超微粉碎和高压均质联合处理对几丁质理化性质及微观结构的影响

Effect of Combined Treatment of Ultra-Micro Grinding and High Pressure Homogenization on the Physicochemical Properties and Microstructure of Chitin

天然几丁质具有高度有序的晶体结构以及较强的分子间和分子内氢键,其不溶于水,因此难以被酶促降解。为了提高几丁质的酶促降解效率,本研究采用超微粉碎和高压均质联合处理对几丁质进行改性,测定改性处理前后几丁质的一系列理化性质,并用傅里叶变换红外光谱、元素分析、X射线衍射、热重-差示扫描量热法和扫描电子显微镜等对几丁质的微观结构进行表征;此外,利用非特异性酶进行酶解验证联合处理对几丁质的酶解效率的影响。结果表明,与原几丁质相比,联合处理改性后的几丁质平均粒径减小99.71%,比表面积增加85.11%,孔隙体积增大29.03%,黏均分子质量降低85.80%,通过振实密度所计算膨胀比增加1.02倍。与原几丁质相比,联合处理改性后的几丁质在3 448 cm和3 263 cm附近吸收峰强度提高,在896 cm处的吸收峰强度变弱;脱乙酰度没有明显变化;在(110)晶面和(020)晶面的结晶度指数分别降低了17.49%和1.31%;热稳定性被破坏;结构变得疏松多孔。联合处理改性后的几丁质更易被纤维素酶和木瓜蛋白酶降解。此外,联合处理的改性效果优于超微粉碎和高压均质单一处理。综上所述,超微粉碎和高压均质联合处理可以有效地改变天然几丁质的理化性质和微观结构,从而提高几丁质的酶解效率。

Natural chitin has a highly ordered crystal structure and strong intermolecular and intramolecular hydrogen bonds,and is insoluble in water, so it is difficult to enzymatically degrade. In order to improve the enzymatic degradation efficiency of chitin, combined treatment of ultra-micro grinding and high-pressure homogenization was used to modify chitin in this study. The physicochemical properties of modified chitin were determined, and its microstructure was characterized by Fourier transform infrared(FTIR) spectroscopy, elemental analysis, X-ray diffraction, thermogravimetric-differential scanning calorimetric(TG-DSC) analysis and scanning electron microscopy(SEM). Besides, non-specific enzymatic hydrolysis experiments were carried out to validate the effect of the combined treatment on the hydrolysis efficiency of chitin. The results showed that after the modification treatment, the average particle size of chitin decreased by 99.71%,the specific surface area increased by 85.11%, the pore volume increased by 29.03%, the viscosity-average molecular mass decreased by 85.80%, and the expansion ratio increased by 2.02 times as compared from tap density. Moreover, the intensity of the absorption peaks near 3 448 and 3 263 cmincreased, whereas the absorption intensity of the absorption peak at 896 cmdecreased. However, there was no obvious change in the degree of deacetylation. The crystallinity index on the(110) and(020) plane decreased by 17.49% and 1.31%, respectively. The thermal stability was destroyed. The structure became loose and porous. The modified chitin was more easily degraded by cellulase and papain. In addition, the combined treatment was more effective than either treatment alone. In summary, the combined treatment of ultra-micro grinding and high-pressure homogenization can effectively modify the physicochemical properties and microstructure of natural chitin,thus improving the enzymatic hydrolysis efficiency of chitin.