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Li C.,Northeast Agricultural University | Wang M.,Northeast Agricultural University | Qi X.,Northeast Agricultural University | Sun J.,Northeast Agricultural University | And 3 more authors.
Journal of Chinese Institute of Food Science and Technology | Year: 2015

The fermentation technique for sialic acid production has attracted more and more attention due to a lower price of raw material and a higher recovery rate of sialic acid for stable quality, which can be easily applicated in continuous production. The aim of our study is to investigate the effect of different content of sodium pyruvate, precusor substance, on ferment of Escherichia coli K235 to produce sialic acid and further improve the yield of end-product by combining with fed-batch fermentation. Sialic acid concentration and dry cell weight are used for parameters, the optimized quantity of sodium pyruvate and the optimized feeding period was confirmed by single factor experiment method and one-time feeding, respectively. Experimental results showed that adding 4 g/L of sodium pyruvate at the beginning of fermentation and using flask-3-neck simulate fermentor, sialic acid yield reached to 4.10 g/L after acid hydrolysis of fermentation production was performed. 3.7 L automatic biological fermentation tank used to further confirme the final yield of sialic acid can reach to 5.24 g/L, increasing by 146% as compared with fermentation production without sodium pyruvate. Sodium pyruvate combined with one-time feeding culture in at 8 h, sialic acid yield reached to 6.47 g/L in fermentation tank, increasing by 23.5% as compared with adding sodium pyruvate in single batch fermentation. ©, 2015, Chinese Institute of Food Science and Technology. All right reserved. Source


Wang C.,Heilongjiang Dairy Industry Technical Development Center | Wang C.,Northeast Agricultural University | Li M.,Heilongjiang Dairy Industry Technical Development Center | Liu N.,Heilongjiang Dairy Industry Technical Development Center | Liu N.,Northeast Agricultural University
Journal of Chinese Institute of Food Science and Technology | Year: 2015

This research studies on the tertiary structure of human β-Casein by using Small-angle X-ray Scattering and Structure Prediction, and then analysed its physiological functions. By using DEAE Sepharose FAST Flow agarose gel to get the Human β-Casein that their purity higher than 90%, and then analysed the solution (0.2 mol/L phosphate buffer, 10 mmol DTT, pH 6.7) through Small-angle X-ray Scattering. Comparing the structure information of Human β-Casein and the prediction models of fold recognition and ab initio, selected the model that was the most closed with the result of the experiment. This model is loosely in structure, containing less a helices and β fold. At the same time, we also had a brief analysis on the phosphorylation, glycosylation and Lipidated protein functional sites of Human β-Casein that comparing with the model. We thought there were 12 glycosylation sites that may combine with lactose and glucose and 7 lipidated sites in the Human β-Casein molecular. Its phosphorylation sites matched with five known phosphorylation sites. © 2015, Chinese Institute of Food Science and Technology. All right reserved. Source


Sun C.,Northeast Agricultural University | Sun C.,Heilongjiang Dairy Industry Technical Development Center | Li D.,Northeast Forestry University | Liu Q.,Northeast Agricultural University | Kong B.,Northeast Agricultural University
Asian Journal of Chemistry | Year: 2013

This study was conducted to investigate the antioxidant activity of whey protein hydrolyzate by conjugation with glucosylation. The reaction conditions of whey protein hydrolyzates conjugated with glucose were optimized with the response surface methodology using the central composite rotatable design. The optimisation parameters studied were glucose concentration 8 %, temperature 94 °C and reaction time 3.2 h. Under this optimum condition, the reducing power, hydroxyl radical scavenging activity, scavenging of the ABTS radical, copper and iron chelating, thiobarbituric acid-reactive substances of whey protein hydrolyzates by conjugation with glucose through Maillard reaction are higher than whey protein hydrolyzates. The result showed that whey protein hydrolyzates by conjugation with glucose had high antioxidant activities. Source

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