Xu Chunping

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.

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.