Effect of different drying methods on drying characteristics of gerbera flowers

Abstract

Fresh flowers, through exquisite in their beauty, but have short life due to their highly perishable nature. The charm of flowers can be maintained and preserve for several years by employing the technology of drying. Dried flowers can be put to many beautiful and varied uses. The principle behind preservation of flowers by drying is based on quickly reducing moisture content of flowers to a point at which biochemical changes can be minimized or brought to a standstill while maintaining cell structure, petal pigment level and shape of flower. The different flowers required suitable drying method with appropriate drying parameters according to their foliage characteristics. Moreover, the dried flowers should retained their colour, shape, texture and dry matter. Gerbera (Gerbera jamesonii Bolus ex Hook.F) belongs to the family of Asteraceae, is most commonly used world wide as a cut flower and occupies fourth position among the top ten cut flowers. The gerbera flowers, were dried by employing different drying methods such as hot air drying at 40, 50 and 60 °C, microwave oven drying with silica gel at 50 °C, vacuum drying at 40 °C and 760 mm Hg pressure besides solar and shade drying to find out the most suitable method and drying parameters for drying. The Exponential and Page's model were tested for their validity to gerbera flowers drying. The results were drawn from drying behaviour and statistical analysis. he maximum and minimum drying time for rose flowers was observed as 5 days and 13 minutes during shade and microwave oven drying respectively. While in case of gerbera ^°C flowers the maximum and minimum drying time was found as 5 days and 25 minutes during shade and microwave oven drying respectively. The drying of both the flowers under all the treatments completely took place in the falling rate period. The drying behaviour was predicated reasonably by Exponential and Page's model. Though, from the value of coefficient of variations the Page's model was found to be best fitted. The maximum over all drying rate was found during microwave oven drying with silica gel at 50 °C which was 3.2164 %/min respectively followed by vacuum drying at 40 °C, while minimum overall drying rate was observed during shade drying. From the drying characteristics, microwave oven drying with silica gel at 50 °C followed by vacuum drying at 40 °C was found reasonably good method for quality dried produce of rose and gerbera flowers.