Bio-Colours From Spices

Abstract

Colour is an important aspect influencing every moment of our life. It may be the clothes we wear, furnishings of our home, religious ceremonies and even the food we relish. Colour is a molecule that absorbs certain wavelengths of visible light and transmits or reflects others. There are four different types of colours viz., natural colours, nature identical colours, synthetic colours and inorganic colours. Bio-colour is a dye or pigment of biological origin (plants, insects, animals or microbes) that imparts colour when applied to food, drug, textiles or cosmetics. Bio-colours are classified into five groups viz., anthocyanin, betalain, carotenoid, chlorophyll and caramel. Spices are generally used for seasoning and flavouring. Some spices can also be used as bio-colourants. The common spices used as colourants are turmeric (curcumin), paprika (capsanthin), saffron (crocin), tamarind (leucoanthocyanidine) and kokum (anthocyanin). Use of colour is regulated by laws, such as U.S. Food and Drug Act (1960) and Food Drug and Cosmetic Act (1938). Although bio-colourants have potential benefits, the tedious extraction procedures, low colour value and instability during processing hinder their popularity. More detailed studies on the production and stability of bio-colours are necessary for their promotion in various sectors.

1. Introduction

Colouring is an important aspect of our lives for many decades. It may be the clothes we wear, furnishings of our home, religious ceremonies and even the food we relish. The various evidence related to synthetic colours usage showed harmful effects over the years, now a day’s need of consumers is shifting towards bio-colours. There is an emerging trend for the use of bio-colours as they are available naturally and are non-renewable [1].

A recent survey conducted in northern Kerala revealed excessive use of synthetic colours in sugar-based confections, posing a serious health risk, especially for children. Out of the 14 samples collected from different locations showed 97 per cent of non-permitted colours. On analysis about 82 per cent showed the higher level of permitted colours than the required limit (more than 100 ppm) [2].

Colour is a molecule that absorbs certain wavelengths of visible light and transmits or reflects others [3]. It will correct the natural variations in colour and enhance the colours that occur naturally. It is added mainly to maintain or improve the safety and freshness of the food material. It will also improve taste, texture, appearance and thereby its nutritional value [4].

Colours are mainly classified into four different types viz., Natural colours are pigments obtained from living organisms such as caramel, anthocyanin, betaline. Nature - identical colours are man-made pigments which are also found in nature - e.g. Carotene. Synthetic colours are man-made colours that are not found in nature, these are often azo-dyes and Allura red and Inorganic colours are non-edible which are used in paints and plastics [5].

2. Bio colours

Any dye or pigment, of biological origin (plants, insects, animals or microbes) impart colour when applied to food, drug, textiles or cosmetics. Bio means natural and colouring means anything used for colouring purposes [6].

2.1 History

From time immemorial, colour has been an important criterion for the acceptability of products like textiles, cosmetics, food and other items.

• The earliest written record of the use of natural dyes was found in China dated 2600 BC.

• According to the reports, the product appearance was enhanced by the addition of natural extracts and wine by Egyptian candy makers during 1500 BC.

• During the Indus Vedic period (2500 BC) the dyeing was known in the Indian subcontinent and later it has been replaced with the new coloured cloth garments including the Mohenjo-Daro and Harappa civilization (3500 BC) madder dye.

• The cochineal dye was used by the people of Aztec and Maya culture periods of Central and North America.

• Saffron is mentioned in the Bible.

• Use of natural bio-colourants in food is known from Japan in the Shosoin text of the Nara period (Eighth century), which contains references regarding colouring soybean and adzuki-bean cakes.

2.2 The need for bio-colourants

• They are stable in their nature during different process.

• They maintain their character during uneven climatic conditions.

• They will enhance the product colour and retains its quality.

• They reduce the vitamin loss and maintains the original flavour.

• Their addition will meet the people demand and is considered as a consumable food.

Bio-colours can be classified into three main classes [7].

1. Anthocyanin

2. Betalain

3. Carotenoids

4. Chlorophyll

5. Caramel

Anthocyanins, a group of water-soluble pigments, impart red to blue colours (250–650 nm). Betalains yield betacyanin (red) and betaxanthin (yellow) pigments. Carotenoid groups are responsible for the yellow and orange pigments (250–650 nm). Chlorophylls are found in two forms: chlorophyll a (blue-green) and b (yellow-green). Caramel is obtained by heating carbohydrates, which imparts a brown colour.

2.3 Insects

The bodies of some scale insects produce carminic acid- a red/purple colour called Cochineal (Dactylopius coccus). They consume cactus leaves as their food and their bodies are allowed to dry and crushed to get the red colour. These are mainly used in Africa, Spain and Central America.

2.4 Microbes

Microbes like Monococous sp. (Carotenoids) Dunaliella salina and Blakeslea trispora (β-carotene) Arthrospira platensis (spirulina bacteria) produce certain bio-colours. Phycobiliproteins, algae belonging to Rhodophyta and Chlorophyta produces red and blue colours.

2.5 Animals

Sea fishes (Hexaplex trunculus) produces purple colour from its shell due to the presence of bromine. It is mainly used in the fabrics and textile industries.

2.6 Advantages of bio-colours

Bio-colourants are gaining importance because of health, hygiene, nutrition, pharmaceutical activities, fashion and environmental consciousness. Some of the advantages of using bio-colours are:

• They are protective in their action thereby prevents from cell degradation.

• They are having anti-microbial properties and thereby increase the shelf life.

• They will enhance the nutritional quality of the food as they are rich sources of carbohydrates, minerals and vitamins.

• They will strengthen the human immune system as they have free radical scavenging properties.

• They are non - carcinogenic and safe.

3. Spices as colourants

The spices are the food additives that are mainly added to impart flavour. Besides, they can also be used as a colouring agent due to the presence of several chemical compounds, the principal compound responsible for the colour are the carotenoids, such as beta carotene, lutein, and neoxanthin [8].

The most common spices used for colouring are turmeric, red pepper, saffron, kokum and tamarind. Other compounds that provide these colouring properties to spices are flavonoids with yellow colours – curcumin and chlorophyll with green (Table 1). Spices provide strong colour pigments commonly between orange, yellow, and red, this can be advantageous since spices can be used as natural colourants especially for food. Using spices as colourants in food is a natural alternative that avoids the use of conventional synthetic colourants.

Crop	Part used	Pigment	Colour shade	Applications	Reference
Turmeric	Rhizome	Curcumin	Yellow	Food colourant	[9]
Chilli	Pericarp	Capsanthin	Red	Culinary preparation	[10]
Saffron	Stigma	Crocin	Yellow-Orange	Colourant in sweet preparations	[11]
Tamarind	Pulp; Seed	Leucoanthocynidine; Tannin	Red; Brown	Textiles; Dye	[12]
Kokum	Rind	Anthocyanin	Red	Beverages, textiles	[13]
Fenugreek	Seed	Carotenoid	Yellow	Dye	[9]
Sea fennel	Leaves	Phycocyanin	Green	Colourant in food	[14]

Table 1.

Spice bio-colours and their applications.

3.1 Turmeric

Curcuma longa L. belongs to the family Zingiberaceae. It is mainly used as a food additive, preservative and colouring agent. The economic part is a rhizome that yields a phenolic compound Curcumin (3–4%). Some of the varieties rich in Curcumin are CIM-Pitamber (12.1%), Suroma (9.3%), Rajendra Sonia (8.1%), Varna (7.8%) and cultivars such as Wayanad Local (9.5%) and Duggirala (7.5%) [15].

3.2 Properties of curcumin

• Orange-yellow crystalline powder

• Stable at high temperatures and in acids, but unstable in alkaline conditions

• Light-sensitive in nature

• First isolated by Roughley and Whiting [16]

• Structure of curcumin (C₂₁H₂₀O₆)

• Melting point: 176–177°C

• Hydrophobic in nature- Soluble in ethanol, alkali, ketone and chloroform

• Absorption maxima: 420 nm

3.3 Extraction of curcumin

Curcumin is extracted from the dried root of the rhizome C. longa. For extraction, the raw materials are crushed to make into powder form and are treated with a specific solvent to obtain the required coloured compound. After distillation, the obtained product called as oleoresin is a mixture of volatile oils along with other extracts produces about 25–35 per cent coloured compound. The oleoresins are then subjected to further washes using selective solvents that can extract the curcumin pigment from it. This process yields a purified food colour which is known as Curcumin. It contains 90 per cent colouring matter and very little volatile oil and other dry matter. The extractability and regulatory criteria depend on the selection of solvent [17].

3.4 Chilli

Capsicum annuum is one of the major spices used as a natural flavouring and colouring agent. Its extract contains carotenoid pigment Capsanthin which has a major role in the food industry. Paprika oleoresin is manufactured by solvent extraction of the dried capsicum pods. One kg of pods yields 90 to 120 g of extract. Varieties and cultivars rich in capsanthin: KTPL - 19 (233.70 ASTA), Bydagi chilli (159.9 ASTA), Kashmiri chilli (54.1 ASTA), Sanam S-4 (70.4 ASTA) [18].

3.5 Properties of Capsanthin

• Capsanthin is fat and lipid-soluble

• Capsanthin increases proportionally with advanced stages of ripeness

• It is more stable at neutral pH

• Colour saturation level: 100 mg/kg (ppm) colouring matter

• It is sensitive to heat.

Saffron

Crocus sativus L., a perennial flowering plant and most expensive spice in the world. The economic part is the dried stigmas which are the source of a natural dye. It is mainly used as a colouring agent, for dyeing silk and fabric rugs, painting, cooking and as medicine. The Colouring principle: Crocin (4–6%) isolated in the crystalline state by Karrer et al. [19].

Properties of Crocin

• Crocin: Soluble in hot water, giving an orange-coloured solution

• Sparingly soluble in absolute alcohol, ether and other organic solvents

• Golden yellow pigment

• Absorption spectrum: 435 nm [20]

Cultivars of saffron

• Kashmiri saffron: Famous for its thin and longer stigma throughout the world.

• Spanish saffron: Highest Crocin content with thicker stigma.

Extraction technique

• Saffron Stigma (10 g) were suspended in 80% ethanol at 0°C and extracted for 2 minutes

• Centrifugation at 4000 rpm for 10 min and the supernatant was separated

• 25 ml of 80% ethanol to the sediment and the extraction is repeated

• Crystal storage: thick-walled glass container at −5°C for 24 days in darkness

• Obtained crystals were separated from solution washed with acetone

• Dissolved in 120 mL ethanol 80% at −5°C in darkness for 20 extra days for re-crystallisation which yields 1.2 g of crystals [21].

Kokum

Garcinia indica well-known tropical fruit, widely used in South Indian and Konkan delicacies for imparting colour and flavour. The economic part is the dried outer cover of fruit which contain a very high concentration of anthocyanins (2.4/100 g of kokum fruit).

Properties

• The red colour in Kokum is due to the presence of anthocyanin

• The colouring compound is cyanidin 3-glucoside (C₂₁H₂₁O₁₁; MW: 449.38 g)

• Bright red colour at a pH of 2 to 3

• Stable at high temperature and water-soluble

Extraction of anthocyanin

• The fruit pulp is extracted by manual method.

• It is mixed in a 1:2 ratio with acidified water (0.1% hydrochloric acid).

• Then the mixture was subjected to a hydraulic press.

• The extract was filtered using a muslin cloth and stored in a cold room at 4–5°C.

Tamarind

Tamarind is one of the most important multipurpose trees which is grown in farmland and also occurs naturally in the forests. The red tamarind is a rare mutant and its availability is not well known. The red tamarind fruit contains rosy red pigments. The red colour is due to the presence of water soluble red-rose anthocyanin pigment.

Extraction of Leucoanthocyanidine

• It involves maceration and refrigerated storge of the prematured fruit whole night in a solution of acidified methanol (0.01% HCl in methanol) [22, 23, 24].

• The process is continued to obtain the end point with least colour and the filtrates were added together.

• The product was subjected to rotary evaporator to remove the solvent at 40°C under vacuum.

• Finally purify the product to obtain the pigment [12].

4. Sea fennel as a new spice-colourant

The sea fennel (Crithmum maritimum L.) belongs to the family Apiaceae of grows wild on maritime rocks, piers, sandy beaches along the Mediterranean sea. This is consumed as a traditional vegetable due its sensory traits like salty and similar tastes to celery, common fennel and peel of green citrus along with some pungency in many countries.

Bio-colours as health enhancers

Bio-colourants are prepared from renewable sources and the majority are of plant origin. In addition to food colouring, bio-colourants also act as anti-oxidant (chilli), anti-obesity (kokum), anti-carcinogenic (turmeric), anti-asthmatic (tamarind) and anti-depressant (saffron) and thereby prevent several diseases and disorders in human beings [25].

5. Food colour laws and regulations

The use of colour is regulated by some laws and regulations and will also provide information about its components. Some of them are:

• 1906 - US Food and Drug Act (FDA) - Prevents the use of misbranded colours.

• 1938 - Federal Food, Drug and Cosmetics Act - Inspection on the usage of colours in cosmetics and drugs.

• 1960 - FDA approved list of colours to be used in the food industry.

• 1990 - Nutrition Labelling and Education Act - This mainly regulates the labelling of food products and also their nutrient contents.

• 2006 - Regulation of colouring additive to food is mainly regulated by FSSAI in the case of exports.

5.1 Bio-colours approved by FDA

Natural biocolourants are exempt from the certification category of FDA, and European Union for food use and are annatto extract, beet, canthaxanthin, carotene, Dactylopuis coccus extract etc. (Table 2).

Colour	EEC	Source	Year (approved)
Bixin, nor-Bixin	E160b	Annatto	1963
Capsanthin	E160c	Chilli	1966
Crocin	E164	Saffron	1966
Curcumin	E100	Turmeric	1966
Lutein	E161b	Marigold	1968
Lycopene	E160	Tomato	2006
Carmine	E120	Cochineal	2009

Table 2.

List of Bio-colours approved by FDA.

5.2 Market trend for bio-colours

The growth rate is going to be large for naturally derived colours with a predicted annual growth rate of 5–10%. The natural food colour reached the US 1 billion dollar in the market throughout the world. This trend is increasing day by day as natural colours are preferred by the consumers in the food related industries over the harmful synthetic colours (Table 3).

Name of the organisation	Product
Roche products Pvt. Ltd., Australia	Carotenoids
Synthetic industrial chemicals Ltd., India	Xanthophylls
Bush boake allen company, USA	Natural colours
Aarkay food products Ltd., Gujarat	Fruit and vegetable powders
Vinayak ingredients Pvt. Ltd., Mumbai	Natural colours
Synthite industries Ltd., kolenchery, Kerala	Lutein

Table 3.

Companies dealing with bio-colours.

5.3 Applications of bio-colours

Drawbacks

Even though biocolours have several applications, but they also got certain limitations like sensitivity to low pH and heat sensitive, etc.

Lack of eyesight:

Food gives a great palatability only if it is consumed natural. But the natural colours are not that much attractive as compared to synthetic colours.

Lack of wide applications:

These are product specific in nature. Beet colour is only used in soda as it turns blue in milk. This also not suitable in the baking industry.

Lack of colour stability and fading:

These colours change its nature sometimes and are failed to maintain their originality.

Heat Sensitivity:

They are susceptible to heat and losses its main trait.

Higher price and lesser availability:

These are highly priced and are not easily available in the commercial market as that of other products.

6. Conclusion

The demand for natural colourants is high now a days. Spices are the one of the main ingredients in Indian food diet on daily basis. Pigments obtained from these spices are natural with health benefits and are seeking the attention of the consumers.

Although bio-colourants have potential benefits, the tedious extraction procedures, low colour value and instability during processing hinder their popularity. Encapsulation is one of the new technique to reserve the available natural pigments. Microencapsulation and nanoencapsulation are the methods to overcome the environmental drawbacks and increase its bioavailability. More detailed studies on the production and stability of bio-colours are necessary for their promotion in various sectors.