全脂奶粉中的两种自由基。乳糖结晶、脂质氧化和褐变反应的影响。
Two types of radicals in whole milk powder. Effect of lactose crystallization, lipid oxidation, and browning reactions.
作者信息
Thomsen Marianne K, Lauridsen Lene, Skibsted Leif H, Risbo Jens
机构信息
Department of Food Science, Food Chemistry, Royal Veterinary and Agricultural University, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark.
出版信息
J Agric Food Chem. 2005 Mar 9;53(5):1805-11. doi: 10.1021/jf0485483.
Whole milk powder was stored in closed vials at 60 degrees C to induce crystallization of lactose within a short time scale. After an induction period of 3-4 days simultaneous crystallization of lactose, increase of water activity, formation of browning products, and increase of radical content took place. Radicals detected before lactose crystallization were characterized by a narrow ESR spectrum (g = 2.006) and could be depleted by removal of oxygen and therefore were assigned to oxidation processes. Late-stage radicals present after crystallization of lactose gave much wider spectra (g = 2.0048) and were independent of oxygen availability and assigned to late-stage Maillard reaction products. The study indicates that the processes of lactose crystallization, browning, and formation of radical species (g = 2.0048) are strongly coupled, while lipid oxidation is less dependent on the other processes.
全脂奶粉在60摄氏度下储存在密闭小瓶中，以便在短时间内诱导乳糖结晶。经过3 - 4天的诱导期后，乳糖同时结晶、水分活度增加、褐变产物形成以及自由基含量增加。在乳糖结晶之前检测到的自由基具有狭窄的电子自旋共振光谱（g = 2.006），并且可以通过去除氧气而减少，因此被归因于氧化过程。乳糖结晶后出现的后期自由基给出更宽的光谱（g = 2.0048），并且与氧气供应无关，被归因于后期美拉德反应产物。该研究表明，乳糖结晶、褐变和自由基物种形成（g = 2.0048）的过程紧密耦合，而脂质氧化对其他过程的依赖性较小。
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