Abstract: Seabuckthorn pomace is rich in phenolic acid and is a byproduct produced during the processing of seabuckthorn pulp. However, the astringency and bitterness of seabuckthorn pomace hinder its utilization in the feed industry. The preparation of microcrystalline cellulose from seabuckthorn pomace is a potential solution to this problem. Therefore, in this study, the crude cellulose extracted from seabuckthorn pomace was hydrolyzed with commercial cellulase S10041 to obtain microcrystalline cellulose. Eight processing parameters were investigated, namely solid-to-solvent ratio, enzyme dosage, hydrolysis time, temperature, buffer pH, centrifugal rotational speed, drying temperature, and comminution degree of cellulose. The significant factors were selected and optimized using one-factor-at-a-time method, Plackett-Burman design, steepest ascent path design and Box-Behnken design combined with response surface methodology. The prepared microcrystalline cellulose was structurally elucidated. The results showed that the degree of polymerization of seabuckthorn microcrystalline cellulose was 355 ± 1.02 under the optimal follows: ratio of buffer solution to cellulose, 49:1 (mL/g); enzyme dosage, 68 U/mL; hydrolysis time, 1.3 h; and centrifugal rotational speed, 3 640 r/min, which was close to that of cotton microcrystalline cellulose. The analysis of variance showed that the four selected factors had independent influences on the degree of polymerization but their interactions had no significant effect on the response (P = 0.10). The scanning electron micrograph revealed that the surface structure of seabuckthorn microcrystalline cellulose was more porous as compared to cotton microcrystalline cellulose. The infrared spectra of two microcrystalline celluloses revealed that similar functional groups existed.

Key words: seabuckthorn pomace, microcrystalline cellulose, cellulase