Overview of Food Colorants in Agriculture

Food colouring, or colour additive, is any dye, pigment, or substance that imparts colour when it is added to food or drink. They come in many forms consisting of liquids, powders, gels, and pastes. Food colouring is used in both commercial food production and domestic cooking. In this article we shall examine, Food Colorants; synthetic food colorant and natural colour additives.

Synthetic Food Colorants in Agricultural Products

In nature, colour is determined by a food’s inherent qualities, indicating types of flavour, and degrees of sweetness, ripeness, or decay. However, humans have contrived to add or change the natural colour in foods from very early times and for a variety of reasons for aesthetic purposes, to increase appetite appeal, for symbolic effect, to make a less desirable food seem more desirable, and to mask defects.
From ancient times, wide varieties of food colorants were derived from natural sources plant, animal, or mineral. This changed in the middle of the nineteenth century with the discovery of synthetic dyes that soon found their way into food.

These synthetics were, in general, less expensive as well as more stable, controllable, and intense in hue than natural colour sources. Since that time, the safety and acceptable use of food colorants, both natural and synthetic, remain controversial topics, eliciting debate, continual scientific study, and periodic legislative action.

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Regulation of Food Colorants in Agriculture

Government attempts to regulate colouring agents in food have had a long history. There was a 1396 edict in Paris against colouring butter. In 1574 French authorities in Bourges prohibited the use of colour to simulate eggs in pastries, and Amsterdam forbade annatto for colouring butter in 1641.

Denmark listed colours permitted for food colouring in 1836, and Germany’s Colour Act of 1887 prohibited harmful colours in food. A report to the British Medical Association in Toronto in 1884 resulted in the Adulteration Act, the first list of prohibited food additives. Australia passed the Pure Food Act in 1905.

The United States Food and Drug Act of 1906 restricted synthetic food colours to those that could be tested as safe. Of the eighty colours in use, only seven were approved as certified colours.

In 1938 the Food, Drug, and Cosmetics (FD&C) Act approved fifteen dyes for use in food, drugs, and cosmetics and assigned colour numbers instead of their common names (thus, amaranth became Red No. 2).

Government and consumers’ concerns regarding food additives intensified in the 1950s with new scientific findings. In 1960 the U.S. Congress passed the Colour Additives Amendment to the FD&C Act, which placed the burden of establishing safety on the food manufacturing industry and created a new category, “colour additives exempt from certification.

This includes both “natural colours” and “nature-identical” colours (those synthetically made but chemically identical to natural colours, like beta-carotene and canthaxanthin).

The Delaney Clause prohibited any colour additive that could be shown to induce cancer in humans or animals.
Since the 1970s the inclusion of colorants in food has received considerable scrutiny based primarily on concerns regarding the carcinogenic properties of colorants.

In 1992 a U.S. court decision interpreted the Delaney Clause to mean that zero levels of carcinogens are permissible. With further research findings, certified colours continue to be delisted.
In response to increased consumer perception that natural colorants are safer, manufacturers have moved toward more natural and less synthetic colorants in food.

However, the term “natural,” as it pertains to colours, has never been legally defined and has no universally accepted definition. In addition, a small percentage of the population demonstrates sensitivity or allergic reactions to some natural colorants such as cochineal.

Currently, consumer groups advocate the minimized use of food colorants, as well as a detailed listing of specific colorants on food labels.

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Applications of Colorants in Agricultural Food Products

Colorants are added to consumable products for the sole purpose of enhancing the visual appeal. Possible reasons underlying the need for enhancement include:

i. Correcting for natural variations in food or ingredient colours

ii. Correcting for colour changes during storage, processing, packaging, or distribution

iii. Emphasizing associated flavours or preserving unique identifying characteristics

iv. Protecting flavour and vitamins from photo degradation

Safety Standards for Food Colorants in Agriculture

The passage of the Pure Food and Drug Act of 1906 formalized the requirements that all synthetic dyes be manufactured under strict control and undergo voluntary certification; certification of synthetic colorants became mandatory with the passage of the Food, Drug and Cosmetic Act of 1938.

Finally, the Color Additive Amendments of 1960 required additional testing using modern techniques, and also invoked the Delaney Clause regarding carcinogenicity.

It was clearly recognized from Hesse‘s time that, even though the primary role of food colorants is cosmetic (their only nutritional contribution being indirect, in the preservation of light-degradable vitamins), colorants nonetheless can have a significant impact on human health.

Toxicological Considerations for Agricultural Colorants

Given the ubiquity of colorants in the diet, their inherent safety is, of course, of preeminent concern. In order to safeguard the populace, the concept of an acceptable daily intake (ADI) level was introduced by FDA scientists in the 1950s.

ADIs are most commonly established through extensive animal studies; the current Redbook requirements for toxicological testing include [FDA Redbook, cited in IFT (1986)]:

1. One subchronic feeding study, of 90 days duration, in a nonrodent species, usually the dog
2. Acute toxicity studies in rats
3. Chronic feeding studies in at least two animal species (one with in utero exposure), lasting at least 24–30 months
4. One teratology study
5. One multigeneration reproduction study using mice
6. One mutagenicity test
   Such testing establishes no adverse effect dietary levels for each specific colorant; these levels are then adjusted by a safety factor (typically 100) to arrive at ADIs. Daily intake levels for the certified colorants and their respective

Natural Color Additives in Agricultural Applications

Most natural colorants are extracts derived from plant tissues. The use of these extracts in the food industry has certain problems associated with it, including the lack of consistent colour intensities, instability upon exposure to light and heat, variability of supply, reactivity with other food components, and addition of secondary flavours and odours.

In addition, many are insoluble in water and therefore must be added with an emulsifier in order to achieve an even distribution throughout the food product.

Pigments from Plant Sources in Agriculture

The plant kingdom, with its multitude of colours, is most widely studied as a major source of food colorants. Flavonoids, carotenoids, and chlorophyll are the major contributors to the natural colours of most plants, with betalines and curcumin playing a minor yet significant role.

1. Flavonoids in Agricultural Colorants

Anthocyanin, chalcone, and flavones belong to a group of compounds collectively known as flavonoids.
i. Anthocyanin: Anthocyanins are the most established food colorants and may be found in a wide variety of edible plant materials, such as the skin of red apples, plums, and grapes, in addition to strawberries, red cabbage, and shiso (Perilla ocimoidis Varcripsa) leaves and blueberries.

Concentrated or spray-dried juices of cranberries, raspberries, and elderberries have also been reported to be used as food colorants in certain food products.

ii. Application: – Application of anthocyanins in food is restricted due to their ability to participate in a number of reactions, resulting in its decolorization.

These include reactions with ascorbic acids, oxygen, hydrogen redisulfide, and sulfur dioxide to form colourless compounds; formation of complexes with metal ions and proteins; and hydrolysis of the sugar moieties to form unstable anthocyanidins.

iii. Toxicology: In view of the considerable consumption of anthocyanin, toxicological as well as mutagenic studies of the pigment have been carried out. Reviewed of the studies that have been done and concluded that anthocyanin is neither toxic nor mutagenic.

On the other hand, anthocyanins were found to have beneficial therapeutic properties and would, therefore, find increasing application in not just the food area but in the medical field as well.

Carotenoids in Agricultural Food Coloring

Carotenoids are noted for their great diversity and distribution. They can be found not only in plants (e.g., carrots, tomatoes, and capsicum) but also in bacteria, fungi, algae, and animals. To date over 500 carotenoids have been isolated and identified.

Beta carotene is the most abundant carotenoid in nature, particularly in plant materials. It is the major colouring principle in carrot and as well as palm oil seed extracts. The extracts are oil soluble and impart a yellow colour to foods; they find applications in dairy products, cakes, soup, and confectionery.

It is also a known fact that beta carotene is a precursor of vitamin A while possessing antioxidation properties which may help in the prevention of cancer and other diseases.

This has resulted in the incorporation of beta carotene in health products, such as functional or nutraceutical beverages, with increasing usage being predicted in the future.

i. Usage: Although present in a lesser amount than beta carotene, annatto, saffron, and gardenia extracts are the more commonly used carotenoids for colouring foodstuffs. Paprika, tomato, carrot, and palm oil seed have also been utilized for the extraction of carotenoids.

The carotenoids are used to provide orange and yellow colours in food, particularly in fat based food products.

Chlorophyll in Agricultural Food Applications

Chlorophyll is the green pigment found in all green plants as well as green alga. The pigment is responsible for the photosynthetic process in plants. Chlorophylls a and b are the two main types of chlorophyll pigment found in nature.

The former is a bluish green pigment, while the latter is yellowish green in colour. In addition, related pigments known as bacteriochlorophylls are found in photosynthetic bacteria.

1. Usage: The oil-soluble and water-soluble forms of chlorophyll are commercially available in the form of the stable copper complex. Both forms of commercial chlorophyll are relatively stable toward light and heat. However, unlike the water-soluble chlorophyll, the oil-soluble form is not very stable in acids and alkalis.

A major portion of the commercial chlorophyll is used in the food industry for colouring dairy products, edible oil, soups, chewing gum, and sugar confectionery. It is mainly added to fat-based food, particularly canned products, confectionery, and pet foods.

2. Legislation: The development of food colorant legislation in the rest of the world followed the same pattern as that in the United States. Nevertheless, the list of permitted natural food colorants differs from country to country.

An attempt is therefore being made to create a worldwide permitted list of food colorants. This involves rationalization of food colours legislation by the joint FAO/WHO Codex Alimentarius Commission. Since 1975, the EEC Scientific Committee for Food (SCF) has also undertaken a toxicological review of all permitted colours of member states.

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