Science of Bread: Bread Science 101 | Exploratorium Chinese Taro Root Buns From Chinese baozi to Armenian lavash, bread comes in thousands of forms. What do they have in common? On the most basic level, they all involve cooking a mixture of milled grains and water. Armenian lavash Imagine a continuum of breads, ranging from the thinnest flatbreads to the fluffiest brioche. Some are amazingly simple: Matzoh, for example, is nothing more than flour and water, baked until crisp. Raised breads, on the other hand, involve the complex interactions between flour and the leaveners that give them their porous, tender quality. Leaveners come in two main forms: baking powder or soda and yeast. Matzoh Baking powder or baking soda work quickly, relying on chemical reactions between acidic and alkaline compounds to produce the carbon dioxide necessary to inflate dough or batter (more on this later). Baking powder and baking soda are used to leaven baked goods that have a delicate structure, ones that rise quickly as carbon dioxide is produced, such as quick breads like cornbread and biscuits. Saccharomyces cerevisiae, or baker's yeast.

Photos courtesy of Peter Hollenhorst and Catherine Fox. Yeast, on the other hand, is a live, single-celled fungus. There are about 160 species of yeast, and many of them live all around us. However, most people are familiar with yeast in its mass-produced form: the beige granules that come in little paper packets. This organism lies dormant until it comes into contact with warm water. Once reactivated, yeast begins feeding on the sugars in flour, and releases the carbon dioxide that makes bread rise (although at a much slower rate than baking powder or soda). Yeast also adds many of the distinctive flavors and aromas we associate with bread. For more on yeast, check out our fun yeast activity . But leavening agents would just be bubbling brews without something to contain them. Heres where flour comes in. There are lots of different types of flour used in bread, but the most commonly used in raised bread is wheat flour. This is because wheat flour contains two proteins, glutenin and gliadin, which, when combined with water, form gluten. As you knead the dough, the gluten becomes more and more stretchy.

This gum-like substance fills with thousands of gas bubbles as the yeast goes to work during rising. gluten animation To learn more about gluten, check out the gluten animation . Starch, a carbohydrate that makes up about 70% of flour by weight, also gets in on the act. When starch granules are attacked by enzymes present in flour, they release the sugars that yeast feeds on. Starch also reinforces gluten and absorbs water during baking, helping the gluten to contain the pockets of gas produced by the yeast. Sometimes, a baker will let the dough rise several times, allowing the gluten to develop more completely and the yeast to add more of its flavors. When the dough is finally cookedeither in an oven, over a fire, or in a steamer, depending on what kind of bread youre bakingthe yeast inside it continues feeding, and the pockets of gas in the dough continue to expand. As the temperature of the cooking dough rises, the yeast eventually dies, the gluten hardens, and the dough solidifies. Et voilà! Bread! For more about bread science, check out these links ! Why does Yeast Make Bread Rise? (with pictures) Why does Yeast Make Bread Rise?

Last Modified Date: 23 December 2016 Copyright Protected: 10 hilariously insightful foreign words If you’ve ever taken a bite of bread you’ve made, you may wonder how simple ingredients like flour, salt and yeast can produce raised, sometimes wonderfully bubbly bread. It makes people a little squeamish to know it that yeast makes bread dough rise because it is a live single-celled organism. Specifically it is a variety of fungi called Saccharomyces cerivisiae, which is harnessed to eat, drink and be merry, before dying a quick death when exposed to oven heat. You can buy several different types of yeasts on the market. The first of these is called live or fresh yeast. This is relatively unstable, requiring refrigeration, and it has a very short shelf life. Dried versions, sold in packages or cubes is essentially cells of Saccharomyces cerivisiae, which are waiting to be activated. Like many fungi types, yeasts for bread dough responds to warm water, which begins to bring the little cells to life. Then when exposed to sugars in bread and in flour, it begins to eat, digesting portions of these sugars.

This eating process goes on for a short period of time only. Eventually the yeast will die within a few hours, especially if the dough is allowed to grow cold or exposed to too much air. Don’t feel too sorry for it when you have a slice of bread, as its life would be short under any circumstances. At least by using it for bread or wine, you get to give this fungus a happy and full life. It might be embarrassing to the yeast to have to admit that this rapid eating/digestion cycle makes it just a trifle gassy. As Saccharomyces cerivisiae is feasting, it begins to release gas bubbles of carbon dioxide, and small amounts of ethanol alcohol. These bubbles, trapped in the bread dough, cause the rising action with which we’re familiar. This is why bread making can be time consuming; you’ve got to let this fungus work for a couple of hours in order to sufficiently rise dough. Once dough has been acted upon by fungi, not all of the cells are quite dead. Putting the bread in the oven is relatively macabre, from the standpoint of the yeast (if it had a point of view).

The heat from the oven makes remaining cells go into overdrive, madly munching away at the sugars and expelling carbon dioxide prior to expiring from the oven heat. This is why bread continues to rise during its early cooking stages, and then may deflate slightly as cooking continues. There are a few things that inhibit these microbes from their natural function. Too much salt can halt its rising action. Therefore bread dough recipes usually contain a little salt and a little sugar for balance. Shortening and animal fats can also inhibit the fungi, and you’ll note that breads that have butter in them, especially salted butter may not have the same rise due to the butter’s presence. Sometimes inactivated or dry yeast unfortunately dies before you get a chance to use it. This is why many bakers use a proofing process, adding a package to warm water to make sure the yeast is alive before combining it with flour. Within a few minutes of exposure to warm, not hot water or milk, the fungi begin to bubble up and expand if it is alive.

Ad anon344702 Post 30 I liked the article and understand the basic chemistry of adding acid to yeast in order to facilitate rising; however, and this is what I was hoping to ascertain from the article, this source does not direct me to the ratio of vinegar to flour. anon319648 Post 28 Not that it really matters, but "ethanol alcohol" (from the article) is over-specified. It would simply be ethanol or ethyl alcohol because the "ol" at the end of the ethanol implies it is an alcohol, which is a functional group that behaves in a certain manner. anon312712 Post 27 My daughter and I conducted a science fair project to see which "food" would cause the yeast to produce the most "gas". The two ingredients that did the best were when yeast was mixed with flour and when it was mixed with pancake syrup (high-fructose corn syrup). Between these two, do you know why the yeast/flour mixture produced more gas then the yeast/syrup mixture? anon309170 Is there any harm to let yeast bread rise for 13 hours?

andee Post 24 I have never used live yeast and wonder if this works the same as dried yeast? The biggest reason I probably haven't used this is because it has such a short shelf life. I never know when I am going to be in the mood to bake some bread and like to keep packets of dried yeast on hand. I usually use the rapid-rise yeast, which doesn't take nearly as long to make the dough rise as the regular yeast. I have also had problems with my bread deflating and sinking after it had been in the oven for a while. Once I started adding some dough enhancer to my batter, this made a big difference. myharley Post 23 I finally got in the habit of taking the temperature of the water I used when I dissolved my yeast. Before doing this, I would just guess when the water was lukewarm and this ended up in many loaves of bread that didn't rise. If the water is too hot or too cool, the yeast won't respond the way it should and you will be disappointed.

Now I use a handy thermometer so I don't have to guess when the water is at just the right temperature to dissolve the yeast, yet not kill it off before it goes in the oven. sunshined Post 21 Baking bread can be a challenge even though it only requires a few ingredients. I have learned a few things from trial and error, but every now and then, still have a loaf of bread that doesn't rise like it is supposed to. I got in the habit of proofing my yeast and know that if it gets bubbly on the top it is good to go. I also watch the expiration date on the package, but if it is past the date and the yeast still proofs, it will be OK for your bread. Yeast breads are my favorite type of breads but sometimes if I want something that doesn't take as much time I will bake quick breads . Baking things like banana bread and muffins don't require yeast and they still rise because of the baking soda that is in them. As far as traditional bread goes though, I don't know of a way of getting it to rise without using yeast.

SarahSon Post 20 @surreallife: Not only do changes in temperature affect yeast, but humidity levels do as well. We have a lot of humidity during the summer months and I have to watch my bread more closely when we have high levels of humidity like this. It is hard to think about yeast actually being a fungi when the end product is such delicious bread. I have always enjoyed baking my own bread and feel like the time is well worth it. There is nothing better than a slice of warm bread from the oven with a little bit of butter and honey on it. surreallife Post 13 To Clayton: I know that when you bake regular bread, sweet bread, pastry or anything else involving yeast, you have to keep the oven door closed for the first 20 minutes of baking. Only after 20 minutes you should open the oven door and check on the progress. Yeast is very finicky and can not handle changes in temperature. anon155480 Post 11 This quick, fast, easy to read article made it so easy for me to study for my seventh grade science test. Thanks so much. anon150004 Thank you!

This really helped with background info for my science fair project! anon116712 My bread falls when I bake it. Why? --Clayton anon111880 Post 7 does anyone know any more resources on yeast bread? i need more help on teaching myself how to make yeast bread! motherteresa Post 2 nhusein - There are two things I can recommend for your bread making adventure. If you have to leave while your dough is rising, do not put it in warm oven, since heat speeds up the rising action. Cover your bread with a clean kitchen cloth, and leave it at room temperature to rise. This process will take longer, and give you more time for your errands. Then when you come home if the dough did not grow enough, you can put it into the warm oven for a while before baking. Second, I am not positive about this, but I think if you kneed the dough one more time and let it rise for the third time, I think it will turn out reasonably well. But whatever you do, do not give up. Somehow when you bake your own bread it tastes so much better, and also after a while you will get the feel for it. Happy baking!

How To Make Bread : The Reluctant Gourmet G. Stephen Jones • July 17, 2012 • 19 Comments Here’s How To Make Great Bread At its simplest and most straightforward, yeast bread is made up of flour, water, salt and yeast. That’s it. Let me list them again: flour, water, salt, yeast. This page will teach you in detail what you need to know to make great bread at home but if you want to get right into the process, check out my Basic 4 Ingredient Bread Recipe here . Just four little ingredients, but never have four ingredients sparked such fear and awe. People say in reverential tones, “I would love to make homemade bread like my mom!” All kidding aside, making bread can be a very intimidating proposition, even for the most seasoned home cook. Someone who doesn’t think twice about putting together a traditional cassoulet with an ingredient list as long as their arm might experience a pang or two of doubt when faced with a bread recipe with those four little ingredients. It’s All In The Technique Baking bread is really all about technique. It’s about developing a feel for the ingredients. And you can’t do that without practicing.

Let’s all swallow our fear and take a closer look at the magic that is yeast bread. Remember, flour is cheap, so if you really want to do this, get ready to practice. First, we’ll take a brief look at bread’s basic ingredients and find out what makes them tick. Then, we’ll address the necessary equipment and techniques you must master to make great bread. Last, we’ll look at additions and/or substitutions you can make with the basic ingredients to change the taste, texture and look of bread. Take a deep breath, and get ready to get up close and personal with one of the oldest prepared foods known to man: bread. What’s In The Bread Flour provides bulk and structure to the bread. Wheat flour, specifically, contains two proteins, gliadin and glutenin which, in the presence of water, combine and produce gluten, the stretchy protein substance that lets wheat breads rise, rise, rise, and then set, locking in the cells where the air bubbles used to be. The higher the protein content of the flour, the more gliadin and glutenin are in it, and the more gluten will form. The flours highest in protein are made with hard winter wheat.

Look for them labeled as Bread Flour or even High Gluten flour. Water provides for gluten formation and yeast reproduction. Without water (either straight water or as a component of another liquid, such as milk), all you have is a pile of flour, salt and yeast. No amount of tossing together will yield a dough unless water is added to the mix. Water re hydrates yeast and activates gluten formation. For bread making, harder water works better than soft water because harder water will yield more stable dough. Salt gives bread flavor, and it also inhibits yeast growth. This might sound counterintuitive, but without the presence of some salt, yeast growth will continue until the flour matrix can no longer support it, and your bread will deflate. Too much salt, and your yeast won’t give you enough rise. Too little, and your bread will rise too much. The trick is in getting the right salt to yeast ratio. Yeast are single celled organisms that live solely to eat sugars, give off gasses, and reproduce. In the US, your choices for yeast are fresh, or cake, yeast, active dry yeast and instant, or rapid rise yeast.

For a home baker, fresh yeast is difficult to find, can get moldy if left too long in the refrigerator, and can be temperamental. Many bakers swear by fresh yeast, but there are more standardized choices for the home baker. Rapid rise, or instant yeast, is a relatively new type of dried yeast. It can be added along with dry ingredients without the need for proofing, and it produces a very rapid rise. However, what you gain in time, you lose in flavor, so the third choice is probably the best. Active dry yeast is just that—active yeast that are dormant until you add them to water. Active dry yeast does better if you proof it first—add it to slightly warm water with a bit of sweetener (for food) until it gets bubbly and creamy. When using a recipe that calls for fresh yeast, use 1/3 to ½ of what is called for. For example, for 1 oz. of fresh yeast, you will use 1/3-1/2 ounce (approximately 9-14 grams) of active dry yeast. What Equipment Do I Need? The absolute essential pieces of equipment necessary for baking bread are two hands and an oven. Honestly.

Purists will mix and knead their dough right on the counter—no bowls necessary. For most of us, though, it’s nice to have a large, heavy bowl on a non-skid base (a damp towel will do) and a scale. If you are going to be baking a lot of bread, you might consider investing in either a baking stone or just lining the bottom of your oven with a clean unglazed terra cotta tile. If you are interested in making homemade bread but not so enchanted with the idea of kneading for ten or fifteen minutes, invest in a very sturdy stand mixer with all metal gearing and a dough hook. Loaf pans of different sizes are nice to have as well, for sandwich bread, but wonderful breads can be made right on a stone. Steps To Great Bread There are quite a few steps to making bread. Don’t worry, most steps flow naturally from one to the next. Here they are: scaling, mixing, fermenting, punching, dividing, rounding, benching, panning, proofing, baking, cooling and storing. Whew! First, you have to measure/weigh all your ingredients, then mix them together. This is where the kneading happens.

Then, you have to give the yeast a chance to work, or ferment. (That’s where lots of recipes tell you to “let dough sit in a warm place until doubled in bulk”). After that, you need to gently press out the gasses in the dough and redistribute the yeast. After that, you’ll divide the dough in pieces the weight that you need (if you’re just making one loaf, you’ll of course skip that step). Next, you’ll round your dough and let it hang out, covered for a few minutes. These two steps are optional, but follow them, if the fermentation has really heated up your dough. The rest period gives the dough a chance to cool off a bit—you don’t want to kill those little yeasties by getting them too hot before they’ve given you all the rise that they can. After that, you’ll pan up your dough, and let it proof in the pan. Last, you’ll bake, cool and then store (or eat) your creation. The step that most of us have the most difficulty with is mixing.

Two questions come up: “How do you know when you’ve put in enough flour?” and “How/how long do I knead?” I’ve seen the same recipes you’ve seen. Ones that say “5 to 6 cups of flour.” How frustrating is that, not to know exactly how much of an ingredient we’re supposed to put in something?! It kind of makes you get a little hot and sweaty as you slowly keep adding flour, hoping that the dough will eventually look “right.” The sweating continues as you frantically knead, eyes on the timer. When it goes off, you still wonder, “Have I done enough? How do I know if I have done enough?” Let’s look at these techniques one at a time. Mixing the Dough First, almost any bread recipe will give you a range for the amount of flour called for. This is because, on any given day and depending on the protein content of your particular flour, it will accept more or less water depending upon the humidity and temperature in the air and the humidity and temperature of your flour.

If making a standard, four ingredient bread in a stand mixer, a good rule of thumb is to add the last few ounces of flour a bit at a time, stopping when the dough doesn’t stick to the sides or bottom of the bowl when kneading. If you’re making the dough by hand, knead in the last few ounces a bit at a time until the dough is no longer sticky. Even that is a vague instruction: add flour until the dough is soft and smooth, not wet and sticky, but not completely dry, either. (See why I say that this takes practice)?! To get a better feel for this, make your dough with a stand mixer, and then take it out of the mixer bowl when it clears the sides and bottom. Now you can examine it for feel and texture before you knead. Here’s another rule for you: never add more than the maximum flour called for in the range. If you have to err, err on the side of too little flour rather than too much flour—a bit too little flour will give you a very good rise; too much flour will yield a dense loaf. Now, on to kneading.

First, here’s a quick definition: kneading is the process by which you align and elongate gluten strands to develop them to the point that it can hold the gasses that the yeast give off. This makes your bread rise and then set in the oven. The more well-developed your gluten “web,” the more gasses your bread will hold, the higher it will rise and the more open and airy its texture. Kneading also helps to evenly distribute the yeast and the gasses it creates throughout your dough. This will result in a more even crumb in your finished loaf. Everything you try so hard to avoid doing to pie dough, you try to do when making bread. Pie dough = minimal mixing. Bread dough = long mixing time. Pie dough = short, weak (or no) gluten strands. Bread dough = long, tough gluten strands. You can accomplish kneading in a variety of ways. As long as you have enough water in your dough and work it well, you’ll get good gluten development. The most-often described method of kneading is to push the dough away from you with the heel of your hands, fold the dough over, give it a quarter turn, and do it again.

I’ve seen people lift the dough up and slap it on the table to develop the gluten. The trick is to work the dough as a continuous mass – if you tear the dough into little pieces, you break the gluten strands you’ve worked so hard to form. So, however you choose to knead, put some muscle into it, put on some good music, and develop a rhythm. The next trick is in knowing when you’ve kneaded the dough enough. When your dough is well kneaded, it should be very smooth and springy—it should bounce back when you pull on it or poke it. Windowpane Test You can also double check to see if you’ve got good gluten development by doing the “windowpane” test. Take about a one ounce piece of your dough, shape it into a ball and then start pinching it flat like a little pizza. Once you’ve gotten the dough thinned out, spread it out with your fingers. If the dough stretches until translucent, and you can see the gluten strands, you’re done. If the dough tears or doesn’t stretch to the point of translucence, keep kneading.

Some cookbooks warn you not to over-knead to avoid breaking the gluten structure down, but if you are using bread flour and kneading by hand, you shouldn’t have to worry about that. If using a stand mixer set on low for kneading, check your dough after 5 minutes and every minute after that to guard against the possibility of overworking it. Now that you have an idea of the function of the basic ingredients of bread as well as the fundamentals of making it, check out this basic 4-ingredient bread recipe . It will walk you through the entire process in simple step-by-step instructions. Substitute Ingredients To Make Different Types of Bread There are many kinds of breads on the market as well as products made similar to bread but are know as something else like bagels, pizza, croissants, cinnamon rolls, etc. They may all be based on the basic four ingredients in classic yeast bread, but these substitutions are important for the final end product. To learn more about these bread ingredient substitutions and how they change the characteristics of the bread, click on the link. What makes bread dough rise What makes bread dough rise?

Our whole-wheat bread is made from five simple ingredients - honey, whole wheat flour, water, salt, and yeast. If you've ever seen a loaf of bread being made, you've probably noticed that it's much smaller when it's in its dough form, growing bigger through the time it's fully baked. This "bread rising" happens when the yeast and honey are mixed together, the yeast feeds on the honey and gives off a gas, called carbon dioxide. This carbon dioxide gets trapped in the bread dough, causing the dough to rise and helping give our bread its wonderful taste! To find out how carbon dioxide is created, similar to what happens when a loaf of bread rises, try this simple experiment at home: a glass bottle (12 ounces to 20 ounces in size will work) a balloon 5 ounces of luke-warm water 1 tablespoon of honey a package of dry yeast Here's How: 1. Fill the glass bottle with 5 ounces of luke-warm tap water. 2. Add the honey, and swirl it around in the water until it dissolves. 3.

Open the packet of dry yeast and add it to the water and honey solution, and swirl the bottle a couple of times to distribute the yeast in the solution. 4. Put the balloon over the mouth of the bottle. Check back in roughly 30 minutes. What's happened? As the yeast ate the honey, carbon dioxide was formed which caused the balloon to partially inflate. When we add yeast to the honey in our bread dough, the same thing happens, causing our bread to rise. This process, the yeast eating the honey and creating carbon dioxide, is called fermentation. Fermentation helps give our bread its great taste, and also causes our bread to rise from the time it's in its dough form to the time it's fully-baked. How Does Yeast Make Dough Rise? How Does Yeast Make Dough Rise? 2007.10.16 2014.07.25 | Filed Under: Accomplishments The tiny, rounded, colorless one-celled plant called yeast floats through the air everywhere, but it is responsible for making all our cakes and breads rise to a nice, fluffy texture. This happens because yeast creates chemical reactions on the starch and sugar in the cake or bread batter.

Here’s how it works. Yeast cells reproduce very rapidly no matter where they are. This reproduction goes on through a process called budding. In budding, each tiny cell swells, and soon the swollen part separates from the main cell. The new tiny cell then goes on to grow to full size on its own and the budding process continues to repeat itself. During this growth process, the yeast cells produce substances called enzymes. So when the yeast is added to cake or bread dough, one enzyme goes to work on the flour, changing the starch in it into sugar. Another enzyme then takes over and changes the sugar into alcohol and a gas called carbon dioxide. This gas spreads through the dough in the form of bubbles. As the dough bakes into bread and cake, the heat causes the alcohol to evaporate and the bubbles to break. This leaves the tiny air pockets in the final bread or cake, making it light and fluffy. Before yeast was manufactured commercially, women did their baking by mixing flour, salt, sugar, and potato water, and letting yeast cells in the air supply the enzymes!

Read More yeast is a fungi, not a plant :) Anonymous My children and I bake bread and cinnamon rolls every Sunday for the week and they always ask how does the dough grow bigger! This site has helped me explain that. Thanks! Very helpful and easy to understand. wierdo bob ya yeast is a fungis like a mushroom jimmay1963@yahoo.com yeasts are fungi. yeast is a fungus. get it straight!:) Scientist Yeast is a fungi, not a plant! Princess :) I know that yeast is a fungi not a plant…. Rosnah Mahmood Yeast & Baking Lessons - Rising & Ripe Test (First Rise) | Red Star Yeast Yeast & Baking Lessons Rising & Ripe Test (First Rise) Rising & Ripe Test (First Rise) When making yeast bread, the kneaded dough has to have some rise time. During rising, the yeast ferments (eats) the sugar and develops the dough. Rising also improves the flavor and texture of the bread. After kneading, round your dough into a ball. Place the dough ball in a lightly oiled, large mixing bowl. The dough should be turned over to oil the top so that it doesn’t dry out.

Cover the bowl loosely with plastic wrap, foil, or a towel. Let the dough rise in a warm, draft-free location. Ideal rise temperatures are between 80°F – 90°F; higher temperatures may kill the yeast and keep the dough from rising; lower temperatures will slow the yeast activity which will increase your rise time. Suggested Rising Methods 1. Oven Rising The oven is an ideal place for rising. For an electric oven or a gas oven with the electronic ignition, heat the oven at the lowest setting for one or two minutes, then TURN IT OFF. In other gas ovens, the pilot light will provide enough warmth, so you don’t need to turn it on at all. The oven temperature should not exceed 90°F during the rising time. Place a pan of very warm water toward the back of the oven to provide moisture, which keeps the dough soft during rising. Place the covered bowl or pan of dough on the center rack and close the door. 2. Microwave Rising The microwave oven can also be used for the first rising of doughs. Place 1 cup of water in a glass measuring cup in the microwave. Heat on high for 2 minutes.

This creates a moist environment to keep the dough soft during rising. Place covered bowl of dough in microwave and close the door. 3. Warming Drawer Rising Put 1 cup of very hot water in a glass measuring cup or small bowl in warming drawer. This adds moisture and will keep the dough soft during rising. Turn knob to low or “proof”. Place covered bowl of dough in warming drawer and close door. Ripe test (First Rise) Many factors, including the recipe, room temperature, and humidity, will determine how long it takes for your dough to rise. Yeast dough is considered “ripe” when it has risen enough – usually doubling in size. The ripe test determines if the dough is ready to be punched down and shaped. Gently stick two fingers in the risen dough up to the second knuckle and then take them out. (Click on picture for larger view) If the indentations remain the dough is “ripe” and ready for punch down. If not, cover and let the dough rise longer. Repeat test. (Click on picture for larger view) » Making Bread – Use Yeast or Baking Powder? Making Bread – Use Yeast or Baking Powder? When you bake bread, should you use yeast or baking powder?

Bread dough rising Baking powder or baking soda both contain sodium bicarbonate, a salt. Baking powder is used to cut the time required to rise and bake bread. So, if your main goal is to make bread as fast as possible, then baking powder is a better choice. Many bread companies that care most about saving time and increasing their profits will bake their bread using baking powder. If you want bread with higher nutritional value and better flavor, then yeast is the way to go. It takes longer for the yeast to make the bread rise compared to using baking powder, but the increase in nutrition and flavor is worth it to me. Yeast makes CO2 bubbles in bread dough Back in 1921, the American Journal of Physiology had an issue with an article titled: “The Nutritive Value of Yeast in Bread” The authors were concerned that the increased use of baking powder instead of yeast might reduce bread’s nutritional value. They performed a study on rats and found a substantial difference between standard bread and bread made with extra yeast. Rats fed bread with extra yeast were heathier looking and weighed more.

Rat fed standard bread Rat fed extra yeast bread The rats in one group were fed white bread, while the rats in the other group were fed bread made with extra yeast. The high-yeast bread was made using six times as much yeast as was used in making the standard bread. The only other difference was that the high-yeast bread was made with 6 teaspoons sugar while the standard bread was made with 3 teaspoons sugar. The rats of both groups weighed the same at the beginning of the study. At the end of the study, the rats fed high-yeast bread gained three times as much weight as the standard bread group. The article makes the conclusion that yeast increases the water soluble B vitamin content of bread and increases the protein quality of wheat. Yeast as an Antineuritic One interesting line in the article said that yeast is known to contain an antineuritic substance. What’s that? It acts to prevent inflammation or degenerative lesions of nerves. Neuritis is marked especially by pain, sensory disturbances, and impaired or lost reflexes. This is related to neuralgia. So yeast could help prevent this. Yeast and Nitrogen Retention Experiments with dogs showed greater nitrogen retention when dogs were fed yeast in their diet.

Bodybuilders know that nitrogen retention means bigger muscles. So if you want strong, fuller muscles, consuming yeast in your diet could help. Yeast’s Nutritional Value Yeast is high in protein, folate, riboflavin (vitamin B-2), and thiamin (vitamin B-1). [source: WolframAlpha ] Yeast is high in choline, which protects the liver and is essential for metabolism. [source: avianweb.com ] How to Make Bread My Personal Conclusion I’ve started making my own bread at home. I’ll be adding extra yeast to the dough. Whole wheat bread made at home with yeast — Update, Jan-15-2010… I made bread again and forgot the salt! Oops. I realized it after I had already made the dough so it was too late. I wondered what would happen. Surprisingly, I can’t tell a difference. I left the dough overnight and the dough had risen. I punched it down and put it in pans to cook. The cooked bread looked normal and tasted fine. So why should we add salt? I previously read that it retards the activity of the yeast. But in my experience I did not notice a difference.

Here are some pictures of the bread made with no salt. Yeast' s Crucial Roles in Breadbaking Yeast's Crucial Roles in Breadbaking It acts as a leavener, dough developer, and flavor builder by Shirley Corriher fromFine Cooking Issue 43 Yeast is the driving force behind fermentation, the magical process that allows a dense mass of dough to become a well-risen loaf of bread. And yet yeast is nothing more than a single-celled fungus. How does it do it? Yeast works by consuming sugar and excreting carbon dioxide and alcohol as byproducts. In bread making, yeast has three major roles. Most of us are familiar with yeast's leavening ability. But you may not be aware that fermentation helps to strengthen and develop gluten in dough and also contributes to incredible flavors in bread. Yeast makes dough rise Yeast cells thrive on simple sugars. As the sugars are metabolized, carbon dioxide and alcohol are released into the bread dough, making it rise. Photo: Scott Phillips. The essentials of any bread dough are flour, water, and of course yeast. As soon as these ingredients are stirred together, enzymes in the yeast and the flour cause large starch molecules to break down into simple sugars.

The yeast metabolizes these simple sugars and exudes a liquid that releases carbon dioxide and ethyl alcohol into existing air bubbles in the dough. If the dough has a strong and elastic gluten network, the carbon dioxide is held within the bubble and will begin to inflate it, just like someone blowing up bubblegum. As more and more tiny air cells fill with carbon dioxide, the dough rises and we're on the way to leavened bread. Yeast strengthens bread dough When you stir together flour and water, two proteins in the flour—glutenin and gliadin—grab water and each other to form a bubblegum-like, elastic mass of molecules that we call gluten. In bread making, we want to develop as much gluten as we can because it strengthens the dough and holds in gases that will make the bread rise. Once flour and water are mixed together, any further working of the dough encourages more gluten to form. Manipulating the dough in any way allows more proteins and water to find each other and link together. If you've ever made homemade pasta, you know that each time you roll the dough through the machine, the dough becomes more elastic; in other words, more gluten is developed.

And with puff pastry dough, every time you fold, turn, and roll the dough, it becomes more elastic. Yeast, like kneading, helps develop the gluten network. With every burst of carbon dioxide that the yeast releases into an air bubble, protein and water molecules move about and have another chance to connect and form more gluten. In this way, a dough's rising is an almost molecule-by-molecule kneading. Next time you punch down bread dough after its first rise, notice how smooth and strong the gluten has become, in part from the rise. At this stage, most bakers stretch and tuck the dough into a round to give it a smooth, tight top that will trap the gases produced by fermentation. Then they let this very springy dough stand for 10 to 15 minutes. This lets the gluten bonds relax a little and makes the final shaping of the dough easier. This rounding and resting step isn't included in many home baking recipes, but it's a good thing to do. Fermentation generates flavor in bread This loaf of artisan bread owes its complex flavor to a lengthy fermentation, which breaks down big molecules into smaller flavorful ones. Photo: Judi Rutz.

As Harold McGee, the author of On Food & Cooking, has pointed out, big molecules in proteins, starches, and fats don't have much flavor, but when they break down into their building blocks—proteins into amino acids, starches into sugars, or fats into free fatty acids—they all have marvelous flavors. Fermentation, whether it's acting on fruit juices to make wine or on flour to make bread, does exactly that—it breaks down large molecules into smaller, flavorful ones. At the beginning of fermentation, enzymes in the yeast start breaking down starch into more flavorful sugars. The yeast uses these sugars, as well as sugars already present in the dough, and produces not only carbon dioxide and alcohol but also a host of flavorful byproducts such as organic acids and amino acids. A multitude of enzymes encourages all kinds of reactions that break big chains of molecules into smaller ones—amylose and maltose into glucose, proteins into amino acids. As fermentation proceeds, the dough becomes more acidic. This is due in part to rising levels of carbon dioxide, but there are also more flavorful organic acids like acetic acid (vinegar) and lactic acid being formed from the alcohol in the dough.

(This is similar to what happens to a bottle of wine that has been left uncorked for a while: the alcohol combines with oxygen to make vinegar.) The acidity of the dough causes more molecules to break down. The dough becomes a veritable ferment of reactions. Eventually, the amount of alcohol formed starts to inhibit the yeast's activity. Yeast has help in producing flavorful compounds. Bacteria are important flavor builders as well. There are bacteria in the dough from the beginning, but as long as the yeast is very active, it consumes sugars as quickly as they're produced, leaving no food for the bacteria, which also like sugar. But when bakers chill a dough and slow down its rise, the cold dramatically reduces yeast activity. The bacteria, on the other hand, function well even in cold temperatures, so they now have an opportunity to thrive, producing many more marvelously flavorful acids. Page:

Question: Which substance makes bread rise?
Answer: Yeast