Anthocyanins is a group of natural colorants that gives color to many different berries and flowers, but also to black carrots. The anthocyanins are colored glycosides appearing in color shades between orange, red, and blue depending on raw material, extraction method, and pH. Anthocyanins from black carrots are more stable than those from berries due to a higher degree of acetylation with organic acids of which aromatic acyl groups normally result in higher stability than aliphatic groups. Over 80% of black carrot anthocyanis are acylated with either hydroxycinnamic acid, hydroxybenzoic acid, sinapic acid, ferulic acid or coumaric acid. Generally, a high number of acylations increases the stability towards heat or light. However, detailed knowledge on how specific positions of acylation, number, size, and type of acylation and degree of co-pigmentation and metal complexation affects the overall color shade and stability needs developing.
The aim of the project is to purify and analyze the structure of anthocyanins and correlate it to color stability. The knowledge can be used to develop more stable natural colorants for the food industry. You will examine extraction methods, and use preparative HPLC-VIS/MS for purification, HPLC, spectroscopy and LC-MS/MS for characterization and stability studies of anthocyanins from different carrots.
