Papers by Author: Bao Guo Sun

Abstract: A novel synthesis method of bromoalkanol at high selectivity from the monobromination of diol with aqueous HBr (48%) in toluene under microwave irradiation was reported in this paper. Based on orthogonal tests results, 10-bromo-1-decanol was synthesized in 53.5% yield and at 95.2% selectivity. Other six bromoalkanols were synthesized according to the above method in 40.9%-78.7% yield and at 90.5%-96.6% selectivity, which were as follows: 8-bromo-1-octanol, 9-bromo-1-nonanol, 11-bromo-1-undecanol, 12-bromo-1-dodecanol, 13-bromo-1-tridecanol and 14-bromo-1-tetradecanol.

Abstract: 1-(3,3-dimethylcyclohexyl) ethyl acetate was synthesized by the reaction of dihydromycene with acetic acid in the presence of sulfuric acid. The effecting factors including the amount of catalyst, the reaction temperature, the molar ratio of raw materials and the reaction time were investigated. The experimental results showed that the molar raio of the dihydromyrcene to acetic acid to sulfuric acid was 1:3:0.2, the reaction temperature is 60 °C and the reaction time was 6.5 h. The yield reached 45.3%. The structure of product was characterized by gas chromatography, mass spectrometry, infrared spectroscopy and nuclear magnetic resonance. The odor evaluation result indicated that the product had a sweet, woody, floral odor.

Abstract: 1,1,2,3,3-Pentamethylindane was synthesized by alkylation of tert-amyl alcohol and α–methylstyrene (AMS) using sulfuric acid and sulfolane as catalyst. The effect of the volume of sulfolane on the selectivity for the cross-dimerization as compared to the dimerzation of the AMS was studied. The result shows that the selectivity increased by 32% after adding even 1 ml of sulfolane as solvent.

Abstract: A commercial electronic tongue (ET) with specific sensors was applied on taste distinction and physicochemical characterization of seven kinds of sweet sauces. The response signals of ET sensors were analyzed by Principal Component Analysis (PCA) and Discriminant Factor Analysis (DFA). Meanwhile, these signals were transformed into the four relative taste scores (sourness, saltiness, umami and sweetness) by macro operation, followed by comparing with the corresponding four physiochemical indexes (total acids, sodium chloride, amino nitrogen and reducing sugars) which were determined by the methods in GB/T. The results show that ET can be used to distinguish different kinds of sweet sauces according to overall taste. Moreover, the intensity order of taste scores that obtained from ET is basically matched with the sequence of the corresponding physicochemical indexes, which proves that ET technique can be an effective approach to monitor and guarantee the quality of sweet sauce on line.

Abstract: Benzyl 4-ethyloctanoate was synthesized by the reaction of 4-ethyloctanoyl chloride with benzyl alcohol, and its synthesis conditions were optimized. The yield of benzyl 4-ethyloctanoate was about 93%. Based on the synthesis of benzyl 4-ethyloctanoate, phenethyl 4-ethyloctanoate, phenylpropanol 4-ethyloctanoate and cinnamyl 4-ethyloctanoate were prepared. The odor evaluations indicate that these four new ester compounds have floral and sweet note. These ester compounds have relatively high molecular weights and can be used as fixing agent to prolong the fragrance compounds lifetime.

Abstract: The volatile flavor compounds of Huizhou preserved vegetable were extracted by hydrodistillation (HD) and simultaneous distillation-extraction (SDE). The essential oils obtained were analyzed by gas chromatography-mass spectrometry, accompanying by comparison of the retention time of authentic samples and by calculation of retention index about the separated constituents. 50 volatile flavor compounds were identified in the essential oils of Huizhou preserved vegetable obtained by HD and SDE in all. 41 compounds were identified in the essential oil from HD and 36 compounds identified in the essential oil from SDE. The constituents which are very important to the odor of Huizhou preserved vegetable include 3-hydroxy-2-butanone, dimethyl disulfide, hexanal, furfural, 2-furanmethanol, 2-methylbutanoic acid, benzeneacetaldehyde, phenylethyl alcohol, 5-ethyldihydro-2(3H)-furanone, 5-pentyl-dihydro-2(3H)-furanone, etc. The exclusive compounds in the essential oil gained by HD consist of hexanol, heptanol, 1-(2-furanyl)-ethanone, 5-methyl-dihydro-2(3H)-furanone, benzaldehyde, phenol, benzyl alcohol, methyl benzoate, ethyl benzoate. The exclusive compounds obtained by SDE are 3-hydroxy-2-butanone, dimethyl trisulfide, trans-2-(2-pentenyl)-furan, camphor, vanillin, etc. The differences result in the two essential oils with a few distinctions on aroma characteristics.

Abstract: Xylanase has a wide range of potential biotechnological applications in pulp and bleaching processes, textile industries, food and bread making, fruit juice clarification and so on. In order to explore and utilize xylanases using actinomycetes, collected dozens of soil samples beneath decaying wood or leaf debris of different parts of China, 102 xylanase producing actinomycetes were isolated by plate screening with home-made corncob xylan as the sole carbon source. All strains degraded xylan and produced evident xylan hydrolyzed circles. 37 actinomycetes were selected by shake flask cultivation, and among them 7 stains with high producing xylanase were submerged fermentation again. Xylanase activities of 7 strains except L1904 (158U/ml) were all beyond 200U/ml and stable. L2001 as the most promising strain, xylanolytic activity of which was 815U/ml. The project set up foundation for the further study in the future.