Analysis of variation of main components during aging process of Shanxi Aged Vinegar

Shanxi aged vinegar (SAV) is the most famous traditional vinegar in northern China. It is produced from several kinds of cereal by spontaneous solid-state fermentation techniques. The distinctive processing techniques such as smoking of the Pei, aging by insolating in summer and taking out ice in winter formed during the long-term production practice have been named as the national intangible cultural heritage. Some research reports about the nutritional composition, flavor compounds of SAV have been published, but there is no report on the changes of main components during aging process in SAV. In this study, the volatile flavor compounds, amino acids, organic acids, trace elements and other conventional ingredients in SAV were examined by headspace solid-phase microextraction gas chromatography-mass spectrometry, automatic amino acid analyzer, high performance liquid chromatography, plasma emission spectroscopy and other modern analytical techniques. The results showed that most conventional ingredients (organic acids, free amino acids, carbohydrates) were increased during aging process. There were 20 different amino acids in SAV, the concentration of total amino acids reached 19.73 mgxmL^–1 in eight-year-old vinegar. There were 8 different organic acids in SAV, and acetic acid and lactic acid were main organic acids. A total of 58 different flavor compounds were detected in SAV. The results of this study can help us to understand the class and concentration of main components in SAV, and provide data for manufacturers to improve production process and product quality.