The main pigments from natural sources imparting yellow, orange to red color shades to food and beverages belong to the large pigment family of carotenoids. This group comprises both the polyunsaturated hydrocarbon chains of carotenes and also the oxygenated xanthophylls. Although lutein, carotene, annatto, paprika and lycopene all fall within this large group of pigment, they all have different technical properties. A detailed review of these pigments shows that the chemical structure directly impacts the colour shade and stability of each pigment. All these carotenoids pigments are naturally oil dispersible and therefore require emulsification and dispersion processes to deliver water dispersible solutions for the food and beverage applications. Various emulsifying systems can be used to achieve excellent stability and avoid the destabilisation of the emulsion. In addition to this these emulsions need to be stable in diluted beverages and avoid destabilisation in the drink. The formation of an oily ring can be due to a poor size distribution of the colour emulsion leading to droplet coalescence and phase separation. It can also be caused by the interaction with hydrocolloids that are often used to emulsify flavour and cloud emulsions triggering the depletion flocculation of the beverage emulsion. Polysorbate 80 is a non-ionic surfactant that is commonly used to manufacture carotenoids colour emulsions to provide clarity in final beverages application. However, high content of Polysorbate 80 can cause foaming issues and impact the taste of beverages. Alternative emulsifier systems such as sucrose ester and lecithin will be discussed to demonstrate how to achieve a uniform particle size distribution with d (0.5) < 100nm. However the common factor that link all these pigments is their sensitivity to heat, light and oxygen. In addition to meeting the target shade, the choice of the pigment is also driven by the specificity of the heat treatments applied during the food process, as well as the storage conditions during shelf life of the finished product. Antioxidants are commonly used in carotenoids formulations and show good stabilisation of the C40 chains. Tocopherols, and ascorbyl palmitate protect the carotenoids against light triggered oxidation, whilst Rosemary prevent degradation upon heat triggered oxidation processes. Also the recent need for the ultimate �All Natural� label has raised the issue of the use of non natural additives within colour formulation. Natural antioxidants can be used to re enforce the stability of the colour emulsions/dispersions to ensure long term stability to offer longer shelf life to ship color across the world and store them for longer. But also natural antioxidants can be added directly to the finished products to ensure stability over the shelf life of the end product. Oil soluble and water soluble Rosemary extracts have been shown to significantly improve the stability of carotenoids based colours. Oil soluble carnosic acid and carnosol as well as water soluble rosmarinic acids are known antioxidants capable of chelating metals. Examples of colour emulsions stabilised with natural antioxidants such as Acerola and Rosemary extract showed some significant improvement when compared to non stabilised carotenoids emulsions in various food and beverages applications. The stability of some of these examples was also compared when natural antioxidants are added directly to the end products and showed further stability improvement to heat and light when stored in various conditions to cover temperature range of 40-90C. Natural antioxidant such as acerola and rosemary extracts showed significant improvement when compared to other antioxidant systems.

Improvement of carotenoids pigments stabilisation by the use of natural antioxidants

247th National Meeting (2014)

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