Microfibrillated cellulose from the peel of prickly pear fruits

Cellulose microfibrils were isolated from the skin of Opuntia ficus indica (prickly pear fruits). Defatted skin powder was processed through consecutive extraction steps in order to remove mucilage, pectin and hemicelluloses. The cellulosic residue was made up of disencrusted cell-ghosts, having ovoid or elongated shapes, as revealed by optical microscopy. Transmission electron microscopy showed that, at the ultrastructural level, the cell walls of these cell-ghosts consisted of a loose network of cellulose microfibrils. This residue was subjected to mechanical homogenisation, leading to a stable and non-flocculating suspension by cellulose microfibril individualisation. This cellulosic material was characterised in terms of chemical composition, morphology and crystallinity, using sugar analyses, transmission electron microscopy and X-ray diffraction, as well as solid state NMR 13C spectroscopy.