If yeast is fermented at 30℃, the yeast and sugar reaction will occur the quickest, because the higher temperature will assist the yeast, in turn accelerating the reaction, therefore more alcohol will be created. Heat will give energy to the yeast molecules, making them excited, and since they are moving so fast, they will come in contact with more sugar molecules, conveying that more sugar is being fermented.

Yeast:

Yeasts are single-celled fungi, with about 1500 species. Most yeasts are from the phylum Ascomycota, with a few being Basidiomycota. Yeasts are found in soils and on plants. They are very prominent in sugary substances such as flower nectar and fruits. There are hundreds of varieties of yeast used in daily life: the types used to make bread, beer, and wine are strains of Saccharomyces cerevisiae. There are dangerous pathogens to humans and other animals, with the most being Candida albicans, Histoplasma, and Blastomyces.

Since yeasts are fungi, they are eukaryotic organisms. They are usually about 0.075 mm (0.003 inch) in diameter, and can be spherical, egg-shaped, and filamentous. The majority of the yeasts reproduce asexually by budding: starting with a daughter cell growing and detaching from the parent cell. Some yeasts also reproduce by fission, which is when the parent cell divides into two equal daughter cells. There is one genus, Torula, which are wild yeasts that are genetically asymmetrical, therefore never creating sexual spores.

In conclusion, hundreds of yeasts are used for cooking and making alcohol. Yeasts are especially abundant in sugary mediums such as flower nectar or fruits. The type that is used in baking and making alcohol are all strains of Saccharomyces cerevisiae. Few species are dangerous to humans. Yeasts are fungi, so they are eukaryotic organisms, and they are 0.075 mm (0.003 inch) in diameter and can be spherical, egg-shaped, and filamentous. Most yeasts reproduce asexually by budding, starting with a daughter cell growing and splitting from the parent cell. Some yeasts reproduce by fission, when the parent cell is divided into two identical daughter cells. One genus, Torula, is genetically asymmetrical, therefore they never create sexual spores.

Measuring Alcohol:

One alcohol unit equals 10ml or 8g of pure alcohol. Alcohol units are the same as alcohol by volume (ABV). ABV measures the percentage of alcohol in the total volume of a drink. 12% ABV means that 12% of the volume is pure alcohol. To determine how many alcohol units are in a drink, multiply the total volume by the ABV, and divide by 1,000.

There are 2 main methods for measuring alcohol content in a beverage. You can use a hydrometer, which is a weighted tube with a numerical scale on it. You submerge the tube inside the beverage, and the hydrometer sinks depending on the density of the liquid. The density changes during fermentation since sugar transforms into alcohol. The hydrometer floats more before fermentation because it is less dense than alcohol before fermentation. More sugars are converted to alcohol after fermentation, resulting in the hydrometer sinking. Using these measurements, you can find out the ABV percentage of a liquid since you know how much sugar changes to alcohol through fermentation. If you subtract the first reading from the second one, you can measure the volume of alcohol.

In summary, you can use a hydrometer or refractometer to measure alcohol concentration. Alcohol concentration can be measured using ABV (Alcohol by volume) and alcohol units. An alcohol unit is 10ml or 8g of pure alcohol. ABV refers to the percentage of the liquid that is pure alcohol. Alcohol units can be calculated using the following formula: Multiply the total volume by the ABV and divide by 1,000 to get the alcohol units. A hydrometer is a weighted tube with a numerical scale. When you submerge the hydrometer into the water, it sinks depending on the density of the liquid. During fermentation, the density changes, since sugar is converted to alcohol. Before fermentation, the hydrometer floats because it is less dense than the alcohol in the liquid. After fermentation, when more sugar is converted into alcohol, the hydrometer sinks since it is denser than the alcohol.

Yeast Uses:

Fermentation is a process that has been used for thousands of years to produce alcohol and bread. Biochemically, fermentation is when an organism converts carbohydrates to alcohol or acid. An example of fermentation is yeast converting sugar to alcohol to obtain energy. Most industries use a yeast strain called Saccharomyces cerevisiae, which is the most common and widespread. It is well known for its consistency and quality. Many products use fermentation such as yoghurt, cheese, bread, and coffee. Yeast is also a crucial part of wastewater treatment and biofuel production. Fermentation is carried out by yeasts when glucose is broken into ethanol and carbon dioxide. The equation of ethanol and carbon dioxide production from glucose due to yeast fermentation is C6H12O6 (glucose) → 2C2H5OH (ethanol) + CO2 (carbon dioxide). When there is little to no oxygen, yeast cells must work harder to deliver energy, so fermentation activity stagnates.

Alcoholic beverages are among the oldest and most economically important biotechnologies involving yeast. Yeast plays a significant role in alcoholic fermentation, and choosing the right strain is crucial to maintain quality and have the greatest yield.

Yeast is additionally used in bread-making, with the fermentation of the dough by the yeast being the most critical step. The final quality of bread products depends on how plentiful the yield of yeast cells is. Yeast cells produce carbon dioxide and other metabolites that influence the final appearance, volume, texture, and taste of the bread. The yeast strain, growth conditions, its activity during the dough fermentation process, the fermentation conditions, and the dough ingredients are essential to control the process. The fermentation rate is also controlled by the ingredients of the dough, including the amounts of sugar and salt. Commercial bread producers produce various types of dough including lean, sweet, or frozen dough. Depending on the type of dough, and to obtain optimal fermentation rates, it is recommended to use compatible yeast strains with specific phenotypic traits.

In finality, yeast is used in many industries, even ones like alcoholic beverage and bread production. The quality and efficiency of the products depends greatly on the yeasts yield. This is why specific yeast strains are used.

Effect of Temperature on Yeast:

At lower fermentation temperatures, the yeast strain factor was less powerful for the various physicochemical parameters considered. The polyphenolic content increased as the fermentation temperature decreased, and immensely higher amounts of tyrosol were found in the samples fermented at 12 °C. However, the turbulent content heightened for beers fermented at 18 °C, these beers being superior from the sensory point of view.

To sum up, lower fermentation temperatures lead to more polyphenolic content and tyrosol, which in turn is healthier, but at higher temperatures, the taste and smell improve immensely. This means that alcohol produced at higher temperatures is more attractive.

Manipulated:

• The temperature(°C) of the fermentation environment.

Responding:

• The amount of ethanol produced.

Controlled:

• Yeast, brand, and batch are important to measure the fermentation reaction accurately.
• The quantity of yeast (In grams)(g) may have a significant impact on the fermentation process, altering the experiment's outcomes.
• Amount of sugar (In grams)(g). This can also influence the fermentation process and change the result of the experiment.

1. Fill the fermenter with 2 litres of water at 30℃.
2. Add 1.3 kg of granulated sugar to the fermenter.
3. Mix until the sugar is fully dissolved, then top up with water to 4 litres.
4. Add 23g of Extreme Turbo Yeast, and right after 23g of liquid Carbon, to the fermenter.
5. Put on the lid, fill the airlock halfway with water, and close with the stopper.
6. Place the fermenter in a 21℃ room. This will be your control sample.
7. Wait 5 days until the wash stops fizzing.
8. Repeat steps 1–7 with 6℃ and 30℃ room temperatures (put in the garage to cool to 6℃ and use a heating mat to heat to 30℃).
9. Record observations of the fermenter every 8 hours and measure the amount of alcohol manufactured every 24 hours.

SG=Specific Gravity (Density of Solution)

ABV%=Potential Alcohol (Percent)

° Brix=Sugar Content (Percent)

Qualitative Observations

The control sample had small bubbles appearing that kept getting slighter progressively, until they disappeared. Additionally, there was more carbon dioxide produced by the chemical reaction as time went on, since bubbles of carbon dioxide attempted to escape more frequently through the airlock, which I filled with water. This allowed me to see the release of carbon dioxide. The experimental liquid spread over the side on the second day and stayed like that until it was exposed to oxygen. The 6℃ sample showed no identifiable signs of fermentation and stayed constant throughout the entire iteration. On the other hand, the 30℃ sample showed the same characteristics as the control sample, but the amount of carbon dioxide that was produced was greater, as the water in the airlock showed more frequent bubbles. Subsequently, we can assume that the 30℃ sample had a more potent chemical reaction because the alcohol volume was also higher than the controlled sample. A yeast chemical reaction yields carbon dioxide and ethanol, both of which were higher in results gathered from the 30℃ sample, thus there was more fermentation taking place.

ABV%=Alcohol by Volume Percentage

Comparison

The 2 samples had comparatively unique results, differing immensely from the control sample at room temperature. The sample that was placed in a 6℃ environment exhibited no fermentation due to the low temperature. On the other end of the spectrum, the sample that was in a 30℃ environment thrived, achieving a higher ABV% and almost reaching the level of the starting potential ABV%. The sample in a 30℃ environment had an end ABV% that was 3% higher than the control sample. The sample in a 6℃ environment did not display any yeast reaction with the sugar and therefore, no ABV%.

Trends and Outliers

An outlier that I identified in my results was on the 2nd measurement in the iteration that was performed in a 6℃ environment. In this iteration, no reaction seemed to occur, but the 2nd measurement was higher than the preliminary measurement. This measurement is a deviation, as the rest of the measurements recorded were identical to the preliminary measurement. As a consequence of executing the experiment with three separate temperatures, the results were all remarkably distinct, ensuing that there are no trends in the data gathered from the study.

My hypothesis was correct, as the 30℃ environment allowed for the most efficient fermentation. This was evident in the data taken from the experimental liquid that was fermented at 30℃. The above result emerged because the enzymatic activity of the yeast was higher, due to greater temperatures. Fermentation is performed by many enzymes in yeast cells, and when these enzymes are heated, they are sped up, rendering them more capable of fermenting sugar.

If I were to experiment again with more time, I would conduct more iterations and implement some other factors that may influence fermentation, for example, nutrients, pH, volume of the fermenter, and oxygen access. If I had access to more professional equipment, I would make more accurate measurements and link my studies to more pertinent subjects such as food and beverages, biofuels, and medicine. By connecting my learnings with these domains, I can aid in achieving a more efficient and renewable global community.

Yeast fermentation is a vital part of brewing and baking, and industries specializing in brewing and baking have to monitor and tweak the temperature at which they ferment their products to project a desirable flavour and texture. Brewers use temperature control in beer-making, since different types of beer ferment at various temperatures (e.g. lagers and ales), to prevent unwanted by-products. Temperature control is also essential in wine-making, as temperature influences the extraction of flavours, tannins, colours, and aromas from grape skins (e.g. red wine is fermented at a higher temperature to maximize tannin and colour extraction, while white wines are fermented at lower temperatures to maintain as much of the flavours and aromas as possible). The dairy industry also uses temperature control in cheese and yogurt production, as they use bacterial fermentation, which is highly sensitive to temperature (e.g. yogurt ferments at 43℃ to allow for the growth of fruitful bacteria). Cheesemaking likewise requires high amounts of temperature control to reach the desired texture and flavour. Some more industries that capitalize on temperature control include ethanol and biofuel production, pharmaceuticals, and biotechnology. Temperature control is crucial in maintaining the proper temperature to produce the most efficient and plentiful yield of ethanol. Additionally, converting algae and other biomass into bioethanol and biogas depends on specific temperatures to achieve peak productivity of the microbial organisms and efficient conversion. Pharmaceuticals and biotechnology are some significant examples of important industries worldwide, and they rely on temperature control to produce antibiotics, enzymes, and many other biotechnological products. In every one of these instances, temperature control allows for consistency, efficiency, and quality, all of which are key factors in commercial production. Ultimately, we use many of these products in our day-to-day lives, and it is critical to learn about the science behind their development, which is precisely what I have investigated in this lab report.

Possible sources of error in this experiment could have included not having enough of the experimental liquid in the graduated cylinder while measuring its specific gravity. Other possible sources of error include inconsistent temperatures, inaccurate measurements, yeast viability due to improper storage, sugar concentration, uncalibrated instruments, and environmental factors like humidity, air pressure, and light. Nonetheless, the most probable cause of oversight is human error, whether it pertains to inaccurate recording of results or improper handling of materials. All these possibilities could make the lab inaccurate or misleading, which is why it is important to identify what could have occurred to drive these results.

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Research about yeast.

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Research about how to measure alcohol percentage.

Jansen, M. L. A., Bracher, J. M., Papapetridis, I., Verhoeven, M. D., de Bruijn, H., de Waal, P. P., van Maris, A. J. A., Klaassen, P., Pronk, J. T., & Fleminglaan, A. (2017, August 1). Saccharomyces cerevisiae strains for second-generation ethanol production: From academic exploration to industrial implementation. FEMS yeast research. https://pmc.ncbi.nlm.nih.gov/articles/PMC5812533/

Research on industrial uses of yeast fermentation.

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Research on how temperature affects yeast.

• My parents for helping me conduct the experiment
• My science teacher Lyne Sleiman, for assisting me in making an original idea