CARMINIC ACID INCORPORATED INTO SPHERICAL CELLULOSE NANOPARTICLES. THEIR PREPARATION AND CHARACTERIZATION

Carminic acid (CA) was added by two processes: dipping or in situ, to cellulose nanoparticles previously obtained using Span 80 and 85 as emulsifiers. The resulting nanoparticles were analyzed by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and Fourier Transform Infrared (FTIR) spectroscopy. According to both SEM and AFM studies, the pure cellulose nanoparticles showed spherical geometry with an average diameter in the range of 150-400 nm. At concentrations of 0.2 and 0.5 wt% of CA, the cellulose nanoparticles increased their average diameter and aggregation state. It was observed that the cellulose nanoparticles absorbed CA, which was spotted to be higher when using the in situ process, compared to the dipping process. However, with the dipping process, the spherical geometry of the nanoparticles was maintained after CA absorption, resulting in a significant increase in their diameters from 150-400 nm to 900 nm. The molecular associations between nanoparticles and CA were determined by FTIR studies, which revealed that an increase of the absorbance ratio occurred upon the addition of CA. Thus, in this work, the process of CA absorption was established, which opens a new perspective for the fabrication of a safety indicator in packaged foods, where CA could serve as a new sensor to measure the quality of food.