268: Optimizing Drying Techniques for Bioactive-Loaded Aerogels: A Comparative Study of Air, Supercritical CO2, and Freeze Drying

Introduction

Emulsion gels are promising delivery systems to encapsulate lipophilic bioactives like β-carotene, protecting them throughout storage and obtaining products with solid-like mechanical characteristics. However, the drying process is known to significantly influence the physicochemical and functional properties of the delivery systems. Additionally, lentil protein and pectin are gaining popularity as wall materials for delivery systems due to their abundance, biocompatibility, and functionality. This study investigates and compares different drying processes: air-drying, freeze-drying and SC-CO2 drying to optimize the encapsulation efficiency, structural characteristics and application of bioactive-loaded gels.

Methods

First, emulsion gels were prepared by high-intensity ultrasound treatment. A biopolymer solution was prepared using lentil protein (15% w/v) and pectin (5% w/v). The oil phase was prepared by solubilizing β-carotene (5 mg/g) in sunflower oil by sonicating the solution for 2 min. Then, the oil phase (10% v/v) was added to the biopolymer solution (90% v/v) and homogenized, followed by HIUS treatment (0-900 W). The emulsion gels were characterized for rheological, and textural properties and loading capacity was determined. Air drying, freeze drying and SC-CO2 drying were performed on these gels to improve the overall stability. The dried gels were then characterised for density, porosity, surface area, crystallinity, and structural conformation. The encapsulation efficiency, storage stability and bioaccessibility were evaluated.

Results

The loading capacity of the β-carotene emulsion gels ranged from 78 to 93% and the bioaccesibility varying significantly from 2 to 50%. In comparison to air drying, freeze-drying and SC-CO2 drying produced aerogels with lower density, higher porosity and improved β-carotene retention. Freeze drying and SC-CO2 drying resulted in aerogels with similar thermal stability and encapsulation efficiencies. The oil absorption capacity was in the range of 3.7 – 9.4 g oil/g aerogel for SC-CO2 drying process and 1.4 – 2.7 g oil/g aerogel for freeze-drying process. These results suggest the feasibility of using these aerogels as fat replacers in the food industry.

Significance

This research also contributes to sustainable innovations in the food and pharmaceutical industries by developing high-performance delivery systems through elucidating the relationship between drying methods, aerogel properties and bioactive functionality.

Authors: Srujana Mekala, Natalie Aranda Siloto and Marleny D.A. Saldaña