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Yan Z.,Beijing Technology and Business University | Yang R.,Beijing Technology and Business University | Li X.,Beijing Technology and Business University | Li X.,Beijing Key Laboratory of Flavor Chemistry
Journal of Chinese Institute of Food Science and Technology | Year: 2013

In recent years, with the development of molecular biology and the deepening of study on cloning expression, the exogenous gene expression systems are being further researched. Microbial expression systems have many advantages, such as simple culture, short period and low cost. Up to now, several relatively mature expression systems have been set up. Such as Escherichia coli expression system, Bacillus subtilis expression system, yeast expression system and Filamentous fungal expression system. These expression systems are the important foundation for proteinic production and research. This paper reviews the characteristics of the above expression systems, the influencing factors on high level expression and their current application. Source


Liu Y.,Beijing Technology and Business University | Miao Z.,Beijing Technology and Business University | Guan W.,Beijing Technology and Business University | Sun B.,Beijing Key Laboratory of Flavor Chemistry
Molecules | Year: 2012

The organic volatile flavor compounds in fermented stinky tofu (FST) were studied using SPME-GC/MS. A total of 39 volatile compounds were identified, including nine esters, seven alcohols, five alkenes, four sulfides, three heterocycles, three carboxylic acids, three ketones, two aldehydes, one phenol, one amine and one ether. These compounds were determined by MS, and conformed by comparison of the retention times of the separated constituents with those of authentic samples and by comparison of retention indexes (RIs) of separated constituents with the RIs reported in the literature. The predominant volatile compound in FST was indole, followed by dimethyl trisulfide, phenol, dimethyl disulfide and dimethyl tetrasulfide. In order to find a better extraction time, the extraction times was optimized for each type of SPME fiber; the results show that the best extraction time for Carboxen/PDMS is 60 min, for PDMS/DVB 30 min, for DVB/CAR/PDMS 60 min and for PDMS 75 min. Of the four fibers used in this work, Carboxen/PDMS is found to be the most suitable to extract the organic volatile flavor compounds in fermented stinky tofu. © 2012 by the authors. Source


Liu Y.,Beijing Technology and Business University | Guan W.,Beijing Technology and Business University | Miao Z.,Beijing Technology and Business University | Sun B.,Beijing Key Laboratory of Flavor Chemistry
Advanced Materials Research | Year: 2012

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. Source


Li X.,Beijing Technology and Business University | Li E.,Beijing Technology and Business University | Zhu Y.,Beijing Technology and Business University | Teng C.,Beijing Technology and Business University | And 4 more authors.
Carbohydrate Research | Year: 2012

The activity of the extracellular xylanase produced by Streptomyces rameus L2001 against different xylans and xylooligosaccharides (XOS) was investigated. The main products of hydrolysis of birchwood xylan and oat-spelt xylan by the S. rameus L2001 xylanase were xylobiose (X2) and xylotriose (X3), suggesting that this is an endo-acting xylanase. This was confirmed by analysis of XOS degradation products. The enzyme hardly hydrolyzed X2 and X3, but hydrolyzed xylotetraose (X4) and xylopentaose (X5) producing mainly X2 and X3 through transglycosylation. Depending on the substrate, different quantities of reducing sugars were produced by the xylanase: 150 mg/g from corncob, 105 mg/g from bean culms, and 133 mg/g from bagasse. With the bagasse substrate, the xylanase yielded 2.36, 2.76, 2.03, and 2.17 mg/mL of X2, X3, X4, and X5, respectively. The structure of xylobiose and xylotriose from the hydrolysis of corncob xylan was identified by MS and NMR. The production of XOS from various agricultural wastes has potential industrial applications. This is the first report of XOS production by S. rameus L2001. © 2012 Elsevier Ltd. All rights reserved. Source


Zhu Y.P.,Beijing Technology and Business University | Teng C.,Beijing Technology and Business University | Sun B.G.,Beijing Technology and Business University | Sun B.G.,Beijing Key Laboratory of Flavor Chemistry
Food and Bioproducts Processing | Year: 2013

The strain Bacillus subtilis B2 isolated from a Chinese traditionally fermented food was capable of producing α-glucosidase inhibitor (AGI). On the basis of single-factor experiments, the optimum culture conditions using okara as the substrate were achieved by response surface methodology (RSM). The experimental results lead to the conclusion that the highest yield of AGI was reached at the fermentation time 65.6 h, fermentation temperature 39.0°C, Okara concentration 4.5% and pH 7.11. A second-order model developed for the production of AGI prediction exhibits a F-value of 15.8 and a high value for the coefficient of determination (R2 = 0.933). Under these conditions, the AGI activity of the broth reached 29.4. In comparison with the highest AGI activity (24.3) obtained at the one-factor-at-a-time fermentation condition, the AGI activity increased by 21%. The AGI in the fermentation broth of B. subtilis B2 was also partially purified and determined by HPLC-ELSD. One of effective AGI, deoxynojirimycin (DNJ) has been proved in the fermentation broth, which indicated that the fermented okara might be considered as one of the promising materials for producing the food-derived DNJ products. © 2012 The Institution of Chemical Engineers. Source

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