鸡蛋壳低温直接制备柠檬酸钙

Direct Preparation of Calcium Citrate as a Food Additive Using Eggshells at Lower Temperature

运用容量分析的方法测定出脱膜后的鸡蛋壳中含有93.5%的碳酸钙。将鸡蛋壳洗涤后用氢氧化钠水溶液脱去内膜,干燥后磨成粉末,然后与柠檬酸溶液直接反应,在较低温度下,可以有效地生成食品添加剂柠檬酸钙。鸡蛋壳脱膜的最佳条件是,氢氧化钠水溶液的浓度为5.5%(质量分数),脱膜温度为95℃,经15min时间,蛋壳基本完全脱膜。柠檬酸钙的生成反应条件为,蛋壳粉的细度为300目,反应温度为65℃,柠檬酸过量25%,柠檬酸溶液的浓度为20%,柠檬酸钙的最高产率可以达到99%以上。

There was about 93.5 % of calcium carbonate in the eggshell without membrane determined by volumetric analysis.Inner eggshell membrane was separated from washed eggshell using solution of sodium hydroxide.Dry eggshell without membrane was ground into powder,and then react directly with the solution of citric acid,the calcium citrate as a food additive can be formed efficiently at lower temperature.The optimum conditions for taking off inner membrane from eggshell can be regarded as following,the concentration of solution of sodium hydroxide should be taken as 5.5 %（wt）,the temperature for taking off inner membrane was chosen at 95 ℃ ,the inner eggshell membrane can be taken off completely within 15 minutes.The eggshell powder with particle size of 300 meshes reacted with solution of 20 % of citric acid at 65 ℃,an excess of 25 % of citric acid was used in the reaction,under such circumstances,the 99 % or more of calcium citrate as the maximum rate of resultant formation was achieved.