Multiscale Analysis Comparison of Cellulose in Apple Cultivars: Structure, Morphology, and Properties

This investigation aims to extract cellulose from four distinct apple varieties-Golden Delicious, Granny Smith, Gala, and Red Delicious-and determine its structural characteristics at different scales using advanced techniques such as super-resolution microscopy and spectroscopy. The cellulose microfibrils (>1 µm diameter) consist of nanofibrils (<500 nm) containing 2D nanofibers (30-200 nm). The crystalline structure of cellulose in the four apple varieties presents a range of lattice spacing between 3.82 and 5.96 Å. This is measured by using microscopy and computational simulation to determine the corresponding crystalline structure from the d-spacings and angles between different crystalline planes in the crystalline regions of the different apple celluloses. It is shown that the triclinic phase is predominant in all cellulose types under investigation. At the same time, measurement of nanomechanical properties shows that the Young's modulus of cellulose is around 2.50-4.54 GPa. The novelty of this contribution is to demonstrate that the simulated unit cells differ from other reported types of cellulose because the unit cell depends upon the microstructural arrangement and the morphology of the different tissues, giving rise to distinct properties.