Caulobacter crescentus蔗糖水解酶突变体S271A的重组表达及其转化蔗糖制备松二糖的研究

松二糖具有低热量和不致龋齿的特性,在食品工业具有广泛的应用前景.与淀粉蔗糖酶相比,Cau-lobacter crescentus蔗糖水解酶突变体S271A(CcSH S271A)转化蔗糖过程中产生的麦芽寡糖副产物少,可代替淀粉蔗糖酶用于松二糖制备.该研究将CcSH S271A在枯草芽孢杆菌(Bacillus subti...     

离子色谱法测定蜂蜜中松二糖含量

目的 建立离子色谱法测定蜂蜜中松二糖的检测方法,初步分析市售蜂蜜松二糖含量情况。方法 用水作为样品提取剂,以136 mmoL/L氢氧化钠溶液和20 mmoL/L无水乙酸钠溶液作为淋洗液等度洗脱,进样量20 μL,流速0.7 mL/min,采用Metrosep Carb 2（250mm×4.0mm）分离柱,以安培检测器进行测定。结果 离子色谱法测定蜂蜜中松二糖相关系数为0.99955,检出限达0.02g/100g,定量限为0.05g/100g,定量和定性的相对标准偏差分别为1.62%和0.089%,加标回收率为98.3%。结论 本实验建立的检测蜂蜜中松二糖含量的方法,前处理简单,分离效果好,灵敏度高,检测结果稳定可靠,可用于蜂蜜中松二糖含量的检测。通过对84个市购蜂蜜样品中松二糖含量测定分析,可对蜂蜜中松二糖的含量测定、蜂蜜真伪鉴别以及制定蜂蜜相关标准提供技术支持。     

Effect of turanose on the rheology and oil uptake of instant fried noodles

Effects of turanose on the functional properties of instant fried noodles were assessed mainly in terms of rheology- and oil uptake-related characteristics. The Mixolab results showed that the water absorption of dough decreased as the turanose level increased, whereas the gel stability and starch retrogradation increased. Also, the use of turanose lowered the storage and loss moduli of the dough, showing a more viscous nature. These viscoelastic characteristics were correlated with the decreased resistance to extension and increased extensibility. NMR spin–spin relaxation analysis showed three distinct water populations in the turanose noodle doughs whose relaxation times were varied depending on the level of turanose. After frying, the noodles with turanose exhibited a continuous and smooth surface as well as a less porous structure. These microstructural characteristics were correlated with the reduced oil uptake by 20.8%, the enhanced oxidative stability and furthermore the improved breaking stress.