Ultrastructural Characterization of Oil Bodies in Different Coffea Species

Abstract

In the coffee seed, the lipid component known as coffee oil is stored in the endosperm tissue as an energy reserve for germination and post-germination growth. This coffee constituent is present in the form of subcellular spherical oil bodies (“oleosomes”) in a typical size range of 0.2–2.5 μm. These particles are filled with an osmiophilic matrix of triglycerides, delimited by a single protein membrane, typical of oleaginous plant tissues. The object of this study is to characterize the morphology and distribution of oil bodies in different coffee species. In particular, we studied Indian samples of Coffea arabica, C. canephora, C. liberica, C. stenophylla and C. salvatrix. After appropriate fixation and preparation, the samples were examined and oil bodies characterized by optical microscopy and transmission electron microscopy. Oil bodies morphology, tissue distribution and size distribution were determined and several features of these subcellular structures were observed and discussed for the first time in the framework of a coffee inter-species comparative study.