Studies On Chemical Constituents Of Litchi Fruit Stone (â… )

This dissertation mainly dealt with the extraction and purification conditions of the pigment of litchi fruit stone and its stability. The results obtained laid theoretical foundation for large-scale extraction and purification of the pigment from litchi fruit stone. The contents and varieties of Free Amino Acids in the litchi fruit stone were determined too.The optimum extraction conditions of ethanol extraction were obtained by experiments. The optimum conditions of ethanol extraction were ethanol/water (6:4), extraction time 180 min at 70℃, litchi fruit stone :solvent =1:15. As a result, the yield of the extracted and the color index of the extracted pigment achieved 88.31% and 23.21, respectively.The optimum purification conditions of the pigment by macro-porous resin adsorption were studied. Adsorpting flow rate at 1.5ml/min, running flow rate at 1.0ml/min with 80% ethanol and at the routine temperature. The purificated pigment colourity enhanced by 5 times.The pigment was stable and was not sensitive to light, heat, acid, sucrose, sodium chloride, Mg²⁺, K⁺, Ca²⁺ and so on.Based on the experiment, the pigment structure was analyzed by the chemic experiment and by infrared absorption spectra and ultraviolet absorption spectra. The result showed the brown pigment was phenols.The free amino acids composition of litchi fruit stone was analyzed by Automatic Amino Acids Analyzer .The results showed that there were 15 kinds of amino acids (AA) and 26.9μg/100g total AA determined by water extraction, while there were 14 kinds of AA and 30.7μg/100g total AA determined by ethanol extraction. Four kinds of AA did not identified. The results of color reaction of ninhydrin showed that the content of AA in litchi fruit stone was 35.468μg/100g by water extraction and the other was 40.229μg/100g by ethanol extraction. The analyzing and comparing results supported that the ethanol extraction was the best extraction method.