How long can you safely keep an all shortening based icing?
I'm not sure exactly, but I've never had it go bad. I usually try to limit time at room temperature to 3 days, but I'm pretty sure it will last even longer. I've kept it about 2 weeks in the fridge without any problems. I've also frozen it for over 6 months. It freezes fairly well. Sometimes I have to just mix it up again with my mixer after thawing because of a lot of condensation.
When I took my cake decorating class (not Wilton), the instructor gave us an all-crisco recipe to use. She said that it would be good for 6 weeks at room temperature...
After the second class, I no longer used that icing to frost the cakes, just decorations/class stuff. And I used one batch for 4 weeks and it was fine the whole time.
I've left it on the counter for several weeks and have had no problem. If you think about it, shortening last a long time in the cabinet, P. sugar, vanilla, and any other flavorings last forever and water. I have an extra frig, so I put all my icing in it now in air tight containers and it will last for a really long time. If you're using milk or butter I'd say not very long.
I use milk and it sits on the counter for a long (!) time ... it's fine.
I also use a shortening BC (vegan one) with a bit of soymilk...
I'm thinking, soymilk has a much longer shelf-life and fridge-life than cow's milk... so do you think my BC can go longer than 3 weeks in the fridge? I just don't want to make anyone sick...
thanks for posting this question..
... so do you think my BC can go longer than 3 weeks in the fridge?
I leave my regular-milk-bc on the COUNTER longer than that.