| Microelement amino acid chelates with good stability, high bioavailability, anti- interference, and alleviate minerals between antagonism competition effect, which is suitable for absorption mechanism and characteristic of human body, and play a dual role of adding trace elements and amino acids. Chelate of glutamic acid and ferrous salt, combination of essential trace elements in human body, has good physical, chemical properties and biological activity. It is a new type of high efficient trace element additive, flavor, bacteriostasis, supplement nutrition. Ferrous glutamate was prepared by ferrous chloride and sodium glutamate as raw material in the solid- liquid phase method, which has anion less interference, high purity, good stability and good taste.By single factor experiment, the suitable synthetic conditions were determined: the reaction system p H was 6.0, the reaction time was 1 h, the reaction temperature was 60 ℃, and the molar ratio of reactant was 1:1. Using ethanol, the method of organic solvent precipitation product, made ferrous glutamate in the form of precipitation in ethanol, which implemented the chelate iron and inorganic iron separation. O n this condit ion, the ferrous content of ferrous glutamate was 23.55%, the yield was 80.6%. Analysis of the composition and the physical and chemical properties were determined. The stability test results showed that the stability of ferrous glutamate was significantly better than that of ferrous chloride; the ultraviolet spectroscopy and infrared spectrum scanning results showed that the ferrous ion chelate reacted with hydroxyl O and amino N of glutamic acid; The DSC thermal analysis and thermogravimetric analysis res ults showed that the ferrous glutamate with two crystal water.Using spectrophotometry to measure composition and stability constant of ferrous glutamate, the results showed that the coordination reaction of glutamic acid and ferrous ions was 1:1; stability constant was 4.8×104, which is beneficial to the body’s absorption of iron. Basis on the results of single factor level determination and composition determination, p H, temperature and reaction time were chosen as the factors and the yield as the response value in RSA. The results showed that the optimal condition of the preparation were as follows : molar ratio of C5H9NO4 to Fe2+ was 1:1, the p H was 5.76, the reaction temperature was 58.9℃, the reaction time was 0.75 h, the product yield was 77.64%, the chemical formula of the ferrous glutamate was Fe(C5H7NO4)·2H2O.In order to explore the anti-bacterial effects of ferrous glutamate on food spoilage bacteria, the anti- microbial activity of the ferrous glutamate was examined in vitro against Staphylococcus aureus, Bacillus cereus, Escherichia coli, Salmonella paratyphi, Bacillus subtilis, Proteus vulgaris, and Pseudomonas aeruginosa in terms of inhibition zone diameter, MIC(minimum inhibitory concentration) and MBC(minimal bactericidal concentration).The results showed that the mass concentration of 7.50 mg/m L of ferrous glutamate solution(p H=5.13) for all kinds of food spoilage organisms has obvious inhibitory effect, the inhibition zone diameter was larger than 12 mm. Bacteriostatic activity: Staphylococcus aureus>Bacillus cereus>Salmonella paratyphi>Escherichia coli>Bacillus subtilis>Proteus vulgaris>Pseudomonas aeruginosa. The minimum inhibitory concentration was 1.00~4.00 mg/m L, the minimal bactericidal concentration was 1.00~4.00 mg/m L. Under the acidic condition, the anti-bacterial effects of ferrous glutamate were obvious, the anti- microbial activity was falling with the increasing of p H. Added the ferrous glutamate to the two kinds of soy sauce of not added preservatives, the anti-bacterial effects of soy sauce of Xiang Man Yuan was better than that of Dong GU. Ferrous glutamate is expected to be applied in soy sauce preservation and iron- fortified. |
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