Mao Duobin

Fermentation characteristics in stirred-tank reactor of exopolysaccharides with hypolipidemic activity produced by Pleurotus geesteranus 5 #

In this study, the hypolipidemic effect of exopolysaccharides (EPS) from Pleurotus geesteranus 5# fermenting liquor by the optimal culture conditions in a 5-L stirred-tank reactor was investigated. The hypolipidemic effect of the polysaccharide, investigated in streptozotocin induced diabetic mice, decreased plasma glucose, total cholesterol and triacylglycerol concentrations by 17.1 %, 18.8 % and 12.0 %, respectively. The results of the present investigation strongly demonstrate the potential of this polysaccharide to prevent hyperglycemia in the experimental animals. Under optimal culture conditions, the maximum concentrations of mycelial and EPS were 22.63 g/L after 7 d cultivation and 11.09 g/L after 10 d, respectively. Furthermore, the morphological parameters (i.e. mean diameter, circularity, roughness and compactness) of the pellets and the broth viscosity were characterized. It was proved that compactness of the pellet morphology (R²=0.963, p<0.01) was significantly and positively determined with mycelial biomass. Moreover, mean diameter (R²=93.3, p<0.01) and broth viscosity (R²=0.950, p<0.01) were significantly and positively determined with EPS content.

UPLC-MS n 法分析烟叶中蔗糖四酯类化合物

建立了烟叶样品中蔗糖四酯类化合物的超高效液相色谱-多级质谱（UPLC-MSn）分析方法。采用超声辅助萃取技术，用甲醇萃取烟叶样品中的蔗糖四酯，采用正交试验对超声萃取条件进行优化；萃取液经分离除杂后，在选择反应监测（SRM）模式下进行UPLC-MSn定性和定量分析，通过与标准品对照及对目标物的多级质谱数据进行分析，定性鉴定样品中的5组蔗糖四酯；并采用内标标准曲线法同时定量测定5组蔗糖四酯化合物的质量分数。结果表明：① 优化后的最佳萃取条件为料液比1：30[质量（g）：体积（mL）]，超声功率120 W，萃取时间40 min；② 定量分析方法的回收率在80.67%~89.35%之间，相对标准偏差均小于5%；相关系数r均大于或等于0.999 0；方法的检出限（LOD）和定量限（LOQ）分别为14.71~38.42、49.02~128.05 μg/kg。该方法前处理简单，定量分析灵敏度和准确度均较高，适合烟叶中蔗糖四酯类化合物的定量分析。

Determination of odor activity values (OAVs) of selected volatile organic acids in mainstream cigarette smoke

In this study, the effect of volatile organic acids on the expression of cigarette smoke sensory characteristics was investigated by evaluating the odor activity values (OAVs) of selected organic acids. The OAVs of the organic acids were calculated by the ratio of the organic acid contents in the mainstream cigarette smoke determined by GC-MS and their threshold values using the sensory evaluation method of functional thresholds for tobacco flavors. The results showed that the functional thresholds of 14 volatile organic acids were in the narrow range of 1.93×10 -9 and 4.61×10 -8 μg/cig. The total content of 14 volatile organic acids in mainstream smoke was 56.98 μg/cig, and acetic acid was the highest (33.54 μg/cig) and accounted for 58.86% of the total content. Isovaleric acid and valeric acid were 5.17 and 4.06 μg/cig (9.07% and 7.12% of the total content), respectively. According to the OAV, acetic acid (with an acid aroma note) could play a major role in the expression of cigarette aroma characteristics. Isovaleric acid, valeric acid and 4-methylvaleric acid (with a cheesy and fruity aroma note) and decanoic acid (with a fatty wax aroma note) were also important for expressing cigarette smokes aroma characteristics.

Pyrolysis Analysis of Phenylethyl β-D-Glucopyranoside

The thermal mass loss and pyrolysis products of phenylethyl β-D-glucopyranoside were investigated with thermogravimetry and differential thermal analysis(TG-DTA) and online pyrolysis gas chromatography/mass spectrometry(Py-GC/MS).The TG curve showed that the largest mass loss occurred from 240 to 350 ℃,within that temperature range,the sample lost nearly all its mass.The DTA curve illustrated that melting temperature was 107.63 ℃,and pyrolysis temperature was 325.29 ℃.The main pyrolysis products were benzenoid and heterocyclic compounds.The number of pyrolysis products increased with the rise of temperature.This study provided a reference for investigating the transformation behavior of phenylethyl β-D-glucopyranoside during cigarette combustion.

Analysis of Pyrolysate of 1-L-Phenylalanine-1-deoxy-D-fructose

The thermal mass loss and pyrolysis temperatures of 1-L-phenylalanine-1-deoxy-D-fructose(PDF) were tested by thermogravimetry-differential thermal analyzer(TG-DTA).The pyrolysis behavior of PDF was identified by on-line pyrolysis and gas chromatography/mass spectrometry(Py-GC/MS) at 350,450,550,650,750 and 850 ℃,respectively.The results showed that the primary pyrolysis temperature of PDF was 145.91 ℃,and the secondary one was 170.70 ℃.The thermal mass loss of PDF reached about 80% at 500 ℃.The major pyrolytic products of PDF were aromatic hydrocarbons and heterocyclic compounds.The number of pyrolytic products of PDF increased with the rise of temperature,especially aromatic hydrocarbons.

Determination of pH Values of Particulate Matter and Vapor Phase of Mainstream Cigarette Smoke

In order to determine pH values of particulate matter(PM) and vapor phase matter of mainstream cigarette smoke(MS),the influences of the number of cigarette smoked,puff volume,concentration and volume of extraction or absorption solutions,time and frequency for oscillation extraction,acidity and basicity of blank extraction and absorption solutions on pH determination were studied.The results were as follows: 1) the proper conditions were puff volume 40 mL,cigarette number 15;extraction solution 50% isopropyl alcohol-water solution,extraction volume 80 mL,oscillation frequency 175 r/min,extraction time 30 minutes;and absorption solution 50% isopropyl alcohol-water solution,volume 100 mL;2) the relative standard deviation of the method was from 0.20% to 0.27%;3) the blank extraction solution and absorption solution presented alkaline,both of them affected the pH measurement of PM and vapor phase of MS.This method is suitable for the determination of pH values of PM and gas phase of MS.