Like fire, yeast is a powerful force of nature harnessed by our ancestors in food preparation. We have been using yeast to leaven our breads for over 5000 years. As Ryan Lilly says; “Yeast is to flour as action is to ambition. Rising to success requires adding and alternating starters.”
Yeasts are funghi that proliferate as individual or small clusters of cells. This differentiates them from the long, tubular chains of that compose most fungi. Yeasts are found naturally on just about every surface on earth as well as floating in the air.
Yeast helps us to produce bread through its skills in harvesting energy from the sugars found in flour without oxygen, a process called fermentation. In addition to energy, it produces two by-products: carbon dioxide, which adds lift in leavened bread and the alcohol called ethanol, which evaporates in the bread oven. Yeast is an important element in creating light texture and a delicious taste.
Whilst there is much more to be said about the history, science and personality of yeast, let’s focus for now on one aspect of use; yeast conversion for fresh, dry and instant dry yeasts.
Here is a formula you can use to convert the amount of fresh yeast required by a recipe, to the amount you would need if using dry yeast or instant dry yeast. As of our last research we found that dry yeast is not as readily available any longer, while you can find instant dry yeast quite easily. Check the package carefully.
To do the conversion, take the amount of fresh yeast stated in your recipe, and divide it by 2 to reach the amount of dry yeast you would use. To establish how much instant dry yeast you would need, divide the amount of fresh yeast stated in your recipe by 3. So, if you are using instant dry yeast, you would need a third, or 33%, of the amount you would need if using fresh yeast.
Example- based on amounts in VIMEO Video Baguettes & Ciabattas
FRESH YEAST – 100 % 15 g
DRY YEAST – 50 % 7.5 g
INSTANT DRY YEAST – 33 % 5g
Note: Fresh yeast and dry yeast must always be dissolved in tepid to warm water before being added to your dough mixture especially when hand mixing. Instant dry yeast gets added to the flour– in other words, as a dry ingredient.
Availability of dry yeast
In our recent local research we found that dry yeast is almost no longer readily available, and has been replaced by instant dry yeast. Instant dry yeast is very practical to use, has shelf-life at room temperature, and does not fluctuate in its effectiveness. They come in practical small pouches for the casual user. It seems that dry yeast is disappearing very much like fresh yeast became less available over the last decades.
Effectiveness of different instant dry yeast brands
We have tested on our diamond scale that ¼ teaspoon of instant dry yeast is 1.2 g. It is worthy noting that some instant dry yeast brands are not as effective as others. If you find that your dough is fermenting slower than normal, you give the dough a bit more time during the bulk fermentation so that it resembles the rise of your fresh yeast recipe or the recipe that you are used to. It will most likely also take a bit longer for the final fermentation (before you place your loaf in the oven). You are basically allowing more time for the yeast cells to multiply and do their ‘full’ work.
On the next batch you can either choose to ferment longer or increase your instant dry yeast amount for the next batch by a small amounts.
Example (using rounded percentages)
Instead of adding 33% of instant dry yeast (5 g as per example above), add 6 g ( or 40 %) to make up for the lack of activity. Make changes in small increments and monitor. Then lock in (note) the recipe with the brand or type of yeast you are using.
Using and storing fresh yeast
Fresh yeast is often used by artisan bakers, when available, not for its better quality – but perhaps more out of nostalgia and habit. It feels more ‘alive’. It has limited shelf-life (about two weeks) at temperatures of 4 degrees Celsius (in other words, it must be refrigerated). After two weeks, its effectiveness slowly starts to deteriorate. The texture becomes softer and wetter.
View our full instructional video “ Baguettes and Ciabattas” online
Yeast. The word comes to us through Old English, from the Indo-European root ‘yes’- meaning boil, foam, bubble. It does all those things, and more. And would it not be the Egyptians, who construct the largest, most sophisticated buildings in the land, to also harness the tiniest microbe?
Of course, they know nothing of yeast. To them, it is magic.
They are called the ‘bread eaters.’ “Dough they knead with their feet, but clay with their hands,” Herodotus wrote with derision. The Egyptians do not care. They understand their bread is from the gods, for king and peasant alike. They invent ovens to bake this new, breath-filled dough because it cannot be cooked like the flat breads they know first. They construct clay vessels to hold it. They watch it rise in the heat. They add butter and eggs and honey and coriander, and save soured dough from one batch to add to the next. They eat.They live.”― Christa Parrish, Stones for Bread
Additional resources: scientificamerican.com, cn.utexas.edu, insanitek.net