Experimental and Mathematical Modeling Study for Solar Drying of Mint

Abstract

Mint plant was dried using greenhouse solar dryer. Two of the forced convection operating modes (continuous and intervals) were used and compared with the open sun drying method. The drying kinetics of mint (Mentha spicata L.) in terms of moisture content, moisture ratio, drying time and drying rate was investigated. The continuous forced convection mode gives the highest drying rate for mint than the interval mode and open sun drying. The drying data of solar and open sun drying of mint were fitted to ten thin layer drying models and the Modified Henderson and Pabis model satisfactorily described the drying behavior of mint with highest R 2 (0.99) and lowest P and RMSE values than other models. The results of the study are very useful for commercial scale drying of mint to optimize the drying process and to achieve a superior quality dried product.INTRODUCTION int leaves can be used as a medicinal and aromatic plant. It helps in colds, flu, fever, poor digestion, food poisoning, rheumatism, motion sickness, hiccups, stings, earaches, flatulence and for throat and sinus ailments (Akpinar, 2010). Because of high moisture content (78-85%, w.b), mint is ordinarily dried for market, in order to slow microbial growth and biodegradation and to reach a final product with an effectively increased shelf life (Tarhan et al., 2010;Sallam et al., 2015). Also, drying brings about a substantial reduction in weight and volume, minimizing packaging, storage, and transportation costs (Doymaz, 2006;Kadam and Samuel, 2006). Drying is the most common method of medicinal plant preservation and due to high investment and energy costs, drying is also a large expense in medicinal plant production.

Thermal Performance of Different Solar Dryers and Application in Jew's Mallow Drying

“…The greenhouse dryer minimizes the shortcomings of the cabinet dryer such as capacity of full load operation, expenditure, and moisture condensation under the glass surface (Kumar et al, 2014). Studying the possibility of using the greenhouse as a solar dryer for some agricultural crops under Egyptian climatic conditions has been investigated by many investigators (Radwan, 2002;Abu-Habaga et al, 2010;Abdellatif et al, 2010;Kishk et al, 2018). Radwan (2002) evaluated a greenhouse solar dryer for drying fresh grapes compared with natural sun drying.…”

“…Solar energy is considered to be an important alternative source of the conventional energy and it is relatively preferred to other sources because it is free, abundant, inexhaustible and non-pollutant in nature compared with higher prices and shortage of fossil fuels (Basunia and Abe, 2001;Santos et al, 2005). The conventional sun drying technique for agricultural products is still used by farmers in most developing countries such as Egypt (Kishk et al, 2018;2019). However, the contamination with foreign particles and insects are some problems associated with this method (Sallam et al, 2015;Sreekumar et al, 2008).…”

The Mathematical Modeling, Diffusivity, Energy, and Enviro-Economic Analysis (MD3E) of an Automatic Solar Dryer for Drying Date Fruits

“…It is critical to eliminate moisture from the product using heat to ensure safe storage, avoid marketing degradation within a set duration, ease processing, and permit product transportation [2,6]. Sun drying is the traditional way of drying agricultural goods in many developing countries, including Egypt, and entails spreading the produce on an open floor or field under the sun for a certain period until the required moisture content is obtained [7][8][9]. However, this approach is prone to contamination by dust, dirt, sand particles, and insects [10,11].…”

“…When compared to typical sun drying methods, solar dryers considerably shorten the drying time, eliminate product losses, and improve product quality. Egypt, with a high yearly daily average solar radiation on a horizontal plane (8 kW/m 2 •day) and average daily sunlight duration (about 11 h), offers enormous potential for using solar energy as an efficient energy source for food drying [7,22]. Drying is an energy-intensive process, with estimates indicating that drying operations account for 10-15% of overall energy needs in industrialized nations' food sectors [23][24][25].…”

“…The mathematical modeling of the drying process under various operating circumstances is critical for creating models that may be used to regulate commercial-scale drying plants and improve the overall product quality [32]. Several mathematical models have been developed to study the drying properties of various products, for example, garlic slices [33], pearl millet [34], tomato [35][36][37][38][39][40], pumpkin slices [41], potato cubes [42], maize seeds [43], galangal [32], paddy grains [44], mint [7,45], onion [46], unbleached kraft pulpboard [47], apple [48], moringa oleifera leaves [2], kodo millet grains and fenugreek seeds [49], sorghum seeds [50], olive [51], black tea [52], and date fruit [53][54][55][56]. When evaluating the applicability of a mathematical model, higher values of R 2 and lower values of χ 2 , RMSE, and E% are generally considered more favorable [57][58][59].…”