الفهرس 
Stevia definitionOnly 14 pages are availabe for public view
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Abstract
In recent years, there has been a significant increase in the occurrence of diet-dependent diseases, such as obesity, diabetes, cancer, cardiovascular diseases, and also dental problems, which are a consequence of, among others, inappropriate diet and a lack of physical activity. Due to the high intake of sugars, especially sucrose, global trends in food processing have encouraged producers to use sweeteners, particularly synthetic ones, to a wide extent. Sweeteners are food additives that are used to improve the taste of everyday foods. For several years, increasing attention has been paid in the literature to the stevia (S. rebaudiana). Stevia, a natural sweetener plant having medicinal and commercial importance is being used all over the world. chronic disease constitutes a fast increasing burden to society. The World Health Organization (WHO) estimates that 46% of global disease and 59% of mortality is due to chronic diseases. Therefore, the present work was aimed to study the biological and technological study on stevia as a natural sweetener. To achieve these aims, the design of the study were as follows: stevia aqueous extract was prepared by adding 5gm dried leaves: 95ml hot water then we used debittered agents (sodium glyconate, fructose and β - glactosidase enzyme) with different concentrations (0.1, 0.2, 0.3, 0.6 and 1% for sodium glyconate), (10, 20, 30, 40 and 50% for fructose) and (1, 2, 3, 4, and 5% for β-galactosidase enzyme) after that the best debittering agents concentration was used in the experiment. ENGLISH SUMMARY 150 from the best concentration of the debittered agent the mixtures were prepared as well as for further biological and technological experiment. All groups of rats were fed on the experimental diet for 42 days according to the following groups. First group: Negative control group (normal) (6rats) Rats fed on standard diet only Second group: Hepatotoxic diabetic rats (42 rats) Hepatotoxic diabetic rats were divided into seven sub group (6 rats each) according to the following Sub group (1): positive control group Rats fed on standard diet Sub group 2: stevia group Rats fed on standard diet plus oral administrating with 400mg/kg B.W/ day dry matter of stevia leaves extract. Sub group3: stevia + fructose group Rats fed on standard diet plus oral administrating with 400mg/kg B.W/day dry matter of stevia leaves extract treated with 40%fructose. Sub group 4: Rats fed on standard diet plus oral administrating with 400mg/kg B.W/day dry matter of stevia leaves extract treated with 0.6% sodium glyconate. Sub group 5: Rats fed on standard diet plus oral administrating with 400mg/kg B.W/day dry matter of stevia leaves extract treated with 5% β - glactosidase enzyme. ENGLISH SUMMARY 151 Sub group 6: Rats fed on standard diet plus oral administrating with mixture (400mg/kg B.W/day dry matter of stevia leaves extract treated with 40%fructose, 0.6% sodium glyconate and 5% β - glactosidase enzyme). Sub group 7: Rats fed on standard diet plus oral administrating with 400mg/kg B.W/ day of aspartame. At the end of experimental period (42days), blood samples were collected for serum separation serum liver enzymes (ALT, AST, ALP and GGT), total protein, albumin, total billirubin, glucose, total cholesterol, triglycerides, HDL-c, LDL-c, VLDL-c, creatinine, uric acid, antioxidant enzymes activity markers GST, CAT and MDA on erythrocytes. Liver, heart, spleen, kidneys and lungs were removed, cleaned in saline solution and drained then weighed, while liver and kidneys kept in formalin solution for histopathological examination. The obtained results could be summarized as follow: 1. Stevia leaves are a good source of carbohydrates (49.48%), protein (18.25%), and fiber (18.22%), Also, stevia leaves contain low fat value (4.5%). On the side it’s a good source of total phenol (7.6%) and total flavonides (9.2%). 2. Regarding sensory evaluation of stevia aqueous extracts debittered by different concentration of sodium glyconate. The crude extract treated with 0.6 % was more effective (P ≤0.05) in reducing bitterness than other different sodium glyconate concentrations by 38.68%. 3. Concerning sensory evaluation of of stevia aqueous extracts debittered by different concentration of fructose. Results showed that adding of 40% fructose significantly (P ≤0.05) increased sweetness and overall acceptability compared with crude extract and the otherdifferent concentration of fructose (10% and 30 %) by ratio of 56.82 and 54.73%, respectively. Also, bitterness significantly (P ≤0.05) decreased in 40 % fructose concentration compared with crude extract and the other different concentrations of fructose by 67.2%. 4. According to sensory evaluation of of stevia aqueous extracts debitterd by different concentration of β-galactosidase enzyme. The results showed that there were significantly (P ≤0.05) increased in sweetness and overall acceptability in 5% β-galactosidase enzyme concentration compared with crude extract and the other different concentrations of β-galactosidase enzyme by ratio of 35.77 and 25.95%, respectively. On the other hand there was significant (P ≤0.05) decreased in bitterness in 5% β-galactosidase concentration compared with crude extract and the other different concentrations of β-galactosidase enzyme by 59.37%. 5. Results indicated that Mixture I (crude extract, fructose, sodium gluconate and β-galactosidase enzyme) significantly (P ≤0.05) decreased bitterness compared with crude extract and other different mixtures, Mixture II (stevia, sodium gluconate and β-galactosidase enzyme) and Mixture III (stevia, fructose and β-galactosidase enzyme) by ratio of 68.02%. On the other hand sweetness and overall acceptability increased compared with crude extract and the other mixtures by ratio of 30.6 and 36.59%, respectively. 6. Organoleptic characteristic of instant coffee 2x1 sweeted with different debittered freezedryed. stevia aqueous extract showed there were no significant (P ≥0.05 difference in taste, aftertaste, aroma, bitterness, sweetness and general acceptability between formula II (instant coffee 2x1 plus adding stevia treated with 40% fructose) and.