Attokaran M. Natural Food Flavors and Colorants

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266 Individual Flavors and Colorants

References

Leung , Albert Y. ; and Foster , Steven . 1996 . Encyclopedia of Common Natural Ingredients . New York : John

Wiley and Sons , pp. 342 – 344 .

NIIR Board . 2009 . The Complete Technology Book of Essential Oils . Delhi : Asia Paciﬁ c Business Press ,

pp. 48 – 69 .

Introduction

There are two types of lemongrass oil, one West Indian ( Cymbopogon citratus ) and

the other East Indian ( Cymbopogon ﬂ exuosus ). Both are valued as a source of lemon-

grass oil, which has great value as a low - cost fragrance oil in a number of toiletries.

One of the major uses of lemongrass oil was as a source of citral, from which

vitamin A used to be made. Citral is the starting material for making β - ionone, which

is a valuable intermediary for the synthesis of a number of compounds. Now alternate

routes for synthesis of products such as vitamin A have been developed, and this has

reduced the importance of lemongrass oil. Of the two, the East Indian variety typically

yields a much higher level of citral.

Lemongrass as such is used as a spice in Southeast Asian cuisine, especially in that

of Thailand, Vietnam, Malaysia, Indonesia, China, and in some parts of India. For this

use, the West Indian grass gives a more balanced ﬂ avor. Food manufacturers are

beginning to realize the utility of lemongrass oil and oleoresin as a ﬂ avoring material

for processed foods.

Plant Material

West Indian lemongrass ( C. citratus ) is a tall perennial grass. The plant emits the

characteristic aroma of citral. The dense fascicle of leaves starts from the underground

rhizome. The blade of the leaf is long and tapering to the top with a length of 90 cm

and width of 1.7 – 2.0 cm. They are glabrous but may be smooth or rough on the upper

side and along the edges. The inﬂ orescence spatheate panicle is 30 – 60 cm long.

The plant thrives in an annual rainfall of 200 – 250 cm with an average temperature

range between 23 and 27 ° C. The plant is mainly cultivated in the Caribbean islands,

Guatemala, and certain parts of Brazil. In Southeast Asia where lemongrass is culti-

vated for use as a spice, the West Indian type of lemongrass is common.

The East Indian type of lemongrass ( C. ﬂ exuosus ) is indigenous to southwest

coastal areas of India. Two types of grass are common, red grass and white grass.

When the oil was valued for citral content, cultivation was at its height. A considerable

amount of lemongrass oil with more than 75% citral content used to be exported from

the port of Cochin.

Lemongrass

Cymbopogon citratus (DC) Stapf; C. ﬂ exuosus (Stend

Wats) ( Poaceae ; Gramineae )

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268 Individual Flavors and Colorants

The plant is an aromatic grass with a height of 2 – 3 m. The leaves are linear from

the rhizome and lanceolate. The length of the leaves is 1 – 1.5 m with a width of 1.5 –

2 cm. Panicles are large and drooping, with a gray or grayish - green color, with raceme

pairs spreading 1 – 1.5 m tall, and slightly hairy.

The lemongrass plant thrives in a warm and humid climate with a rainfall of over

250 cm. The plant is hardy and can resist drought up to a point. It grows well in alti-

tudes of 100 – 1200 m and can tolerate relatively poor soil as is found on hillsides. It

primarily grows in the rainy regions of South India. By extension work, the grass has

been successfully cultivated in other parts of India.

Systematic research has produced other varieties that can be grown in other less

favorable regions of India. Cymbopogon pendulus is one such variety.

Chemistry

The main constituent of the grass is citral. It is a monoterpene aldehyde (Fig. 68.1 ).

The oil from the East Indian variety contains 75 – 85% citral. The citral content of West

Indian oil is 65 – 80%.

Citral, which is 2,3 - dimethyl 2,6 - octadienal, occurs in two geometric isomeric

forms, geranial (citral A) and neral (citral B).

Essential Oil

The main constituent of the grass is the essential oil. Because of its low value, it is

common for local people to distill oil in crude stills using water distillation. The oil

vapor mixed with water vapor passes through a tube to a receiver vessel kept cool by

immersion in water, sometimes in the shallow running water of a small stream. Oil is

decanted from the top of the still.

In larger production centers, large mild steel vessels are loaded with cut and slightly

dried grass, and steam from an external boiler is introduced. These stills are capable

of distilling 5 – 10 tonnes of grass. The vapors are cooled by water condenser and oil

is collected in a Florentine ﬂ ask arrangement. By this method, the yield of oil in the

case of East Indian grass will be 0.2 – 0.4% and, for West Indian grass, 0.1 – 0.24% on

a fresh weight basis.

Figure 68.1. Citrals. (A) Geranial. (B) Neral.

68 Lemongrass 269

The main ingredient of lemongrass oil is citral, which accounts for three - fourths

of the oil. There are other terpene hydrocarbons. Among the alcohols, linalool, methyl

heptanol, α - terpineol, geraniol, nerol, farnesol, and citronellol have been reported in

West Indian oil. Many volatile acids such as isovaleric, geranic, caprylic, and citro-

nelic have also been noticed (Leung and Foster 1996 ). East Indian oil has similar

constituents. Geraniol - dominated varieties are now being developed, but this oil is

primarily used in the fragrance industry.

According to the FCC, East Indian oil is a dark yellow to light brown - red liquid

and West Indian light yellow to light brown liquid. Lemongrass oil has a lemon odor

and is soluble in mineral oil, freely soluble in propylene glycol, but practically

insoluble in water and in glycerin. The East Indian type readily dissolves in alcohol

but the West Indian type yields a cloudy solution.

The physical characteristics of lemongrass oil as deﬁ ned by the FCC are as

follows.

Optical rotation − 10 ° to 0 °

Refractive index 1.483 – 1.489

Speciﬁ c gravity

East Indian 0.890 – 0.904

West Indian 0.869 – 0.894

Solubility

East Indian 1 mL dissolves in 3 mL 70% alcohol

West Indian Yields cloudy solution with 70 – 95% alcohol

Oleoresin

Since cut leaves are used as a leafy spice, oleoresin has some demand in the making

of processed foods popular in some Asian countries and in the Western world where

Asian populations live.

In this author ’ s lab, commercial extraction is carried out as described. The leaf is

cut and sun - dried, giving a yield of 42% dry material with 10 – 12% moisture. This is

pulverized in a hammer mill into a coarse powder, then passed through a roller mill

and extracted by gravity percolation in a large stainless steel vessel using a mixture

of hexane and acetone (75:25). After the removal of solvent from the miscella, oleo-

resin is obtained with a yield of 4.3% on dry basis and approximately 1.8% on wet

basis. It can be diluted with vegetable oil.

Lemongrass oleoresin is a dark green viscous liquid with the characteristic aroma

of lemongrass with a noticeably green ﬂ avor. By dilution with sunﬂ ower seed oil, the

volatile oil content is adjusted between 5% and 10% of the oleoresin.

Uses

While cut lemongrass is used as a ﬂ avoring spice in Asian cuisine, the oil has not been

developed into an exact replacement. Oleoresin can serve this purpose. The oil,

however, is used in various beverages, some baked goods, and confectionery. It may

also ﬁ nd use in herbal tea.

270 Individual Flavors and Colorants

Lemongrass oil has great value as a low - cost fragrance material in some toiletries

and cosmetics. The use of the oil as a source of citral to make vitamin A and β - ionone

is decreasing. Citral still has some value as the starting material for the synthesis of

some compounds.

Identiﬁ cation Numbers

FEMA No. CAS US/CFR E - No.

Lemongrass oil (West Indian) 2624 8007 - 02 - 1 182.20 –

89998 - 14 - 1

Lemongrass extract (East Indian) 2624 – – –

Reference

Leung , Albert Y. ; and Foster , Steven . 1996 . Encyclopedia of Common Natural Ingredients . New York : John

Wiley and Sons , pp. 344 – 346 .

Introduction

Licorice (spelled liquorice in England) is the root of a perennial plant. Its alternate

botanical name is Liquiritia ofﬁ cinalis L ( Leguminosae ). The root has a sweet constitu-

ent. The name licorice is derived from a Greek name meaning “ sweet root. ”

Licorice was used in ancient Egypt, Rome, and Greece as a curative against cough

and cold. The great Greek physician Theophrastus remarked that the root has the

special property of quenching the thirst if held in the mouth and that it has sweet

components that are safe for diabetic patients. Licorice probably originated in China,

though among the plants grown in different regions, Chinese plants are the smallest.

It is now grown in Central Europe, Turkey, Spain, Russia, and China. Licorice has

value in Ayurvedic therapy and is grown in India. It is also used in traditional Chinese

medicines. Many attributes such as prevention of stomach ulcers, reduction of low -

density cholesterol, reduction of body fat, and control of HIV have been attributed to

it, but glycyrrhizic acid, the sweet component, has the harmful effect of increasing

blood pressure. In fact, in 2008, the European Commission suggested that intake of

glycyrrhizic acid should be restricted to below 100 mg/day to avoid a rise in blood

pressure, muscle weakness, chronic fatigue, and lowering of testosterone levels in

men. The main use of licorice is as a ﬂ avor.

Plant Material

The licorice plant is a legume, like peas and beans, native to Europe and some parts

of Asia. Although anise, star anise, and fennel contain similar ﬂ avoring compounds,

there is no botanical connection between these and the licorice plant.

It is an herbaceous perennial plant that grows to a height of 1 – 1.5 m. It has green,

spreading, attractive foliage. It has pinnate leaves that droop during the night. Each

pinnate leaf has 10 – 18 leaﬂ ets. The ﬂ owers, which are about 1 cm long, with pale blue

to purple color, are produced in a loose inﬂ orescence. The pod that comes out of the

ﬂ ower is 2 – 3 cm long containing ﬁ ve to eight seeds. The rhizome has a gray - brown

color, and its inside is ﬁ brous. It is the rhizome that gives the sweetness.

Chemistry

The active component of the licorice rhizome is glycyrrhizin, which is the main sweet

compound, being 30 – 50 times as sweet as sucrose. Chemically, it is a triterpenoid

Licorice

Glycyrrhiza glabra L ( Papillionaceae )

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272 Individual Flavors and Colorants

saponin glycoside of glycyrrhizic acid. On hydrolysis, it is converted to aglycone,

glycyrrhetinic acid, and two molecules of glucoronic acid. Aglycone obtained on

hydrolysis is free of sweetness. Although sweet, it is different from sugar. The sweet-

ness of glycyrrhizin is slow to feel but lingers in the mouth for a longer time. It retains

sweetness even on heating. It is generally recognized as safe (GRAS) in the United

States as a ﬂ avor but not as a sweetener. It is used as a ﬂ avoring in candies, pharma-

ceutical, and tobacco products. The European Union advises people not to use more

than 100 mg/day. In Japan where there has been a shift to plant - based sweeteners from

synthetic sweeteners, it is used especially in combination with another plant - based

sweetener, Stevia . The Japanese government, however , advises people to limit the

usage of glycyrrhizin to 200 mg/day.

The aroma of the licorice plant is caused by a terpene anethole, which is the char-

acteristic ﬂ avor of anise oil and star anise (see Chapter 16 on anise).

Extraction

Licorice products are made from peeled or unpeeled dried rhizome. These are ﬁ nely

cut or powdered for use in teas, capsules, and medicinal tablets, as well as for extracts.

To make extracts, roots are boiled in water to obtain a solution of water solubles. The

insoluble solids are ﬁ ltered off. The combined extract is then concentrated by evapo-

rating off the moisture. The heavy, pasty product that results will contain 80 – 85%

soluble solids. This represents 30 – 40% starch and gums, 16% sugar, and 12 – 20%

glycyrrhizin (Farrell 1990 ). The concentrated pasty product is further dried under a

vacuum or spray dried to a moisture level of below 5%.

The United States imports a large quantity in concentrated extract form usually in

stick or solid block forms. Another common form is as concentrated extract, in which

the active component is an ammonium salt (Leung and Foster 1996 ). Some extracts

are freed of glycyrrhizin and are known as deglycyrrhizinated licorice (DGL). DGL

does not harm adrenal glands or have other unwanted side effects. This is used mainly

for medicinal purposes and not for ﬂ avoring.

Analytical Method

The AOAC has a GC method for ammonium glycyrrhizinate and an HPLC method

for both free acid and salts.

A reliable and efﬁ cient method of analysis is by ﬁ rst converting to aglycone fol-

lowed by reverse - phase HPLC using C8 column and UV detector (Lauren et al. 2001 ).

This method has a satisfactory recovery in a large number of analyses.

Uses

Licorice extracts are used in the tobacco industry as a ﬂ avor. Licorice contributes a

mellow, sweet, woody ﬂ avor, which enhances the taste of tobacco. The active com-

ponent expands airways, enabling smokers to inhale more smoke, though at the same

time it generates some of the toxins found in the smoke. It is also used widely in

confectioneries. The extract and glycyrrhizin, both as such and in ammoniated form,

69 Licorice 273

are used in licorice candy where anise oil is also often used for better effect. The above

are also used in alcoholic beverages such as beer, nonalcoholic beverages such as root

beer, frozen dairy desserts, and meat products. Its sweet aftertaste is desisted in some

soft drinks and herbal teas, and to disguise the unpleasant ﬂ avors of medical prepara-

tions. In Chinese cuisine, the rhizome ﬂ avor is used in savory products.

Ayurvedic therapy and Chinese medicine both recognize the medicinal qualities of

licorice. It is an expectorant and is sometimes used in cough syrups. While it has many

beneﬁ cial medicinal qualities, its negative effect on blood pressure should be kept

in mind.

Identiﬁ cation Numbers

FEMA No. CAS US/CFR E - No.

Licorice extract 2628 97676 - 23 - 8 184.1408 –

84775 - 66 - 6

Licorice extract powder 2629 68916 - 91 - 6 184.1408 –

84775 - 66 - 6

References

Farrell , T. Kenneth . 1990 . Spices, Condiments and Seasonings , 2nd edition . New York : Chapman and Hall ,

pp. 121 – 123 .

Lauren , Denis R. ; Jensen , Dwayne J. ; Douglas , James A. ; and Follett , John M. 2001 . Efﬁ cient method for

determining the glycyrrhizin content of fresh and dried root and root extracts of Glycyrrhiza species .

Phytochem. Anal. 12 ( 5 ), 332 – 335 .

Leung , Albert Y. ; and Foster , Steven . 1996 . Encyclopedia of Common Natural Ingredients , 2nd edition .

New York : John Wiley and Sons , pp. 346 – 350 .

Introduction

Limes are small citrus fruits with green or greenish yellow skin and ﬂ esh. Well - known

varieties of limes are sour, being rich in citric acid, although sweet limes are also

available. Sour limes have more sugar and citric acid than lemons and therefore have

a tart taste. Sweet limes have less citric acid and taste sweeter. Limes originated in

the Himalayan region of India.

The lime became important during the early days of exploration, when British

sailors were prone to scurvy, which was identiﬁ ed as caused by a deﬁ ciency of vitamin

C, or ascorbic acid. This was prevented by a daily ration of lime. While it was a

satisfactory solution to the problem, it also led to the nickname of “ limey ” for all

British people.

While lime juice is an important food ﬂ avoring material, for other food items it is

the peel ’ s essential oil that is the important ﬂ avoring material.

Plant Material

The lime tree is an evergreen tree that grows to a height of 4 – 6 m. It has sharp spines.

Lime leaves have some characteristic ﬂ avor and are therefore used in Southeast Asia

as an herb in cooking. West Indian trees are small and bushy, with ﬁ ne twigs and small

leaves. Tahitian and Persian trees are larger and more spreading. The twigs are coarser

and almost free of thorns. The fruits are larger, with transverse diameter of 5 – 6 cm

and longitudinal diameter of 6 – 7.5 cm. The rind is thin and smooth. The average

diameter of an American lime is 3.8 – 5 cm; the transverse diameter is 3 – 6 cm.

Most production ﬁ gures available are for limes and lemons combined, as in many

places the two are considered together since their uses are similar. In India, both lemon

and lime are used for making hot pickles. Excepting major branded items, even in soft

drinks there is no strict differentiation. In household cooking and in use as fresh ﬂ a-

voring for alcoholic beverages, not much attention is paid to whether a lime or lemon

is used. India accounts for 16% of the world ’ s overall production of lime and lemon,

followed by Mexico (14.5%), Argentina (10%), Brazil (8%), and Spain (7%).

Essential Oil

When the skin of a fresh fruit is punctured, oil oozes out on the application of some

pressure. This is cold - pressed lime oil. When juice is expressed, some peel oil gets

Lime

Citrus aurantifolia (Christm) Swingle ( Rutaceae )

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