Volatile compounds, bioactive properties and chlorophylls contents in dried spearmint (Mentha spicata L.) as affected by different drying method

This study presents a comparison of the quality characteristics of spearmint (Mentha spicata L.) dried by a photovoltaic thermal dryer (PDS), the shade (SDS), and an oven (ODS). The samples obtained were evaluated with respect to volatile compounds (VC), total phenolic (TPC) and flavonoid content (TFC), antioxidant capacity (AC) and chlorophyll contents. PDS had the highest amount of TPC, TFC and AC, while SDS and ODS did not differ significantly from each other concerning the values of these features. SDS exhibited the highest chlorophylls a (Chl a) and b (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 typical aroma spearmint in SDS was higher than that of the other, while the concentrations of most of VC in ODS were the lowest. The results show that the photovoltaic thermal dryer (PVT) can be recommended for spearmints drying.