Natural Orange Coloring From Avocado Seeds

CHICAGOCrushing avocado seeds along with air generates an orange color that may one day be used as natural coloring for food products, according to a study published in the Journal of Food Science. The findings represent a potential added value for avocado growers and companies that process avocado into oil or food products, like guacamole.

While artificial colors are often easy to produce, stable, less expensive and have better coloring properties than natural colorants, there has been an increased effort to discover new natural alternatives in order to keep up with consumer trends.

Researchers from Pennsylvania State University found avocado (Persea americana) seed crushed with water develops an orange color in a time-dependent manner. Heat treatment of the seed prevented color development, whereas the addition of exogenous polyphenol oxidase (PPO), but not peroxidase, restored color development. Color development was also inhibited by the addition of tropolone, an inhibitor of PPO. Color formation resulted in a decrease in the concentration of polyphenols indicating utilization for color formation.

The orange color intensified as the pH was adjusted from 2.0 to 11.0; the changes were only partially reversible when pH was adjusted from 7.5 to 11.0 in the presence of oxygen, but completely reversible when the pH was changed in the absence of oxygen. The color was found to be stable in solution at −18 °C for 2 months. The results suggest that the avocado seed may be a potential source of natural colorant, and that color development is PPO-dependent.