Study On The Pulsed Electric Field Assisted Preperation Of Amino-Acid-Cu And Its Properties

The aim of the study was to investigate the effect of pulsed electric fields (PEF)on the reaction between amino acids and copper sulfate, in order to modify thepreparation of Cu-AA. Tryptophan was selected to investigate the effect of PEF on asingle amino acid. Based on this, PEF was applied in the preparation of amino acidand copper chelates, using glycine, lysine and methionine and copper sulfate as rawmaterial. Furthermore, the chemical structure was presented to show the difference ofPEF treated and untreated products. Stability of various products was alsoinvestigated through the determination of stability constant as well as its chelation rate.Detail research contents were as following.The results showed that with the increase of PEF intensity and pulse number, thesolubility of L-tryptophan was gradually increased reaching its peak at40kV/cm,followed by a slight decrease. Conductivity and pH value were generally increased,with a very limited degree, while the surface tension was decreased slowly, and adrastic decrease was observed after40kV/cm. The increase in pulse number causedred shift of2~4nm in the fluorescence spectra of L-tryptophan, and the maximumrelative fluorescence value was increased and then decreased, all are in closeagreement with the solubility results. Which indicated that the solubility was modifiedand PEF treated L-tryptophan got better quality.Glycine and copper sulfate was mixed and reacted in the aqueous solution. Thecontent of glycine copper chelate was determined using EDTA titration. It was foundthat factors influencing the yield are: the mole ratio of amino acid and copper sulfate,temperature, and pH value. PEF was applied to the optimum original method toobserve its effect. Results showed that when the mole ratio was2:1, pH at7.0and at50oC, when applying PEF, the yield was the biggest. And also with the increase of thePEF intensity, the reaction was more fast and complete. In addition, the chemicalstructure was more stable.Several properties of PEF treated and untreated amino acid copper chelates wereinvestigated, including the molar conductivity, stability constant as well as the storing stability under different temperatures. Using data of pH, conductivity and chelationrate in0-60days, the stability of each product was evaluated. The results showed thatthe products are molecular compound and were more stable after PEF treatment.During storage, the chelation rate decreased with time since chelation reaction isreversible, however, the product prepared with the aid of PEF showed better stabilityand decomposed more slowly.Finally, FITR and X-ray was applied to detect the structure of PEF treated anduntreated chelation products, results showed that the chemical bond between copperions and oxygen atoms are more strong, indicating that PEF is an efficient methodthat could be used in the preparation of amino acid copper chelates with better quality.