Yeast Types

The one that artisan breadmakers typically want to avoid is "rapid-rise yeast". Which, contrary to what many references state, is NOT the same as the "instant yeast" that Floydm recommends. Rapid-rise yeast has additional chemicals added to make it rise, well, rapidly, but it dies faster as well and doesn't work for multiple risings.

In the US, jars of "bread machine yeast" are usually instant yeast.

So go with "instant" or "bread machine", unless you want to get all traditional with moist yeast. But none of my local grocery stores even carry moist yeast anymore.

Personally I think the yeast makers have too many types of yeast - it puts people off. They should stick with moist and instant. I have never had a problem getting instant to rise as fast as I need it to if artisan flavour is not a concern.

sPh

From Tom Lehmann on Pizza Today:

First, there is compressed yeast, also known as wet yeast (or sometimes brick yeast due to the fact it is commonly sold in one-pound bricks).

Yeast in this form is alive and potentially ready to begin feeding and producing all of those useful byproducts we discussed last month. It only needs to be warmed to a temperature of 50 F or more to get this yeast activated and feeding. This is the reason why the yeast must be kept refrigerated at all times.

This is also the type of yeast for which the old admonishment-never allow the yeast to come into direct contact with either salt or sugar-was developed.

What happens here is if the yeast is allowed to contact salt or sugar, either of the two substances will draw the moisture out of the yeast, thus damaging it to a point where it may lose its fermentative properties. In some instances, the yeast may actually be killed.

For this reason, fresh yeast is best used when making fresh dough on a regular basis. It is also widely used by those manufacturers who produce frozen dough. The reason for this is that the yeast cells will be in excellent condition, provided the yeast has not been temperature abused.

Having the cells in undamaged condition allows the production of the highest quality frozen dough. By high quality, I am referring to frozen dough with a shelf life of 19 weeks or more.

The next type of yeast we commonly see is instant, active, dry yeast, also known as instant yeast (it's often abbreviated to IDY).

This type of yeast is unique in that it is either dried and vacuum packaged, or packaged with an inert gas flush. This is what gives the instant yeast its excellent, long shelf life of one to two years, depending upon the manufacturer.

Have you ever wondered about the word "instant" associated with this product? Instant refers to the rate at which this type of yeast absorbs water. If you could look at each one of those rods of yeast under a microscope, you would see that each one has the characteristics of a sponge: many openings, holes and voids that allow water to readily come into contact with the yeast, thus allowing it to hydrate.

This feature allows the instant yeast to simply be put into dough, along with all the other ingredients, without pre-hydration. The fact the yeast is dry allows it to be used in dry mixes for pizza dough or in goody bags containing salt and sugar. Remember, the yeast is dry so there will be no affect of the salt and sugar on the yeast. Just be careful that you don't try to pre-hydrate a goody bag containing salt, yeast and sugar before adding it to the flour.

The third type of yeast we see commonly used is active dry yeast, or ADY.

Active dry yeast must be hydrated before it can be added to the flour. In pre-hydrating active dry yeast, it is very important that warm water be used. Most manufacturers will specify a temperature between 100-105 F. The ADY is then sprinkled into the water and stirred thoroughly, using a hand whisk or a spoon to suspend the yeast in the water.

After stirring, it is important to wait about 10 minutes. During this time the yeast will hydrate, become active and begin producing byproducts, which we will see as small bubbles of CO2 (or even froth on the surface of the yeast suspension). At this point you know the yeast is fully active and ready to be added to the mix.

It is good to remember that you now have wet yeast, which again should not be allowed to come into direct contact with salt or sugar, but you can put it into the mixer along with your other ingredients and immediately begin mixing.

While we are on the subject of talking about warm water, have you ever wondered why the water must be warm?

When the yeast is dried, the cell membrane shrinks, much like a grape will shrink when it is dried into a raison. In addition to shrinking, small cracks, or fissures, also form on the surface of the yeast cells. If the dry yeast were put into cold water, the yeast would hydrate very slowly, allowing the fissures to open up during the hydration process and allow for a flushing effect upon the yeast cells. When warm water is used, the yeast cells hydrate much more rapidly and allow the cracks and fissures to seal themselves, thus preventing the flushing effect.

Earlier, I had mentioned that compressed yeast is the most commonly used in frozen dough and I explained that fresh yeast generally has yeast cells that are in better condition than dried yeast cells. This is not meant to say that compressed yeast is any better than dried yeast, but the fact remains that when subjected to the drying process, either ADY or IDY will have some of the yeast cells damaged to the point of inactivation by the drying process.

These dead yeast cells can create a problem in a frozen dough system. Through the release of a material called glutothione, which is very similar to L-cysteine (the active ingredients in PZ-44), these dead cells can create a softening effect on the dough, especially as the dough ages under frozen storage. The combined dough softening and potential loss of yeast activity due to freezing is the main reason most frozen dough manufacturers elect to use compressed yeast over dry forms.

It should be kept in mind that if you are a small producer of frozen dough-or operate a commissary producing frozen dough-in all likelihood you may not see any difference in the performance of your frozen dough whether it is made with IDY or fresh compressed yeast.