here is an answer i gave to a similar question a few months ago. the thing to remember is that the form of yeast products (active dry, compressed or cake, rapid rise) differs but they perform in the same way. (note website at end of comment for conversion information)
my understanding of yeasts is that any kind of yeast can be used in any recipe. active yeast comes in packets or cakes (a kind available before powdered yeast was available). instant or rapid rise yeast comes in packets also (marked as such). they are all usually sold at the same place on the grocery shelf. (sourdough is another leavening method but we'll focus on off the shelf yeast for this answer.)
the caviat though is that the METHOD of preparing the yeast differs and the amount has to be adjusted per the kind used. so once you know the conversions, any yeast can be substituted for any other in the equivalent amount & method to match a recipe. so if an old recipe, for instance, says x amount of cake yeast, the yeast used does not need to be cake yeast but an equivalent of the yeast you have on hand or available. or if a newer recipe specifies rapid rise yeast, slower yeasts can be used but they will rise more slowly & that has to be accounted for.
(an aside, rapid rise yeasts have only been on the market since the late 70's/early 80's. they were designed to shorten the rise times. back then, they were "proofed" in water like the older cake & powdered active yeasts. i quit baking about that time & lost track of the point at which rapid rise yeast started to be added to dry ingredients. maybe when dough hooks were an attachment to mixers!?)
anyway, although it seems confusing to understand all the terminology of this, the thing to remember is that yeast is yeast.
it's preparation and conversion that you need to be concerned about . there is a wonderful website called food subs or cooks thesaurus that is great for equivalents and substitutions of ingredients. look there to learn more about this subject (and how to use them interchangeably):
http://www.foodsubs.com/LeavenYeast.html
i hope that helps with a little overview of why the different terms exist in different recipes & what to do about the confusion.
2 Comments
my understanding of yeasts is that any kind of yeast can be used in any recipe. active yeast comes in packets or cakes (a kind available before powdered yeast was available). instant or rapid rise yeast comes in packets also (marked as such). they are all usually sold at the same place on the grocery shelf. (sourdough is another leavening method but we'll focus on off the shelf yeast for this answer.)
the caviat though is that the METHOD of preparing the yeast differs and the amount has to be adjusted per the kind used. so once you know the conversions, any yeast can be substituted for any other in the equivalent amount & method to match a recipe. so if an old recipe, for instance, says x amount of cake yeast, the yeast used does not need to be cake yeast but an equivalent of the yeast you have on hand or available. or if a newer recipe specifies rapid rise yeast, slower yeasts can be used but they will rise more slowly & that has to be accounted for.
(an aside, rapid rise yeasts have only been on the market since the late 70's/early 80's. they were designed to shorten the rise times. back then, they were "proofed" in water like the older cake & powdered active yeasts. i quit baking about that time & lost track of the point at which rapid rise yeast started to be added to dry ingredients. maybe when dough hooks were an attachment to mixers!?)
anyway, although it seems confusing to understand all the terminology of this, the thing to remember is that yeast is yeast.
it's preparation and conversion that you need to be concerned about . there is a wonderful website called food subs or cooks thesaurus that is great for equivalents and substitutions of ingredients. look there to learn more about this subject (and how to use them interchangeably):
http://www.foodsubs.com/LeavenYeast.html
i hope that helps with a little overview of why the different terms exist in different recipes & what to do about the confusion.