Aroma profile and colour of fresh and processed different species mints

Abstract

Plants of mint genus (lat. Mentha) belongs to the Labiatae family. It is one of the most important aromatic plant in the world. Mint species differ not only by chemical content, usage but also by appearance and volatile compounds. Postharvest mints are extremely sensitive to ethylene-induced senescence there for processing method and conditions are the main factors of mint products quality. The research was carried out at the Aleksandras Stulginskis University, Lithuania, in 2014-2015. The influence of freeze drying on different mints species aroma profile and color was determined. The three species of mints 'Swiss'(Mentha spicata var. 'Swissˈ), 'Apple' (Mentha suavolens Ehrh.) and 'Chocolate' (Mentha x piperita var. ‘Citrata’) were freeze dried. Color of fresh and freeze dried mints was detected by spectrophotometer ColorFlex (Hunter Associates Laboratory Inc., USA) assessing coordinates L*, a*, b*. The chroma (C*) and hue angle (h°) were also calculated. Volatile compounds in mints were analyzed using the Heracles II electronic nose (Alpha M.O.S., Toulouse, France) based on ultrafast gas chromatography. During processing it was observed degradation of photosynthetic pigments (a* value becomes lower by 2.07 NBS units in 'Chocolate') and plants of all mints species become lighter. Processing lead to incensement of yellowness: after processing the lightest and the most yellow mints was 'Swiss' variety and the darkest - 'Chocolate'. It was determined 25 volatile compounds in mints which composition depended on variety as well as on processing.