Cup # | Sweetener | O min | 5 min | 10 min | 15 min | 20 min | 25 min | 30 min | 45 min |
| 1 | None | 1 ¼ | 1 ¼ | 1 ¼ | 1 ¼ | 1 ¼ | 1 ¼ | 1 ¼ | 1 ¼ |
| 2 | Sugar | 1 ¼ | 1 ½ | 2 | 2 ½ | 3 | 2 7/8 | 2 7/8 | 2 7/8 |
| 3 | Equal® Spoonful | 1 ¼ | 1 3/8 | 1 ¾ | 2 1/8 | 2 ¼ | 2 1/8 | 2 1/8 | 2 1/8 |
| 4 | Honey | 1 ¼ | 1 ½ | 2 1/8 | 2 ¾ | 3 1/8 | 3 | 3 | 3 |
Measurements were taken in inches. Height of the mixture plus “foam” were measured.
The measurements of the contents of cups # 1-4, including “foam” formed from production of carbon dioxide gas during the fermentation process, were measured immediately after mixing ingredients (O minutes). Measures were taken at 5 minute intervals for 30 minutes, and a final measurement was taken at 45 minutes.
The “foam” observed was a bubbling, light-beige froth formed on top of the yeast and water mixtures in cups # 2, 3, and 4 only; no “foam” was observed in cup # 1. Photographs were taken at time intervals of 0 minutes, 10 minutes, 20minutes, 30 minutes and 45 minutes.
This data indicates that the honey (fructose and glucose) produced the largest volume of “foam” with the maximum height of 3 1/8 inches and a final height of 3 inches. Next, table sugar (sucrose) produced a maximum height of 3 inches and a final height of 2 7/8 inches of “foam”. Equal® Spoonful (Aspartame) produced a maximum height of 2 ¼ inches and a final height of 2 1/8 inches of “foam”. The control (no sweetener added to the yeast and water mixture) maintained the original height of 1 ¼ inches throughout the experiment.
The amount of “foam”, measured by its height, was used to determine the effectiveness of the fermentation of the yeast. The data indicates that honey and table sugar both aide in the fermentation of yeast better than Equal® Spoonful (Aspartame).
Calculated Averages
Sum all measurements taken of a particular cup’s content at each interval of time divided by number measurements taken equals average height of contents of cup.
Cup # 1: [1.25+1.25+1.25+1.25+1.25+1.25+1.25+1.25] / 8 = 1.25 inches avg. ht.
(none)
Cup # 2: [1.25+1.50+2.00+2.50+3.00+2.88+2.88+2.88] / 8 = 2.36 inches avg. ht.
(sugar)
Cup # 3: [1.25+1.38+1.75+2.13+2.25+2.13+2.13+2.13] / 8 = 1.89 inches avg. ht.
(Equal® )
Cup # 4: [1.25+1.50+2.13+2.75+3.13+3.00+3.00+3.00] / 8 = 2.47 inches avg. ht.
(honey)
These calculated averages of the height of the contents of the cups (including the “foam”) confirm Table 1’s results. Honey (2.47 inches) had the largest average of “foam” produced, followed by table sugar (2.36 inches), and finally Equal® Spoonful (1.89 inches). The control, cup # 1, height of 1 ¼ inches was maintained throughout the experiment, which was the height of the water and yeast mixture added to all four cups at the beginning of the experiment.
Table 2: Maximum Height Attained vs. Maximum Height Sustained
CUP # | SWEETENER | MAXIMUM HEIGHT ATTAINED | MAXIMUM HEIGHT SUSTAINED* |
| 1 | NONE | 1 ¼ INCHES | 1 ¼ INCHES |
| 2 | SUGAR | 3 INCHES | 2 7/8 INCHES |
| 3 | EQUAL® | 2 ¼ INCHES | 2 1/8 INCHES |
| 4 | HONEY | 3 1/8 INCHES | 3 INCHES |
Table 2 compares the maximum height attained by the four mixtures with the maximum height the four mixtures were able to sustain during the last 20 minutes of the experiment. This also confirms that honey produced the largest height (volume), followed by table sugar, and finally Equal® Spoonful . Again cup # 1 (control) maintained the identical height throughout the experiment.
Graph
The graph charts the maximum height of the contents of cups # 1 - 4 of the mixture plus the “foam” formed during the experiment. The maximum height of the substances in cups # 2, 3, and 4 was obtained just before or at the 20 minute interval. After which, some of the bubbles in the “foam” popped and deflated the amount slightly in cups # 2, 3, and 4. The contents of cup # 1 remained constant throughout the experiment.
Table 3: Observation noted before and after mixing
OBSERVATIONS (before mixing) | QUALITATIVE | QUANTITATIVE |
| Yeast-- light beige color | Sight | |
| Yeast-- light grainy (soft) | Touch | |
| Yeast-- uniquely sweet | Smell | |
| Water--clear | Sight | |
| Water--hot | Touch | 120° -- 130° F |
| Water--equal amount/cup | Sight | 1 ¼ inch / cup |
| Honey--yellow | Sight | |
| Honey--sticky/gooey | Touch | |
| Honey--thick (slow ) | Touch, Sight | |
| Honey--sweet | Smell | |
| T. Sugar--white | Sight | |
| T. Sugar--grainy (hard) | Touch | |
| T.Sugar--faint sweet | Smell | |
| Equal® --white | Sight | |
| Equal® --grainy powder | Touch | |
| Equal® --faint sweet | Smell | |
| (after mixing) | | |
| all --light beige color | Sight | |
| Cup 1--no reaction | --- | recorded every 5 min. |
| Cup 2-foam quickly rising with gas bubbles | Sight | recorded every 5 min. |
| Cup 3-foam slowly rising with gas bubbles | Sight | recorded every 5 min. |
| Cup 4-foam quickly rising with gas bubbles | Sight | recorded every 5 min. |
CONCLUSION
In this experiment, the fermentation of yeast using table sugar (sucrose) and honey (fructose and glucose) was compared to the fermentation of yeast using Equal® Spoonful (aspartame). Carbon dioxide gas is a by-product of the fermentation of yeast, a microorganism. By measuring the contents of the cups, which included the “foam” formed by the CO2 , a comparison of the three sweeteners’ ability to ferment yeast could be made.
This experiment measured the amount of the mixture together with the “foam” produced during the fermentation process. The “foam” referred to is the result of bubbles produced in the mixture due to the fermentation process of the yeast. During fermentation, carbon dioxide gas is produced causing the mixtures to bubble and produce “foam” on top of the mixture. The more carbon dioxide gas given off, the better the yeast has fermented.
Carbohydrates (sugars) are utilized by the yeast to form energy during the fermentation process. Carbon dioxide gas and ethyl alcohol are by-products of this process. Aspartame, the sweetening agent in Equal® , is not considered a good replacement for sugars in the bread-making process by Equal® ’s manufacturer as well as yeast manufacturers (Equa®; Fleischmann’s Yeast , 1996). Therefore, I was surprised that Equal®, which is considered a nonnutritive, artificial sweetener, aided in the fermentation of the yeast. Although both the table sugar and the honey produced better results, aspartame was able to help the yeast to ferment. After some research, I found that the manufacturers of Equal® add dextrose (a form of sugar) to help “stabilize” the sweetener . This helps explain why the artificial sweetener was able to aid in the fermentation process of the yeast albeit not as effectively as the honey and table sugar. However, I found the sweetness of Equal® dissipates at 85° F and therefore is not a good substitute for sugar in most cases . (Equal®)
Honey did produce better results. There may be a couple of explanations for this outcome. One, one teaspoon of honey contains more sugar per gram than one teaspoon of table sugar. Secondly, the glucose is the sugar directly used in the fermentation process. Sucrose and fructose have to convert to glucose to be used to produce energy. This could explain why honey, which contains glucose, acted more efficiently.
More precise instruments could have been used to measure the volume of the water and yeast. A different process, such as water displacement, could have been used to measure the production of carbon dioxide gas. The same number of grams of sugar (to produce the same joules of energy) in table sugar and honey could be measured rather than using one teaspoon of each as if they were equivalent. According to the manufacture, one teaspoon of Equal® Spoonful is equivalent to one teaspoon of table sugar in terms of sweetening potential; therefore, these measurements or their equivalents should be maintained.
This experiment helped me learn about microbes, fermentation, and the bread making process. It was very interesting to learn about the ancient practices of bread making and the discovery of yeast as a single-celled microorganism in the 19th century. Each part of the experiment (observing, classifying, inferring, questioning, hypothesizing, research, designing the procedure and fulfilling it, measuring and analyzing materials and data, graphs and charts, and the whole write up) was key to my new understanding of the fermentation of yeast.
PROCESS SKILLS:
OBSERVING | I had seen bread rise and wondered why. I also observed during my experiment so I could collect data and learn about the process of fermentation. |
| INFERRING | I inferred that the bread must rise because the yeast was being fed by something. I wasn’t sure what would cause the yeast to ferment the best. |
| QUESTIONING | My mother is a diabetic so it led me to the following question: Will Equal® Spoonful (Aspartame) ferment dry active yeast as well as table sugar (sucrose) and honey (glucose and fructose)? |
| HYPOTHESIZING | If sugar is needed to ferment yeast, then table sugar (sucrose) and honey (fructose and glucose) will produce more carbon dioxide gas “foam” by fermenting yeast better than Equal® Spoonful (Aspartame), an artificial “sugar-free” substitute. |
| RESEARCH | I used the internet to look up information about the history and scientific nature of yeast and bread making. |
| CLASSIFYING & IDENTIFYING VARIABLES | I classified Equal® , honey, and table sugar as sweeteners that would promote fermentation of yeast. Then I identified the variables: Independent (Manipulative) variable: Type of sweetener -- table sugar (sucrose), honey (fructose and glucose), and Equal® Spoonful (Aspartame) .Dependent (Responding) variable: “Foam” produced as a result of carbon dioxide gas formation during fermentation process by yeast. Controlled variables: Volume of water, temperature of water, volume of yeast, type of yeast, capacity of cup, time intervals, and number of stirs when mixing ingredients. |
| DESIGNING | After I identified my variables and did preliminary research I decided on a procedure and carried out the experiment. |
| MEASURING | I measured out all of my variables so an equal amount of each would be used. I also set up a timeframe for measuring change in height. |
| GRAPHS AND CHARTS | After I collected my data I put them in chart and graph form so my work would be easily represented and understood. |
| COMMUNICATING | I communicated each step of my experiment within the paper, charts and graphs, and the experiment board. |
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