Volatile Compounds, Bioactive Properties and Chlorophylls Contents in Dried Spearmint (Mentha spicata L.) as Affected by Different Drying Methods

This study presents a comparison of the quality characteristics of spearmint (Mentha spicata L.) dried by a photovoltaic thermal dryer (PVT), the shade dried spearmint (SDS), and an oven dried spearmint (ODS). The obtained samples were evaluated with respect to volatile compounds (VC), total phenolic content (TPC) and flavonoid content (TFC), antioxidant capacity (AC) and chlorophylls (Chl) contents. PDS had the highest amount of TPC, TFC and AC, while SDS and ODS did not differ significantly from each other in terms of these features. SDS exhibited the highest Chl a and Chl b contents, whereas ODS showed the lowest. The composition of VC in the dried spearmints was significantly affected by the drying methods used. The total amount of terpenoids, especially carvone, responsible for spearmint's characteristic aroma in SDS was higher than those of the others, while the concentrations of most VC were lowest in ODS. According to the results, the PVT can be recommended for drying spearmint.