Highly crystalline cellulose from brown seaweed Saccharina japonica: isolation, characterization and microcrystallization

Highly crystalline cellulose was isolated from kelp (Saccharina japonica) and used to prepare microcrystalline cellulose (MCC) via an optimized chemical-mechanical approach. The purity of the cellulose reached 99.9% (dry basis) according to HPLC and FT-IR analysis, with extraction yield reaching 9.9% on a dry kelp basis. The kelp cellulose (KC) had a degree of polymerization (DP) of 695, and featured natively highly crystalline structure with a crystallinity index (CrI) as high as 90.9% according to X-ray powder diffraction analysis. The KC was subjected to successive hydrochloric acid treatment and ball-milling to obtain MCC having a DP of 235 and a CrI of 88.6%. The kelp MCC exhibited comparable quality attributes to commercially available MCC. Polymorphic analysis based on peak deconvolution of the diffractograms revealed that the crystalline region of the kelp cellulose featured one-chain triclinic (I-alpha) rich polymorph, in contrast to two-chain monoclinic (I-beta) dominant structure found in higher-plant cellulose. [GRAPHICS] .