Spray Drying Microencapsulation Preserves Anti-Aflatoxin B1 Activity of Plant Aqueous Extracts

Aflatoxin B1 (AFB1) is a major global health concern due to its carcinogenic effects in humans and animals. Because AFB1 is highly stable once produced, the most effective strategy is to prevent its synthesis by toxigenic fungi. Currently, plant extracts have been increasingly studied for this purpose. These extracts often contain polyphenols as active compounds against AFB1, which are effective but unstable over time. Therefore, it is necessary to develop new formulations that enhance their preservation, storage, and applicability.

Microencapsulation through spray drying is a promising approach. This technique converts a liquid into a dry powder by spraying it into a hot air chamber, embedding the bioactive compounds in a protective matrix. Spray drying offers several advantages, including high encapsulation efficiency, stability, and low production costs, making it a practical solution for preserving plant-derived antifungal agents targeting AFB1.

This study aimed to evaluate the potential of spray drying encapsulation to preserve the anti-aflatoxin activity of different plant aqueous extracts able to inhibit AFB1 synthesis. A total of 11 coating materials were screened based on their impact on Aspergillus flavus growth and AFB1 inhibition. Pectin, maize starch, and maltodextrin were identified as the most suitable, showing no effect on fungal development and AFB1 synthesis. Maltodextrin was selected to encapsulate aqueous extracts of Mimosa tenuiflora and Aloysia citrodora. These extracts inhibited AFB1 by 66% and 76 % at the concentration of 0.3 mg of dry matter /mL and displayed IC50_AFB1 of 0.15 and 0.11 mg/mL, respectively. After encapsulation, the extracts inhibited AFB1 by 60% (IC50 _AFB1= 0.29 mg/mL) and 65% (IC50 _AFB1= 0.26 mg/mL) in a dose-dependent manner.

Different core-to-wall ratios were tested, with 1:2 being the most effective, preserving 92% of anti-AFB1 activity. After 1 year of storage, the encapsulated extract preserved 90% of its activity, which is better than freezing (61%). Spray drying proved to be an efficient, low-cost method for preserving anti-aflatoxin properties of plant-based extracts.