index

ISO: 1.4830-1.4890 at 20C
FCC: 1.483-1.489 at 20 C

Distillation range

Not applicable

Solubility in alcohol

ISO: Soluble in 70% (v/v) ethanol at 20C
FCC: Passes test

Solubility in water

Not available

Solubility in other solvents

Not available

Moisture

Not available

Major components assay (if applicable)

ISO: Carbonyl content, as citral: 75% min.
FCC: Aldehyde (as citral) 75.0% min.

Other

FCC: Steam-volatile oil 93.0% min.

Recommended JECFA specifications for chemical assay

Not less than 70% and not more than 90% primary terpenoid alcohols, aldehydes, carboxylic acids, and related esters, calculated as citral (decision-tree class I).
Not more than 10% nonconjugated unsaturated linear and branched chain aliphatic primary alcohols, aldehydes, carboxylic acids, and related acetals and esters (decision-tree class I).
Not more than 10% aliphatic and aromatic terpenoid hydrocarbons (decision-tree class I).
Not more than 2% aliphatic or alicyclic epoxides (decision-tree class III).

COE, Council of Europe; FCC, Food Chemical Codex; FDA, Food and Drug Administration; ISO, International Organization for Standardization

As has been common practice by the Committee since 1996, intake of individual flavouring agents is based on a conservative estimate, with the assumption that only 10% of the population consumes all of the substance as a flavouring agent, Clearly the use of natural flavouring complexes, such as vanilla extract and lemon oil, that are used at high volume is not limited to 10% of the population. It is recommended that in the case of natural flavouring complexes that are used at high volume (e.g. >100 000 kg/year) that the Committee use the actual percentage of users as estimated from databases on food intake. This would provide more realistic estimates of daily intake.

The data on poundage and intake for bois de rose oil and lemongrass oil are show in Table 6. For these natural flavouring complexes, it is valid to estimate daily intake using the principles and procedures that are used for individual flavouring agents.

Exposure to constituents of the natural flavouring complex in the various con-generic groups does not solely occur via intake of the complex. These constituents, mainly terpenes, are also present as common components of many traditional foods. In fact, the majority of terpenes that are constituents of a natural flavouring complex are also consumed in the normal diet. For example, exposure to linalool, limonene, linalyl acetate and other terpenes in bois de rose oil also occurs by daily consumption of spices (e.g. coriander), fruits (e.g. oranges), wine, and certain vegetables. Exposure to the constituents found in bois de rose oil occurs mainly from consumption of a normal diet. This is to be expected, given the ubiquitous presence of simple monoterpenes in all plants.

Table 6. Poundage and intake data for bois de rose oil and lemongrass oil

 

Bois de rose oil

Lemongrass oil

USA annual poundage (1995)

2902 kg

1470 kg

Per capita intake, USA

38 mg/person per day

19 mg/person

"Eaters only", per capita intake, USA 10

380 mg/person per day

194 mg/person

2.3 Proposed modification to the current procedure for the safety evaluation of flavouring agents

It is recommended that the current Procedure for the Safety Evaluation of Flavouring Agents be expanded to include the option to evaluate both individual flavouring agents and natural flavouring complexes. Like individual flavouring agents, flavouring agents present in a natural flavouring complex will be assigned to the appropriate congeneric groups. Subsequently, each congeneric group will be evaluated according to the current steps in the Procedure (see Figure 1). Once all congeneric groups contained within the natural flavouring complex have been evaluated, a conclusion can be made concerning the safety of the combination of congeneric groups that constitute the complex. This modification to the existing Procedure to allow the inclusion of assessments for congeneric groups will permit the evaluation of all types of flavouring agents, including relatively pure individual flavouring agents (chemical assay >95%), agents containing appreciable amounts of secondary components minimum chemical assay, <95%), and natural flavouring complexes containing different congeneric groups of individual flavouring agents. The proposed modification to the Procedure constitutes an efficient use of resources because it builds upon the evaluations previously conducted and relies on the extensive series of monographs on well-defined congeneric groups of flavouring agents already published by the Committee.

Figure 1

Figure 1. Procedure for the Safety Evaluation of Flavouring Agents and Natural Flavouring Complexes

As a test, two natural flavouring complexes, bois de rose oil and lemongrass oil, were evaluated using the modified Procedure. The results of these evaluations (shown in Table 7 and Table 8, respectively) indicate that at current levels of intake these natural flavouring complexes would not be expected to present a safety concern.

Table 7. Safety evaluation of bois de rose oila,b

Flavouring agent or congeneric group of NFC

Congeneric group number

Structural class I

 

Aliphatic, alicyclic, and aromatic saturated and unsaturated tertiary alcohols and esters

6

Aliphatic and aromatic hydrocarbons

31

alpha,beta-Unsaturated straight-chain and branched-chain aliphatic primary alcohols, aldehydes, acids and esters

3

Structural class II

 

Aliphatic and alicyclic ethers

16

NFC, natural flavouring complex; NR, not required for evaluation because consumption of the substance was determined to be of no safety concern at step A3 of the decision-tree

a

If members of the congeneric group have different structural classes, assign the highest structural class to the congeneric group. If the flavouring agent or natural flavouring complex contains more than one congeneric group, assign a decision-tree classification to each of the congeneric groups that make up the flavouring agent or natural flavour complex

b

Step 2: All of the congeneric groups in this NFC are expected to be metabolized to innocuous products. The evaluation of these congeneric groups therefore proceeded via the A-side of the decision-tree

c

The thresholds for human intake for structural classes I and II are 1800 and 540 g/day, respectively. Daily intake for each congeneric group was calculated by taking the highest analytical value (%) from the complete analyses and multiplying by the daily per capita intake ("eaters only") of the NFC. The daily per capita intake ("eaters only") is 380 g/person per day from use of bois de rose oil as a flavouring agent in the USA

Notes:

1.

To be evaluated by the Committee in 2004: aliphatic and aromatic hydrocarbons (Group 2)

2.

To be evaluated by the Committee in 2004: a,b-unsaturated aldehydes (Group 3)

3.

To be evaluated by the Committee in 2004: monocyclic and bicyclic secondary alcohols and ketones (Group 4)

4.

Evaluated by the Committee in 2003 (WHO Food Additives Series 52, in preparation): aliphatic branched-chain saturated and unsaturated alcohols, aldehydes, acids, and related esters

5.

Evaluated by the Committee in 2003 (WHO Food Additives Series 52, in preparation): aliphatic and aromatic ethers

Table 8. Safety evaluation of lemongrass oila,b

 

 

Congeneric group number

Structural class I

 

alpha,beta-Unsaturated straight-chain and branched-chain aliphatic primary alcohols, aldehydes, acids and esters

3

Aliphatic and aromatic hydrocarbons

31

Unsaturated straight and branched chain ali primary alcohols, aldehydes, acids, acetals and esters

4

Straight chain aliphatic primary alcohols, aldehydes, acids, acetals and esters

1

Structural class II

 

Aliphatic, alicyclic secondary alcohols, ketones, ketals and esters

5

Aliphatic, alicyclic and aromatic tertiary alcohols and esters

6

Secondary alicyclic saturated and unsaturated alcohols, ketones, ketals and esters

8

Structural class III

 

Epoxides

32

Notes to Table 8

NR, not required for evaluation because consumption of the substance was determined to be of no safety concern at step A3 or B3 of the decision-tree; NFC, natural flavouin complex

a

If members of the congeneric group have different structural classes, assign the highest structural class to the congeneric group. If the flavouring agent or natural flavouring complex contains more than one congeneric group, assign a decision-tree classification to each of the congeneric groups that make up the flavouring agent or natural flavour complex

b

Step 2: Seven congeneric groups in this natural flavouring complex are expected to be metabolized to innocuous products. The evaluation of these congeneric groups therefore proceeded via the A-side of the decision-tree. Congeneric group 32, epoxides, is in structural class III; and limited metabolic data exists for this congeneric group. The evaluation of this congeneric group therefore proceeded via the B-side of the decision-tree

c

The thresholds for human intake for structural classes I, II and III are 1800, 540 and 90 g/day, respectively. All intake values are expressed in mg/person per day. Daily intake for each congeneric group was calculated by taking the highest analytical value (%) from the complete analyses and multiplying by the daily per capita intake ("eaters only") of the natural flavouring complex. The daily per capita intake ("eaters only") is 194 g/person per day from use of lemongrass oil as a flavouring agent in the USA

Notes:

1.

To be evaluated by the Committee in 2004: aliphatic and aromatic hydrocarbons (Group 2)

2.

To be evaluated by the Committee in 2004: a,b-unsaturated aldehydes (Group 3)

3.

To be evaluated by the Committee in 2004: monocyclic and bicyclic secondary alcohols and ketones (Group 4)

4.

Evaluated by the Committee in 2003 (WHO Food Additives Series 52, in preparation): aliphatic branched-chain saturated and unsaturated alcohols, aldehydes, acids, and related esters

5.

To be evaluated by the Committee in 2005

3. CONCLUSIONS AND RECOMMENDATIONS

Procedures that allow the Committee to evaluate individual flavouring agents as well as natural flavouring complexes are already in place. The examples provided indicate that the modified Procedure for the Safety Evaluation of Flavouring Agents also works for natural flavouring complexes. It is recommended that the Committee should evaluate several natural flavouring complexes using the modified Procedure at a future meeting.

4. REFERENCES

Food Chemicals Codex (1996) Food Chemicals Codex, 4th Ed., Washington: National Academy Press.

WHO (1987) Principles for the Safety Assessment of Food Additives and Contaminants in Food (Environmental Health Criteria, No. 70), Geneva.

Acknowledgement

The authors offer special thanks to Dr Timothy Adams and Ms Christie Gavin of the Flavor and Extract Manufacturers of the United States for providing analytical data on flavour composition and for many useful ideas in the formulation of the modified Procedure for the Safety Evaluation Of Flavouring Agents.



    See Also:
       Toxicological Abbreviations