Sitti N. Mamogkat Date Performed: June 22, 2011

2009-37346 Date Submitted: June 29, 2011

I. Introduction

The word "yeast" comes from the Sanskrit 'yas' meaning "to seethe or boil".  Yeast is a living organism and is in the air around us.  It is a  member of the fungus family and is a single-celled fungi of which there are about 160  different species.  Baker's yeast as well as brewer's yeast belong to the Saccharomyces cerevisiae species.  Louis Pasteur in the 1850's is credited with first discovering and understanding the fermentation process which led to the development and cultivation of the yeast we use today. 

Baker's yeast, like baking powder and baking soda, is used to leavened baked goods (breads, Danish pastries, brioche, croissants).  The difference between these two leaveners is that baking powder/soda react chemically to produce the carbon dioxide that makes the baked goods rise.  Yeast, on the other hand, is a living organism and the carbon dioxide it produces is the result of the yeast feeding on the dough. 

The two forms of baker's yeast are; compressed cakes (also called fresh yeast) and dehydrated granules (dry yeast). Fresh yeast is ivory colored with a yellowish hue and is soft and moist and should easily crumble.  Make sure it is fresh smelling and there are no dark or dried places on the yeast.    It is mainly used by professionals as it is highly perishable and must be used within a short time of opening.   It is sold is .06 ounce foil packages and must be refrigerated.  For longer term storage it can be frozen.  Compressed yeast contains about 70% moisture.   It needs to be proofed before using and should have a pleasant yeasty smell and be foamy. (joyofbaking.com)

Like most other living creatures they require moisture, food, and a hospitable environment. In a moist environment, yeast will grow rapidly. A bread dough that is too dry will take a long time to rise because the yeast will not multiply as rapidly and because the dry dough is stronger and more difficult to lift. Yeast feeds on sugar or converts the starch in the flour to sugar for food. Without the capability to convert starch to sugar for food, yeast would not thrive in sugar free breads such as French bread. (preparedpantry.com)

To bake breads, the temperature of the oven must be at least 170°C or 338°F and only for 15 minutes or else the bread would get burned. If the temperature is lower than 170°C then the bread would get a case hardening. This means the outside of bread would get overbaked/overcooked and the inside of the bread would be uncooked or still fresh dough, and baking time would take more than 15 minutes to wait for the inside of the bread to be cooked.

II. Objective

To be able to know the principles involved in the preparation of “Pan de Sal”.

III. MaterialsIngredients:

1 big bowl Tray Flour 100 gWeighing scale Cheesecloth Water 20.0 mlOven Baking tin Sugar 4.6 gKnife Salt 1.5 g

Yeast 1.6 gShortening 4.3 g

IV. Procedure

The yeast was dissolved in lukewarm water (part of the 50 ml). Then, the mixture was added to the mixed dry ingredients.

The dry ingredients were mixed for 7 minutes before shortening was added. (The ingredients were mixed through hand kneading.)

Mixing and kneading were resumed for 5 minutes after the shortening was added.

The dough was placed on a greased bowl.

The bowl was covered with damp cloth and set aside to ferment for 2 hours.

The dough was folded into a “baston” shape after fermentation.

The dough was cut into 1 square inch per piece and proofed for 1 hour.

The dough was baked for 1 hour at a temperature started from 120°C to 170°C.

V. Results

Figure 1 Yeast dissolved in lukewarm water.

Figure 2 Mixed dry ingredients (salt, sugar and flour).

Figure 3 Mixed dry indredients with shortening.

Figure 4 Dough kneading for 5 minutes.Figure 5 Dough covered with damp cloth.

Figure 6 The dough arises after 1 hour. Figure 7 The dough shaped into a “baston” shape.

Figure 8 Cut-up dough roll. Figure 9 Dough was baked supposedly for 15 minutes.

Figure 10 A Freshly baked pan de sal. Our bread had a case of case hardening.

VI. Discussion of Results

Before anything starts, yeast was suspended or dissolved in lukewarm water. This is done to activate yeast from its inactive condition when it was dry and powdery. Most yeast that are commercially sold are dry yeasts. The reason for why it is dry is to achieve a longer shelf life than fresh yeast and would not need refrigeration for preservation. Dry yeast is fresh compressed yeast that has been pressed and dried until the moisture content is only about 8% which makes the yeast dormant.  The granules only become active again when mixed with a warm liquid. (joyofbaking.com) It should be noted that the water used for suspension should not be too warm or too cold because any degree of temperature below or above the optimum range of growth for yeast (Saccharomyces cerevisiae), which is from 25°C-35°C, will slow down enzyme kinetics and consequently, cellular processes. (molbiolcell.org) In simpler words, it would be harmful for the life of the fungi. Another reason why lukewarm water is used is because warmth and moisture are 2 of the things yeast needs in order to grow, aside from food. At the same time, lukewarm water sped up the suspension process because any solid dissolves faster as the temperature increases.

The dry ingredients (flour, salt and sugar) with the yeast dissolved in 50 ml lukewarm water was mixed for 7 minutes. The mixing of ingredients was done to distribute all of the ingredients thoroughly and rigorously at every part of the dough. Some bread makers add shortening while mixing the ingredients.

Sugar is used to feed yeast. Yeast breaks down sugar into its simpler forms like glucose and fructose. Sugar could also be used to slow down the fermentation, if in large amounts, because in a very sweet dough the rising time is longer. Sugar tenderizes dough and batter products and may help the baked product to brown. (foodworks-intl.com) CO2 gases or leavening gases are contained in the elastic framework of gluten during fermentation. Gluten is a protein composite that gives elasticity to dough, helping it to rise and to keep its shape, and often giving the final product a chewy texture. Gluten is the composite of prolamin (a group of plant storage proteins having a high proline content and found in the seeds of cereal grains: wheat (gliadin), barley(hordein), rye (secalin), corn (zein) and as a minor protein, avenin in oats.) and glutelin (proteins are soluble indilute acids or bases, detergents, chaotropic or reducing agents.) (en.wikipedia.org) Gluten is produced from flour because flour has proteins that interact with each other when mixed with water, forming gluten. Some bread makers do not add sugar, so yeast gets sugar from breaking down some starch in the flour. Salt impedes the growth of yeast so the rise is slowed down with salt. (preparedpantry.com)

Shortening is 100 percent fat and is solid at room temperature. It is often made of hydrogenated (solidified by adding hydrogen) vegetable oils, but sometimes contains animal fats. The flakiness of

pastry comes from solid fat such as shortening or lard rolled in layers with flour. In some recipes for cookies or cake, shortening is creamed with sugar to trap air. A lighter product will result. There are emulsifiers in shortening to help emulsify shortening and liquid. This means that oil and water stay mixed together, creating an even distribution of flavors and a consistent texture in batters and dough. However, instead of shortening, the class used fat in liquid form. Fat contributes tenderness, moistness, and a smooth mouthfeel to baked goods. Fats enhance the flavors of other ingredients as well as contributing its own flavor, as in the case of butter. In baked goods such as muffins, reducing the amount of fat in a recipe results in a tougher product because gluten develops more freely. Another tenderizing agent, such as sugar, can be added or increased to tenderize in place of the fat. A small amount of fat in yeast dough helps the gluten to stretch, yielding a loaf with greater volume. (foodworks-intl.com)

Once the yeast, liquid, and flour are mixed together and distributed, the next step is to knead the dough.  This step is done to aerate the dough and develops the gluten (elasticity) in the flour.   As you knead (press-fold-turn action) pockets of air are developed in the dough.  The more you knead the smaller and more numerous the pockets of air become.  How the dough is kneaded will determine the final texture of the bread.  Dough with larger air pockets will produce a bread with a coarser texture.  Commercially made breads or homemade ones that are kneaded by machine tend to have a finer texture than breads kneaded by hand.  You'll know when the dough has been kneaded enough as it takes on a smooth and satiny appearance. (joyofbaking.com)

The next step is the fermentation or rising of the dough. The dough was placed on a greased bowl to prevent it from sticking with it. The damp cloth is used to prevent the dough from having moisture loss and dry, crusty surface. And fermentation begins after leaving the bowl in room with a normal or room temperature for 2 hours. This is the time where yeast would feed itself with the sugar present in the dough, as well as the starch from the flour. To feed itself, yeast will break down sugar into its simpler form. Simple sugars like glucose and fructose are what yeast is after. The yeast respires in the presence of sugar and oxygen to give CO2 (carbon dioxide) and H2O (water). The CO2 produced causes the rising of dough. (homepage.eircom.net)

C6H12O6    ====>   2(CH3CH2OH)      +        2(CO2)    +  Energy (which is stored in ATP) Sugar     ====>       Alcohol            +   Carbon dioxide gas + Energy(Glucose)               (Ethyl alcohol)

During fermentation is also where the bread’s flavor is developed.

After 2 hours, the dough arose in volume very visibly. Then it was folded into a ‘baston’ shape. The term ‘baston’ is the one used by most Filipinos to refer to the long roll of dough. ‘Baston’ literally means a cane in English. The dough was cut approximately into 1 square inch cube and then proofed for 1 hour. Proofing simply meant to leave the cut doughs that were placed on a baking tin and covered with a damp cloth; so it is like fermentation all over again but only for 1 hour. It simply means that it is the final dough-rise step before baking.

During the exercise, the dough was baked at a temperature starting from 127°C when it should have started at a temperature of 170°C. This is to avoid case hardening. Case hardening means overcooked on

the outside, undercooked on the inside, which was exactly what happened to our bread. It took us 1 hour in baking when it should only have been 15 minutes because we waited for the surface of the bread to have a brownish color. We did not know that sugar forms the browning of the surface of the bread.

If the baking was done correctly, before yeast is killed, dough will rise as it gets a last bit of CO 2

being released and expanding the air pockets. Once the yeast is killed and the interior of the baked good heats up enough, the dough will set. Some techniques to get browned and glossy surface of bread are first, by brushing with an egg wash and second, by spraying the dough with water periodically during baking. (joyofbaking.com)

VII. Conclusion

Basically, my conclusion would be that yeast gives us energy for our daily life. It is because yeast produces not just CO2 gas but also energy. Yeast has been used as leavening agent by humans in bread making for a long period of time; it has become a part of our tradition, culture and lifestyle. Although we could use baking powder as a substitute for yeast, it is still better to use yeast because it has properties that are only found in yeasts and using substitutions may not have the end result to what we want to have.

VIII. References

greensim.com/lemonade/ediblescience.html accessed on June 26, 2011baking.about.com/library/weekly/aa020100.htm accessed on June 26, 2011adventuresofclayball.com/tag/how-to-knead-dough/ accessed on June 26, 2011suburbangrandma.com/saving-money/steamed-fruit-dumplings-recipe-and-technique/

accessed on June 26, 2011breadmakinglessons.com/the-pandesal-cut.php accessed on June 26, 2011adobolife.com accessed on June 26, 2011molbiolcell.org/cgi/content/full/18/12/5100 accessed on June 26, 2011joyofbaking.com/Yeast.html accessed on June 26, 2011homepage.eircom.net/~kogrange/6th_yeast.html accessed on June 26, 2011foodworks-intl.com/page47_baking_ingredients_function.htm accessed on June 26, 2011en.wikipedia.org/wiki/Glutelin accessed on June 26, 2011en.wikipedia.org/wiki/Prolamin accessed on June 26, 2011en.wikipedia.org/wiki/Gluten accessed on June 26, 2011preparedpantry.com/howyeastworks.htm accessed on June 26, 2011fitday.com/fitness-articles/nutrition/healthy-eating/substitute-yeast-for-baking.html

accessed on June 29, 2011