The nonvolatile and volatile substances changes based on non-target metabonomics reveals the formation mechanism of Tsamba flavor before and after roasting of highland barley

As the traditional staple food for Tibetan people in northwest China, Tsamba is the main processing product of highland barley and roasting is the key processing step to determine the flavor of Tsamba. In this study, non-targeted metabonomics were employed to analyze the changes of non-volatile and volatile metabolites, as well as active substances, before and after roasting. The active substances in tsamba were significantly increased after roasting. The primary metabolome identified 625 non-volatile components, with lipids having the highest content and amino acids and their derivatives showing the greatest changes before and after roasting. A total of 243 volatile flavor compounds were detected, with heterocyclic compounds, terpenoids, and esters being the main substances that increased after roasting, providing the sweet, green and fruity flavor for Tsamba. Afterwards, 113 main volatile flavor substances were screened from volatile metabolomics data, and 5-ethyl-3-hydroxy-4-methyl-2 (5H) -furanone, 2-ethyl-3, 5-dimethylpyrazine, 2, 3-diethyl-5-methylpyrazin were the key volatile flavor substances. This study will help to reveal the unique flavor source of highland barley Tsamba and promote the standardisation of Tsamba food, which will help to improve the quality of Tsamba production.