Attokaran M. Natural Food Flavors and Colorants

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Introduction

Fresh curry leaves are widely used in the culinary practices of South India. The deli-

cate, savory aroma is so well liked that it ﬁ nds use in almost all curries and prepara-

tions of vegetables, meat, and ﬁ sh in India. But the taste of the actual leaf is so

unwelcome that the ﬁ rst thing a person does who is eating a meal that contains the

leaves is to remove them. It is to be concluded that once the aroma is absorbed, the

leaf has no value. In fact, it has some nonvolatile toxic constituents. How convenient

it would be if there were an essential oil that had all the volatile characteristics but

none of the nonvolatile ones. However, the whole leaf is believed to have some cura-

tive effect, as it is recommended in the treatment of ailments such as dysentery, as a

febrifuge for fever, and as a general tonic in Ayurvedic therapy. After boiling in milk

and grinding, it is applied to external eruptions and venomous bites. But its primary

use is as a food ﬂ avor.

Plant Material

The curry leaf tree is grown mainly in India and Sri Lanka. It is a small tree of 4 – 6 m

in height and has a narrow trunk of 15 - to 30 - cm width. Leaves are pinnate with 10 – 20

leaﬂ ets, each 2 – 5 cm long and 1 – 2 cm broad (see Photo 12 ). The leaves emit the

characteristic aroma of the plant. The leaves resemble the leaves of a neem tree.

Because of this, the vernacular names of both are similar.

The ﬂ owers are relatively small and white in color. The tree has small dark berries

whose seeds are toxic. However, the fresh leaves are in demand as a seasoning. The

plant grows well in warm conditions with full or partial sun. The tree is found in

almost all of India but thrives best in Southern India and Sri Lanka. On a dry basis,

the leaf has about 6% protein, 1% fat, 16% carbohydrate, and 6 – 7% crude ﬁ ber. It has

minerals, a fair amount of vitamin A, ascorbic acid, and some B vitamins. However,

it is reported to have over 1% oxalates, and for this reason the leaves are rarely eaten

as such (Pruthi 1976 ). The fresh leaves have 2.6% volatile oil, which is the signiﬁ cant

constituent of the curry leaf.

Essential Oils

Well before the advent of GC - MS, analyses of the curry leaf had been carried out.

Water distillation yields 1% essential oil, which contains mainly l - pinene, dipentene,

Curry Leaf

Murraya koenigii L ( Rutaceae )

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Natural Food Flavors and Colorants Mathew Attokaran

178 Individual Flavors and Colorants

l - terpineol, l - caryophyllene, and l - cadinene (Nigam and Purohit 1961 ). The oil is

reported to be a bright yellow mobile liquid. In the 1950s, other workers found pinene,

dipentene, caryophyllene, cadinene, and a few compounds (Prakash 1990 ).

In recent years, Rana et al. (2004) have used GC - MS to analyze the essential oil

from fresh leaves growing wild in the Himalayan region. They identiﬁ ed 34 com-

pounds representing 97.4% of the oil. The major components are α - pinene (51.7%),

sabinene (10.5%), β - pinene (9.8%), β - caryophyllene (5.5%), limonene (5.4%), bornyl

acetate (1.8%), terpinen - 4 - ol (1.3%), γ - terpinene (1.2%), and α - humulene (1.2%).

Chowdury and Yusuf (2008) ﬁ nd that the curry leaf contains 39 compounds, of which

3 - caryone 54.2% and caryophyllene 9.2% are the most notable components.

Oil obtained by steam distillation of curry leaves grown at 1750 m elevation in

Uttarakand, India, showed α - pinene (8.08%), sabinene (44.10%), β - caryophyllene

(12.22%), β - phellandrene (3.19%), terpinen - 4 - ol (3.25%), β - cubebene (4.05%), α -

humalene (2.80%), germacrene D (3.09%), bicyclogermacrene (3.11%), and a few

other components in small proportions (Pande et al. 2004 ).

The free and glycosidically bound aroma compounds from the curry leaf are iso-

lated and separated on column and eluted. The aroma compounds are released by β -

glucosidase hydrolysis and analyzed by GC - MS. Linalool has been found to be the

main component out of 67 constituents. Out of 78 free aroma fractions, octyl acetate

is the major component. In the hydrolyzed oil, β - caryophyllene is the major compound

out of 56 compounds identiﬁ ed (Padmakumari 2008 ).

Studies of the levels of antioxidants in fresh curry leaves show that lutein is present

to a level of 9744 ng, α - tocopherol 212 ng, and β - carotene 183 ng/g fresh weight

(Palaniswamy et al. 2003 ).

Photo 12. Curry leaf. See color insert.

45 Curry Leaf 179

In this author ’ s lab, it has been seen that β - phellandrene is the major component,

accounting for 40 – 55%, followed by β - caryophyllene 12 – 20%, 3 - carene 4 – 8%, α -

pinene 2 – 5%, and β - pinene 1 – 4%.

The oil obtained is light yellowish mobile liquid with a green note combined with

a curry - like aroma. The average yield obtained on fresh weight basis is 0.12 – 0.20%.

Physical characteristics are as follows.

Optical rotation + 3 to + 12 ° at 25 ° C

Refractive index 1.4800 – 1.4900 at 25 ° C

Speciﬁ c gravity 0.8520 – 0.8750

Oleoresin is not generally made, mainly because of unwanted nonvolatile compo-

nents such as oxalic acid.

Uses

The curry leaf is used in a wide range of curries, chutneys, soups, and snacks, all of

which are hot to taste. When processed foods are made, it is more convenient to use

the essential oil. The oil is used in diluted buttermilk, which is becoming popular as

a soft drink. Use of the leaf may be a source of contamination. Curry leaf oil allows

Asians who have settled in the West to add a highly prized native ﬂ avor to their savory

preparations.

Srivastava et al. (2007) have found that essential oil and carbazole alkaloids from

the leaves have antifungal properties. The activity is found to be enhanced by

derivatization into N - methyl compounds, although hydrogenation reduces the activity.

Such observations are encouraging factors in making curry leaf oleoresin a ﬂ avor

material, provided that toxic components such as oxalic acid are removed.

References

Chowdury , Jasim Uddin ; and Yusuf , Mohammed . 2008 . Aromatic plants of Bangladesh: constituents of leaf

oil of Murraya koenigii and M. paniculata . Indian Perfumer 52 ( 1 ), 65 – 68 .

Nigam , S.S. ; and Purohit , R.M. 1961 . Chemical examination of the essential oil derived from the leaves of

Murraya koenigii Spreng (Indian curry leaf) . Perfum. Essent. Oil Rec. 52 , 152 – 155 .

Padmakumari , K.P. 2008 . Free and glycosidically bound isolates in curry leaves ( Murraya koenigii (L

Spreng) . J. Essent. Oil Res. 20 ( 6 ), 479 – 481 .

Palaniswamy , Usha R. ; Caporuscio , Christian ; and Stuart , James D. 2003 . A chemical analysis of antioxidant

vitamins in fresh curry leaf ( Murraya koenigii ) by reverse phase HPLC with UV detection . Acta Hortic.

620 , 475 – 478 .

Pande , C. ; Chamotiya , C.S. ; and Padalia , R. 2004 . Essential oil of Murraya koenigii from north eastern

Himalayan region . Indian Perfumer 48 , 407 – 410 .

Prakash V. 1990 . Leafy Spices . Boston : CRC Press , pp. 35 – 42 .

Pruthi , J.S. 1976 . Curry leaf . In Spices and Condiments . New Delhi : National Book Trust , pp. 108 – 111 .

Rana , V.S. ; Juyal , J.P. ; Rashmi ; and Blazquez , M. Amparo . 2004 . Chemical constituents of the volatile oil

of Murraya koenigii leaves . Int. J. Aromather. 14 ( 1 ), 23 – 25 .

Srivastava , Sanjay ; Ray , D.P. ; and Singh , R.P. 2007 . Chemical examination and antifungal activity of curry

leaf ( Murraya koenigii (L) Spreng) . Pesticide Res. J. 19 ( 2 ), 149 – 151 .

Introduction

The date is the fruit of a palm tree and is valued as an unprocessed food. It is gener-

ally eaten after some drying. The date has been a staple food of the Middle East. It

was believed to have originated in the Persian Gulf region. It was in use in ancient

Mesopotamia (present Iraq) and Egypt from around 4000 BC. There is evidence that

it was cultivated in Arabia even as early as 6000 BC, in lands adjacent to the desert

where cultivation of other food crops is rather difﬁ cult. From Arab countries it was

introduced to European Mediterranean countries. Spaniards introduced date palms to

Mexico and California in the mid - eighteenth century.

Plant Material

Like many palm trees, the date palm is an erect tree that grows to a height of 20 – 30 m.

The date palm has spread all over the world, sometimes in a haphazard manner.

Therefore, there is great variation in size and other characteristics. In some cultivars,

several trunks spring from the same root system. Covered over the trunk will be an

overlapping, upward - pointing woody leaf base. The leaves are pinnate, each 2 – 5 m in

length, with spines on the petiole having a sturdy midrib and with 120 – 160 leaﬂ ets.

Each leaﬂ et comes as a sheath that divides into a network of ﬁ bers at the base.

The date palm is dioecious, having separate male and female plants. Small fragrant

ﬂ owers are born on a branched spadix divided into a number of strands. The female

ﬂ owers are whitish, male ﬂ owers, waxy and light yellow - colored. The fruits are

oblong, with a length of 3 – 8 cm, with a thin or thick skin when ripe. Inside it has a

hard, oval - shaped stone which is grooved on one side. The inside ﬂ eshy portion is

yellow or reddish - brown in color, but develops into a darker color when dried.

The tree can be grown from the hard seed, but the disadvantage of this method is

that only 50% of the trees will be date - bearing female plants. Therefore, commercial

farms use cuttings of heavily cropping cultivars that produce a large number of sweet

fruits. Plants thus grown from cuttings will bear fruits 2 – 3 years earlier than plants

produced from seedlings.

Dates are naturally wind - pollinated plants, but today, it is common to use manual

pollination. By such a method, one male tree can pollinate about 100 female trees.

Manual pollination is carried out by skilled workers who climb on a ladder or use a

climbing tool that wraps around the trunk of the tree.

Date

Phoenix dactylifera L ( Palmae )

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182 Individual Flavors and Colorants

Date trees thrive best in sandy, clayey, or other heavy soils. They are tolerant of

alkalinity and a moderate degree of salinity. The tree needs full sun and grows best

in warm, dry weather. It can withstand periods of drought, but for greater yield it needs

water.

Dates are harvested when they are fully ripe, when the pulp turns soft from a

crunchy texture. It is eaten after the shell is removed and usually after some sun drying.

Fully ripe fruits are also available after the hard stony seed is removed and are

often chopped, usually longitudinally. They can also be dehydrated and ground and

blended with grain or combined with almonds, walnuts, cashew nuts, or candied citrus

peel.

According to the Food and Agricultural Organization of the U.N. report of 2007,

the top producers are Egypt (1.3 million tonnes), Iran (1 million tonnes), and Saudi

Arabia (0.98 million tonnes). Other major producers are United Arab Emirates,

Pakistan, Algeria, Iraq, Sudan, Oman, and Libya.

The dried date has about 73% carbohydrates, much of which are sugars. One

hundred grams of dried dates accounts for approximately 275 kcal of energy. They are

rich in vitamins and minerals and are therefore a wholesome food. In some countries,

palms are tapped for the sweet sap, which is converted into palm sugar and alcoholic

beverages. Date seeds, after soaking in water and being partially disintegrated, are

used as cattle feed. Date fruit has polyphenolic compounds such as ﬂ avanols and caf-

feoyl shikimic acid which, by the action of phenolase enzyme, bring about browning

during drying and storage. Polyphenolic constituents also contribute a mild, desirable

astringency to the fruit.

Extractives

Dates have no essential oil. Since the main constituents are carbohydrates, date extract

is made with hot water.

A typical process carried out in this author ’ s lab is as follows. About 30 kg of

ripened and dried dates with seeds are boiled in a kettle provided with a steam jacket

in the bottom and sides. It is brought to boiling after adding 15 L of water. When

boiling starts, it is maintained for about 10 minutes. During this time, the cooked and

softened dates are broken by pressing with a ﬂ at ladle so as to crush the pulp. The

pulp is then ﬁ ltered through a ﬁ lter cloth, while being stirred gently so that all the

juice passes through. The residue is then transferred to the kettle, water added and

boiling continued as before, using the ladle to further break the pulp. After ﬁ ltration,

the residue is given one more extraction with boiling water. Generally, the extraction

will be complete after three boilings. This can be checked by tasting the residue for

a sweet taste. If needed, a fourth boiling is done.

The combined ﬁ ltrate, approximately 40 L after evaporation and absorption by the

pulpy residue, is then placed in a ﬂ at kettle with more surface area and provided with

a steam jacket in the bottom. The extract is concentrated until a total soluble solid

strength of 75 – 80 ° Brix is obtained. The yield will be 50 – 55%. Seeds will account for

20%. The rest will be insoluble ﬁ brous residue. About 750 ppm of citric acid is added

so that the pH is 3.7 – 3.9. The ﬁ nal water extract will have a reddish - brown color and

a viscous consistency. It will have the rich sweet taste of dates.

46 Date 183

Uses

Date extract is used as a ﬂ avor in tobacco. It gives a ﬁ ne, mild, sweet taste during

smoking. Date extract serves the same purpose as the extract of carob fruits, which is

also used widely.

In the Ayurveda, sweet rasayans are made using dates. Rasayans are rich nutrient

broths prescribed to improve general health. Currently, date extracts are used, because

they are a more standardized product.

Date extract can be used as a sweet ﬂ avor in cakes, puddings, and sweet sauces.

Identiﬁ cation Numbers

FEMA No. CAS US/CFR E - No.

Date extract – 90027 - 90 - 0 – –

Introduction

The main part of the davana plant is the inﬂ orescence, which has a ﬁ ne aroma. The

ﬂ owers are used to make garlands for religious purposes. South Indian women adorn

their hair with the fragrant ﬂ owers. Davana is also distilled for its aromatic oil. Davana

oil is an expensive oil used in food and beverage products and sometimes in perfum-

ery. Ernest Guenther visited Mysore, India, and made observations of the crop and

the oil (Guenther 1952 ). There are two cultivars, but the one whose oil gives a rich

fruity note is the most highly valued. Today, there is a small but systematic cultivation

and distillation of this plant to obtain the desired sensory characteristics.

Plant Material

The main centers of cultivation of the davana plant are in South India, especially in

the Karnataka State. The state of Tamil Nadu, which used to grow the inferior variety,

is now switching over to the more desired variety with support given by the Central

Institute of Medicinal and Aromatic Plants, Lucknow (Aktar et al. 1988 ).

Davana is an annual plant. It has an erect stem with near vertical branches. The

height of the herb can be 45 – 60 cm. The leaves are alternate and lobed to pinnatisect

gray. The inﬂ orescence consists of glabrous ﬂ orets, which have ﬁ ve lobes and are

bisexual.

The davana plant prefers light showers, bright sunshine, mild winters without frost,

and heavy morning dew. The crop cannot tolerate very heavy rainfall. For propagation,

seeds are sown in nursery beds and seedlings are transplanted. From 1 ha, 12 – 15 tonnes

of fresh herbage is obtained. On distillation, this can yield 10 – 12 kg of davana oil.

Essential Oil

The herbage is partially dried in the shade, which requires 2 – 3 days. Generally, the

weight decreases by half due to the escape of moisture. Bright sunlight may be dam-

aging to the oil and will also cause evaporation of some of the oil. The yield is reported

to be 0.2% (Aktar et al. 1988 ).

In this author ’ s lab, commercial distillation is carried out ﬁ rst by a short period of

drying in the shade. By exposing the plant to shade drying for 4 – 6 hours, moisture

loss is only 5 – 10% of the original 80 – 88%. No advantage in loading capacity, yield

Davana

Artemisia pallens Wall ( Asteraceae , Compositae )

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Natural Food Flavors and Colorants Mathew Attokaran