Attokaran M. Natural Food Flavors and Colorants

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46 General

during normal processing. However, curcumin, especially in extract form, is sensitive

to light. In fact, all natural colorants are affected by exposure to light and therefore

need protection.

Autoxidation

Autoxidation is a process where molecules such as unsaturated lipids are converted

to peroxide through the inﬂ uence of atmospheric oxygen. It is a free radical chain

reaction. Unsaturated fatty acids of an oil get converted to peroxide and further to

carbonyl compounds and can even result in breakdown products. In food, propagation

of the reaction can lead to rancidity, which will cause an unwelcome off - ﬂ avor. During

the process of secondary reaction, an autoxidized molecule can give off energy to

another unsaturated molecule, which then continues the chain reaction through forma-

tion of peroxide, oxygenated carbonyl derivative, and breakdown products with

unwanted rancid odor.

Keeping material protected from light and heat will reduce the intensity of autoxi-

dation. An effective method is the addition of antioxidant, which acts as a chain

breaker. Iron and other metals act as prooxidant; therefore, keeping the material in

metal containers will increase autoxidation. Storage has to be in food - grade stainless

steel, appropriate polymer, or glass packaging containers. Some of the antioxidants

used in natural ﬂ avors and colors are listed below.

Antioxidants

Antioxidants are required in the case of carotenoid colors, especially when dissolved

in a fatty oil as is the case with paprika oleoresin. While there are many synthetic

antioxidants like butylated hydroxyl anisol (BHA), butylated hydroxy toluene (BHT),

tertiary butylated hydroxy quinone (TBHQ), and ethoxyquin (EQ), many people prefer

natural antioxidants.

Tocopherol mixture (vitamin E) is a valuable natural antioxidant. It is usually a

mixture of α , β , γ , and δ tocopherol. Commercial tocopherol manufactured for anti-

oxidant use comes in a strength up to 70%. The product is a golden brown - colored

oily liquid with a mild characteristic odor. China has become a good source for

tocopherols.

Rosemary extracts are now considered to be a valuable natural antioxidant. The

active component in these is carnosic acid. Commercial preparations are available

from 5% carnosic acid, but can be found as high as 50%. Recently, rosmarinic acid

of rosemary has been found to be even more effective as an antioxidant.

Ascorbic acid is a synergist and works more effectively with a proper antioxidant.

While it is available as a salt, one derivative that is effective is ascorbyl palmitate.

Both ascorbic acid and ascorbyl palmitate come as a white powder.

References

Binu , Paul ; Mathull , T. ; Issac , Anil ; and Mathew , A.G. 2007 . Acetone originating from curcumin during

determination of residual solvent . Indian Perfumer 1 ( 2 ), 41 – 43 .

12 Deterioration During Storage and Processing 47

Chen , Chu - Chin ; and Ho , Chi - Tang. 1988 . Gas chromatographic analysis of volatile components of ginger

oil ( Zingiber ofﬁ cinale R) extracted with liquid carbon dioxide . J. Agric. Food Chem. 36 , 322 – 328 .

Erler , J. ; Vostrowsky , O. ; Strobel , H. ; and Knobloch , K. 1988 . Uber atherische ole deslingwer, Zingiber

ofﬁ cinale R . Z. Lebensm . Urters. Forsch. , 186 , 231 – 234 (see Lawrence, B.M., Progress in essential oils,

Perfumer Flavorist 1990, 15 , 167 ).

Rios , Jose J. ; Fernandez - Gracia , Elisabet ; Minguez - Mosquera , Maria Isabel ; and Perez - Galvez , Antonio .

2008 . Description of volatile compounds generated by the degradation of carotenoids in paprika, tomato

and marigold oleoresins . Food Chem. 106 , 1145 – 1153 .

Part II

Individual Flavors and Colorants

Introduction

This part deals with a wide range of natural materials that are already in production

and use. In each case, there is a description of the plant (or animal) material, matters

relating to extraction, a bit of the chemistry of the active components, and their pro-

perties. Identiﬁ cation numbers of major regulatory bodies will help students in obtain-

ing more details. Some relevant references are listed for each item.

It can be seen that some colorants are from microbial and others from entomologi-

cal sources. In fact, these two sources have a very promising future. Biotransformation

of molecules by microorganisms and tiny insects is a dynamic tool which produces

biologically oriented molecules that have the desired ﬂ avor and color useful in making

foods more appealing and safe.

Natural Food Flavors and Colorants Mathew Attokaran

Introduction

Ajwain (spelled “ ajowan ” outside the United States) is also known as Bishop ’ s weed.

It is a small caraway - like seed which belongs to the parsley family and is sometimes

mistaken for lovage seeds. It is not clear how it acquired the name Bishop ’ s weed. It

is very important in Ayurvedic therapy as a medicinal product. The name originated

from Sanskrit and almost all over the world it has a similar sounding name. In Arabic,

it translates as “ cumin of the king. ” It grows wild in Africa and its Ethiopian name is

“ azmud. ” The plant most likely originated in the eastern Mediterranean, probably in

Egypt. Thymol is its principal constituent and therefore its ﬂ avor has some resem-

blance to thyme.

Plant Material

Ajwain is an annual herbaceous plant, growing to a height of 90 cm, with a profusely

branched stem. The leaves are primately divided with 24 × 14 cm size and with clasp-

ing leaf base. The inﬂ orescence is a compound umbel, each containing a few hundred

ﬂ owers. The fruit is 2 – 3 mm long. On drying, the gray - brown fruit becomes the spice,

generally referred to as seed. Often, the seed will have a hair - like attachment to the

plant. Mild roasting gives it an enhanced aroma.

India is a major producer of ajwain, as it is used in many vegetarian dishes. It is

also grown in Egypt, Afghanistan, and Iran. Ajwain has 15.4% protein, 18.1% crude

fat, 38.6% carbohydrates, and 11.9% crude ﬁ ber. It is rich in minerals: calcium 1.42%,

phosphorus 0.30%, and iron 14.6 mg % (Pruthi 1976 ).

Essential Oil

In India, the seeds are mostly distilled in primitive stills, but there are also modern

facilities that produce quality oil. The yield is reported to be 2.5 – 4%. In early twentieth

century, some seeds were exported to Europe and the United States for distillation.

Most likely this was for the separation of thymol, which has demand in medicinal

preparation. However, with the introduction of synthetic thymol, export for this

purpose died out.

Some monoterpenes have been reported in the literature (Akhtar et al. 1988 ). They

include α - pinene 1.8%, camphene 0.5%, β - pinene 3.5%, myrcene 0.3%, δ - 3 - carene

Ajwain (Bishop ’ s Weed)

Trachyspermum ammi L Sprague ( Umbelliferae )

Natural Food Flavors and Colorants Mathew Attokaran

52 Individual Flavors and Colorants

0.5%, limonene 5.1%, α - terpene 34.9 %, and p - cymene . The major oxygenated deriva-

tives are thymol (45.2 – 48.5%) and carvacrol L (4.5 – 6.8%).

In the author ’ s lab, oil is produced by steam distillation. The oil is a colorless to

brownish liquid possessing a characteristic thyme aroma.

Physical characteristics are as follows.

Optical rotation – 1 ° to + 5 °

Refractive index 1.490 – 1.499 at 25 ° C

Speciﬁ c gravity 0.895 – 0.910

No oleoresin is known to be produced.

In the author ’ s lab, a sample of oil produced and analyzed on gas chromatography

(GC) is presented in Table 13.1 . The major constituents seen are γ - terpinene, p -

cymene, and thymol. However, for producing the best quality oil, generally during

distillation the ﬁ rst fraction is cut off and the second fraction is taken. This will show

a thymol content of 40 – 42%, with corresponding reduction in p - cymene (12 – 18%)

and γ - terpinene (30 – 38%).

Analysis of a sample from Algeria and several samples from India was complied

by Lawrence (2006) . The major components are thymol, isothymol, γ - terpinene, limo-

nene, and p - cymene. However, there are also some signiﬁ cant minor components.

Uses

Ajwain has a characteristic phenolic/medicinal ﬂ avor due to its thymol content. Its

herbaceous and acrid taste is used in some vegetarian dishes. Ajwain could be useful

in processed foods such as caramelized onion soups and similar dishes, where it can

give an interesting ﬂ avor variation.

The main uses of ajwain and its oil are in medicinal preparations for stomach and

intestinal treatment. It also has use in the treatment of bronchitis and asthma.

References

Akhtar , Husain ; Virmani O.P. ; Sharma , Ashok ; Kumar , Anup ; and Misra , L.N. 1988 . Major Essential Oil -

Bearing Plants of India . Lucknow, India : Central Institute of Medicinal and Aromatic Plants , pp. 1 – 3 .

Lawrence , Brian M. 2006 . Progress in essential oils . Perfumer Flavorist 31 ( 6 ), 60 – 70 .

Pruthi , J.S. 1976 . Spices and Condiments . New Delhi : National Book Trust , pp. 6 – 8 .

Table 13.1. Analysis of ajwain oil

Constituent Content as % v/w

α - Pinene 0.2 – 1.0

β - Pinene 2.0 – 5.0

Limonene 0.1 – 0.6

p - Cymene 20.0 – 25.0

γ - Terpinene 40.0 – 45.0

Thymol 20.0 – 30.0

Introduction

When Spanish explorers under Columbus entered the West Indies, they thought that

they had discovered the source for black pepper when they saw the berries of the

allspice tree. This is because the dried berries are round with a dark wrinkled surface

similar to that of pepper. Consequently, the explorers gave the tree the name pimenta .

The berries have the same astringency and aromatic ﬂ avor as black pepper, though

they lack the extreme hotness. Allspice berries are also a bit larger than pepper berries.

It is reported that Azetics used them to ﬂ avor the cocoa drink. Pirates of the Caribbean

Islands used it to ﬂ avor their meat; it used to be called Jamaican pepper. The name

“ allspice ” was earned because the ﬂ avor appeared to be a combination of cloves, cin-

namon, nutmeg, and black pepper.

Plant Material

Jamaica is the major producer of allspice. It is also grown in Mexico, other West

Indian islands, and countries of Central America. The Jamaican government prevented

the spread of the plant for some time by restricting the export of the plant and its

seedlings. Many early efforts to germinate the seed in other tropical lands met with

failure, so much so it was thought that it would not grow outside Jamaica or other

nearby areas. It is now understood that passage through the digestive tract of birds is

helpful to prepare the seeds for germination. With better knowledge of biochemistry,

allspice is now making its appearance in places such as the Kerala state in India, Sri

Lanka, and Indonesia, where the agro - climatic conditions are favorable for tree spices

like allspice.

Allspice is a bushy tree with a height of 6 – 9 m. The vegetative growth is profuse

and spreads in a globe of 4 – 7 m wide. In the main growing region of Jamaica, the tree

is semiwild. The trees are either male or female, so cultivation has to be performed

in such a way that male and female trees grow side by side for easy pollination.

The leaves are about 15 cm long and oblong in shape. Leaves are aromatic and

yield an essential oil. The aroma characteristic resembles that of the bay leaf. The

berries are hard and round (Photo 1). Mexican berries are larger, with a diameter of

5 – 7 mm, while Jamaican berries have a diameter of 4 – 6 mm. On drying, the berries

resemble dried black pepper, except for a larger size and slightly less black color.

Allspice (Pimenta)

Pimenta ofﬁ cinalis Lindley ( Myrtaceae )

Natural Food Flavors and Colorants Mathew Attokaran

54 Individual Flavors and Colorants

Chemistry

Typical allspice, on analysis, shows about 6% protein, 6.6% crude fat, 52.8% carbo-

hydrate, 21.6% crude ﬁ ber, minerals such as calcium, phosphorus, sodium, and potas-

sium, and water - soluble vitamins.

However, the most important constituent of allspice is the essential oil, which is

present to a level of 3 – 4.5% on dry basis. The characteristic aroma is inﬂ uenced by

the main constituent eugenol (see Chapter 36 on clove).

Essential Oil

Allspice seeds from three origins have been analyzed for volatile oil content and yield

of resin by solvent extraction of the deoiled residue. For this, deoiled material is dried

and extracted by cold gravity percolation using hexane as the solvent. The results are

presented in Table 14.1 . Jamaican allspice shows a higher yield of both oil and

oleoresin.

Photo 1. Dried allspice (pimenta). See color insert.

Table 14.1. Analysis of pimenta of different origins

Origin Volatile Oil (vo) Content

Clevenger Method,

Water Distillation % v/w

Resin % by Hexane

extraction

Total Yield of Oleoresin

(vo + Resin )

Jamaica 3.2 5.0 8.2

Mexico 2.3 4.7 6.8

Guatemala 1.8 4.0 5.8

14 Allspice (Pimenta) 55

Commercial steam distillation using external steam and a stainless steel still is

carried out. Size reduction is done using a roller mill where round berries are turned

into ﬂ at ﬂ akes. Steam is let in at a slow rate at normal pressure for a period of 18 hours.

Most of the oil is heavier than water, with a small quantity being lighter. On mixing,

the total yield is 4.0%.

A typical GC analysis of Jamaican allspice oil is presented in Table 14.2 .

Much analytical work carried out in recent years shows that the allspice oil contains

mainly methyl eugenol and eugenol. There are some minor components that will natu-

rally inﬂ uence the quality of the oil. Lawrence (2006) has compiled this list into a

useful review for further information.

Pimenta berry oil is a heavy yellow to reddish - yellow clear oil with a ﬁ ne

aroma reminiscent of clove, cinnamon, nutmeg, and black pepper. It turns darker on

keeping.

According to the Food Chemical Codex (FCC), pimenta oil occurs as a colorless,

yellow, or orange liquid that becomes darker with age. It has the characteristic odor

and taste of allspice. It is soluble in alcohol, in propylene glycol, and in most vegetable

oils.

Physical characteristics as deﬁ ned by the FCC are as follows.

Optical rotation − 4 ° to 0 °

Refractive index 1.527 – 1.540 at 20 ° C

Speciﬁ c gravity 1.018 – 1.048

Solubility 1 mL dissolves in 2 mL of 70% alcohol

Oleoresin

Hexane is a satisfactory solvent for extraction of deoiled Jamaican allspice. Deoiled

material is packed in a percolator and extracted using hexane by cold percolation.

The combined miscella on removal of solvent yields 3.8% of resin on the basis of

whole allspice. Resin can be blended with the required quantity of previously collected

oil.

Pimenta oleoresin is a dark greenish - brown, viscous liquid with a pleasing spicy

aroma and ﬂ avor of clove, cinnamon, nutmeg, and pepper.

Table 14.2. GC analysis of Jamaican pimenta

oil (area percentage)

Constituent Percentage Range

Eugenol 80 – 87

β - Caryophyllene 4 – 8

β - Phyllandrine 0.2 – 0.5

1,8 - Cineole 1 – 3

α - Pinene < 0.3

β - Pinene < 0.3

δ , - 3 - Carene 0.5 – 2

Limonene < 0.5