Obtaining cumin (Cuminum Cymminum) essential oils by steam distillation. Part I: investigation of operation parameters on essential oil yield and distribution of oil composition

BACKGROUND The effect of pretreatment (grinding), packing material (raschig rings) and vacuum on the yield and the component distribution of the essential oil of cumin during steam distillation was investigated. Concurrently, kinetic studies were conducted to examine the essential oil yield. RESULTS At the end of 120 min, the yield under normal conditions was 0.79, 1.26, 1.90 and 2.36 for nonground and 20‐, 40‐ and 80‐s ground cumin seeds, respectively. Equivalent figures in a vacuum were 0.64, 1.56 and 1.95 for nonground, 40‐ and 80‐s ground cumin seeds, respectively. When raschig rings were used, the yield value was 1.99 and 2.06 under normal and vacuum conditions, respectively, for cumin seeds ground for 80 s. Under normal conditions, the cumin aldehyde percentages of the nonground sample, and the 40‐ and 80‐s ground samples was 51.31, 33.59 and 32.54, respectively, and under vacuum, 70.00, 49.02 and 40.59, respectively. Six kinetic models were applied with sufficient R2 values. Drug release models were first applied to kinetic data successfully. Conclusion Grinding cumin seeds in a blender increased the essential oil yield up to three‐fold and Raschig rings as a packing material also contributed to this increase. The effect of complex mechanisms such as sample positioning and flow regime on the essential oil yield during the washing stage was observed. Although there was minimal difference (3.8%) in the yield values for the experiments with nonground cumin samples, the slight variation in essential oil yield observed in the experiments with each ground cumin sample may be attributed to the particle distribution, positioning and flow regime. So, five cases were determined depending on positioning. Cumin aldehyde has the highest composition in all time intervals after 10 min at the fractional distillation under vacuum. However sabinene was relatively higher only in the early time interval at 0‐10 min. © 2023 The Authors. Journal of Chemical Technology and Biotechnology published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry (SCI).