酵母β-葡聚糖增溶改性与构效关系

The Solubilization Modification and Structure-activity Relationship of Yeast β-Glucan

酵母β-葡聚糖具有良好的生物活性,然而溶解性差,应用范围较窄。为提高酵母β-葡聚糖的溶解性,扩大其应用范围,以水溶性β-葡聚糖得率为指标,考察酶添加量、底物质量浓度、温度、时间等因素对得率的影响,并利用响应面试验优化工艺,比较酶解前、后酵母β-葡聚糖的功能性质及结构的变化。结果表明:在酶添加量4.30%,底物质量浓度15 mg/mL,酶解温度45℃,酶解时间83 min的条件下,水溶性β-葡聚糖得率为56.12%,溶解性达89.74%,分子质量降为2.99×106,6.68×10^(4) u和1.40×10^(4) u,D_([4,3])由67.49μm降至38.25μm,热稳定性改善。红外图谱表明:酵母β-葡聚糖结构无明显变化,仍以β-1,3-糖苷键连接。圆二色谱表明:水溶性β-葡聚糖的不对称性增加,具有高度有序的结构。扫描电镜表明:酵母β葡聚糖由完整的颗粒变为杂乱无章的片状结构。

Yeastβ-glucan has attracted much attention due to its good biological activity,but its low solubility limits its application.In order to improve the solubility ofβ-glucan and expand its application range,the effects of enzyme dosage,substrate concentration,temperature and time on the yield of water-solubleβ-glucan were investigated.The process was optimized by response surface methodology.The functional properties and structural changes ofβ-glucan before and after enzymatic hydrolysis were compared.The results showed that the yield of water-solubleβ-glucan was 56.12%under the conditions of enzyme dosage 4.30%,substrate mass concentration 15 mg/mL,enzymolysis temperature 45℃,enzymolysis time 83 min.The solubility of the product was reached 89.74%,the molecular weight was decreased to 2.99×106,6.88×10^(4) u and 1.40×10^(4) u,D_([4,3])was decreased from 67.49μm to 38.25μm,and the thermal stability was improved.The structure ofβ-glucan remained unchanged,which was still connected withβ-1,3-glycoside bond.Circular dichroism chromatography showed that the asymmetry of water-solubleβ-glucan was increased and the structure was highly ordered.Scanning electron microscope showed that the yeastβ-glucan was changed from intact granules to irregular slice shape.