Stabilization of refrigerated avocado pulp: Effect of Allium and Brassica extracts on enzymatic browning

- Allium and Brassica extracts as antibrowning agents on avocado were investigated.
- During refrigeration storage browning was retarded in parallel to PPO inhibition.
- Scallion, onion, white cabbage and cauliflower extracts reduced color changes.
- Antibrowning properties were closely related to polyphenol content and PPO activity.

The aim of this paper was to study the effectiveness of Allium and Brassica extracts to inhibit the evolution of enzymatic browning of avocado pulp tissue stored at refrigeration temperature (4 °C). Color parameters and mathematical modeling were employed to determine browning kinetics. In general, the addition of Allium extracts to avocado pulp was more effective in delaying luminosity decrease during the first days of storage, compared to Brassica. Scallion, onion, white cabbage and cauliflower inhibited polyphenol oxidase (PPO), and avocado paste, could be preserved for more than 30 days. Brussels sprouts treatment generated the highest browning kinetic constant (0.86) and conserved acceptable color for less than 10 days. Scallion and garlic showed the great antibrowning indexes (0.96 and 0.77 respectively) considering L* decrease. Multivariate analysis indicated that vegetable extracts tested could be grouped by variety according to polyphenol content, and by their influence on PPO activity. The results allow the conclusion that polyphenol content of vegetables extracts influence the change of color variables during the first days of storage, while PPO activity influence these parameters in the last period of refrigeration.