Microencapsulation of Essential Oils within Alginate: Formulation and in Vitro Evaluation of Antifungal Activity

E. A. Soliman, A. Y. El-Moghazy, M. S. Mohy El-Din, M. A. Massoud

Department of Plant Protection, Faculty of Agriculture-Saba Basha, Alexandria University, Alexandria, Egypt.
Department of Polymer Materials, Advanced Technology and New Materials Research Institute, City of Scientific Research and Technology Applications, New Borg El-Arab City, Egypt.

DOI: 10.4236/jeas.2013.31006                

Abstract

Essential oils (EOs) are the volatile lipophilic components extracted from plants. Many EOs have demonstrated strong antimicrobial properties when tested in in vitro experiments. The commercial applications of these EOs require a suitable formulation constituted by biodegradable compounds that protect them from degradation and evaporation at the same time that allows for a sustained release. The objective of this study was therefore to reduce the rate of evaporation of the oil via microencapsulation. Alginate microspheres (AMSs) were prepared using emulsion extrusion method. The AMSs were hardened with a cross-linking agent, calcium chloride. The effects of the three variables: alginate concentration (0.5% - 8%), the amount of cross-linking agent (0.125% - 2%) and time of cross-linking (5 - 30 min.) on loading capacity and encapsulation efficiency (EE, %) were studied. The effect of the amount of cross-linker was significant on loading capacity (%) and EE (%). The AMSs under the optimized conditions provided loading capacity of 22% - 24% and EE of 90% - 94% based on type of EO. The antifungal activity of vapors of microencapsulated and non-microencapsulated oils were evaluated against two of pathogenic fungi species for stored grains: Aspergillus niger and Fusarium verticillioides. The optimized MSs were observed to have a sustained in vitro release profile (50% of the antifungal activity was maintained at the 8th day of the study). In conclusion, encapsulation in Ca-alginate microspheres may effectively reduce the evaporation rate of essential oils, thus increase the potential antifungal activity.

Keywords

Essential Oils; Alginate Microspheres; Extrusion; Antifungal Activity

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	N. Paster and L. B. Bullerman, “Mould Spoilage and Mycotoxin Formation in Grains as Controlled by Physical Means,” International Journal of Food Microbiology, Vol. 7, No. 3, 1988, pp. 257-265. doi:10.1016/0168-1605(88)90044-X
[2]	N. Paster, M. Menasherov, U. Ravid and B. Juven, “Antifungal Activity of Oregano and Thyme Essential Oils Applied as Fumigants against Fungi Attacking Stored Grain,” Journal of Food Protection, Vol. 58, No. 1, 1995, pp. 81-85.
[3]	T. R. Hamilton-Kemp, D. D. Archbold, J. H. Loughrin, R. A. Andersen, C. T. McCracken, R. W. Collins and E. Fallik, “Stimulation and Inhibition of Fungal Pathogens of Plants by Natural Volatile Phytochamicals and Their Analogs,” Current Topics in Photochemistry, Vol. 4, 2000, pp. 95-104.
[4]	J. F. Ayala-Zavala, L. del Toro-Sanchez, E. Alvarez-Parrilla and G. A. Gonzalez-Aguilar, “High Relative Humidity In-Package of Fresh-Cut Fruits and Vegetables: Advantage or Disadvantage Considering Microbiological Problems and Antimicrobial Delivering Systems,” Journal of Food Science, Vol. 73, No. 4, 2008, pp. 41-47. doi:10.1111/j.1750-3841.2008.00705.x
[5]	T. P. Bergkvist, “Antimicrobial Activity of Four Volatile Essential Oils,” M.Sc. Thesis, School of Biomedical Science, Charles Sturt University, Dubbo, 2007.
[6]	H. Yoshizawa, “Trends in Microencapsulation Research,” Kona, Vol. 22, 2004, pp. 22-31.
[7]	J. Shaikh, R. Bhosale and R. Singhal, “Microencapsulation of Black Pepper Oleoresin,” Food Chemistry, Vol. 94, No. 1, 2006, pp.105-110. doi:10.1016/j.foodchem.2004.10.056
[8]	J. Lazko, Y. Popineau and J. Legrand, “Soy Glycinin Microcapsules by Simple Coacervation Method,” Colloids and Surfaces B: Biointerfaces, Vol. 37, No. 1, 2004, pp. 1-8. doi:10.1016/j.colsurfb.2004.06.004
[9]	C. P. Chang, T. K. Leung, S. M. Linc and C. C. Hsu, “Release Properties on Gelatin-Gum Arabic Microcapsules Containing Camphor Oil with Added Polystyrene,” Colloids and Surfaces B: Biointerfaces, Vol. 50, No. 2, 2006, pp. 136-140. doi:10.1016/j.colsurfb.2006.04.008
[10]	S. Yuliani, P. J. Torley, B. D'Arcy, T. Nicholson and B. Bhandari, “Extrusion of Mixtures of Starch and D-Limonene Encapsulated with β-Cyclodextrin: Flavour Retention and Physical Properties,” Food Research International, Vol. 39, No. 3, 2006, pp. 318-331. doi:10.1016/j.foodres.2005.08.005
[11]	á. Martín, S. Varona, A. Navarrete and M. J. Cocero, “Encapsulation and Co-Precipitation Processes with Supercritical Fluids: Applications with Essential Oils,” Open Chemical Engineering, Vol. 4, 2010, pp. 31-41. doi:10.2174/1874123101004020031
[12]	B. Amsden, “Solute Diffusion within Hydrogels,” Macromolecules, Vol. 31, No. 23, 1998, pp. 8382-8395. doi:10.1021/ma980765f
[13]	E. S. Chan, “Preparation of Ca-Alginate Beads Containing High Oil Content: Influence of Process Variables on Encapsulation Efficiency and Bead Properties,” Carbohydrate Polymers, Vol. 84, No. 4, 2011, pp. 1267-1275. doi:10.1016/j.carbpol.2011.01.015
[14]	Q. Wang, J. Gong, X. Huang, H. Yu and F. Xue, “In Vitro Evaluation of the Activity of Microencapsulated Carvacrol against Escherichia coli with K88 Pili,” Applied Microbiology, Vol. 107, 2009, pp. 1781-1788. doi:10.1111/j.1365-2672.2009.04374.x
[15]	N. Parris, P. H. Cooke and K. B. Hicks, “Encapsulation of Essential Oils in Zein Nanospherical Particles,” Journal of Agriculture and Food Chemistry, Vol. 53, No. 12, 2005, pp. 4788-4792. doi:10.1021/jf040492p
[16]	W. Feng, J. Chen, X. Zheng and Q. Liu, “Thyme Oil to Control Alternaria alternata in Vitro and in Vivo as Fumigant and Contact Treatments,” Food Control, Vol. 22, No. 1, 2011, pp. 78-81. doi:10.1016/j.foodcont.2010.05.010
[17]	D. K. Pandey, H. Chandra and N. N. Tripathi, “Volatile Fungitoxic Activity in Higher Plants with Special Reference to that of Callistemon lanceolatus D.C.,” Phytopathologische Zeitschrift, Vol. 105, No. 2, 1982, pp. 175-182. doi:10.1111/j.1439-0434.1982.tb00675.x
[18]	Costat Software, “Microcomputer Program Analysis,” CoHort Software, Berkely, 1988.
[19]	K. M. Manjanna, B. Shivakumar and T. M. P. kumar, “Formulation of Oral Sustained Release Aceclofenac Sodium Microbeads,” International Journal of Pharm Tech Research, Vol. 1, No. 3, 2009, pp. 940-952.
[20]	S. B. Sevda and L. Rodrigues, “The Making of Pomegranate Wine Using Yeast Immobilized on Sodium Alginate,” African Journal of Food Science, Vol. 5, No. 5, 2011, pp. 299-304.
[21]	A. A. El-Zatahry, E. A. Soliman, E. A. Hassan and M. S. M. Eldin, “Preparation and in Vitro Release of Theophylline Loaded Sodium Alginate Microspheres,” Proceedings of the ASTF, Scientific Research Outlook Conference, No. 155, 2006, pp. 1-20.
[22]	F. Lai, G. Loy, M. Manconi, M. L. Manca and A. M. Fadda, “Artemisia arborescens L. Essential Oil Loaded Beads: Preparation and Characterization,” AAPS PharmSciTech, Vol. 8, No. 3.2007, pp. 1-7.
[23]	A. R. Kulkarni, K. S. Soppimath, T. M. Aminabhavi, A. M. Dave and M. H. Mehta, “Glutaraldehyde Crosslinked Sodium Alginate Beads Containing Liquid Pesticide for Soil Application,” Journal of Controlled Release, Vol. 63, No. 1-2, 2000, pp. 97-105. doi:10.1016/S0168-3659(99)00176-5
[24]	M. E. Guynot, A. J. Ramos, L. Setó, P. Purroy, V. Sanchis and S. Marín, “Antifungal Activity of Volatile Compounds Generated by Essential Oils against Fungi Commonly Causing Deterioration of Bakery Products,” Applied Microbiology, Vol. 94, No. 5, 2003, pp. 893-899. doi:10.1046/j.1365-2672.2003.01927.x
[25]	K. M. Soliman and R. I. Badeaa, “Effect of Oil Extracted from Some Medicinal Plants on Different Mycotoxigenic Fungi,” Food and Chemical Toxicology, Vol. 40, No. 11, 2002, pp. 1669-1675. doi:10.1016/S0278-6915(02)00120-5
[26]	A. Pandey, J. V. Jagtap and S. A. Polshettiwar, “Formulation and Evaluation of in Vitro Antimicrobial Activity of Gel Containing Essential Oils and Effect of Polymer on their Antimicrobial Activity,” International Journal of Pharmacy and Pharmaceutical Sciences, Vol. 3, No. 1, 2011, pp. 234-237.
[27]	F. V. Leimann, O. H. Gon?alves, R. A. F. Machado and A. Bolzan, “Antimicrobial Activity of Microencapsulated Lemongrass Essential Oil and the Effect of Experimental Parameters on Microcapsules Size and Morphology,” Materials Science and Engineering: C, Vol. 29, No. 2, 2009, pp. 430-436. doi:10.1016/j.msec.2008.08.025
[28]	S. G. Passino, E. Bazzoni and M. D. L. Moretti, “Microencapsulated Essential Oils Active against Indian Meal Moth,” Boletín de Sanidad Vegetal Plagas, Vol. 30, 2004, pp. 125-132.