Prterrell, a member of this forum, created a recipe similar to Publix. From a 2007 thread:
Just heat equal parts water and sugar (by weight) until it boils and the sugar has completely dissolved. Let it cool and then you can use it. Store it in the fridge.
This aerating business doesn't work with just any buttercream recipe, though. Really what's going on is they make the buttercream unfinished and when you add the simple syrup and aerate it, you are finishing the process of making the buttercream.
I wanted a buttecream I could use at home that was at least as good as what they make. So I did some experimenting and came up with a recipe that is BETTER!. Oh, and when you're done with the last step, you're done - you don't need to add simple syrup and aerate it - it is the perfect consistency and thickness and lightness when you are done.
I've posted it on here before, but for your convenience, I'll post it again:
Note: This is my own personal recipe that I developed. Please credit me if sharing with others. Thanks, Promise Whitley
3 tablespoons Wilton meringue powder
1/2 cup cold water
2 cups granulated sugar
¼ cup corn syrup
1/2 cup warm water
4 sticks (1 pound) unsalted butter, just at room temp (50-60 deg Fahrenheit is ideal)
1 stick (1 cup) of Crisco
1 teaspoon extract/flavoring: vanilla, lemon, orange, almond, mint, or crème bouquet
Wipe a large mixing bowl and beaters with a paper towel dampened with white vinegar, let air dry.
Once dried, in this mixing bowl and using these beaters, whip 3 tablespoons of Wilton meringue powder and 1/2 cup of cold water to stiff peaks.
While you are whipping this up, in a saucepan over medium, heat 2 cups granulated sugar, ¼ cup corn syrup and 1/2 cup warm water to 250 deg F then immediately transfer to a heatproof measuring cup and cool to 240 deg F.
Slowly add the syrup to the whipped meringue. To insure that the syrup does not crystallize from hitting the beaters, pour in a little at a time (about ¼ cup) and whip it in completely before adding more, but this all has to be added in before the syrup cools too much and starts to harden.
Once the syrup is all added, beat on high for 3 minutes until the meringue is very stiff and shiny.
Then place the bowl of meringue in an ice water bath and continue to beat on high for another 3 minutes.
Beat in the stick of Crisco until it is completely incorporated.
Then beat in 1 stick of butter at a time, completely incorporating each stick before adding the next one.
Add 1 teaspoons of extract or flavoring of you choice (vanilla extract, lemon extract, orange extract, almond extract, mint extract, or crème bouquet) and then whip on high for 3-7 more minutes (approx) until the fats and liquids are completely emulsified.
May be stored in on counter for up to 3 days as long as temp in house is 70 deg F or less or store in the fridge for up to 1 week. Allow to come to room temp and then rewhip on high for 3 to 5 minutes before using. Freeze up to 3 months. Thaw in fridge and then follow refrigerated directions.