Extraction, Characterisation and Formulation of Natural Blue Pigment from Black-footed Abalone (Haliotis iris)
An ubiquitous and important factor in everyday life is the colour which invigorates substances. Most pigments used in food and cosmetics are made synthetically, and nearly all blue pigments available commercially are synthetic. This thesis aims to extract natural blue pigments from abalone (Haliotis iris) shells to provide as an alternative colour to synthetic pigments. In this project, blue pigment was extracted from the shell of abalone by a solvent extraction technique and purified by solid phase extraction, which yielded 500 mg of pigment from 5 kg abalone shell. The cytotoxicity of the extracted blue pigment was tested for food and cosmetics applicability by using a Cell Counting Kit-8 (CCK8) in vitro test, and the minimum lethal dose was determined to be about 5000 µg/ml. Stability of the aquatic blue pigment was tested by exposing the pigment to different light regimes (Indoor light, UV light and sunlight), extreme temperatures (25, 50, 75 and 100°C), different pH values (2, 4, 6, 8, 10 and 12), oxidising agents (H2O2), reducing agents (Na2SO3), food additives (starch, citric acid, sodium tartrate, glucose anhydrous, sucrose and sodium chloride) and metal ions (Al3+, Ca2+, Cu2+, Fe2+, Fe3+, K+, Mg2+, Zn2+). It was found that, the aquatic blue pigment was unstable when exposed to the lights (Indoor light, UV light and sunlight) and high temperature (100°C), as well as in the presence of reducing agents and some metal ions (Cu2+ and Fe2+). Microencapsulation was then used to enhance the stability of the pigment. Different formulations consisting of Gum Arabic, maltodextrin DE 11-12 and DE 17-19 mixtures as wall material were used to retain the colour intensity of the pigment. Particle morphology of encapsulated pigment was characterised by scanning electron microscopy. All particles obtained were spherical and smooth with different sizes. However, the smallest particle belonged to formulations containing Gum Arabic. In addition, formulations containing Gum Arabic had higher stability in comparison with other formulations, which did not have Gum Arabic. The extracted aquatic blue pigment can have potential applications in food and cosmetics. To demonstrate its use, hand creams and lipsticks containing the pigment were formulated. In conclusion, aquatic blue pigment was successfully extracted from black-footed abalone (Haliotis iris) shells and formulated for use in cosmetics. The stability of the pigment, when exposed to various environmental conditions was significantly improved after microencapsulation. While the results from this project present a promising stepping-stone for developing a commercial natural aquamarine pigment, further studies are required to increase the extraction yield to make the process commercially viable.
Extraction, Purification, Characterisation, Blue color, Paua shell, Black-footed abalone
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