Impact of post-harvest drying on the volatile flavours of spiny coriander (Eryngium foetidum L.): Emphasis on fatty aldehyde reduction

Spiny coriander (Eryngium foetidum L.) is a traditional food flavouring herb of tropics with coriander-like odour. This study evaluated six different drying conditions (sun, shade, oven at 40°C and 60°C, microwave, freeze-drying) for spiny coriander leaves, emphasizing on the drying time, essential oil yield and composition. Fatty aldehydes, especially trans-2-dodecenal, majorly abundant key aromatic flavour of spiny coriander underwent probable enzymatic reduction to alcohols upon long-term oven-drying, affecting the oil quality. Non-conventional techniques like microwave and freeze-drying, despite their certain advantages significantly reduced the oil yield (0.030%–0.031%) in comparison to fresh leaves (0.045%). Sun drying was found to be superior among the tested conditions, considering a reasonable drying time (4 h) and ability to retain the oil yield (0.043%), composition (quality) and chlorophyll content. It can be a sustainable drying technique for spiny coriander in the tropical region with abundant sunlight, especially for its value addition and commercialization in future.