Determination of anthocyanins in miscellaneous matrices

The separation and identification of two novel anthocyanins from red onion, Allium cepa, have also been reported. Scales of 2.37 kg red onion were cut and extracted twice with methanol containing 0.5 per cent TFA. The extract was filtered, extracted with ethyl acetate and the aqueous phase was further purified in an ion-exchange and an SEC column. SEC separation was performed in a Sephadex LH-20 column (100 X 5 cm i.d.) applying methanol-water-TFA (39.6 60 0.4, v/v) as the mobile phase at a flow rate of 2.5 ml/min. 

Preparative and analytical HPLC were carried out in an ODS column using gradient elution. The gradient was composed of methanol, water and formic acid. The chemical structures of the new pigments were elucidated by UV-VIS, 2D NMR and LC-MS. MS conditions were capillary 3 kV, cone 30 and 60 V, extractor 7 V, sources block temperature 120°C, desolvation temperature 150°C [257],The chromatographic profile of the SEC fraction containing the new pigments is shown in Fig. 2.116. The chemical structures of the new derivatives identified by various spectroscopic techniques are shown in Fig. 2.117. 

It was established that each pigment was acylated by hydroxycinnamic acid and the acylation increased the stability of the pigments. Furthermore, the data demonstrated that the tubers of pinta boca can be employed as a natural colourant in the food industry [259], 

Because of their marked importance in human nutrition, the analytical techniques employed for the separation of biologically active compounds in potatoes (Solatium tuberosum), tomatoes (Lycopersicum esculentum) and jimson weed (Datura stramonium) seeds have been reviewed before [260], 

RETENTION TIME AND PROPOSED IDENTITY FOR ALL THE COMPOUNDS FOUND IN THE CONCENTRATE OF PINTA BOCA TUBERS 

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