The best replacement for meringue powder is cream of tartar.

The best alternatives to meringue powder are rated as following:
★★★★★  cream of tartar
★★★  egg whites
★★  powdered egg whites
★★  dried egg whites
★  egg white powder
★  color flow
★  egg whites in royal icing
★  meringue

Your alternative for meringue powder is not listed? Suggest!
Speaking about meringue powder, one probably shouldn't forget about royal icing.

Other search terms related to meringue powder and their ratings are:
★★★★★ royal icing
★★★★ cream of tartar
★★★★ buttercream icing
★ egg whites
You have in mind a companion for meringue powder and it is not yet here? Propose!



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meringue powder
cream of tartar
egg whites