Influence of the Drying Method on the Volatile Component Profile of Hypericum perforatum Herb: A HS-SPME-GC/MS Study

Hypericum perforatum L. (St. John’s wort) is one of the most popular medicinal plants in the world. Due to its documented antimicrobial and antioxidant properties, it is used in the treatment of bacterial and viral infections as well as inflammations. It is also used to treat gastrointestinal diseases and mild to moderate depression. In recent years, there has been an increase in the popularity of herbal medicine. Many people collect their own herbs and dry them at home. A common choice for quick drying of fruits, vegetables and herbs at home are food dehydrator machines. There are not many publications in the scientific literature examining the quality of dried herbal material obtained in such dryers. We characterized St. John’s wort harvested in southern Poland and investigated the effect of specific drying methods on the volatile component profile. The herbal raw material was dried using three methods: indoors at room temperature, in an incubator at 37 °C and in a food dehydrator machine. Volatile components were analysed by HS-SPME GC/MS. The herb dried in a food dehydrator, compared to other drying methods, retained similar or slightly smaller amounts of the compounds from the mono- and sesquiterpenes group, aromatic monoterpenes, aromatic monoterpenoids, sesquiterpenoids, aromatic sesquiterpenes and alkanes. However, monoterpenoids and compounds coming from decomposition reactions, such as alcohols, short-chain fatty acids and esters, were noticed in larger quantities. Usage of a food dehydrator at home can be a convenient alternative to drying herbs. However, due to a different profile of volatile components depending on the drying method, the amount of biologically active substances needs to be considered. By using various methods of drying, the medical effects of herbs can be enhanced or weakened; therefore, further research in this direction should be continued.