YEAST HELP PLEASE

So far as I know, the main differences are (1) fresh or dried, and (2) with dried, whether there are additives to help the rise.

Fresh yeast is lovely to work with because it gets to work straight away, but it doesn’t keep very long. Dried yeast is very convenient because it keeps reasonably well (although only a few weeks or two once the tub is opened) but you have to rehydrate and feed it then allow the yeast time to come out of ‘hibernation mode’.

”Instant” yeast is powdered dried yeast with extra additives (e.g. citric acid) that help accelerate its metabolism. It works well but loses its vigour within a few days once the packet is open and the air gets to it. Definitely open a fresh sachet every time.

Overall it’s worth remembering that in general the more time it takes your bread to rise, the more flavour you’ll get. Often it’s worth using just a very small pinch of powdered yeast to make an overnight ‘sponge’ (mix of flour and water) that you then use to raise your main dough :-)

As always, the best way to learn is by experimenting! I’m a big fan of mixing up small quantities of yeast and flour and then taking time-lapse videos of it (easy, with a smartphone) to see what’s going on.

All the different types will work, provided you adapt the method and quantities in your recipe... it’s hard to give completely general rules but you can’t go too far wrong by making sure that the yeast is in a fully active and vigorously growing state before adding it to your dough; and then judging when the dough is sufficiently expanded :-)

As to the adaptation for quantity, within reason it’s just a trade-off between how much you add versus how long the rise will take. As per my previous post however, I’m personally of the opinion that ‘slower is better’ :-)

1. Fresh yeast, sold to consumers in "cakes" or little rectangular packages .  This needs to be kept refrigerated.  Expires quickly once opened, or if left out of refigerator.  I do not use this, so I am unfamiliar with the benefits.  Though it does have some benefit because pizzerias and bakeries are known to use it.

2. Instant dry yeast (IDY). Also known in the US  as "Rapid Rise Yeast" "Fast Rise", or "Bread Machine Yeast."  It __generally__ does not have to be hydrated with water before adding it to the dough mix.  Just the moisture in the dough is enough to wake up the dormant yeast cells. It does not have the protective coating on the teeny tiny granules like Active Dry Yeast does.  

(Be sure to put it in LAST in the bread machine, not touching any liquid, or it will clump and not be evenly distributed.  This is especially important when using the machine's delay timer.) 

Some bakers (not using a bread machine) hydrate (let soak in a little water) Instant Dry Yeast anyway, in order to give it a head start, especially if their dough is not high hydration. 

3. Active Dry Yeast (ADY).  This yeast does need to be hydrated (soaked in water) before adding to the dough mix.  The water in the  dough is usually not enough to get through the protective layer on the granules and "turn on" or awaken the yeast cells. 

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Proving / Hydrating 

The term "proofing" can apply to all three types, but is usually mentioned for Instant Dry or Active Dry.  This involves adding some sugar or flour to lukewarm water (just 1/4 or 1/2 cup) and then adding in all the yeast for the recipe, and looking for some bubbling action to verify ("prove")  that the yeast is alive, and not dead.    This way, you don't have to  wait an hour  or so into the rise to find out if the yeast was dead or alive.  But if your yeast was not past the expiration date, and was kept cool, it is generally not a problem.

But... the main purpose or proofing/proving  is to wake up the dormant yeast cells.  Which is _needed_ (required) for the "Active  Dry" variety, regardless of whether you add a little sugar to see the foam/bubbles.

When you proof/prove/hydrate dry yeast in water, be sure to stir it so that it does not clump.  If it clumps it may not get evenly distributed in the dough.

Fresh yeast  needs to be totally dissolved and dispersed in the water before mixing with flour.

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Interchangeable:

1) Instant dry yeast can be used in most plain recipes that call for Active Dry Yeast.  Unless there is some complicating factor.

2) Active Dry yeast should not be used in a bread machine (there is a work-around if you do not use the delay timer).

3) If the recipe calls for Instant Yeast, use it. (There is a work-around that "may" let you use Active Dry or Fresh.)

4) Fresh yeast should not be used in a bread machine (there is a work-around if you do not use the delay timer.)

5) There is a rule-of-thumb about converting Fresh yeast cakes to/from dry yeast.  (Use the search box, or google, or www.kingarthurflour.com )  But sources slightly  differ on the factor.

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Hope this helps.