The effect of different solvents on the production of rose concrete and rose absolute, experimental study and thermodynamic aspects using the UNIFAC model

Abstract

Rosa damascena Mill. is one of the rosa species that is broadly used for commercial products such as rose concrete and rose absolute. First, the effect of two organic solvents of hexane and ethyl acetate and three alcohols of methanol, ethanol, and 2-propanol were studied on the yield and quality of the rose concrete and rose absolute from air-dried petals of Rosa damascena Mill. Then, a predictive thermodynamic model based on the UNIFAC activity coefficient was employed to predict the composition of rose absolute obtained from the rose concrete. The extraction of rose concrete from dried rose petals was performed at 30 °C by hexane or ethyl acetate, and then the produced rose concrete was combined with an alcohol and the mixture was placed at −18 °C for 48 h to produce rose absolute. Based on the results, the maximum yield of rose absolute was achieved if the extractions were performed with ethyl acetate to extract rose concrete, and ethanol to extract rose absolute. The extracts were analyzed using a GC-MS method to determine the effect of the solvents on the quality of the rose absolute. The most critical constituents detected in the extracts were high-value fragrant components of phenyl ethyl alcohol, citronellol, geraniol, nerol, and farnesol. The results showed that using the pair of hexane and methanol led to achieving a rose absolute with the highest odor value (16,038) but a low extraction yield. Using ethyl acetate and ethanol, the maximum yield of rose absolute was achieved. Finally, the thermodynamic model showed a good agreement in predicting the rose absolute production from the rose concrete with the alcohols.