Thermal and microstructural properties of cuticle hydrophobic compounds from four species of Opuntia

The vegetable waxes are widely used in the agri-food, cosmetic and pharmaceutical industries. Epicuticular wax of Opuntia spp could be a new alternative able to satisfy industrial needs. The objective of this research is to characterize the thermal and structural properties of cuticle hydrophobic compounds from four species of Opuntia [O. robusta Wendl, O. leucotricha DC., O. streptacantha Lem. and O. ficus-indica (L.) Mill]. The content of hydrophobic compounds was determined by Soxhlet. The melting and crystallization profiles of the extracts were obtained by differential scanning calorimetry (DSC). The microstructure of the cuticle surface was observed by Scanning Electron Microscopy and the crystalline characteristics of the extracts were observed using Polarized Light Microscopy. Results showed that O. streptacantha contains both the highest concentration of hydrophobic compounds (3.97 %) and the melting temperature (78.25 °C). In addition, O. Streptacantha showed the highest quantity of hydrophobic compounds on the surface of the cladode with small crystals of colloidal dimensions and irregular plate-like form. Therefore, the four involved Opuntia species,especially O. streptacantha, contain hydrophobic compounds with thermal characteristics like high value-added vegetable waxes.