Abstract：
Levans of different structures and molecular weights (MW) can display various techno-functional and health-promoting properties. In the present study, selected levans were produced by the transfructosylation of sucrose catalyzed by levansucrases from Bacillus amyloliquefaciens and Gluconobacter oxydans, and their structural, techno-functional and anti-inflammatory properties were investigated. NMR and methylation/GC analysis confirmed the structure of β-(2, 6) levans. The structural characterization led to the classification of levans as high MW (HMW, ≥100 kDa), low MW (LMW, ≤20 kDa) and mix L/HMW ones. Levan with higher MW had more linear fructosyl units with fewer reducing ends and branching residues. LMW levan showed the highest foaming capacity and stability while HMW levan had the highest emulsion stability. HMW and mix L/HMW levans showed comparable water and oil-holding capacities, which were higher than LMW. HMW and mix L/HMW levans were found to have gelling properties at low concentrations. The rheological behaviour of HMW levan-based gel was a more viscous-like gel, while that of mix L/HMW levan-based one showed more elastic solid like-gel. The temperature also influenced the rheology of levan, showing that the mix L/HMW levan gel network was the most thermal stable as its viscoelasticity remained constant at the highest temperature (75 °C). Studies on the biological activity of levans of HMW and LMW revealed in-vitro anti-inflammatory properties as they significantly reduced the production of LPS-triggered pro-inflammatory cytokines in differentiated Caco-2 cells.
摘要：
具有不同结构和分子量（MW）的Levans可以显示出各种技术功能和促进健康的特性。在本研究中,选定的果聚糖是通过解淀粉芽孢杆菌和氧化葡糖杆菌的果聚糖蔗糖酶催化的蔗糖转果糖化产生的，和它们的结构，研究了技术功能和抗炎特性。NMR和甲基化/GC分析证实了β-(2,6)果聚糖的结构。结构表征导致Levans分类为高MW(HMW，≥100kDa),低MW(LMW，≤20kDa)并混合L/HMW。具有较高MW的Levan具有更多的直链果糖基单元,具有更少的还原末端和分支残基。LMW果聚糖显示出最高的发泡能力和稳定性，而HMW果聚糖具有最高的乳液稳定性。HMW和混合L/HMWlevans显示出可比的持水和持油能力，高于LMW。发现HMW和混合L/HMW果聚糖在低浓度下具有胶凝特性。HMW果聚糖基凝胶的流变行为是一种更粘稠的凝胶，而基于L/HMW的混合物显示出更有弹性的固体样凝胶。温度也影响了果聚糖的流变学，显示混合物L/HMW果聚糖凝胶网络是最热稳定的,因为其粘弹性在最高温度(75°C)下保持恒定。对HMW和LMW的果聚糖的生物活性的研究揭示了体外抗炎特性，因为它们显着减少了分化的Caco-2细胞中LPS触发的促炎细胞因子的产生。
