Investigation on drying behavior of Isparta rose flowers (Rosa damascena mill.) under natural shade conditions

A. K. Bayhan, E. Dikmen, S. Boyar

Abstract: The present study was carried out to determine drying characteristics of Isparta Rose (Rosa damascena Mill.) under natural shade conditions. Four experiments were conducted during the rose flower harvest session. Fresh rose flowers, harvested between 13th May and 11th June 2010. A naturally ventilated storage building was modified into an ideal ambience for shaded natural drying and designed trays with shelves were used for drying. For the drying process 1000±1 g samples were laid onto each shelf. During the experiments, indoor and outside climate conditions such as temperature, humidity and weight loss and drying time were continuously recorded. The moisture content (MC), moisture ratio (MR) and drying rate were calculated. Those data correlated with 13 different drying rate kinetic models. The initial average moisture content of the rose flowers was 79.6±2.32% w.b. After drying, the product with an average weight of 214.1±24.6 g and with a final average moisture content of 7.11±0.83% w.b. was obtained. Drying time varied between 72-162 h (3-7 day) depending on the climatic conditions. Models developed by Bala (1998) and Verma et al. (1985) were found to be the most suitable for describing the drying curve of the Isparta Rose with r2 of 1.00 and 0.99, χ2 of 0.000023 and 0.001813 and RMSE of 4.6x10-12 and 0.038388, respectively. As a result, during the natural shaded drying process it is seen that rose flower has hygroscopic characteristics. Rose flower is highly affected by air temperature and humidity during drying. For this reason, the drying process must be conducted properly in a short period.

Keywords: drying model; drying rate; isparta rose (rose damascena mill.); moisture ratio; natural drying

Date published: 2019-03-25