Effect of Different Drying Methods and Pretreatments on Cyanogenic Glycosides, Calcium Oxalate, and Bioactive Compounds of Arum rupicola Boiss. var. virescens (Stapf) P.C. Boyce

In this study, the effects of vacuum combined infrared radiation (VCIR), microwave (MW), conventional (CV), shade, and sun drying of Arum rupicola Boiss. var. virescens (Stapf) P.C. Boyce leaves were investigated for their effects on the contents of certain compounds, including cyanogenic glycosides and calcium oxalate. Additionally, the effects of ultrasonic (100% amplitude, 10, 20, and 30 min), blanching (90 °C for 5 and 10 min), and freeze-thawing (−18 °C for 16 h) pretreatments on the cyanogenic glycoside and calcium oxalate contents in the samples were also investigated. The drying methods affected the total phenolic, total flavonoid, total chlorophyll, and total carotenoid contents. In addition, the antioxidant activity of these compounds was assessed, with higher activity observed in samples dried using VCIR. The cyanogenic glycoside amount and calcium oxalate raphide crystal sizes decreased compared to the fresh sample. The most effective method for reducing the cyanogenic glycoside content and the raphide crystal size is VCIR among the drying processes and 30 min of ultrasonication among the pretreatments.