Ultrasound-assisted freezing for the preparation of aerogel-based intelligent packaging

Abstract

Due to their highly porous and high specific surface area, aerogels are promising materials for intelligent food packaging. However, aerogel-based intelligent packaging prepared by traditional freeze-drying methods severely limits the preparation efficiency and the packaging performance of the aerogels due to the low freezing efficiency and the large and uncontrollable pore size caused by the uncontrolled growth of the crystals during freezing; this leads to the destruction of the aerogel structure. In this study, an aerogel-based food intelligent packaging was prepared using gelatin and gum Arabic (GG) as the substrate materials for real-time shrimp freshness detection. An ultrasound-assisted freeze-drying (UAFD) strategy was applied to improve the freezing efficiency of the cavitation-induced nucleation of aerogel. By affecting secondary nucleation, the UAFD-160 W strategy produced aerogels (GG-160) with smaller pore sizes (14.76 μm) and narrower pore size distributions than those using intelligent packaging prepared by the traditional freeze-drying method (GG-0, pore size = 254.14 μm). Due to the advantages of the above structure, the GG-160 aerogel has a significantly improved hardness (28956.5 ± 101.6 N), excellent water resistance and hydrophobicity (93.6 ± 0.99°), sensitive ammonia responsiveness, and stable properties under high humidity. Consequently, compared with that in the GG-0 treatment, the color of the shrimp in the GG-160 treatment was more sensitive to spoilage. The proposed UAFD strategy provides a new way to improve the properties of aerogels by structural modulation such that the prepared aerogels have better food packaging applications.