The influence of sugar on the rising of bread. Bonnie, M. , Geluk, I., & Vlaar, J. C. Huygens College, The Netherlands. Received February 2010 Summary. Bread is a basic product in our diet. In Western society most people eat bread every day. One of the increasing health problems in western society is that people are gaining too much weight. Bread is seen as one of the more healthy products, but what a lot of people don’t know is that sometimes more sugar is used in it than necessary. So we decided to examine the influence of sugar in combination with yeast in bread. Yeast is an eukaryotic organism which converts sugar into carbon dioxide and water. This process is called aerobic fermentation. We looked at the rising and the height of the bread after baking. Introduction Experimental procedure and approach Yeast converts sugar and oxygen into carbon dioxide and water. We started with a recipe that we got from the internet. (bibliography 3 and 4)We made six different doughs. In each dough we used a different amount of sugar. Each dough contained 250 grams of flour, 150 mL of water, 5.0 grams of sunflower oil, 5.0 grams of salt and 7.5 grams of yeast. C12H22O11 + H2O C6H12O6 + C6H12O6 Sucrose glucose fructose The fermentation of glucose/fructose C6H12O6 2 C2H2OH + 2 CO2 The oxidation of glucose/fructose C6H12O6 + 6 O2 6 CO2 + 6 H2O We started with sucrose, which converted with water into glucose and fructose. In anaerobic environment glucose and fructose convert into alcohol and carbon dioxide. In our experiment there is a aerobic environment, which causes the glucose/fructose to convert with oxygen into water and carbon dioxide. The carbon dioxide is trapped within the dough. This causes the dough to rise. We expect that the rising of bread depends on the amount of sugar, but that there is also a maximum amount. We expect this because for one reason the yeast won’t have the time to convert all the sugar. Preparation: We mixed the salt and flour in a bowl and we made a hole in the middle. Then we put the right amount of sugar in each beaker. After the sugar was dissolved, we put the yeast in each beaker at the same time and we stirred the mixture till the yeast was also dissolved. Then we poured it into the holes. After that we put a damp tea towel over the bowls and put them near a radiator for 45 minutes (picture 1). We put it near a radiator because this is a warmer spot and will speed up the fermentation. After 45 minutes we put the oil into the holes filled with the yeast mixture. We kneaded this with the flour into a ball. Then we put the damp tea towels back on the bowls. We let the bowls stay at room temperature for two hours. (picture 2) When the two hours were over we kneaded the dough quickly and separated each portion of dough into four pieces with the same weight. Each piece went into a cupcake form. We labeled the dough with different colors. We let them rest for one hour in the cupcake form. (picture 6) Then we put them in an oven that was preheated to 220⁰C (493 K). We placed a bowl of cold water at the bottom of the oven. The doughs stayed there for 30 minutes. When the buns were done we weighed them on a scale. Then we measured the height with a knitting needle. We oiled the needle with the sunflower oil and pricked the bread at its highest point. After we pulled the needle out we measured the height with a ruler. Because we only had one cupcake form we only had room for 3 buns in the oven. So we decided to start with doughs 1, 2 and 3. One hour later we started making doughs 4, 5 and 6 which also means we baked them an hour later . size of the holes, but we couldn’t see a difference. (picture 5) Table 1. Dough Amount of sugar. (gr) Dough 1 0.00 Dough 2 2.50 Dough 3 5.00 Dough 4 7.50 Dough 5 10.00 Dough 6 20.00 Results After the first 45 minutes we noticed that dough 1 had less foam then the other two. After the 2 hours of rising, dough 1 had less volume. When we put the dough into the cupcake form the buns doubled in size after 1 hour. After the baking we noticed a difference in color. Higher amounts of sugar caused a darker brown color. After we had baked the buns we cut them open and looked at the amounts and Figure 1. height of bun (cm) 1. 2. 3. 4. 1. 2. 3. 4. 1. 2. 3. 4. 1. 2. 3. 4. 1. 2. 3. 4. 1. 2. 3. 4. 7.5 7.2 7.4 7.5 7.5 7.5 7.5 7.6 7.5 7.6 7.7 7.6 8.0 7.7 7.8 7.7 8.2 8.3 8.1 8.5 8.5 8.2 8.6 8.2 Average mass and maximum error (cm) 7.4 ± 0.2 7.5 ± 0.1 7.6 ± 0.1 7.8 ± 0.2 8.3 ± 0.2 8.4 ± 0.2 Table 1 presents the height that we measured of four buns per portion of dough, the average of those four and the maximum error. Figure 1 shows the results of table 1. Conclusion Bibliography. The buns with more sugar were higher, because there is more sugar to convert. And we can see in our experiment that there is a maximum amount of sugar that helps the bread rise. In our experiment this is about 10 grams, but in a larger bread this would be more. Because in a larger bread there will be more yeast to convert the sugar and there will be more dough to rise. We can conclude that sometimes there is too much sugar in bread then necessary. This can cause people to think that they are eating healthy, while this is not entirely the case. 1. Chemistry network. Center of Educational Training, Assessment and Research. Vrije universiteit Amsterdam. Fermentation. 2. http://www.mijnwoordenboek.nl/vert alen.php?src=NL&des=EN&woord. 3. http://www.jannekes.nl/index.htm?url =/brood/index.htm 4. http://www.broodrecepten.nl/recepte n/Basisrecepten.htm Discussion Dough 1 had less foam after 45 minutes, because there wasn’t any sugar so fermentation wasn’t possible (picture 1). After we added the oil we saw that the fermentation process started. We think that yeast can also convert oil. Oil seems to be able to replace sugar in this fermentation process. This could be an option for another experiment. With a higher amount of sugar the bread gets darker. Sugar is a carbohydrate and there are proteins in flour. During the baking these two react. This reaction is called the Maillard-reaction. The end product is that the bread turns brown. This is why the bread with a higher amount of sugar is darker. (picture 3&4) We don’t know when the Maillardreaction gets the upper hand and if caramelizing takes place. We were wondering if these two things happened in our inquiry which might explain the sudden change in our graphic. This could be researched in another experiment. Picture 1. Doughs 1 and 3. after 45 minutes. Picture 4. Buns 6 and 1. Picture 2. Dough 2 before and after 2 hours of rising. Picture 5. Bun 2 cut through. Picture 3. All the buns. Picture 6. The doughs 1, 2 and 3 before and after the last hour of rising