Alginate coating with açaí extract on strawberry: Bioactive compounds and enzyme activity

Edible coatings based on biopolymers can extend the shelf life of fruits and vegetables. Sodium alginate stands out for its ability to form semipermeable films and incorporate phenolic extracts, such as acai extract, making it a promising option for preserving strawberries, which are highly perishable after harvest. Therefore, the objective of this study was to evaluate the effect of edible sodium alginate-based coatings incorporating açaí extract on the total phenolic compounds, antioxidant capacity, and enzymatic activity of strawberries stored under refrigeration. Three treatments were applied: no coating (NR), sodium alginate coating (ALG), and sodium alginate coating containing açaí extract (EXT), which were monitored over a 5-day period. Total phenolic compounds, antioxidant capacity using the ABTS method, and the activities of the enzymes polyphenol oxidase (PPO) and peroxidase (POD) were determined. At the end of the fifth day, the NR treatment exhibited the highest values for total phenolics (20.57 ± 1.18 µg EAG/mL) and antioxidant activity measured by the ABTS method (1.19 ± 0.12 µmol Trolox/100 mL). The coating containing açaí extract showed values of (15.62 ± 0.47 µg EAG/mL for CFT) and (0.83 ± 0.17 µmol of Trolox/100 mL) for ABTS. Furthermore, there was no difference in PPO activity among the treatments. For POD, the coatings reduced activity, particularly the EXT coating on day 5 (0.21 ± 0.01 U min⁻¹ g⁻¹), followed by the ALG coating. Based on these results, it can be seen that the coating containing açaí extract is a promising alternative for the postharvest preservation of strawberries.