Antioxidant, anti-microbial, and physical properties improvement of turmeric (Curcuma domestica Val.) effervescent tablets with stevia (Stevia rebaudiana) leaf powder

Turmeric (Curcuma domestica Val.) has been reported to have beneficial health-promoting effects, especially in this pandemic era. Developing effervescent tablets could facilitate turmeric consumption. However, this product generally used artificial sweeteners. The use of Stevia (Stevia rebaudiana) leaf powder (SLP) as a natural and calorie-free sweetener in turmeric effervescent tablets (TET) had never been studied. This study aimed to evaluate the effect of SLP addition on the TET characteristics. The TET was made using the direct compression method. There were five formulations based on the SLP concentrations (0.5%, 1%, 1.5%, 2%, and 2.5%), while 4% aspartame was used as control. An increased antioxidant activity and solubility time, a reduced total microbial number, and no effect on hygroscopicity were observed as SLP concentration increased (P<0.05). The higher SLP concentration also showed the higher color redness and total phenolic content, but the lower color lightness and yellowness (P<0.05). This probably correlated with the organoleptic test result. The SLP formulas had lower preferences in color, taste, aftertaste, and overall liking when compared to control. Based on the effectiveness test result, 1.5% SLP addition exhibited the best result. The values of antioxidant activity, total polyphenols content, total microbial content, solubility time, and hygroscopicity of this formula were 51.86%, 0.9533 mg/g, 5.3x102 CFU/ml, 115 seconds, and 5.1%, respectively. Those properties were better than that of control (P<0.05). Its overall liking was also ranked as the second position. The results indicated that 1.5% SLP was potentially applied to replace the artificial sweeteners in TET development.