In a small bowl or measuring cup, combine the cola-flavored syrup concentrate (0.5 cup), vanilla extract (0.25 tsp), orange extract (0.125 tsp), lemon extract (0.0625 tsp), a tiny pinch of ground cinnamon (0.01 tsp) and nutmeg (0.005 tsp). Stir thoroughly until uniform. This creates the aromatic flavor base.

If using caramel color and phosphoric acid substitute (or citric acid), add them to the flavor blend and stir. Add the caramel color (0.5 tsp) for color and the acid (0.25 tsp) to provide the cola tang. If adding caffeine, dissolve the very small amount (0.01 tsp) into the syrup now.

Taste a very small amount of the concentrated blend (diluted with a tablespoon of water) to verify balance between sweet, citrus, and spice notes; adjust extracts in tiny increments if needed. Keep all adjustments minimal — cola flavor is subtle and concentrated.

Sweeten & Dilute

If using granulated sugar simple syrup, make sure it is room temperature and well mixed (1:1 sugar to water). Add 2 tablespoons of simple syrup to the flavor blend and stir until incorporated. This adjusts overall sweetness. If using a HFCS substitute, add in the same quantity.

Chill the carbonated water thoroughly before mixing. Cold liquid retains carbonation better and gives a crisper mouthfeel.

Assemble Soda

In a chilled 12-16 oz (about 2 cups) glass or bottle, pour the prepared flavor-sweetener blend into the bottom.

Slowly add 2 cups of chilled carbonated water to the flavor base. Pour gently over the back of a spoon or down the side of the glass to preserve carbonation and minimize foaming.

Stir very gently once with a long spoon to evenly incorporate flavors without losing too much carbonation.

Serve

If desired, add ice (about 1 cup) to the glass and garnish with a lemon wedge. Serve immediately chilled.

Store any unused flavor-syrup (not mixed with carbonated water) in a sealed container in the refrigerator for up to 2 weeks. Do not store mixed soda for long periods — carbonation will dissipate.