Using noncaloric stevia as a sugar substitute is gaining popularity in the United States. Unfortunately, many who try stevia or stevia products find it leaves a bitter taste or aftertaste in their mouth. This bitter taste is the result of including stems, roots or leaf veins in the final product. If you buy stevia products, it is important to make sure it contains at least 95 percent steviosides; less will mean a more bitter taste. If you grow your own stevia plants, you can eliminate the bitterness with the proper harvesting process.
Harvest the leaves from your stevia plant just before the plant is ready to flower. The leaves are at their sweetest just before the plant flowers, which should be the end of summer or early fall. To harvest you can either pick the leaves off the plant separately or snip an entire stem of leaves.
Cut all of the stem and center vein in the leaf off the leaves you intend to use fresh for drinks or desserts. The stems and leaf veins contain the elements that leave the bitter taste in your mouth.
Dry your harvested stevia leaves by either placing the individual leaves in a dehydrator or drying screen or, if you harvested an entire stem of stevia leaves, hang the stem upside down in a warm place that has good air circulation. To retain the highest concentration of sweetness, the drying process should be completed within eight to 10 hours.
Crush your dried stevia leaves so the leaf breaks away from the leaf vein that runs down the center of the leaf. To diminish or eliminate the bitter after taste stevia can have, it is important that the leaf veins and stems are removed from your final product.
Grind the crushed leaf parts in a coffee grinder that has metal blades. Fill the grinder half full of crushed leaves, then run the grinder until the leaves turn to powder. This powder is called "Green Stevia Powder" and is used in stevia recipes.
Store your Green Stevia Powder in clean glass jars with tight-fitting lids. Your stored stevia, whether whole leaves or in powder, will keep for many years stored this way. Its sweetness will not diminish, nor will a bitter taste develop.