Comparative Analyses of Different Routes to Prepare Cutin Colloidal- and Nano- Particle Dispersions from Tomato...

Cutin is a natural plant polyester, a constituent of the cuticle that covers aerial plant surfaces. Following the trends of agricultural and food waste reduction and the growing demand for plant-derived nanomaterials, cutin was extracted from tomato peels, a by-product of tomato processing. Subsequently, dispersions of cutin particles in the nano- and colloidal size range were prepared by pH-dependent precipitation. Four types of the dispersions were obtained, i.e., dispersion from cutin extract-NP E dispersion, dispersions from a solution of different cutin isolates, dialyzed cutin isolate-NP D dispersion, washed cutin isolate-NP W dispersion, and standard cutin isolate-NP S dispersion. Cutin precipitation occurred at pH lower than 7 and cutin dispersions with final pH 3-7 were formed. Zeta potential, particle size, and recovery of four cutin dispersions were investigated. All types of cutin particles bear a negative charge which increases on pH increase from 3 to 7, resulting in decrease in cutin nanoparticle size upon pH increase. In addition to that, the influence of cutin solution concentration and storage time on cutin dispersion particle size was found to be mitigated at pH ≥ 6. Among four dispersions, NP S had the highest cutin nanoparticle recovery at all pHs investigated.