Peppermint Drying Performance of Contact Dryer in Terms of Product Quality, Energy Consumption, and Drying Duration

Abstract

TurkeyDrying is a commonly used postharvest operation for medicinal and aromatic plants. Their high initial moisture contents, requirement of moderate drying temperatures, and quick deterioration of their quality attributes make their drying processes energy intensive and time consuming. These properties may also cause the dried product to be of heterogeneous quality. A contact dryer that transferred energy to drying plants mainly by heat conduction was developed and tested by mixing or not mixing batches of 15 kg of chopped peppermint plants. The contact dryer had three main operational units: a drying table, a mobile mixing/aeration car, and a control panel. The contact dryer was operated with one of four drying programs. All programs affected the completion duration of drying, essential oil content, and dried product color differently. The shortest drying time (15 h) was obtained using the drying program of gradually increased water temperature from 55-60 to 75-80 C in 6 h and mixing/aeration. However, mixing and aeration changed the product color slightly more and partially increased essential oil loss. These drawbacks can be alleviated by selecting the appropriate duration of mixing and aeration. The menthol and menthone percentages of fresh peppermint essential oil ranged from 31.02 to 34.02% (average value: 32.52%) and 23.23 to 26.47% (average value: 24.85%), respectively. The menthol and menthone percentages of dried peppermint essential oil ranged from 22.74 to 42.07% and from 8.95 to 21.76%, respectively. The significant variations in the essential oil composition of dried peppermint leaves within replications were possibly caused by the variations associated with the age and cutting order of fresh peppermint plants at harvest. INTRODUCTIONDrying has been a widely used preservation method for agricultural materials and foods since ancient times. The success and sustainability of a drying process are controlled by the quality retention of dried products, specific energy consumption, ability to dry different wet materials, and investment=operational cost. [1][2][3] Successful drying processes can be defined as removing unnecessary water from the materials or foods as fast as possible while preserving product quality and minimizing energy consumption. Using alternative energy sources to operate a dryer, reducing the cost of a dryer, and the use of a dryer for various wet materials influence the environmental and economical sustainability of a dryer. A universal dryer with all of the preferred financial, operational, and environmental attributes has not been developed because each material usually requires unique drying conditions and industrial locations around the world face different financial and technologic conditions. Therefore, many types of dryers (over 400) using various drying methods have been developed and used in industry and agriculture. [3] Specific energy consumption, which is the amount of the energy used to remove 1 kg water from a wet material, is used for cost-effective operation of indu...

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“…In contact dryer, the shortest drying time obtained was 15 h for peppermint (Tarhan et al . ). This drying time was 7.5 h for heat pump‐assisted dryer (Fatouh et al .…”

Drying Kinetics, Microstructure and Antioxidant Properties of Basil Treated by Ultrasound

“…Tarhan et al . () noticed the total energy consumption value of 19.21–29.00 kWh for various program of peppermint contact drying. In this research, the drying energy consumption varied from 0.21 ± 0.00 to 0.31 ± 0.01 kWh for the same mass of the material, as Tarhan et al .…”

“…In this research, the drying energy consumption varied from 0.21 ± 0.00 to 0.31 ± 0.01 kWh for the same mass of the material, as Tarhan et al . () used. Preliminary sonication affected the drying energy consumption significantly and allowed to save 9.7–32.3% of energy during the process.…”

“…Tarhan et al (2011) noticed the total energy consumption value of 19.21-29.00 kWh for various program of peppermint contact drying. In this research, the drying energy consumption varied from 0.21 ± 0.00 to 0.31 ± 0.01 kWh for the same mass of the material, as Tarhan et al (2011) used. Preliminary sonication affected the drying energy consumption significantly and allowed to save 9.7-32.3% of energy during the process.…”

“…Generally, microwave radiation during convective drying led to significant decrease in energy consumption (Alibas 2010). Tarhan et al (2011) noticed the total energy consumption value of 19.21-29.00 kWh for various program of peppermint contact drying. In this research, the drying energy consumption varied from 0.21 ± 0.00 to 0.31 ± 0.01 kWh for the same mass of the material, as Tarhan et al (2011) used.…”