On Tue, 18 Nov 2003 22:25:23 -0700, "Janet Bostwick"
> wrote:

>
>"A.T. Hagan" > wrote in message
...
>> On Tue, 18 Nov 2003 22:01:57 GMT, "Graham" > wrote:
>>
>> >
>> >"A.T. Hagan" > wrote in message
>> ...
>> >> Is the following generally true about interchanging yeast types in
>> >> bread making?
>> >>
>> >>
>> >> "To substitute Rapid Acting yeasts for Active Dry yeasts reduce the
>> >> amount of Rapid Acting used by 25% from the amount of Active Dry the
>> >> recipe calls for then add the dry yeast to the dry ingredients before
>> >> mixing.
>> >>
>> >> To substitute Active Dry for Rapid Acting increase the amount of
>> >> Active Dry by 25% over what the recipe calls for of Rapid Acting yeast
>> >> and dissolve in warm water (100° to 110°F) with a small amount of
>> >> sugar before mixing in with the dry ingredients.
>> >>
>> >Strictly speaking, in the second example you should increase by 33%.
>> >Graham
>> >
>>
>> I won't dispute what you say, but the little (very little) info I
>> could find on this says 25% or thereabouts. Why do you say 33%?
>>
>> It's the standard active dry yeast to rapid acting yeast and vice
>> versa conversion that I was most concerned with.
>>
>> .....Alan.
>The small amount of conversion difference in the above example is not
>necessarily that important. What is important is that the two yeasts are
>used in different ways. The active dry yeast must be hydrated before use to
>be most effective. The instant yeast is mixed with the flour. According to
>Roy Basan just last week, instant yeast has less tolerance to long
>fermentation periods. There is also another dry yeast(instant I believe)
>that has a greater tolerance to high sugar recipes. I haven't checked
>recently, but I believe there may also be a water temperature requirement
>difference between the two. So you probably need to do a little further
>research along the lines of yeast properties rather than relying solely upon
>strict conversion rates.
>Janet
>

Yes. I do mention that if you're replacing Rapid Acting yeast with
standard Active Dry yeast you should still dissolve the yeast in warm
liquid first to get it going. But if you're using Rapid Acting in
place of Active Dry then blend the dry yeast with the dry ingredients
rather than mixing it in with the liquids.

In my baking experience (fairly limited relative to many of you folks)
you end up having to tweak the recipe regardless any time you change
something important like the type of yeast used so what I'm aiming for
is to get them close and then let them tweak to their satisfaction.

I'm still doing Google searches here in rec.food.baking and
alt.bread.recipes on yeast, but haven't found anything on Rapid Acting
yeast needing a different temperature than standard Active Dry yeast,
nor was it mentioned on the yeast manufacturer's web sites that I
looked at so if someone would care to knowledgeably address this I'd
appreciate it.

I did find this though...

>From: Roy Basan )
>Subject: dough wont rise, help!
>
>If I make bread with powdered instant(rapid rise yeast) I mix the
>yeast with an equivalent volume ofwhite flour(omit the sugar)then add
>the lukewarm water to make a thin paste, then let it stand for 15
>minutes(until bubbly).Another alternative way is to blend it with the
>flour before incorporating other ingredients.Sometimes hydration in
>water is not desirable(it will leach out enzymes that are detrimental
>to the dough as well as glutathione,a reducing substance brought about
>by decomposed yeast cells that will weaken the dough).Further these
>reducing materials are mostly formed during improper hydration of dry
>yeast(or given off by old yeast)including these instant/rapid rise
>yeast.

Sounds like with the Rapid Acting stuff you could go either way. Mix
it first with water and some flour (or sugar) or just add it straight
to the dry ingredients.

......Alan.

--
Curiosity killed the cat -
lack of it is killing mankind.