Characterization of Grape Extract-Colored SiO2 Synthesized via the Sol-Gel Method

Numerous studies have focused on the development of active packaging using plastics, but glass-based active packaging represents a more sustainable alternative, offering advantages in terms of recyclability, durability, and reduced environmental footprint. This study proposes a glass-based active packaging system by incorporating anthocyanins-rich grape extract (GRE) into a silica (SiO2) matrix using the sol-gel method. GRE was added at two concentrations, 5% (S5GRE) and 15% (S15GRE). During synthesis, color brightening occurred as anthocyanins shifted to colorless chalcone and pseudo-base forms, but colorimetric analysis confirmed that the hybrid materials retained a red hue after gel drying. Fourier-transform infrared (FTIR) and thermogravimetric analysis (TGA/DTG) investigated the stability of the GRE within the silica matrix and showed that both hybrids formed hydrogen bonds with the inorganic matrix. However, S5GRE exhibited better thermal stability compared to that of S15GRE, possibly due to a greater proportion of the extract being fully entrapped rather than surface-bound. The encapsulation efficiency analysis supported this, showing that 98.12% of the GRE was successfully entrapped in S5GRE, whereas S15GRE retained only 54.62%. These results indicate that, while S5GRE exhibits higher encapsulation efficiency and allows for faster release, S15GRE releases less efficiently due to extract aggregation within the matrix.