I have seen some food writers say that cornmeal is also mixed in, but I haven’t been able to find this on any manufacturer’s list of ingredients; perhaps this was an old practice that has been phased out and replaced by the items I mention above.
The strains of Yeast Cream that are used for Active Dry Yeast are those that best survive the drying and rehydrating process. Dry Yeast will have only a fraction of the moisture that fresh Yeast does (approx 5% compared to 70%.)
When the Yeast is rehydrated, there is always what is called a “lag phase” of 5 to 10 minutes during which the Yeasties come round, and nudge their buddies, telling them to wake up, too.
Many recipes written during the last half of the 1900s will call for Active Dry Yeast, but it is being replaced in newer recipes and on store shelves by “Instant” or “Fast-Rising” Yeast.
In North America, Active Dry Yeast is usually sold in 3 separate but attached little sachets, about 8 grams each, with each package enough for one loaf of bread; or in small brown glass jars, or in tins with resealable plastic tops. In the UK, it is sold in tins with resealable plastic tops or in 7 gram sachets that come in strips of 6 or boxes of 8.
Some food writers advise not to use Active Dry Yeast for bread machines and to use Instant or Bread Machine Yeast instead. Horsefeathers. North American Active Dry Yeast works a charm in all bread machine recipes; Black & Decker’s recipe booklets even call for Active Dry Yeast, and you couldn’t wish for higher, better loaves. British Active Dry Yeast, however, won’t work in bread machines: it just isn’t as active as North American. You must use the Instant Yeast or Bread Machine yeast instead. Which is too bad, as the Instant Yeast remains a few pence more expensive per sachet than the Active Dry. All of which matters, when you are trying to get your cost per loaf down.
While Bread Machine Yeast, Instant Yeast and Active Dry Yeast now seem to be selling for the same amount of money on supermarket shelves in North America (though price differences remain in the UK), what’s made the Active Dry even cheaper is that you can get it at the bulk stores, at close to 1/4 the supermarket cost of any dried Yeast — Active Dry, Instant or Bread Machine.
Your recipe will likely give you directions on how to rehydrate the Yeast, but here’s a rule of thumb: 1 tsp of sugar in 1/4 cup of lukewarm water (water which feels just barely warm on the inside of your wrist, which should be in the range of 100 to 110F), then add the Yeast and let it sit for 10 minutes without stirring. Then give it a stir, and use in your recipe. The Yeast should almost double up to the 1/2 cup mark; if it stays at about the 1/4 cup mark after 10 minutes, your Yeasties have become mummies and you need to buy new ones.
In bread machine recipes, there is of course no need to hydrate the Yeast first.
Instant or Bread Machine Yeast; Fresh Yeast when not using a bread machine.
One package = 2 1/4 teaspoons = 1/4 ounce = 7 or 8 grams = 1 cake compressed fresh Yeast
You can store this Yeast in the cupboard until the expiration date or until 4 months after opening. The expiration date is for room temperature storage: if you keep the Yeast in the fridge or freezer, it will last for up to a year after being opened.
Dry Yeast was invented during the Second World War.