Beyond their striking appearance, natural colours derived from fruits and vegetables offer a stable of important health benefits, due to their anthocyanins, carotenoids and other compounds. Colour expert Helen Vine explains
Eating and drinking are highly complex sensory experiences enjoyed on a daily basis. The quality, freshness and flavour expectations of a food or drink are conferred by its colour; consequently it is important manufacturers meet consumer expectations if they want to secure repeat sales.
Colours in nature exist for reasons far beyond their beautiful and striking visual appearance. Their complex molecular structures are such that not only do they exhibit vibrant shades from yellow to violet, many also possess functional benefits (as powerful antioxidants) for protection of genetic material.
Natural colours have been used for thousands of years when plants were utilised to impart colour to foods. Increasingly, food producers are returning to natural food colours to meet with both retailer and consumer demands. The return to nature has been fuelled mainly by research, media attention and positive support groups such as the UK's Hyperactive Children's Support Group, which have continually called into question the appropriateness and safety of certain artificial colour additives that have demonstrated negative health issues (specifically in children) following their consumption.
Nature in its true form
Consumers and retailers are more concerned than ever with packaging statements that confirm the content of natural and 'healthy' ingredients, completely avoiding the use of colour additives by replacing them with even more natural sources of colour.
During the last 20-30 years, due to revolutionary developments in technology and diversification of raw materials, it has become possible to harness nature's colours to provide rich, vibrant shades in most applications.
In the European Union, 'colouring foodstuffs' is the term used to describe edible fruits, vegetables and plants (food ingredients) that are naturally rich in colourful compounds that are used to provide colour within the food or beverage product. In doing so, it is critical that the colouring foodstuff has not undergone selective extraction processes that merely concentrate the pigments, as this would render it a natural additive colour according to the European Directive. The resulting concentrate should provide colour in a 'holistic' way, retaining the key characteristics and therefore the health benefits of the starting materials.
Such fruit and vegetable concentrates possessing colouring properties are considered to be food ingredients and not additives. The benefits of colouring foodstuffs are essentially two-fold: they offer a more natural / healthy way of colouring foods, and they provide a clean label declaration — 'free from additive colours.'
A cleaner bill of health
Fruits and vegetables that naturally impart colour have been included in product formulations for some years now. These important developments in colouring alternatives have provided manufacturers and health-conscious consumers with ingredient labels that can legitimately state free from additive 'nasties'.
Colouring foodstuffs can only be made from high-quality raw materials that have been carefully harvested at peak ripeness to ensure the maximum content of colourful compounds. Gentle physical processing using only water provides intensely coloured concentrates rich in secondary plant substances (bioactive phytochemicals) including carotenoids and flavonoids that cannot be synthesised in the human body.
Colouring foodstuffs are standardised according to their colour shade and intensity to ensure that manufacturers are able to achieve stable and reproducible shades.
For colouring foodstuffs, raw materials are selected based on a number of criteria, such as quality, content of stable colouring compounds, availability and price, to ensure that the end result is a viable ingredient.
Yellow, orange, red and brown shades have been used successfully in many food and drink applications for some years. More recently, advances in food technology have also provided the industry with stable green and blue shades (used in a range of products such as confectionery and ice creams) that are also now successfully taking the place of the synthetic alternatives that once dominated the market.
Providing added value
Anthocyanins (red flavonoids): These water-soluble compounds found in a wide variety of fruits and vegetables (such as strongly coloured berries, grapes, blackcurrants, black carrots and red cabbage) exhibit shades ranging from blue-violet-magenta-red to orange. Some anthocyanins are acylated (generally those from vegetable sources), which in turn helps to improve stability of the red shade to both light and heat (as opposed to red shades derived from beetroot betalaines — a notoriously unstable source of red colour).
The precise colour shade achieved by an anthocyanin-rich concentrate will depend on the pH of the product. A more red shade will be demonstrated in acidic conditions, whereas in a more pH neutral application, the same anthocyanin can appear quite blue.
The benefits to human health resulting from anthocyanin intake are well documented. An example would be the French Paradox — which refers to the cardiovascular benefits of consuming red wine (rich in anthocyanin polyphenols) despite a diet relatively rich in saturated fat. Further physiological effects that have been reported from diets rich in red anthocyanins include protection against cancers and anti-inflammatory activity; undoubtedly these are all related to the antioxidative capacity of such flavonoids.
Carotenoids: This large group of compounds is responsible for the yellow-orange-red shades in many fruits and vegetables. In rich food sources such as carrots, pumpkins and tomatoes, mixtures of carotenoids are often found. Carotenoids are lipid soluble and their colour shade is the same irrespective of pH. Important carotenoids include lutein, zeaxanthin, a-carotene, ?-carotene and lycopene. Some, including ?-carotene, have pro-vitamin A activity and can provide significant antioxidant benefits against cancers and the ageing process.
Scientific studies have demonstrated that isolated or synthetic ?-carotene/lycopene do not provide the same antioxidant benefits as consumption of mixed carotenoid-containing foodstuffs. Synergistic factors within the food matrix help aid bioavailability and therefore increase efficacy (this is the same for anthocyanins). The precise action of carotenoids is not clear, but it is believed that their benefits extend beyond antioxidant activity and include interactions with immune response.
Lycopene as a pure pigment is not frequently used to colour products and suitable applications are limited due to its solubility. However, tomato concentrates are used widely to impart colour, taste and the known health benefits. A diet rich in tomato products, the classic Mediterranean diet, has been shown to offer protection against certain cancers, cardiovascular disease and has particular benefits in maintaining prostate health.
Others: There are many other compounds found naturally in fruits and vegetables such as polyphenols, phycocyanins, glucosinolates and xanthophylls, which are established rich sources of dietary antioxidants.
The UK government's five-a-day campaign supports increased regular consumption of fruit and vegetables providing a diet rich in valuable and healthy colour-rich phytochemicals.
The expectations of colour performance are increasingly challenging. Stability during manufacture and the shelf life of processed foods are considerations for all colours that are incorporated into product formulations. Investment in research has meant that the stability of colouring foodstuffs is now more clearly understood. Communication with manufacturers of such ingredients is important to ensure that the optimum desired result is achieved.
As consumers are developing greater interest in health and wellbeing, they are actively seeking out product labels that use only well-known pigment-rich fruits and vegetables to provide healthier options. Hence the trend for 'real' natural colours is becoming pronounced. It is these pigment-rich dietary phytochemicals that provide both colour and added value to formulations, due to their powerful antioxidant properties.
The availability of stable, reproducible natural colours (from fruits and vegetables) that are competitively priced now means there is little reason to formulate food and drink products using any other type of colour.
Helen Vine is technical sales director for GNT UK Ltd, a European natural food colouring manufacturer. Bakum House, Etwall Road, Mickleover, Derby DE3 0AL, United Kingdom.
Tel: +44 845 4566460
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