Instituto de Química de Araraquara, UNESP, Araraquara, Brazil.
Faculdade de Ciências Farmacêuticas de Ribeirão Preto, USP, Ribeirão Preto, Brazil.
J Food Biochem. 2019 Aug;43(8):e12937. doi: 10.1111/jfbc.12937. Epub 2019 Jun 7.
Aspergillus thermomutatus produces an extracellular β-D-fructofuranosidase when cultured in Khanna medium with sucrose as additional carbon source at 30°C under agitation for 72 hr. Addition of glucose and fructose in the culture medium affected the production of the enzyme negatively. The optimum hydrolytic activity was achieved at 60°C and pH 5.0, with half-life (T50) of 30 hr at 50°C and 62% of its activity maintained at pH 5.0 for 48 hr. The extracellular extract containing β-D-fructofuranosidase was effective in producing fructooligosaccharides (FOS), mainly 1-kestose. The highest concentration of FOS was obtained at 30°C and 60°C, indicating the existence of at least two enzymes with transfructosylating activity. At 30°C, the maximal FOS concentration was obtained from 48 to 72 hr, while at 60°C, it was achieved only at 72 hr. The best production of FOS (86.7 g/L) was obtained using 500 g/L sucrose as substrate. PRACTICAL APPLICATION: Fructooligosaccharides (FOS) are linear oligomers of fructose units with important applications in the food industry as sweetening agents and biopreservatives. Due to the presence of β-glycosidic bonds, they cannot be hydrolyzed by human enzymes, allowing the use of FOS-containing products by diabetics. FOS used in the preparation of dairy products imparts humectancy to soft baked products, lowers the freezing point of frozen desserts, provides crispness to low-fat cookies, and provides many other advantages. Diets containing FOS can reduce the levels of triglycerides and cholesterol and improve the absorption of ions, such as Ca and Mg . FOS also exhibit bifidogenic effect on Bifidobacterium and Lactobacillus strains in the colon. Industrially, FOS is produced during the transfructosylation reaction of sucrose catalyzed by β-D-fructofuranosidase. Identifying new sources of β-D-fructofuranosidase is an important challenge to meet its industrial demand.
在 30°C 下，于 Khanna 培养基中用蔗糖作为外加碳源进行搅拌培养 72 小时后，嗜热曲霉会产生胞外β-D-呋喃果糖苷酶。在培养基中添加葡萄糖和果糖会对酶的产生产生负面影响。在 60°C 和 pH5.0 时，达到最佳水解活性，半衰期（T50）为 50°C 时为 30 小时，62%的活性在 pH5.0 下保持 48 小时。含有β-D-呋喃果糖苷酶的胞外提取物可有效生产果寡糖（FOS），主要是 1-蔗果三糖。在 30°C 和 60°C 时获得了最高浓度的 FOS，表明至少存在两种具有转果糖基活性的酶。在 30°C 时，最大 FOS 浓度在 48 至 72 小时之间获得，而在 60°C 时仅在 72 小时时获得。使用 500g/L 蔗糖作为底物时，FOS 的最佳产量为 86.7g/L。实际应用：果寡糖（FOS）是果糖单元的线性低聚糖，作为甜味剂和生物防腐剂，在食品工业中具有重要应用。由于存在β-糖苷键，它们不能被人体酶水解，因此可以让糖尿病患者使用含 FOS 的产品。在乳制品制备中使用的 FOS 可使软烘焙产品保持湿润，降低冷冻甜点的冰点，使低脂饼干变脆，并提供许多其他优点。含有 FOS 的饮食可以降低甘油三酯和胆固醇的水平，并改善离子（如 Ca 和 Mg）的吸收。FOS 对结肠中的双歧杆菌和乳杆菌菌株也具有双歧杆菌作用。在工业上，FOS 是在蔗糖的β-D-呋喃果糖苷酶催化的转果糖基反应过程中产生的。确定新的β-D-呋喃果糖苷酶来源是满足其工业需求的重要挑战。
