Mohammed Abdalbasit A Gasmalla1,2,
Habtamu A Tessema3,
Kamal Alahmed3,
Xiao Hua3,
Xiangru Liao4,
Ruijin Yang1,3 
1State Key Laboratory of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, Jiangsu, China;
2Department of Nutrition and Food technology, Faculty of Science and Technology, Omdurman Islamic University, PO Box 382, 14415, Khartoum, Sudan;
3School of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue;
4The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, Jiangsu, China.
For correspondence:- Ruijin Yang
Email: yrj@jiangnan.edu.cn Tel:+ 8651085919150
Received: 3 December 2016
Accepted: 13 May 2017
Published: 29 June 2017
Citation:
Gasmalla MA, Tessema HA, Alahmed K, Hua X, Liao X, Yang R.
Effect of different drying techniques on the volatile compounds, morphological characteristics and thermal stability of Stevia rebaudiana Bertoni leaf. Trop J Pharm Res 2017; 16(6):1399-1406
doi:
10.4314/tjpr.v16i6.26
© 2017 The authors.
This is an Open Access article that uses a funding model which does not charge readers or their institutions for access and distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0) and the Budapest Open Access Initiative (http://www.budapestopenaccessinitiative.org/read), which permit unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited..
Abstract
Purpose: To examine the volatile compounds, thermal stability and morphological characteristics of stevia (Stevia rebaudiana Bertoni) leaves after sun, oven and microwave drying.
Methods: Gas chromatography-mass spectrometry with a spectral analysis manager was used to separate the volatile compounds. Dried stevia leaf powder was characterized morphologically by scanning electron microscopy while thermal properties were determined by differential scanning calorimetry (DSC).
Results: The plant material contained large amounts of spathulenol and caryophyllene oxide. The main compounds were 1-docosanol and hexanoic acid; trans-β-ionone, 5-methylundecane, 2,5,6-trimethyldecane, (+) spathulenol, propanoic acid and 1-chlorononadecane. The surface of the dried leaf powder varied with the treatment applied. Following microwave drying, the particles were even, regular, and compact while the sun- and oven dried particles resembled angular bricks. All samples exhibited a strong endothermic response, indicating stability up to 150 °C; from 150 to 200 °C, thermal decomposition occurred.
Conclusion: Drying method has a signi@257;cant effect on the structure, thermal stability and volatile compounds contents of stevia leaves. All drying methods examined in this study have potential applications in the preparation of stevia as a functional ingredient for the food and pharmaceutical industries.
Keywords: Differential scanning calorimetry, Drying techniques, Stevia rebaudiana, Pharmaceuticals, Scanning electron microscopy, Volatile compounds
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