Attokaran M. Natural Food Flavors and Colorants

Подождите немного. Документ загружается.

Introduction

The tomato is a fruit primarily used as a vegetable. It is not very sweet but has a ﬁ ne

ﬂ avor with some sourness. These qualities make it a favorite item in the kitchen. Its

botanical name is synonymous with Lycopersicon lycopersicum and Lycopersicon

esculentum . Lyco means “ wolf ” and persicum , “ peach ” ; it is named after the wolf

because it was wrongly thought of as toxic due to its membership in the Solanaceae ,

or nightshade, family.

The tomato is a gift from the New World to the Old World after the European

conquest of America. The progenitor of this fruit is probably an herbaceous green

plant with small green fruits growing in the highlands of Peru. The Aztecs and other

civilizations used the tomato for cooking as early as 500 BC. It was Cortez, the

Spanish conquistador, who may have been the ﬁ rst to transfer the small yellow tomato

to Europe after he captured the Aztec city of Tenochtitlan, now Mexico City, in 1521.

However, others believe that Christopher Columbus took the tomato to Europe in

1493.

But it is only in recent years that the fruit was gained its reputation as a producer

of valuable pigment. Lycopene, the characteristic color constituent, is also regarded

as a valuable nutraceutical.

Plant Material

The tomato plant is a perennial plant, which has a weak woody stem and grows to a

height of 1 – 3 m. The leaves are pinnate with a length of 10 – 25 cm and with ﬁ ve to

nine leaﬂ ets on the petiole. Each leaﬂ et has a serrated border. Both the stem and the

leaves are hairy. The ﬂ owers are yellow, 1 – 2 cm in diameter, and are borne in a cyme

of 3 – 12.

Tomatoes are grown all around the world as a popular vegetable. In different agro -

climatic conditions, there are many variations in the characteristics of the plant and

fruit. According to FAO statistics, world production in 2007 was over 126 million

tonnes, of which China accounts for over 33.6 million tonnes, the United States

11.5 million tonnes, Turkey 9.92 million tonnes, India 8.59 million tonnes, and Egypt

7.55 million tonnes. A considerable quantity of this is made into ketchup, which

is undoubtedly the most consumed sauce in the world. Only a small percentage of

Tomato

Solanum lycopersicum L ( Solanaceae )

387

Natural Food Flavors and Colorants Mathew Attokaran

388 Individual Flavors and Colorants

tomatoes go into production of carotene color. Naturally, the red variety is most

popular for this purpose.

Chemistry

Lycopene is the principal pigment of the tomato, accounting for 80 – 90% of the total

carotenoids (Fig. 97.1 ). Though it is a hydrocarbon, it is intensely colored. It has no

carbon rings at the ends as in β - carotene and is an aliphatic compound with 13 double

bonds, all of which are trans . Lycopene is stable like other carotenes but on storage

needs protection from light. It is oil - soluble in very dilute concentrations, as it tends

to crystallize at even slightly above 100 ppm.

Lycopene is also produced synthetically. It comes as dark red to violet crystals.

Extractives

Tomato lycopene extract is made by using red tomatoes and solvents such as ethyl

acetate or hexane. Such tomatoes rich in carotenes will have 200 ppm of lycopene.

The combined miscella is freed of the solvent by evaporation to obtain a rich lycopene

extract (Emerton 2008 ).

Lycopene and β - carotene from ripe tomato pulp and skins are extracted using

supercritical carbon dioxide at pressures between 2000 and 4000 psi and temperatures

at 40 – 80 ° C. With the proper combination of operative conditions, it is possible to

obtain a product with 87% lycopene and 13% β - carotene (Cadoni et al. 1999 ). By

addition of 5% ethanol as cosolvent, 53.93% of lycopene is extracted by supercritical

carbon dioxide with a ﬂ ow rate of 4 kg/hour, at 55 ° C and 300 bar pressure (Baysal

et al. 2000 ).

Rozzi et al. ( 2002 ) extracted lycopene from tomato skins, which, along with seeds,

are the waste of tomato processing. Experiments with temperatures between 32 and

86 ° C and varying pressures show that lycopene extraction increases with a higher

temperature and pressure, resulting in an extraction of 61% of lycopene.

Recently, an environmentally friendly solvent, ethyl lactate, has been suggested as

an excellent solvent for extraction of both trans - and cis - lycopene. Use of an antioxi-

dant such as α - tocopherol during extraction increases the efﬁ ciency of extraction and

the extract ’ s nutritional value (Ishida and Chapman 2009 ).

Analytical Method

The FCC describes a spectrophotometric method for determination for synthetic lyco-

pene, by dissolving it in cyclohexane and measuring at 476 nm.

Figure 97.1. Lycopene.

97 Tomato 389

Uses

Tomato extract provides nearly pure lycopene as it accounts for 80 – 90% of the carot-

enoids present. It has been given an E - number and can be used as a natural color.

Being a hydrocarbon with 13 double bonds, it has intense color and good oil solubility.

Oil suspensions are used in extruded foods, baked products, cheese, butter and other

spreads, pasta, soups, gravies, and sauces (Emerton 2008 ).

Lycopene extract can be made water - dispersible by using an emulsiﬁ er such as

polysorbate or glyceryl monooleate. Such water - soluble color is used in beverages,

ice cream, dairy desserts, candies, meat products, soups, and gravies. The only nega-

tive aspect of tomato lycopene is that it may impart a tomato ﬂ avor where one is not

desired.

Identiﬁ cation Numbers

FEMA No. CAS US/CFR E - No.

Tomato extract – 90131 - 63 - 8 – –

Lycopene – – – 160d

References

Baysal , T. ; Ersus , S. ; and Starmans , D.A.J. 2000 . Supercritical CO

extraction of β - carotene and lycopene

from tomato paste waste . J. Agric. Food Chem. 48 ( 11 ), 5507 – 5511 .

Cadoni , M. Enzo ; De Giorgi , Rita ; Medda , Elena ; and Poma , Gianluca . 1999 . Supercritical CO

extraction

of lycopene and β - carotene from ripe tomatoes . Dyes Pigm. 44 ( 1 ), 27 – 32 .

Emerton , Victoria , ed. 2008 . Food Colours . Oxford, UK : Leatherhead Publishing and Blackwell Publishing ,

pp. 75 – 81 .

Ishida , Betty K. ; and Chapman , Mary H. 2009 . Carotenoid extraction from plants using a novel environ-

mentally friendly solvent . J. Agric. Food Chem. 57 ( 3 ), 1051 – 1059 .

Rozzi , N.L. ; Singh , R.K. ; Vierling , R.A. ; and Watkins , B.A. 2002 . Supercritical ﬂ uid extraction from tomato

processing byproducts . J. Agric. Food Chem. 50 ( 9 ), 2638 – 2643 .

Introduction

Turmeric is a spice valued in the international market more for its bright yellow color

than for its ﬂ avoring properties. Nevertheless, in India, since ancient times, it has been

considered important for its ﬂ avoring, coloring, and therapeutic uses. Because of this,

it is regarded as an auspicious material and is even used in Hindu religious ceremonies.

Turmeric acquired more importance when the Ayurveda, the ancient Indian system of

medical practice, was systematically developed by masters such as Caraca and Sasruta.

Like other spices, turmeric also traveled from the Eastern to the Western world,

perhaps through the Mediterranean countries. Turmeric is present in the Assyrian list

of herbs in 600 BC. It was also found to have been entered in the Materia Medica

compiled by Dioscorides. In the thirteenth century, Marco Polo mentioned turmeric

as growing in the Fokien region of China. He noted its similarity to the color of

saffron; hence, in medieval times, turmeric was known as Indian saffron. Although

turmeric was considered inferior to saffron as a food color, it is valuable for its thera-

peutic qualities.

It is believed that the turmeric plant originated in the hills of Western Ghat of

Southwest India and spread to other regions of India and Southeast Asia. It is probable

that from there it was spread to China, the Caribbean region, and South America by

the Spanish. It probably spread later to some regions of Africa via the colonial powers.

For some time, both in East and West, turmeric had importance as a dye for color-

ing cotton and silk. The dye can be applied without a mordant although the color soon

fades, especially on exposure to the sun. Development of synthetic fast dyes sounded

the death knell to the use of turmeric as a fabric dye.

Although many South and Southeast Asian countries, as well as other tropical

regions, grow turmeric, India remains the major producer. Several cultivars are grown

in South India. Some of the major trade types are Alleppey, Erode, Sangli, Rajapuri,

and Nizamabad.

Plant Material

Turmeric is an herbaceous perennial plant (see Photo 28 ), which grows to a height of

0.5 – 1 m in height. The leaves are clear green, acute at the ends, and broad. The ﬂ owers

are pale yellow and arise from two buds at the axil. The rhizome is the main product.

Turmeric

Curcuma longa L ( Zingiberaceae )

391

Natural Food Flavors and Colorants Mathew Attokaran

Photo 28. (A) Whole growing turmeric plant. (B) Uprooted turmeric. (C) Foreground,

powder; left, dried turmeric; right, fresh ﬁ ngers of turmeric. See color insert.

392

98 Turmeric 393

Propagation is carried out by planting a cut portion of rhizome. Since the plant has to

be plucked every year to harvest the valuable rhizome, turmeric has to be treated as

an annual plant, needing replantation every year.

The rhizome has two parts: a bulbular primary tuber, known as “ mother ” turmeric;

and some cylindrical, multibranched, secondary rhizomes growing from the mother

turmeric, known as “ ﬁ nger ” turmeric. Both parts have transverse leaf scars and dents

from root scars. There are also true roots emerging from the rhizome.

The dried planting material of the previous season gets weakly attached to the

rhizome. While harvesting is done by pulling out the plant, this portion remains stuck

in the earth and will not be removed with the rhizome. For a long time, it was not

recovered. However, in recent years in the Indian state of Tamil Nadu in some regions

farmers are now digging this material out of the earth. It is easy to dry and is the

source of the curcumin - rich Pazhangali grade turmeric that oleoresin manufacturers

buy. It is not harvested in other regions, where farmers claim that the cost of digging

and recovering is not worth it.

Because they contain large amounts of starch, the freshly harvested rhizomes do

not dry easily. To facilitate drying, rhizomes are boiled in water for about an hour or

so while the starch is gelatinized. If inadequately boiled, when the turmeric ﬁ nger is

broken in half, the juicy extract will form threads between the two pieces. When fully

gelatinized, this will not happen. Then the wet rhizomes are sun - dried. On completion

of drying, the dried piece will break cleanly. Even though the yellow pigment is sensi-

tive to sunlight, there is no loss during sun drying as the pigments are well protected

inside the rhizome.

It is customary to slice mother turmeric into four longitudinal pieces, so that it

becomes nearly as thin as ﬁ nger. Both mother and ﬁ nger turmeric are used, but the

ﬁ nger turmeric has a slightly higher value. In the export market, there is some demand

for polished turmeric ﬁ ngers. This is carried out by rotating the ﬁ ngers in a metal

drum with rough sidewalls. Polishing gives a bright, appealing yellow color and com-

mands a higher price.

Turmeric, when dry, has an essential oil content of 2 – 7%, but the oil is not valued

for its aroma characteristics. There is some demand for its medicinal value. The active

component of turmeric is curcumin, the bright yellow food color, which is present to

a level of 1.5 – 5.5%. Table 98.1 represents rhizomes grown in various important

growing areas and their analyses (Krishnamurthy et al. 1976 ).

Chemistry

Dry turmeric has 8.6% protein, 8.9% fat, 63.0% carbohydrate, and 6.9% of crude ﬁ ber.

It has minerals and water - soluble vitamins such as thiamine, riboﬂ avin, niacin, and

ascorbic acid at low levels. As mentioned, it also has volatile oil and curcumin

pigment.

Typical sesquiterpene compounds known as turmerone are characteristic of tur-

meric oil. They are ar - turmerone, α - turmerone, and β - turmerone. ar - Turmerone has

an aromatic ring, as shown in Figure 98.1 . α - Turmerone has two additional H and

β - turmerone four additional H, removing one and two double bonds, respectively,

from the aromatic ring.

394 Individual Flavors and Colorants

The main pigment is curcumin, whose structure is given in Figure 98.2 . This is

bis - (feruloyl)methane, which has a slightly reddish, bright yellow color. Curcumin can

exist in enol and keto forms. There are two other allied compounds that also have a

bright yellow color: p - hydroxy cinnamoyl feruloyl methane (demethoxy curcumin)

and bis - ( p - hydroxy cinnamoyl)methane (bis - demethoxy curcumin).

The characteristic yellow color of turmeric is contributed by the three pigments.

The usual ratio of these is curcumin 80 – 85%, demethoxy curcumin 10 – 15%, and bis -

Figure 98.1. ar - Turmerone.

Figure 98.2. Curcumin. (A) Enol form. (B) Keto form.

OCH

Table 98.1. Yields of volatile oil and curcumin

Cultivar Volatile Oil (% v/wt) Curcumin Content (%)

Waigon 7.20 3.51

Kuchupudi 5.60 4.03

Sugandham 5.30 3.62

Erode 4.00 3.00

Rajapuri 4.50 3.45

Godhvi 6.00 3.49

Tekurpeta 2.50 1.82

Kasturi 5.80 3.44

Miraj 26 6.30 2.87

Alleppey 4.00 5.44

Duggirala 3.80 2.22

Cuddappa 3.30 2.46

98 Turmeric 395

demethoxy curcumin about 5%. As the methoxy group is replaced by hydroxyl group,

there is a very slight drop in the reddish tint to the bright yellow color, although on a

quick glance the difference is difﬁ cult to detect.

Since the three components all have yellow color and similar absorption charac-

teristics, they are referred to together as total curcumin. They have a maximum at

425 nm with an inﬂ ection at 445 nm. The three pigments are difﬁ cult to separate by

ordinary extraction procedure, but can be separated by chromatography.

Essential Oil

There are many people who believe that turmeric is a dye and not a spice, but in India

where for centuries turmeric has been used as an ingredient in curry powder, it has a

deﬁ nite contribution toward the ﬂ avor of the food. In the Western world, turmeric is

mostly used as a food color, although in the case of mustard paste, for example, tur-

meric does contribute its own distinct ﬂ avor. In world trade, however, turmeric essen-

tial oil has very low demand.

Dry turmeric, on coarse grinding and steam distillation, yields turmeric oil, in a

range of 2 – 4%. The oil is a yellowish, mobile liquid with the ﬂ at, slightly medicinal

aroma typical of turmeric. Because of the need to distill for a long period of time, the

deoiled material is not suitable for extraction into oleoresin. This, together with poor

demand for the oil, prompts processors to directly extract for oleoresin. For making

this into curcumin powder, one of the steps is crystallization. This will cause all the

noncrystallizable components including the essential oil, to be removed as the “ oil

part. ” The oil part on steam distillation yields volatile oil at a considerably cheaper

price. For the limited use of turmeric oil, this recovered oil is sometimes used.

Analytical studies of pure turmeric oil are somewhat scarce. Nearly 60% of the oil

is shown to consist of ar - turmerone and α - turmerone. Earlier studies indicate that these

are present in almost equal proportion. However, other studies indicate a ratio of

turmerone and ar - turmerone of 80:20. One study shows this ratio to be 30 : 70, indi-

cating conversion of turmerone to ar - turmerone (Govindarajan 1980 ). The other

major constituent is zingiberene ( ∼ 25%). Also reported are α - phellandrene, cineole,

borneol, sabinene, and some sesquiterpene alcohols (9%). In short, it can be said that

except for the occurrence of turmerones in large proportions, turmeric oil is similar

to ginger oil.

Analysis of commercial true oil and oil recovered from the oil part is presented in

Table 98.2 . It can be seen that true oil contains more of the turmerones (ar, α , and β ),

with a consequent lower level for zingiberene. True oil also shows terpene hydrocar-

bons, alcohols, and cineole in small quantities. Total turmerones ( α and β ) account

for about 45% versus about 16% of ar - turmerone. The ratio of turmerones to ar -

turmeric is 74 : 26; all three put together account for 61% of the total oil as shown by

GC analysis. Volatile oil recovered from the oil part shows similarities to true oil,

except for a decrease in turmerones and some increase in zingiberene.

Oleoresin

Extraction of the ground turmeric with solvent and subsequent removal of solvent

yield turmeric oleoresin, which has all the essential oils present in the rhizome.