DESIGN, CONSTRUCTION AND PERFORMANCE EVALUATION OF A SOLAR DRYING UNIT OF BASIL LEAVES

Imbabi, A. T.; Abdel-Galil, H. S.; Abdel-Kader, T. KH.

doi:10.21608/mjae.2016.98159

DESIGN, CONSTRUCTION AND PERFORMANCE EVALUATION OF A SOLAR DRYING UNIT OF BASIL LEAVES

Document Type : Original Article

Authors

¹ Prof., Agric. Eng.; Fac. of Agric. Fayoum Univ., Egypt.

² Assist. Prof. ; Agric. Eng.; Fac. of Agric. Fayoum Univ., Egypt.

³ Post Graduate Student of Agric. Eng.; Fac. of Ag. Fayoum Univ., Egypt.

10.21608/mjae.2016.98159

Abstract

Two similar solar drying units were designed, constructed and evaluated for drying basil leaves (Ocimum basilicum L.) as a medicinal and aromatic plant at initial moisture content of 590.73% (d.b) or 85.52% (w.b) under Fayoum conditions by using heated air. Each drying unit consists of a flat-plate solar collector, which oriented and tilted with an optimum tilt angle and attached with drying chamber. The drying experiments were carried out to examine the effect of basil leaves thicknesses (2, 4 and 6 cm) and airflow rate (0.015 and 0.025 m³.sec^-1) on the basil leaves drying rate. The obtained results indicated that the daily average total solar radiation flux incident on the tilted solar collector surface (29.30 MJ. m^-2.day^-1) was greater than that incident on the horizontal surface (24.30 MJ.m^-2.day^-1) by 24.58%. The output higher air temperatures were obtained at the lower airflow rate whereas; the energy gained to the air from the solar collector was relatively higher at the higher airflow rate as compared with the lower airflow rate. Consequently, the solar collector with the higher airflow rate increased the overall thermal efficiency by 5.46% as compared to the lower airflow rate. The moisture content of dried basil leaves was strongly affected by the basil leaves thickness and the airflow rate. The final moisture content of dried basil leaves ranged from (11.52% to 14.58% d.b) depending on the drying temperature cycle. Very small changes were observed in the colour and shape of heated-air dried basil leaves as compared to that dried at direct sun rays. The essential oil contents of dried basil leaves were slightly higher for the drying unit with the higher airflow rate as compared with the corresponding values obtained from the drying unit with the lower airflow at all basil leaves thicknesses.
While on Contrast, total chlorophylls contents were slightly higher for the drying unit with the lower airflow rate as compared with the corresponding values obtained from the drying unit with the higher airflow at all basil leaves thicknesses. Effect of the individual variables (airflow rate, basil leaves thickness, moisture removed, and their interactions) on the drying rate was statistically analyzed. Under the conditions of this study, the optimum depth to dry basil leaves by using heated air is 4 cm.

References

Abdel-Galil, H. S. and Tarhuni, M. M. (2005). Solar Drying of Medicinal Plants under Libyan Conditions, Misr J. Agric. Eng., 22(4): 171-191.

Abdel-Galil, H. S. and El-Nakib, A. A. (2008). Effect of natural convection solar drying on quality of peppermint. The 15^th Conference of the Misr Society of Agric. Eng., 12-13 March 2008. Pp: 513 – 534.

Arafa, G. K. (2007). Optimum drying conditions for thin-layer drying of sweet basil. Misr J. Ag. Eng., 24(3): 540- 556.

Banout, J; Havlik, J.; Kulik, M.; Kloucek, P.; Lojka B, and Valterov, I. (2010). Effect of solar drying on the composition of essential oil of sacha cilantro (Eryngium foetidum L.) grown in the peruvian amazon. J. Food Process Eng., 33: 83-103.

Baydar, H. and Erbas, S. (2009). Effects of harvest time and drying on essential oil properties in lavandin (lavandula × intermedia emeric ex loisel.). Acta Horticulturae, 826: 377-382.

Bozin, B.; Mimica-Dukic, N.; Simin, N. and Anackov, G. (2006). Characterization of the volatile composition of essential oils of some lamiaceae spices and the antimicrobial and antioxidant activities of the entire oils. J. Agric. Food Chem. 54 (5): 1822–1828.

Brougham, R. W. (1960). The relationship between the critical leaf areas, total chlorophyll content and maximum growth rate of some pasture and crop plant Amm, 130t. N.S. 24(961): 463-474.

CAGMC, (Central Authority for General Mobilization and Statistics). (2003). “The Annual Stistical Book for A.R.E.:7”.

Ertekin, C. and Yaldiz, O. (2004). Drying of eggplant and selection of a suitable thin layer drying models. J. Food Eng., 63: 349-359.

Hall, C. W. (1980). Drying and storage of agricultural crops. The AVI. Publishing , Inc., Westport, Connecticut, U.S.A.: 291-308.

Hassanain, A. A. (2004).Thermal Performance of an Unglazed Transpired Solar Dryer. Misr J. Agric. Eng. 12 (2):533-552.

Hazra, P., Kahol, A.P. and Ahmed, J. (1990). “Study of the effect of mode of drying on the yield, quality and steam consumption in distillation of the essential oil of Mentha arvesis”. India-perfumer 34(1):47-55.

Kadam, D. M. ; Goyal, R. K. and Gupta, M. K. (2011).Mathematical modeling of convective thin layer drying of basil leaves. Journal of Medicinal Plants Research. 5(19):4721-4730.

Khangholil, S. and Rezaeinodehi, A. (2008). Effect of drying temperature on essential oil content and composition of sweet wormwood (Artemisia annua) growing wild in Iran. Pak.J. Biol. Sci, 11: 934-937.

Muhlbauer, W. (1986). Present Status of Solar Crop Drying. Energy in Agriculture 5, 121-137.

Okos, MR.; Narsimhan, G.; Singh, RK. and Weitnauer, AC. (1992). Food Dehydration. In: Heldman DR, Lund DB (Eds). Handbook of food engineering, New York; Marcel Dekker.

Özcan, M.; Arslan, D. and Ünver, A. (2005). Effect of drying methods on the mineral content of basil (Ocimum basilicum L.). J. Food Eng., 69(3): 375-379.

Oztekin, S and Martinov, M. (2007). Medicinal and aromatic crops: Harvesting, drying and processing. Haworth food agricultural products press, New York, p. 320.

PaTil, B. G. and Ward, G. T. (1989). Simulation of Solar Air Drying of rapeseed. Solar Energy, 43(5):305-320.

Pierce, R. O. and Thompson, T. L. (1980). Management of solar and low temperature grain drying systems. Part II: Layer drying and solution to the over-drying problem. Transaction of the ASAE, 23(4):1020-1023.

Schenkel, E.P.; Gosmann, G. and Petrovick, P.R. (2003). Vegetable products and drug development. In: Simões, C.M.O et al. Pharmacognosy: Plant Med., eds. C. M. O. Editora da UFRGS/Editora UFSC, pp. 371- 400.

Sellami, I.H.; Wannes, W.A.; Bettaieb, I.; Berrima, S.; Chahed, T.; Marzouk, B. and Limam, F. (2011). Qualitative and quantitative changes in the essential oil of Laurus nobilis L. leaves as affected by different drying methods. Food Chem., 126: 691-697

Shahi, N. C.; Anupama Singh, and Kate, A. E. (2014). Activation energy kinetics in thin layer drying of basil leaves.International Journal of Science and Research (IJSR) ISSN (Online): 2319-7064. 3(7).

Tohti, I.; Tursun, M.; Umar, A.; Turdi, S.; Imin, H. and Moore, N. (2006). "Aqueous extracts of Ocimum basilicum L. (sweet basil) decrease platelet aggregation induced by ADP and thrombin in vitro and rat's arterio—venous shunt thrombosis in vivo". Thromb. Res. 118 (6): 733–739.

Yaldiz, O.; Ertekin, C. and Uzun, H.I. (2001). Mathematical modeling of thin layer solar drying of sultana grapes. Energy. Int. J. 26: 457-465.