Analysis on the Changes of Volatile Components and Free Amino Acids in Prunus Salicina Lindl Before and after Fermentation

In order to explore the changes of volatile components and free amino acids before and after Prunus salicina Lindl fermented into enzyme of Prunus salicina Lindl, the volatile components were analyzed by HS-SPME-GC-MS and free amino acids were determined by amino acid analyzer. The fresh Prunus salicina Lindl samples were pitted, homogenized, and ripened, and then fermented with sugar and starter for 3 months to prepare enzyme of Prunus salicina Lindl. The volatile components were extracted by headspace solid phase microextraction, separated on HP-5MS chromatographic column under temperature programmed conditions, determined by MS with EI ion source, and results of qualitative analysis were obtained by mass spectrometry fragment information, retention index, and retention time. LCAK07/Li type standard analysis cation exchange resin was selected as stationary phase. The mixture of three parts of citric acid-lithium citrate buffer solution (pH of 2.90, 4.20 and 8.00) and one part of 0.5 mol·L^-1 lithium hydroxide regeneration solution was used as mobile phase for gradient elution. Free amino acids were determined at 440 nm for proline and 570 nm for the other 30 amino acids, and results of quantitative analysis were obtained by single point external standard method. The results showed that 20 volatile components were added in enzyme of Prunus salicina Lindl, which was the main reason for its strong aroma and the significant improvement of flavor and taste; the total content of free amino acids in enzyme of Prunus salicina Lindl decreased, but types and total content of essential amino acids were increased, and 5 amino acids including taurine, cystine, methionine, 3-methylhistidine, and 1-methylhistidine were newly added.