Yeast and Wine Fermentation

By: Blair Caron

Inquiry Question:

“What happens if not enough yeast is present on the vine? Does the temperature have an impact on the concentration of yeast present on the vine? Do different wine making countries differ in quality of the production of wine due to yeast concentration based on regional temperatures? Is the elapsed time longer or shorter and does the alcohol percentage fluctuate? Is there a specific measurement of yeast that tells how much yeast is needed in wine fermentation? What is the difference between organic and inorganic yeast?”

Wine and Yeast:Yeast is the most important ingredient needed

in Wine fermentation. This airborne organism thrives on the shells and vines of grape plants in vineyards across the world. As it feeds of the sugar from rotting and softened grapes it begins to increase in concentration. A wine maker who produces there wine in vineyards knows that without yeast the process of wine fermentation ceases to exist. It is important not to interact yeast with various elements such as oxygen which can give an environment strong to bacteria. Once bacteria is present the wine may become sour or stop in process. Once the grapes are picked from the vine in preparation for fermenting, the yeast comes along for the ride. The grapes are the squished. As they are squished by the grinder and then sit in an old wooden barrel the yeast allows itself to feed of its number one food source, SUGAR!

Yeast and The Vine:(The following is research gathered based on Robert K. Mortimer, a professor of Molecular and Cell Biology at UC Berkley)

• The Vineyard theory was established after Professor Robert Mortimer worked closely with winemakers across California. He studied the role of yeast in natural fermentations. Saccharomyces Cerevisiae is a type of budding yeast that is regularly used in brewing and baking that is an aerobic yeast cell that grows off the sugar of the vines such as glucose and maltose. He observed that SC is on the grapes but occurs on about 1 in 1000 berries. SC is known as the “true” wine yeast due to it’s alcohol tolerance which helps it ferment up to or more than 13% alcohol. SC is also known to be able to stand up and thrive against other species of wild yeast, bacteria an mold. Once grapes are crushed and sugary juices are released all of these organisms enter the fermentation process. Throughout the fermentation process strains or yeast multiply. SC stays predominate from beginning till end due to its high level.

Factors that Affect Yeast Concentration: •Rain- when rain fall occurs the water can cause the native yeast to wash off of the harvest reducing its population.•Rotting may occur for some clusters on the vine which may seem as a positive due to the sugars being revealed for the yeast to feed off of and reproduce or grow. It is actually negative as well when too much occurs or if it occurs in large sections when other bacteria’s and mold. If rotting encourages the negative and bacteria and mold grow then during the lag phase (the sitting phase) the existence of the large population of bacteria and mold can ruin the wine. •If the winery is a larger size it may come as a negative factor due to irregularities in monitoring the wine which can come easily in a smaller winery. If less monitoring is done on the individual barrels then bacteria and mold can strive in the fermenting barrels and affect the wine. If one barrel is affected bacteria will look for another source.

The Difference Between Organic and Natural Yeast In Wine Making:

ORGANIC NATURAL

•Is a manufactured product made by companies that comes in small twist off containers normally used in Wine Kits

•Natural yeast is found in the vine environment of the vineyard where it is thriving off sugars given by the grapes. It is also found in many of the

•Manufacturers recommend that adding it in large doses insures that fermentation starts rapidly and efficiently.

•Natural yeast is more beneficial due to being a wild yeast already existing in its preferred environment with no chemical additives.

•Organic yeast does not have a problem dealing with bacteria or mold due to being in a container or packet ready to add.

•By growing on a vine environment it risks being exposed to the already present bacteria and mold. Too much bacteria and mold can take over the food necessary for the yeast to survive.

•Chemically altered to keep well which ensures a chemically altered wine.

•Natural ensures a naturally made wine

Wine Around the World

Top Wine Exports:1. Italy- 21%2. France- 19%3. Spain- 19%4. Australia – 8%5. Chile – 6%6. United States- 6%7. Germany- 4%8. South Africa- 4%9. Argentina- 2%---

Wine From Around the World:From previous labs and research conducted in

class I know that Yeast grows in an optimum temperature that is warm and humid. After conducting our own wine making I learned from Mr. Lucarelli that red wine (85 °F (29 °C) is made better in warm temperatures and white wine is better made in cooler temperatures (64-68 °F (18-20 °C).

Average Regional Temperatures:Italy- 59.3F/15.2CFrance – 12.2CSpain-47CAustralia-28.5CChile-57.3CUnited States-60FGermany-9.8CSouth Africa- 30CArgentina- 16.8C/61.8F

Hmm?... I Didn’t Know That (10 interesting facts that may shock you about wine fermentation): Did you know that barrels used for wine fermentation are toasted before hand to caramelize the natural sugars of the wood. This helps to add flavor and keep the wine from touching raw wood. Fact: Oak barrels are used for wine making because oak has the tendency to pull the tannins, acid, and alcohol into a perfect balance. It also adds flavor increasing the acidity, lowers pH, releases tannins. Did you know that on average there are 75 grapes per cluster.Fact: One acre of grape vines produces 800 gallons of wine.Back in the olden days the Irish believed that fairies are extremely found of good wine. The royal would leave a keg out at night and it would be completely gone in the morning.Did you know that Thomas Jefferson helped stock the wine cellar of he first five U.S. Presidents.According to Persian Mythology it is believed that wine was discovered by a woman who drank fermented juice from grapes in a jar. She went to sleep and woke up cured of a headache.Did you know that in the 1996 San Francisco earthquake over 30 million gallons of wine were lost.Fact: California produces about 77% of the U.S.A’s Grape Corporation.In 1300 B.C. King Tut’s Egypt the upper class drank wine while the common people drank beer.

Conclusion:For the first time ever throughout my High School

experience I was asked to apply “the Five E’s” (engage, explore, explain, elaborate, evaluate) to a large experiment of wine fermentation. This experiment was to help us as a class further our knowledge on Ethanol Fermentation. Before this experiment we conducted labs to help us inquire into the characteristics of a living organism. We later on looked into the characteristics of yeast. With this previous knowledge I wanted to gain a further inquiry into yeast and its involvement in wine fermentation. After conducting my research I have been able to answer my very own constructed inquiry question. In doing so I was not successful in finding an accurate measurement but I came to know much more. Over all I learned the average production temperature necessary to red and white wine. I concluded research on organic and natural yeast by comparing them to each other. I also learned that bacteria and mold are uncontrolled variables that have a strong effect on the production and fermentation of yeast. By apply the Inquiry method I was able to ask myself one of the toughest question that I constructed. By asking my own question based on previous knowledge I was more egger to find the answer. It is proven based on this experiment that the inquiry method is a useful one contributing to my problem solving, organization and brainstorming skills. Based on the research found I have a greater insight into wine fermentation and feel confident in future labs by applying the inquiry method.

Sources:

Ross. P, Jordan. “Yeast Going Wild: Wild yeast in wine making.” (2008): n. pag.

Web. 10 Nov 2009. <www.enologyinternational.com/yeast/wildyeast

Workman, Daniel. "World's Top Wine Country." (2007): n. pag. Web. 10 Nov

2009. <www.suite101.com>.

Following Fact Websites:www.weathernetwork.comwww.letsdowine.comwww.articledashboard.comwww.winelit.slsa.sa.gov.auwww.infobarrel.com/facts_about_wineTLC Video: Dirty Jobs: Toasting Barrel with Mike Rowe