1. Hutchings JB (1999) Food colour and appearance. Aspen Publishers, Gaithersburg, Maryland
2. Collins P, Timberlake C (1993) Int Food Ingred 6:32–38
3. Stintzing FC, Schieber A, Carle R (1999) Planta Med 65:632–635
4. Stintzing FC, Schieber A, Carle R (2001) Eur Food Res Technol 212:396–407
5. Waterman PG (1998) Alkaloid chemosystematics. In Cordell GA (ed) The alkaloids—chemistry and pharmacology. Academic Press, San Diego, pp 537–565