Etude de l’extraction des glycosides de stéviol à partir de Stevia et évaluation de leur efficacité en tant qu’édulcorants naturels.

Abstract

Stevia rebaudiana, better known as Stevia, is a plant native to South America. It is distinguished by its high content of steviol glycosides (Stevioside and Rebaudioside A), compounds with intense sweetening power, as well as the presence of essential nutrients beneficial to the body. Used as a natural alternative to sugar, Stevia is a zero-calorie solution that helps limit the harmful effects of overconsumption of sugar. In this study, we performed an extraction of steviol glycosides by decoction, infusion, and starting with washing and drying of Stevia leaves. We also performed a dosage of total sugars. Our results reveal that the nutritional composition of stevia leaves was As follows: lipids 7%, ash 12.39%, humidity83.46, For the extraction of stevioside, we used the infusion and decoction methods, as well as distilled water as a solvent. For the infusion, we soaked 150 g of the plant in 4 L of distilled water at 80 °C. Then, we filtered and soaked a second time with 2 L of distilled water. Then, we filtered and soaked a third time with 1 L of distilled water. After soaking, we obtained: 4 liters at 16.16 mg/ml, 2 liters at 8.2 mg/ml and 1 liter at 1.08 mg/ml. For the decoction, we boiled 150 g of the plant in 4 liters of distilled water at 80 °C, then filtered and boiled a second time with 2 liters of distilled water, then filtered and boiled a third time with 1 liter of distilled water. In the decoction, we obtained: 4 liters 36 mg/ml, 2 liters 33.6 mg/ml, 1 liter 28 mg/ml. For electrocoagulation: infusion 1 liter of 10.22 mg/ml, 2 liters 33 mg/ml, 4 liters 39 mg/ml, decoction 1 liter 27 mg/ml, 2 liters 15 mg/ml, 4 liters 20 mg/ml. The amount of stevioside after lyophilization: infusion 1 liter 2.1412%, 2 L 1.5812%, 4 L 2.1410%, decoction 1 L 2.6715%, 2 L 2.6720%, 4 L 2.6722%. For electrocoagulation: infusion 1 L: 1.5511%, 2 L: 0.3398%, 4 L: 1.1214%, decoction 1 L: 1.0664%, 2 L: 0.6094%, 4 L: 2.2147%. Finally, we conducted a taste test to determine the sweetness and acceptability of the sterilized stevioside sweetener. We sweetened two components: hot coffee and cold plain yogurt. Fifteen tasters tested the sweetness levels (low, medium, and high) and compared them to white sugar to determine acceptability. The results were as follows: Steviol provides sufficient sweetness at a small dose. Optimal dose: 0.02-0.03% for yogurt, 0.01-0.02% for coffee. Secondary taste: grassiness is the most prominent (especially in coffee). Consumer acceptance: 75-82% acceptance rate for steviol, compared to 85-92% for sugar. Taste tests with different concentrations (0.01%, 0.02%, 0.03%) to determine the optimal percentage for each product.