Lycopene-rich watermelon concentrate used as a natural food colorant: Stability during processing and storage.

A lycopene-rich watermelon (Citrullus lanatus) concentrate was incorporated into snack cracker, fusilli pasta, and extruded snacks for coloring purposes. Changes in the L* and a* color coordinates and in the lycopene content were evaluated before and after thermal processes and monitored through 90 days of storage at ambient temperature. The products with the maximum lycopene degradation during processing were snack cracker and extruded snack (between 30 and 45%) whereas no degradation was observed in the fusilli pasta, except during cooking into boiling water (reduction up to 41%). The change in color during processing varied substantially depending on the product, but, in general, thermal treatments applied reduced the a* values (less reddish). The degradation kinetics of the lycopene and the color during storage followed first-order kinetics, with a half-life time of 25 to 315 days for lycopene content and 65 to 210 days for a* coordinate. Snack cracker was the most stable and had more than a 4-month period before losing half of the pigment content.