I received a SodaStream carbonator as a present. Once the main flavor samples and the (low-charge) CO2 canister were used up, I wondered what I could do in my own kitchen for flavorings. After seeing https://www.instructables.com/id/Homemade-Vanilla-Cream-Soda/, I thought about what flavors I could reproduce, or at least semi-synthesize.
So, here is a recipe for a diet grapefruit soda. I call it Frasca, because a) the name is close enough to that commercial product without blatantly violating copyright, and b) just call it a tribute to the designers and manufacturers of those fine Frasca general aviation flight simulators.
Step 1: Acquire Foodstuffs and Tools
1 medium grapefruit
2 cups Splenda or other suitable sweetener
SodaStream straight-up seltzer
Hand or sieve
spatula or other stirring tool
Step 2: Make the Syrup
Juice grapefruit, pour juice through hand or sieve (to remove seeds) into measuring cup. There should be about four ounces of juice. Place juice in measuring cup, and add enough water to bring the amount of liquid to 1 cup.
Heat juice and sugar in saucepan, stirring thoroughly until fully incorporated.
Allow to cool.
Step 3: Mix and Enjoy!
Pour 8 to 12 ounces of SodaStream seltzer into a glass.
Gradually add 1-1/2 ounces of the cooled syrup to the glass. Why? There's something in the Splenda chemical makeup that causes the carbonation to flare up, and fizz-over is possible. It would take a scientist to explain it, and my wife isn't home as I write this. So, add gradually. Trust me.
Some Closing Notes
Yes, I know it's pink, and the commercial stuff is uh--not pink. I happened to have pink grapefruit in the house, courtesy of a food co-op of sorts called SHARE. Now I have a really neat use for them.
For my first batch, I ran out of Splenda and used half that and half actual sugar...probably closer to most of the SodaStream non-diet syrups.