Food Colors and Coloring of Foods.

Food Colors and Coloring of Foods.

Food color/colorant

This is any substance that is added to food or drink to change its color. (http://en.wikipedia.org/wiki/color).

Or

Food additive used to alter or improve the color of processed foods. (http://encyclopedia.farlex.com/additive). Food coloring is applied to both commercial food production and domestic cooking. The utilization of food colorants in foods is an important feature to the food industry (i.e. to both manufacturers and consumers) (Muntean, 2005).

Reasons to use color additives

Consumers recognize color, flavor, and texture as the main attributes of food with color being the most important of the three (Delgado and Lopez 2003, http://en.wikipedia.org/wiki/color). Today, food products are consumed far from where they are produced. As a result, processing and transportation of food are necessary to reduce degradation and loss of appearance. The use of color additives by the food industry is thus necessary to restore the original food appearance i.e. the added colorants, reinstate the novel look/color of foods after processing and storage treatments where natural colorant content has been reduced; ensure batch-to-batch color uniformity and masking natural variations in color; intensify color normally found in food i.e. the addition of colorants enhances naturally occurring colors which are in low intensity to consumer expectations (Muntean, 2005); protect other component e.g. flavors and vitamins from damage by light (Zdzlaslaw, 2002); obtain the best food appearance i.e. decorative or artistic purposes such as cake icing (http://en.wikipedia.org/wiki/color); preserve characteristics associated with food; help as a visual characteristics of food quality i.e. it influences acceptability of food, for example good quality fresh meat is expected to be bright red and any deviation from that is viewed as spoilt (Deman, 1999); and also adds visual delight and recognition/ identity to food products e.g. lime juice is expected to be green while sausages are expected to be pink in color (Fennema, 1996). Therefore, addition of food colorants has become a regular practice in the food industry to better or even alter the color of foods and drinks.

Food Colors/colorants used are either synthetic (artificial), such as tartrazine and amaranth, made from petrochemicals or natural colors such as chlorophyll, anthocyanins, caramel, and carotene (Fennema, 1996).

Choice and application of color

Color is a main quality parameter in foods (in particular meats) to be commercialized (Cornforth, 1994). According to Delgado and Lopez (2003), a number of factors must be considered when selecting the better color additive for specific applications. These include; color hue required, physical form (e.g. liquid, solid, emulsion), properties of the food stuff that will be colored e.g. oily or water- based product, content of tannins, pH and processing conditions (e.g. whether the process requires heating or cooling, storage conditions). In addition to the above, one factor of paramount importance is the relevant legislation (Zdzislaw, 2002).

Classification of colorants

Pigments can be classified in accordance with the different system. These systems are clearly defined, but all are closely related (Zdzislaw, 2002); the same type of colorants can be classified in different groups (e.g. carotenoids). Today, classification of colorants by their origin and legislation are the most important systems. This is in agreement with consumer preferences, which clearly favor natural pigments over synthetic pigments obtained from laboratories (Delgado and Lopez, 2003; Zdzislaw, 2002). Colors can be the natural ingredients of foodstuffs or other natural ingredients that are not normally used, such as a foodstuff or as a typical ingredient for a foodstuff.  Also considered as colors are products that are obtained by physical and/or chemical extraction from foodstuffs and other natural ingredients whose coloring ingredient has been extracted separately from nutritive and aromatic substances (Zdzislaw, 2002).

According to Zdzislaw, 2002, dried and/or concentrated ingredients or spices that are used in the production of foodstuffs and have, in addition to aromatic, flavoring or nutritional properties a secondary coloring effect, are not considered to be colors (for example paprika, curcuma and saffron). If the use of an ingredient is based exclusively on its coloring effect and it has no nutritional or aromatic properties, it is then considered to be a color.

Systems of classification of colorants.

According to Delgado and Lopez (2003), colorants are classified basing on either;

Origin:

As synthetic colorants that are organic compounds obtained by chemical synthesis e.g. Food Drug and Cosmetics (FD&C) colorants, natural colorants that are organic compounds obtained from living organisms. According to Østerlie and Lerfall (2005), the colorants are considered natural if they are from agricultural/biological sources, extracted without chemical reaction and have been in use for a long time e.g. carotenoids, anthocyanins, betalains and organic colorants that are found in nature or obtained by synthesis e.g. TiO₂.

Or

Legislation:

As certifiable; anthropogenic synthetics i.e. FD &C colorants and lakes. E.g. amaranth, allura red, sunset yellow, tartrazine, fast red E, and those exempted from certification; from natural origin (vegetable, mineral or animal) or synthetic counterparts e.g. grape juice, TiO₂, carmine and synthetic β-carotene.

Synthetic food colorants

The use of synthetic organic colors has been recognized for many years as the most reliable and economical method of restoring some of the food’s original shade to the processed product (Muntean, 2005). An even more important application of synthetic colorants is to improve and standardize the appearance of food products that have little or no natural color present, such as dessert powders, table jellies, ice and sugar confectioneries. The synthetic organic colors are superior to the natural pigments in tinctorial power, range and brilliance of shade, stability, ease of application, and cost-effectiveness (Muntean, 2005, Zdzislaw, 2002).

However, from a health and safety point of view, they are less acceptable to consumers. Over the past years increasing interest in natural food colorants has been observed (Zdzislaw, 2002). Synthetic food colorants are regulated by the government with seven synthetic colorants currently approved for use in food. These include 2 reds (#3 and #40), 2 blues (#1 and #2), 2 yellows (#5 and #6), 1 green (#3) (http://en.wikipedia.org/wiki/color). These seven colorants are grouped by the color-giving chemical functional group they contain. FD&C Red #40 and Yellow #6 both contain azo bonds (-N=N-) thus are referred to as azo colorants. FD&C Blue #1, Green #3 and Red #3 belong to the triphenylmethane group which contain three benzene rings attached to a central carbon atom (Delgaldo and Lopez, 2003; http://en.wikipedia.org/wiki/color). Just as with any substance, the chemical structure of these colorants determine its’ characteristics, for example if it is water soluble or not. Water-soluble colorants are useful in water-based foods, but not in fatty foods such as salad dressings and ice cream (Delgaldo and Lopez, 2003).

Natural Pigments

The naturally occurring colorants in food plants are the customary sources of color in food although the added colorants have assumed an extra vital role as the food processing industry is growing. Such colorants are viewed as accidental colorants as they are present only because they or their precursors are present (Mutean, 2000). 

Natural pigments are generally considered the pigments occurring in unprocessed food, as well as those that can be formed upon heating, processing, or storage (Zdzislaw, 2002). Chlorophylls and carotenoids are the most abundant pigments in nature. They are involved in fundamental processes and life on earth depends on them. Chlorophyll is not found in animals but carotenoids accumulate in some organs (e.g. eyes) and tissues e.g. skin of fish, bird plumage (Delgaldo and Lopez, 2003). In addition, flavonoids are scarce in fungi whereas riboflavin imparts the yellow color in the genera Russula and Lyophyllum. Betalains, melanin, a small number of carotenoids and certain anthroquiriones are common to fungi and plants (Delgaldo and Lopez, 2003).

More than 1000 pigments have been identified in fungi. Fungi are not photosynthetic and do not contain chlorophyll (Zdzislaw 2002). Carotenoid distribution in fungi is restricted to some orders (e.g. pharagmobasidiomycetidae, and Discomycetes). All natural pigments are unstable and participate in different reactions, so their color is strongly dependent on conditions (Zdzislaw, 2002).

Limitations of Natural Pigment use.

Delgaldo and Lopez (2003) reported that limitations to the use of natural pigments include; being produced by traditional methods, having a lower intensity in comparison to synthetic pigments and natural pigments require large quantities of raw material to obtain the same depth level like synthetic pigments i.e. they occur in small amounts in plants or plant part. Also natural pigments are highly sensitive to pH and temperature.

Note that all references used in all postings related to the topic of sausages, meat and meat product colorings will be posted in the last article about this topic

About the author
Mr. Sempiri Geoffery, the author of this article graduated from Makerere University with a Bsc In Food Science and Technology Degree in January, 2011.