Objective: To prepare compound amino acid chelated calcium by taking Mactra veneriformis as raw materials. Method: With chelation ratio and calcium content as indexes

based on single factor tests

orthogonal test was adopted to investigate effects of pH

reaction temperature

reaction time and molar ratio of calcium to amino acid on chelating process.Infrared spectroscopy was empolyed to analyze compound amino acid chelated calcium. Result: Optimum conditions was as following:pH of 4.5

reaction temperature of 55 ℃

reaction time of 2 h

molar ratio of calcium to amino acids of 1.5:1.The content of calcium was 79.57 mg·g-1.After coordination of compound amino acid and calcium

characteristic absorption of amino shifted form 3 056.49 cm-1 to 3 245.30 cm-1

characteristic absorption of carbonyl moved from 1 573.53 cm-1 to 1 559.65 cm-1. Conclusion: This chelating process is stable and feasible

reaction product is recognized as an amino acid chelated calcium

which can provide theoretical basis for industrial production of compound amino acid chelated calcium.