The Effect of Temperature and Drying Method on Drying Time and Color Quality of Mint

ماشین های کشاورزی

Article 8, Volume 7, Issue 2 - Serial Number 14, 2017, Pages 415-426   

Document Type: Research Article

DOI: 10.22067/jam.v7i2.51268

Authors

H. Bahmanpour¹; S. M. Sajadiye^{* 1}; M. J. Sheikhdavoodi¹; M. Zolfaghari²

¹Department of Biosystems Engineering, Shahid Chamran University of Ahvaz, Ahvaz, Iran

²Department of Horticulture Science, Shahid Chamran University of Ahvaz, Ahvaz, Iran

Abstract

Introduction
Mint (Mentha spicata L.) cbelongs to the Lamiaceae family, is an herbaceous, perennial, aromatic and medicinal plant that cultivated for its essential oils and spices. Since the essential oil is extracted from dried plant, choosing the appropriate drying method is essential for gaining high quality essential oil.Vacuum drying technology is an alternative to conventional drying methods and reported by many authors as an efficient method for improving the drying quality especially color characteristics. On the other side, solar dryers are also useful for saving time and energy. In this study the effect of two method of dryings including vacuum-infrared versus solar at three different conventional temperatures (30, 40 and 50°C) on mint plant is evaluated while factorial experiment with randomized complete block is applied. Drying time as well as color characteristics areconsidered for evaluation of each method of drying.
Materials and Methods
Factorial experiment with randomized complete block was applied in order to evaluate the effect of drying methods (vacuum-infrared versus solar) and temperature (30, 40 and 50°C) on drying time and color characteristics of mint. The initially moisture content of mint leaves measured according to the standard ASABE S358.2 during 24 hours inside an oven at 104 °C. Drying the samples continued until the moisture content (which real time measured) reached to 10% wet basis. The components of a vacuum dryer consisted of a cylindrical vacuum chamber (0.335 m³) and a vacuum pump (piston version). The temperature of the chamber was controlled using three infrared bulbs using on-off controller. Temperature and weight of the products registered real time using a data acquisition system. The components of a solar dryer were consisting of a solar collector and a temperature control system which was turning the exhaust fan on and off in order to maintain the specific temperature. A date acquisition system was applied to register and monitoring product weight real time. For imaging of dried samples, a semi-professional digital cameras Fujifilm Fine Pix HS55model Barzvlvshn 921000 pixel was applied. Dry samples were used to determine the RGB color model that consists of three whole red (Red), green (Green) and blue (blue) light intensity 0 to 255 (in this case, zero for black and 255 for white pixels) Finally, the average of RGB changes color index were calculated as the mean change color of samples during the drying.
Results and Discussion
The results showed that drying time of solar dryer is more than vacuum-infrared (averaged: 201 versus 153 minutes). For two methods of drying, increasing temperature, made reduction in drying time. The maximum drying time registered 237 minutes for solar method which was set to 30°C and minimum drying time was registered 112 minutes relating to vacuum –infrared which was set to 50°C. Color evaluation showed that the effect of drying method on the changes of colour index (before and after drying) is reasonable. Vacuumed-infrared dryer case with 8.75% color change was showed to be much efficient than solar dryer with 11.96% change. Analysis of variance was performed due to the drying temperature index mint color changes and results showed the reasonable difference. The highest and lowest color change related to the temperature of 50°C (11.767%) and 30°C (9.197%) respectively.
Conclusion
Drying method as well as applying temperature showed rescannable effects on daring time and color quality of mint. The vacuum-infrared method reduces drying time for all temperature treatments considered in this study. Beside this, using vacuum-infrared showed minimum changes on color characteristic and can be say more efficient in aspect of color quality especially at its lowest applicable temperature (30°C). Increasing temperature causes the samples to be more darken for both drying methods. This phenomena may be related to replacement of magnesium by hydrogen inside the chlorophyll and then causing the chlorophyll to be destroyed.

Keywords

Color; Dryer; Mint; Solar; Vacuum-infrared

References

1. Afsharijouibari, H., A. Frahnaki, Gh. Mesbahi, and M. Niakosari. 2012. Effect of temperature and air velocity on drying Mazafati variety by drying cabinet. Iranian Food Science and Technology. Ferdowsi University of Mashhad. (In Farsi).

2. Afzal, T. M. and T. Abe. 1998. Diffusion in potato during far infrared radiation drying. Journal of Food Engineering 37: 353-365.

3. Ali, M. N., Y. A. Yusof, N. L. Chin, M. N. Ibrahim, and S. M. A. Basra. 2014. Drying kinetics and colour analysis of Moringa oleifera leaves. Agriculture and Agricultural Science Procedia 2: 394-400.

4. Arabhosseini, A., and Y. Müller. 2014. Review changes to the essence of medicinal plants during the drying process. The National Conference of Medicinal Plants and Sustainable Agriculture. Shahid Mofateh University of Hamedan. (In Farsi).

5. Arabhosseini, A., W. Huisman, A. Wan Boxtel, and J. Müller. 2007. Long-term effects of drying conditions on the essential oil and color of tarragon leaves during storage. Journal of Food Engineering 79: 561-566.

6. ASABE Standards. S358.2-Moisture Measurement-Forages, 2008. American Society of Agricultural and Biological Engineers: St. Joseph, MI, USA.

7. Belghit, A., M. Kouhila, and B. C. Boutaleb. 2000. Experimental study of drying kinetics of forced convection of aromatic plans. Energy Conversion and Management 41, p. 1303.

8. Buchaillot, A., N. Caffin, and B. Bhandari. 2009. Drying of lemon myrtle (Backhousia citriodora) leaves: retention of volatiles colour. Drying Technology 27: 445-450.

9. Datta, A. K., and M. Almedia. 2005. Properties relevant to infrared heating of foods. Cornell University, Ithaca, New York. Chapter 6. 209-220. (Accessed October 2014).

10. Doymaz, I., N. Tugrul, and M. Pala. 2006. Drying characteristics of dill and parsley Leaves. Journal of Food Engineering 77, p. 559.

11. Ebadi, M. T., M. Azizi, F. Sefidkon, and N. Ahmadi, 2014. Influence of different drying methods of drying period, essential oil content and composition of lippie citriodora kunth. Journal of Applied Research on Medicinal and Aromatic Plants: 1-6.

12. Feleh Karry, M., R. Amiri Chaichan, and J. Amiri Parnian. 2012. Evaluation of some physical properties (color and shrinkage) shallots infrared drying method- displacement.7th National Congress of Agricultural Engineering and Mechanisation. Shiraz Univ. of Shiraz. (In Farsi).

13. Forson, F., M. Nazha, and H. Rajakaruna. 2007. Design of mixed-mode natural convection solar crop dryers: Application of principles and rules of thumb. Renewable Energy 32: 2306-2319.

14. Hafezi, N., M. J. Sheikh Davoodi, S. M. Sajadiye, and E. Khorasani Ferdavani. 2014. Evaluation of energy consumption of potato slices drying using vacuum- infrared method. International Journal of Advanced Biological and Biomedical Research 2 (10): 2651-2658.

15. Kantrong, H., A. Tansakul, and G. S. Mittal. 2012. Drying characteristics and quality of shiitake mushroom undergoing microwave-vacuum drying and microwave-vacuum combined with infrared drying. Journal Food Scientists and Technologists.

16. Lee, J. H., and H. J. Kim. 2009. Vacuum drying kinetics of Asian white radish (Raphanus sativus L.) slices. LWT-Food Science and Technology 42: 180-186.

17. Lee, J. H., H. J. Kim, and J. W. Rhim. 2012. Vacuum drying characteristics of Salicornia herbacea L. Journal of Agricultural Science and Technology 14: 587-598.

18. Li, Z., G. S. V. Raghavan, N. Wang, and C. Vigneault, 2011. Drying rate control in the middle stage of microwave drying. Journal of Food Engineering 104: 234-238.

19. Madamba, P. S., and F. A. Liboon. 2001. Optimization of the vacuum dehyhration of celery (Apium graveolens) using the response surface methodology. Drying Technology 19 (3): 611-626.

20. Mendozaa, F., P. Dejmekb, M. Jos´e. 2006. Aguilera Calibrated color measurements of agricultural foods using image analysis. Postharvest Biology and Technology 285: 41-295.

21. Mongpraneet, S., T. Abe, and T. Tsurusaki. 2002. Accelerated drying of welsh onion by far infrared radiation. Journal of Food Engineering 55: 147-156.

22. Nikjooy, S., and S. H. Hashemi. 2014. The effect of drying conditions on the color of savory (Satureia hortensis) leaves. International Journal of Agriculture and Crop Sciences. 7 (5): 225-229.

23. Omidbaigi, R. 2013. Production and Processing of Medicinal Plants. First volume, 7th edition, Press Astan Ghods Razavi of Mashhad. (In Farsi).

24. Rodrı´guez, R., J. I. Lombrana, M. Kamel, and C. De Elvira. 2005. Kinetic and quality study of mushroom drying under microwave and vacuum. Drying Technology 23: 2197-2213.

25. Rubinskienė, M., P. Viškelis, E. Dambrauskienė, J. Viškelis, and R. Karklelienė. 2015. Effect of drying methods of the chemical composition and colour of peppermint (Mentha piperita L.) leaves. Zemdirbyste-Agriculture 102 (2): 223-228.

26. Sadrnia, H., H. Monfared, and M. Khojasteh Pour. 2015. Compare the two drying methods on energy consumption and quality parameters, despite the purple turnip. Journal of Agricultural Machinery 5 (1): 143-153. (In Farsi).

27. Sharma, G. P., R. C. Verma, and P. B. Pathare. 2005. Thin-layer infrared radiation drying of onion slices. Journal of Food Engineering. 67: 361-366.

28. Therdthai, N., and W. Zhou. 2009. Characterization of microwave vacuum drying and hot air drying of mint leaves (Mentha cordifolia opiz ex fresen). Journal of Food Engineering 91: 482-489.

29. Toujani, M., L. Hassini, S. Azzouz, and A. Belghith, 2013. Experimental study and mathematical modeling of silverside fish convective drying. Journal of Food Processing and Preservation 37: 930-938.

30. VijayaVenkataRaman, S., S. Inian, and R. Goic. 2012. A review of solar drying technologies. Renewable and Sustainable Energy Reviews 16: 2652-2670.

31. Zareh Deh Abadi, S., Z. Asrar, and M. Mehrabani. 2010. The terpenoids in the essential oil mint (Mentha piperita L.) biochemical changes in response to treatment with an excess of zinc (Zn). Journal of Plant Biology. (In Farsi).