Commercial Yeasts: Fresh, IDY and ADY

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Commercial Yeasts: Fresh, IDY and ADY

Postby Paul » Fri Apr 06, 2012 5:02 pm

Recently, Ray (garlicbuddha) posted a note about fresh yeast and I wanted to pass on a little info on the various types of yeasts available to home bakers to help clarify what each does and why you may want to go for one over the other.

There are generally three types of commercial yeasts available to a home baker: fresh yeast, Instant Dry yeast (IDY) and Active Dry yeast (ADY).

I've not heard of any particular benefit for the home baker to using fresh over Instant Dry Yeast (IDY). The benefit generally comes in for bakeries who use a fairly substantial amount of yeast on a daily basis: it's cheaper than IDY for them and they can order a large amount every week or so and not worry about it going off before they get to the end of their stock. Fresh yeast has a rather short lifespan, about two weeks from packaging if kept refrigerated.

For the home baker, fresh yeast can sometimes be found at the local grocer's in small cubes of about 42g each in the UK, 17g each in the USA, usually in batches of eight cubes, or in larger butter-sized block (500g). Due to it's limited popularity and short shelf life, however, most food stores do not carry it, preferring to stock longer lasting dry yeast instead. If you are extra lucky, you may be able to ask your local bakery for some.

Fresh yeast is also referred to as cake yeast or compressed yeast. It is generally crumbled into a little bit of the recipe's liquid to dissolve before being added.

Fresh Cube
Fresh Block

Instant Dry Yeast (IDY) is easier to source, easier to store and easier to mix in to your dry ingredients. These are the important benefits to a home baker. IDY, once opened but well repackaged, can last up to 6 months refrigerated and up to a year (or more) if frozen. This make purchasing a larger 500g vacuum-sealed brick logical. If kept in a well sealed jar in the freezer, you can transfer a small amount to a small jar kept in the fridge as needed, then use the 4 or 7 grams per recipe needed from there. This makes it very economical and much better value than the three packet strip although space considerations may make that the ideal way to go. IDY is a very fine grain texture and is meant to be added directly to your dry ingredients.

Instant Dry Yeast is also found labelled as: Bread Machine Yeast, Rapid Rise Yeast and Pizza Crust Yeast, among other "marketing" gimmicks.

Close up of IDY
IDY 500g brick

Active dry yeast, on the other hand, is the old circa WWII original dried yeast method. The drying process used was an improvement on the keeping ability of fresh yeast but it has since been eclipsed by the newer IDY process developed in the late 70's. Part of it's use required proofing the yeast in some warm water with sugar until bubbly before adding to the recipe. ADY has (generally) never been used in professional bakeries where most will now have IDY on hand as well as fresh. ADY is like the casette tape of yeast: very popular in it's day but now eclipsed by better technology. Still, many home baking books based (and still base) their recipes on it. One should always try and confirm what the author referred to if they simply mention "dry yeast": if they say something about proofing the yeast in water before adding it to the dough, you know the book uses ADY.

Active Dry Yeast is a rounder grain, about half the size of a pin head. You do not add this directly to your ingredients.

Close up of ADY


You may need or want to convert a recipe's given yeast type to another. To do so, use these guidelines based on WEIGHT (not volume):

To convert from FRESH to INSTANT: Use 40% of the Fresh quantity
To convert from FRESH to ACTIVE: Use 50% of the Fresh quantity

To convert from INSTANT to FRESH: Use 250% of the Instant quantity
To convert from INSTANT to ACTIVE: Use 133% of the Instant quantity

To convert from ACTIVE to INSTANT: Use 75% of the Active quantity
To convert from ACTIVE to FRESH: Use 200% of the Active quantity

For a little more in depth review of the history of commercial yeast, visit Wikipedia here.
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Re: Commercial Yeasts: Fresh, IDY and ADY

Postby garlicbuddha » Sat Apr 07, 2012 1:17 am

Thanks Paul,

I'm lucky in that our local supermarket always has fresh yeast on sale. There is something nice in opening a small block and the "snap" you get in breaking fresh yeast, but i end up throwing most of it away. Geraint pointed out in another thread that instant dried yeast also contains an emusifier, sorbitan monostearate


Is that of any concern to anyone here? I have used both types of dried yeast. I tend to use the Active Dried Yeast but more because it comes in a nice resealable tin!

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Re: Commercial Yeasts: Fresh, IDY and ADY

Postby icemaiden » Sat Apr 07, 2012 8:27 am

I mostly prefer to use fresh yeast. Sainsbury's instore bakeries sell 200g for 59p if you ask them nicely. I take it home and form it into teaspoon sized bits using a 'teaspoon' measure and weigh them to make sure it is about 7g. I then just use one for every teaspoon of IDY that the recipes call for. I freeze these little bits in a plastic tub and at the rate I go I haven't noticed a decline in performance over the 3 or 4 weeks it takes to use up. When I want to use them I just pop them into the warm liquid and let them melt/disolve into the mix before adding the dried goods. If I need half a teaspoon then it's easy enough to cut them in half with a knife while they are still frozen. If I were more organised I'd cut them before I froze them.

At this price it is cheaper than packet yeasts and I have found that packet ones decline if I only use a half a pack for a recipe and leave the rest. I don't think the results are really any different but sometimes the fresh yeast seems a bit more frisky.

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Re: Commercial Yeasts: Fresh, IDY and ADY

Postby Leavened_Heaven » Fri Apr 13, 2012 3:25 am

Thanks for a really informative post (sounds like a spammer but I promise I'm not...)

It seems, as with most areas of baking, to be a matter of much difference of opinion, from "it makes no difference" to "I ALWAYS use fresh". Having finally managed to track some fresh down (as Sainsbury's also), I'll have a go at using it for this recipe. I'll try and do a straight comparison at some stage soon, and make a personal policy decision then!

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