91A-10 |
Stability of anthocyanins from strawberries (pelargonidin-3-glucoside, Pgd) and from plums (cyanidin-3-glucoside) in the presence of polyphenoloxidase, caffeic acid and acetaldehyde |
P. WESCHE-EBELING1, A. Argaiz-Jamet, G. Sandoval-Navarro, and A. Costales-Hernández. (1) Laboratorio de Investigación de Alimentos, Universidad de las Américas - Puebla, A.P. 391, Santa Catarina Martir, 72820, Mexico Anthocyanin pigments are widely distributed in many fruits, leaves and flowers. They belong to the flavonoid family of phenolics. Recent consumer trends have shown a desirability towards processed food containing no synthetic additives. Anthocyanins have the great potential as natural additives both for their color and for their nutraceutical properties. The problem with them is that they show instability during processing and storage. The objective of this work was to study the stability of pelargonidin-3-glucoside (Pgd) from strawberries and cyanidin-3-glucoside (Cyd) from plums in the presence of polyphenoloxidase (PPO), caffeic acid (CA) and acetaldehyde (AC) using model systems. Anthocyanins were extracted from nitrogen powders obtained from the fresh fruits. Pigments were extracted in acidified ethanol. After filtering and evaporating the ethanol in a Büchi rotary evaporator the anthocyanins were trapped in a polyvinylpolypirrolidone (PVPP) cake. The PVPP was washed with water and the pigment eluted with acidified ethanol. Model systems were prepared containing anthocyanin, PPO, CA and AC in different combinations. Changes in anthocyanin content, color characteristics and HPLC reverse-phase chromatogram profiles were followed for 10 days. There was a significant loss of anthocyanins in all systems, but the Pgn systems retained red color as evidenced by the presence of a peak at 520 nm in the HPLC chromatograms. In all cases the retention time of the HPLC anthocyanin peak was delayed and the absorbance at 280 nm was greatly increased. The absorbance at 520 nm disappeared in all Cyd systems showing the greater instability of this pigment. This study showed that the structure of anthocyanins plays a significant role in the stability of these pigments. The retention of red color in the Pgd systems seem to come from both copigmention between Pgd and caffeic acid and copolymerization through the action of acetaldehyde and PPO-formed quinones.
Session 91A, Food Chemistry: Enzymes, vitamins and plant pigments
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