摘要
钙作为牛乳中一种重要的营养物质,对人体健康起着至关重要的作用,而且牛乳中钙磷比例协调,易被人体消化吸收。因此,准确分析牛乳中钙的形态并能准确测定牛乳中的各种形态的钙含量显得至关重要。有多种方法测定钙离子,但根据牛乳的流体性质以及牛乳中钙形态的特殊性,采用EDTA络合滴定法较为适宜。本研究对EDTA测定牛乳中钙的方法进行了探讨,并从消化方法、指示剂的选择、NaOH添加量、时间、温度等方面进行了深入探讨,优化并完善了EDTA测定牛乳中不同形态钙的试验测定条件。试验结果表明:牛乳中的钙主要以游离钙和蛋白钙2种状态存在,且存在比例稳定。针对牛乳中钙的特殊存在形态,牛乳中总钙含量的最优测定条件为:在260℃的条件下利用V(HNO3):V(HC lO4)=5:1的混合酸对新鲜牛乳样品进行消化分解4 h,消化后采用EDTA滴定法,在pH=12.0的条件下选用0.5%的液体指示剂对新鲜牛乳进行滴定,此条件为测定牛乳样品钙含量的最优条件。
Calcium is one of the important nutrients in milk. It plays a crucial role in the human health. The ratio of calcium and phosphorus in milk is associated. Therefore, it is very important to be able to accurately analyze the calcium in milk. There are many methods to detect calcium content in milk. But on the basis of the milk＇ s fluid and the calcium＇ s specificity, complex titration with EDTA was the best detection method. The digestion method, the standard solution preparation, the indicator dosage , the amount of NaOH ,time, temperature were discussed. Then the modified method for calcium determination by EDTA titration is proposed. Milk was digested by 5：1 HNO3-HClO4 at 260℃ for 4h. This method saved the reagents and digesting time, the recovery was also high. The best detecting condition was at pH 12.0 with 0.5% liquid indicator.
出处
《食品与发酵工业》
CAS
CSCD
北大核心
2011年第1期137-141,共5页
Food and Fermentation Industries
基金
辽宁省教育厅重点项目(2009A633)
关键词
牛乳
钙
条件优化
形态分析
milk, calcium, condition optimization, speciation analysis
