title: Characterization of crystalline structures in Opuntia ficus-indica.
abstract: This research studies the crystalline compounds present in nopal (Opuntia ficus-indica) cladodes. The identification of the crystalline structures was performed using X-ray diffraction, scanning electron microscopy, mass spectrometry, and Fourier transform infrared spectroscopy. The crystalline structures identified were calcium carbonate (calcite) [CaCO3], calcium-magnesium bicarbonate [CaMg(CO3)2], magnesium oxide [MgO], calcium oxalate monohydrate [Ca(C2O4)•(H2O)], potassium peroxydiphosphate [K4P2O8] and potassium chloride [KCl]. The SEM images indicate that calcite crystals grow to dipyramidal, octahedral-like, prismatic, and flower-like structures; meanwhile, calcium-magnesium bicarbonate structures show rhombohedral exfoliation and calcium oxalate monohydrate is present in a drusenoid morphology. These calcium carbonate compounds have a great importance for humans because their bioavailability. This is the first report about the identification and structural analysis of calcium carbonate and calcium-magnesium bicarbonate in nopal cladodes, as well as the presence of magnesium oxide, potassium peroxydiphosphate and potassium chloride in these plants. The significance of the study of the inorganic components of these cactus plants is related with the increasing interest in the potential use of Opuntia as a raw material of products for the food, pharmaceutical, and cosmetic industries.
authors.affiliation: Centro de Física Aplica y Tecnología avanzada, Universidad Nacional Autónoma de México, A.P. 1-1010, Querétaro, Qro, C.P. 7600, Mexico.
authors.forename: Margarita
authors.initials: M
authors.lastname: Contreras-Padilla
authors.forename: Eric M
authors.initials: EM
authors.lastname: Rivera-Muñoz
authors.forename: Elsa
authors.initials: E
authors.lastname: Gutiérrez-Cortez
authors.forename: Alicia Real
authors.initials: AR
authors.lastname: del López
authors.forename: Mario Enrique
authors.initials: ME
authors.lastname: Rodríguez-García
mesh_terms: D002119:Calcium Carbonate / Q000737:chemistry; D002129:Calcium Oxalate / Q000737:chemistry; D018360:Crystallography, X-Ray; D008274:Magnesium / Q000737:chemistry; D008277:Magnesium Oxide / Q000737:chemistry; D029747:Opuntia / Q000737:chemistry* / Q000254:growth & development; D010545:Peroxides / Q000737:chemistry; D010756:Phosphoric Acids / Q000737:chemistry; D011189:Potassium Chloride / Q000737:chemistry
chemical_list: D010545:Peroxides; D010756:Phosphoric Acids; C005479:magnesium carbonate; C058785:tetrapotassium peroxydiphosphate; D002129:Calcium Oxalate; D008277:Magnesium Oxide; D011189:Potassium Chloride; D002119:Calcium Carbonate; D008274:Magnesium