Comparative analysis of volatile compounds and functional components in fresh and dried monk fruit (Siraitia grosvenorii)

Monk fruit (Siraitia grosvenorii) is a medicinal and edible plant that is often used to prepare tea and alleviate coughs in China. Most of the S. grosvenorii available on the market is dried. However, the drying process affects the composition and content of the chemical components in the plants. To date, there have been few studies that have compared the chemical composition in fresh and dried S. grosvenorii. The chemical composition of fresh and dried plant tissue was analyzed using gas chromatography-mass spectrometry, high-performance liquid chromatography, and spectrophotometry, and their statistical differences were compared. The effect of altitude on the chemical composition of S. grosvenorii was also studied. The volatile compounds in both fresh and dried S. grosvenorii primarily consisted of alkanes, alkenes, organic acids, and aldehydes, which accounted for 93.62 % and 87.64 % of the volatiles in fresh and dried S. grosvenorii tissues, respectively. The most abundant volatile compound was n-hexadecanoic acid (fresh: 31.73 %, dried: 37.49 %). After hot air drying, the contents of alkanes, alkenes, esters, and alcohols increased by 5.76 %, 2.68 %, 2.35 %, and 2.96 %, respectively, whereas the contents of aldehydes decreased by 13.94 %. Compared with fresh S. grosvenorii, the levels of mogroside V, vitamin C, protein, fructose, and glucose in the dried tissue of this plant decreased significantly by 13.13 %, 100.0 %, 46.31 %, 40.39 %, and 75.07 %, respectively, while the contents of total phenolics, total flavones, total flavonols, and sucrose increased significantly by 144.9 %, 84.94 %,142.1 %, and 128.0 %, respectively. The contents of fructose and glucose significantly positively correlated with altitude.