Effect of water activity, temperature and pH on solid state lactosylation of ¦Â-lactoglobulin

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• 作者：Marianne K. Thomsen ; Karsten Olsen ; Jeanette Otte ; Kirsten Sjø ; strø ; m ; Birgit B. Werner ; Leif H. Skibsted ; ^{ls@life.ku.dk}
• 刊名：International Dairy Journal
• 出版年：2012
• 出版时间：March 2012
• 年：2012
• 卷：23
• 期：1
• 页码：1-8
• 全文大小：335 K

文摘

Glycation of whey proteins leads to changes of the nutritional and functional properties of the proteins. Lactosylation of ¦Â-lactoglobulin was monitored under conditions varying with respect to temperature, water activity (a_w), and pH. The rate of the overall lactosylation and the average lactosylation degree increased with temperature (50-70?¡ãC) and a_w of 0.51-0.64, but were only slightly affected by reaction mixture pH (pH?5-7) before drying. The reaction seemed to occur in two phases, the transition between which was related to a lowering of the glass transition temperature of the system. Detailed kinetic analysis of the initial step showed that the pseudo first-order rate constants for formation of mono-lactosylated ¦Â-lactoglobulin in general were higher than the rate constants for formation of di-lactosylated ¦Â-lactoglobulin. However, the temperature dependencies of the two reaction steps were similar, corresponding to an activation energy of about 100?kJ?mol^?.