Nutritional Composition of
Stevia
rebaudiana
Bertoni Leaf: Effect of
Drying Method
Mohammed Abdalbasit A
Gasmalla1,2, Ruijin Yang1*,
Issoufou Amadou1 and Xiao Hua1
1State Key Laboratory of Food
Science and Technology, School of Food Science and
Technology, Jiangnan University, Wuxi 214122, PR China,
2Department of Nutrition & Food Technology,
Faculty of Science and Technology, Omdurman Islamic
University, PO Box 382, 14415, Khartoum, Sudan.
*For
correspondence: Email:
Yrj@jiangnan.edu.cn
Tel:
+86-510-85919150; Fax: +86510-85919150.
Received: 18 October 2013
Revised accepted: 14
November 2013
Tropical
Journal of Pharmaceutical Research, January 2014; 13(1):
61-65
http://dx.doi.org/10.4314/tjpr.v13i1.9
Abstract
Purpose: To determine the effect
of three methods of drying, viz, sun, oven
and microwave, on Stevia rebaudiana Bertoni
leaf’s nutritional composition.
Methods: Fresh Stevia rebaudian
bertoni leaves were dried separately by sun, oven and
microwave. The chemical composition was determined by
Association of Official
Agricultural Chemists (AOAC) method. Tannin
content was measured by titrimetric method while heavy
metals were analyzed by atomic absorption spectrometry.
Results: The following data were
obtained for the plant when the three drying methods
were employed: moisture content, 4.45 – 10.73 %; ash,
4.65 – 12.06 %; protein, 12.44 – 13.68 %; fat, 4.18 –
6.13 %; total dietary fiber, 4.35 – 5.26 % and total
carbohydrates, 63.10 – 73.99 %. The pH value was 5.96,
5.95 and 6.24 for sun, oven and microwave drying,
respectively. Total energy of the plant material was in
the range 362.3 – 384.2 kcal/100 g while tannin content
was in the range 5.43 – 5.91 %. Moreover, reducing sugar
was 4.5, 4.8 and 5.3 %, respectively, for sun, oven and
microwave drying. Heavy metals content varied in stevia
leaves, with lead was detected in high concentration in
sun-, oven- and microwave–dried materials with values of
4.77, 0.14 and 2.16 µg/g, respectively, while the
corresponding values for cadmium were 0.49, 0.44 and
0.33 µg/g, Arsenic level was 0.30, 0.09 and 0.10 µg/g
for sun, oven and microwave drying, respectively.
Mercury level was the same (0.1 µg/g) irrespective of
the drying method.
Conclusion: The results obtained
indicate that Stevia leaves is a good source of
carbohydrate and other nutrients and hence a substitute
for sugar in processed drinks. Furthermore, drying
reduces nutritional values with the exception to fiber
content
Keywords: Stevia rebaudiana Bertoni ,
Nutritional composition, Protein, Heavy metals, Drying,
Total energy
