Morphological structure of <i>Kappaphycus alvarezii</i> under scanning electron microscope after degradation in acidic solution

Abstract

Seaweeds are an increasingly popular macroalgae with intensive cultivation being carried carried out in East Malaysia especially from the species Kappaphycus alvarezii and Gracilaria salicornia. Tese species have unique saccharides that warrant further exploration. K. alvarezii is rich in carrageenan and sulphated sugars. Other important polysaccharides are agars, xylans,
floridean starch and water-soluble sulphated galactan which can be used in many biotechnology applications. Despite this only a few studies have been carried out to understand their hydrolysis behavior into the nanosize level morphological structure using Scanning Electron Microscope (SEM). Seeaweeds are also rich in oxygen believed to be in the form of hydroxyl bond making them harder to be broken down. Generally, chemical method is used to hydrolyse seaweed polysaccharides into their respected monosaccharides. Tis study shows that the morphologies of K. alverazii exhibits smooth surface with salt crystalloid deposition covering the area. Te study samples also show some reticulated and blocky image. Te shrink fibrils could be seen clearly due to the dried sample used before treatment. Te fractured surface after heating treatment at high temperature shows a removal of surface impurities. Te treatment also resulted in the leaching out of the salt crystalloid deposition layer and more internal structure was exposed. Another observation revealed the existence of pores on the surface. Finally the surfaces of K. alverazii contain less microstructures and the microfibrils structure become broken as the broken microfibers can be clearly seen on the fiber surfaces. Tis may benefit to increase total surface area for further hydrolysis process.