Yeast Facts

Yeast is often considered as an unmanageable and untameable beast by many. Some are even scared to think of baking breads because of the word “yeast” that pops up in the mind when you think of breads. But honestly, there are quite friendly and nice 🙂 You just have to take care of few aspects and you are good to go. Here is a small explanation on what yeast is, how it works, the kinds of yeast, its usage, its storage etc. Most of the information are taken from the internet and I do not claim any originality. It is just my compilation in simple words for many of you who have been asking me various queries on yeast.

Many vegetarians ask me is yeast a living organism?
Well, the answer is YES !! It is alive.

What does yeast do?

It basically converts the sugar into carbon di oxide. When the yeast mixes with the lukewarm water, it gets activated or in other words, it wakes up and metabolizes the sugar and releases carbon di oxide. So, when we knead the dough, gluten gets developed and these carbon di oxide gets trapped in the web as the dough proofs. And when we bake the bread, these gases leaven the bread i.e., rises the bread and the dough alters its form. So, the more we knead, the better gluten formation occurs and the dough becomes soft and elastic.

That is the reason why cookie and cake dough are not meant to over mixed, because we do not want the gluten in the flour to get stronger.

Now once the kneading is done and gluten is formed in the dough, the next step is proofing.

What is proofing?

This is the stage where the yeast does maximum work. It eats up all the sugar in the starchy flour and releases carbon di oxide into the gluten web. Hence the dough rises in volume.

What happens during baking?

When the shaped loaf hits the oven, it has already undergone 1-2 rounds of proofing. All the gases that are created will expand due to the heat and the water content in the dough will get converted into steam and both these will inflate the rolled dough like a balloon and the bread will get its final rise in the oven.

What are the types of yeast?

Fresh Yeast: It is mostly used by commercial bakeries and is often found in the form of blocks. The main disadvantage is that it has a very short shelf life, which makes it a bit difficult for home bakers. So, unless you make bread very regularly or almost daily, they are not very feasible. It can stay in the refrigerator for 2 weeks if it is packed well. If you notice any grey spotting on the yeast block, please discard it.

Active Dry Yeast: It is in the dehydrated (water is removed) form and is granular like mustard seeds. It is sold in vacuum packs and has a good shelf life, if stored in air tight containers inside the freezer/refrigerator. ( I store mine in the freezer ) Since it is treated to remove the  water content, some of the yeast granules are already dead. To activate the yeast granules which are alive but still in dormant form, you need to mix it with lukewarm water ( water should not be very hot and you should be able to dip your fingers in it easily ) and little sugar and wait till it gets frothy. Hot water will kill the yeast.  If doesn’t bloom, discard and buy a new pack.

Instant Yeast: As compared to active dry yeast, instant yeast are subjected to milder conditions during  dedhydrating. This is another variant of dry yeast and as the name suggests, it acts pretty fast and can be added directly to the flour.  But if you may choose to proof it first and then add it to the flour, you can very well do so. This will help to check the viability of the yeast in case you are using it after a long gap.

Wild yeast: This is created at home using flour and water and used to make sourdough breads…. I don’t have any knowledge on it, so I am not venturing into it 🙂

How to store yeast:

Unopened packets can last for a long time in dry conditions. Once opened, yeast packet can be stored in small air tight glass or plastic containers and kept inside the freezer compartment for up to 2 years. Just take the container out of the freezer ( no need to thaw them ), simply measure as per your recipe and pop the tin back into the freezer soon.

What are factors which effect the behaviour of yeast?

Now, people often complain that their bread didn’t rise, the yeast was not getting proofed etc… Though I have said in the beginning that these yeast are quite friendly, but they can be a bit moody too at times. So, lets briefly see the reasons as to why the yeast didn’t get frothy while activation.

1. Temperature: Yeast is very sensitive to temperature. It gets activated at around 10 degrees celsius. It is more active between 21-27 degrees celsius and gets ineffective after 49-50 degrees celsius. So, always use lukewarm water for proofing yeast. Hot water will instantly kill the yeast. In our warm Indian conditions, it is ok to use normal room temperature water for proofing. 

2. Sugar: Yeast has a sweet tooth and feeds on sugar 🙂 But the starch in the flour is enough for them. By adding extra sugar to the dough, we are actually speeding up the fermentation. But as we say too much of anything is harmful, so more sweeter the dough is, the more time it will require for proofing. Sugar can be replaced with honey, agave nectar, maple syrup, some fruit juices etc.

3. Salt: Yeast hates salt, as salt slows down its fermentation. So, make sure the yeast and salt doesn’t come into much direct contact with each other. But remember to add salt to your bread, because salt helps in improving the taste of the bread, gives a nice colour to the crust and helps in getting a sturdy crumb.

4. Fat: Any form of fat like butter, oil or egg in small amounts will help the dough to rise better and gives a crispier crust. But too much of  fat will reduce fermentation and the bread wont rise much.

5. Dairy: The sugar found in milk i.e. lactose is not fermented, so milk slows down yeast fermentation.

When to refrigerate the dough?

If your dough is already proofed once and you do not have the time to bake now, you can store the dough inside the refrigerator. Punch out the gases and then store the dough in an air tight container inside the refrigerator till you are ready to bake it. Take it out of the oven, thaw it, shape it and then proof it for the second time and bake it as per your convenience. Or at times just to slow down the fermentation, you can refrigerate the dough and allow it to rise slowly. This enhances the flavour of the bread. You can reduce the yeast and allow the dough to rise very slowly inside the refrigerator.

At times you would have experienced that your dough rises much faster after shaping and you haven’t even preheated your oven, then you can punch down the loaf, remove some of the gases, reshape it and then wait it to proof again and then bake. You can get an okayish bread if not perfect. I prefer to refrigerate after the first proofing if at all I have to.

I will post a comparative study of baking a garlic bread in which (1) the dough was refrigerated for 5-6 hours after the first proof and then shaped and baked and (2) the dough was shaped and then refrigerated for few hours and then baked.

In cold areas, you can proof your dough in your microwave. Just keep the dough in the microwave along with a cup of hot water. This temperature inside the microwave is sufficient for the dough to rise. Or you can simply keep the lights of your oven on and keep the dough inside the oven for proofing. ( No need to put the oven on. )

How much yeast is to be used?

A sachet of yeast is usually 7 gms which is roughly 2 1/2 teaspoons. More yeast makes the bread rise faster. But the main question is do we really need to make the bread rise faster? Also more yeast makes the bread taste a bit yeastier and I am sure many of you don’t like this taste.

I have read and I can speak from my bread baking experience ( though it is very less ) that lesser the yeast, slower the bread rises, but much better it tastes !! There is enough chance for the flavours to develop well and give a nice texture and taste to our bread. Of course, if we are in a hurry, we can always increase the quantity of yeast a bit and get things faster.

Another fact is, the characteristics of your kitchen. If you bake bread quite regularly, your kitchen is full of wild yeast, and any dough you make there will rise vigorously. If you seldom bake bread, or are just beginning, your kitchen will be quite “sterile;” your dough won’t be helped by wild yeast, and will rise more slowly than it would in a more “active” kitchen.

As you get more and more comfortable with bread baking, you can reduce the amount of yeast. From what I read, the general principle is to to use 1-2 % of the flour by weight, i.e., if you are using 400 gm flour, use around 4 gm yeast by weight, which will be around 1 1/2 tsp. But I feel in our hot Indian weather we can still reduce it further. I have been able to bake quite soft and well risen bread with as much as only 1/2 tsp instant yeast for 400 gm all purpose flour.

Too much yeast can also make the bread go flat by releasing gases even before the flour is ready to expand.

Over rising the bread also yields a flatter bread and it will taste yeastier too. This happens because all the yeast will eat up the sugar and the gluten in the flour will be unable to stretch any further.

Effect of kneading on yeast:

Kneading doesn’t directly effect yeast. It helps in the gluten formation and creates enough web to hold the gases released by the yeast after eating up the sugar. Kneading for 1 or 2 minutes after the first proofing is also important to increase the extensibility of the gluten, i.e., will help the dough to rise even in the oven.

Yeast conversions:

Some people use instant yeast and active dry yeast inter changeably. Whereas some mention that active yeast should be almost 1.5 times of instant yeast. Whereas some say active yeast and instant yeast can be interchanged with the same proportion. But instant yeast will work faster and help the dough to rise faster as compared to active yeast. So, in case you have only active yeast with you, do not be dissuaded from trying breads. If the recipe calls for 1 tsp instant yeast, you can very well replace it with either the same amount or slightly higher amount of active yeast and maybe you might have to wait longer for the dough to double in comparison to instant yeast.

Honestly speaking, since I have started baking breads I have been using Gloripan instant yeast and I have finished a big pack of 500 gms in just 7 months 🙂

Also fresh yeast should be almost double ( some say triple ) of instant yeast.

Lastly, one thing I can surely say by experience that little variation in the amount of yeast specified in a recipe doesn’t make much of a difference. It can only bring some difference in the proofing timings. But then the proofing timings depend on a lot of other factors too. The kind of flour, the sugar and fat content in the flour, the weather conditions, temperature of your location and so on. Whole wheat will take longer time than all purpose flour to double and multigrains will take even longer.

So, befriend these tiny little creature called yeast and enter into this beautiful world of bread baking. It is highly addictive and therapeutic and acts as a great stress reliever. Bread baking is a beautiful combination of art, science, magic and involves loads and loads of patience. Happy baking…

Thanks for reading. Please feel free to add any comments, suggestions or a difference of opinion.