الفهرس 
Abstract
Medicinal and aromatic plantsOnly 14 pages are availabe for public view
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Abstract
Objectives: The main goal of this research work was to describe the drying behavior of mint leaves and pot marigold whole flower and petals through controlled air temperature and relative humidity using a laboratory scale dryer, in which forced heated air at constant temperature and relative humidity may be used to remove the excess moisture from the studied plants and to study the effect of both air temperature and relative humidity on the drying process of the studied plants and evaluate the quality changes of the final products. This work also aim to test and evaluate three different empirical drying models for describing the drying behavior of mint leaves and pot marigold flowers and petals in thin laye.Methods & Results: To achieve the objective of the present study, a laboratory scale dryer with controlled air temperature and relative humidity was used at the laboratory of Agricultural Processing Engineering (Agric. Eng. Dept. Fac. of Agric. Mansoura Univ). The laboratory experiments were conducted at four different levels of drying air temperature (50, 55, 60 and 65 ⁰C), four different levels of air relative humidity (25, 30, 35 and 40%) and a constant air velocity of (0.23 m/sec) were used for mint leaves drying during the mint harvesting season (2014). While, four different levels of air temperature (55, 60, 65 and 70°C), three different levels of air relative humidity (40, 50 and 60%) and a constant air velocity of (0.6 m/sec) were used for drying both pot marigold whole flowers and petals during the pot marigold harvesting season (2013). The obtained results revealed that: 1- The reduction in mint leaves and pot marigold flowers and petals moisture content was varied and increased with the increase of drying air temperature while it was decreased with the increase of air relative humidity. 2- No constant drying rate period was detected for all studied levels of drying air temperature and relative humidity while all the drying process occurred at a falling rate, the final moisture content of all the studied plants was decreased with increasing of drying air temperature while it was increased with the increase of air relative humidity. 3- All the drying constants of the three models affected by the drying air temperature and relative humidity. Conclusion: 1- The drying air temperature of 50oC and air relative humidity of 25% are recommended for drying and keeping the final quality of the dried mint leaves. 2- The drying air temperature of 70°C and 40% (RH) are recommended for drying both pot marigold whole flowers and petals and keeping the total carotenoids content. However, it should be mentioned that, for obtaining higher content of total carotenoids with shorter drying time, pot marigold petals drying is recommended. 3- Page’s model could be considered the more proper model for describing the drying behavior of mint leaves and pot marigold whole flowers and petals.