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Science Investigatory Project (Chemistry) Essay


This study aims to find out which among the juices of Mangifera indica, Annona muricata, and Citrofortunella microcarpa fruits ferment fastest. Three treatments were made: 200 mL. of Mangifera indica fruit juice fermented with 20 yeast cells; 200 mL. of Annona muricata fruit juice fermented with 20 yeast cells; and 200 mL. of Citrofortunella microcarpa fruit juice fermented with 20 yeast cells.

The start date of fermentation was recorded as well as the original specific gravity of each treatments. The end of fermentation of each treatment were watched for by the researchers. To verify a treatment ended fermentation, apparent attenuation was computed, computing prior to that the final gravity of each treatment.

The result showed that the treated Citrofortunella microcarpa fruit juice fermented fastest. Next was the treated Annona muricata fruit juice. The last to complete fermentation was the treated Mangifera indica.

This study is economically beneficial to the province, since it is abundant with the fruits used. It would also encourage small and medium enterprises to venture into liquor-making, even via home-based production.

The researchers recommend a similar research on other fruits such as cashew, jackfruit and bananas. Also recommended is the use of variables such as temperature, pressure and amount of fermentors added.

I. Introduction

A. Fermentation

Fermentation, also called anaerobic glycolysis, is “an enzymatically controlled anaerobic breakdown of an energy-rich compound (as a carbohydrate to Carbon dioxide and alcohol or to an organic acid),” according to the 11TH edition of the Merriam-Webster Collegiate Dictionary.

Recorded first in 1601, the word “fermentation” came from the root word “ferment”, a Middle English word derived from the Latin word for yeast, fermentum. To most people, yeast comes to mind whenever fermentation is brought about as a topic for discussion, since the presence of yeast is widely known to cause the fermentation responsible for the production of beer (ibid; Chojnacka, 2008).

In the process of producing beer, yeast enables the fermentation of sugars glucose and sucrose and their conversion into ethyl alcohol, otherwise and more popularly known as ethanol, grain alcohol or drinking alcohol. This is one of two most popular types of microbial fermentation, ethanolic fermentation, which is chiefly used in making alcoholic beverages, industrial biochemicals, cosmetics and pharmaceuticals. Lactic acid fermentation of milk, vegetables, cereals, meats and fish is another kind of microbial fermentation (ibid.).

Fermented products have many advantages over raw materials from which they came from. Fermented products are more digestible; has improved flavor, texture, appearance and aroma; are enriched with synthesized vitamins; have lesser carbohydrates; cooks quickly, stays longer; and stocks up normal intestinal microflora (Shurtleff, et al., 2007).

B. Ciders

Among the thousands of fermentation products are ciders, which are “…expressed juice of fruit[-s] (as apples) used as a beverage or for making other products (as applejack)” (Merriam-Webster). Ciders come from a wide variety of fruits (Cider, Wikipedia)–from apples to grapes, cherries to cranberries, and even bananas.

The island province of Guimaras abounds with vegetation, i.e., fruits and vegetables, with mangoes, coconuts and bananas topping the list (2007 National Statistical Coordinating Board figures). Ciders can be made from most, if not all, of Guimaras fruits. It is the researchers’ task to determine the rate of fermentation of these ciders.

II. Objectives of the Study

1. To find out the rate of fermentation of juices from bountiful Guimaras produce such as mango, calamansi, guyabano, coconut, banana, and cashew; and 2. To help find potential industry for Guimaras folks, from the production of these fermented ciders and their by-products.

III. Significance of the Study

This study on the rate of fermentation of ciders from various Guimaras produce is primarily aimed to benefit local folks by finding new frontiers for the booming food and beverage industry.

IV. Limitation of the Study

This study is limited to the fermentation of mango, calamansi, guyabano, coconut, banana, and cashew juices, and restricted to qualitative observations of their rate of fermentation and color.

V. Review of Related Literature

The history of fermentation predates the history of man, since the process is natural to fruits and, practically, to all vegetation.

Modern manipulation of the process is but a display of man’s superior intellectual ability. In antiquity, though, man’s use of fermentation is more of a product of accident rather than aimed curiosity. It is believed that man’s serendipitous foray into fermentation was made after meat observing that certain elements in salting food made the food more palatable than plain, salted food (Wang et al., 1979).

For those who use crude processes of fermentation, it is more of a mystic art than a science. In fact, not until the 19th Century, was the mechanism of fermentation intelligently applied (Chojnacka, 2008; Shurtleff, et al., 2007).

Records show that man had been utilizing this process to his benefit in as early as the Caucasian era, about 6,000-8,000 years ago in Shulaveri, present-day Georgia. Artifacts such as 7,000-year old jars containing wine residue in Hajji Firuz Tepe in the Zagros Mountains, the largest mountain range spanning present-day Iran and Iraq (Wine History, Beer100.com) are now on display at the University of Pennsylvania.

Accounts of the existence of fermented beverages in Babylon circa 5000 BC, in ancient Egypt circa 3150 BC, pre-Hispanic Mexico circa 2000 BC, and Sudan circa 1500 BC are numerous (Chojnacka, 2008).

Learned use of fermentation can be attributed to the German physiologist Theodor Schwann who in 1840 developed the cell theory and found that fermentation is the result of living things. This was influential to French chemist and microbiologist Louis Pasteur who determined in 1854 that fermentation is caused by yeast. Pasteur assumed that a special element or force called “ferments” gives yeasts the ability to ferment (Dubos, 1951). Though Pasteur believed that ferments is dormant outside a living cell, he endeavored to extract ferments but to no avail.

In 1897, German chemist Eduard Buchner proved that the enzymes in yeast cells, which he called “zymase” causes fermentation, not the yeast itself. He received the 1907 Nobel Prize in Chemistry for cell-free fermentation (NobelPrize.org). In 1929, Arthur Harden and Hans Euler-Chelpin won the Nobel Prize in Chemistry for detailing the exact mechanism of fermentation caused by enzymes (NobelPrize.org)

Since Pasteur’s discovery of the fermenting ability of yeast, mankind has all the more benefited from fermentation products. The essence of fermentation has shifted, though, from for preservation, since we now utilize much better preservation methods, into food and beverage production (Chojnacka, 2008).

VI. Methodology

A. Materials

250 mL. fresh mango juice hydrometer 250 mL. fresh calamansi juice cork stopper/lid cover 250 mL. fresh guyabano juice three pcs. wide-lid glass fermentor 100 small-sized yeast cells (Saccharomyces cerevisiae)

B. Fermentation Process

1. Do this in the early morning to allow ample time for the experiment.

2. Pour each of the prepared fruit juice (250 mL. each of fresh mango, calamansi, and guyabano) in a separate glass fermentor.

3. Measure with the hydrometer the specific gravity of each juice. Mark this as original gravity (O.G.).

Specific gravity is measured by floating the hydrometer in a sample of liquid. The hydrometer must float freely. Read and take note of the point where the surface of the juice being observed lines up with the graduation on the hydrometer.

4. Pitch 20 yeast cells on each fermentor.

5. Close the fermentor with a cork stopper/lid cover to utilize closed fermentation.

6. Note the exact time each fermenting setup was closed.

7. Let off. Have team members take turns every hour in observing the fermenting setups.

8. Fermentation is complete once no more bubbles are produced in the air-locked fermentor, since carbon dioxide (CO2) production is ended at the end of fermentation.

It should be noted that this is not foolproof. If there is still some fizzing and foaming, it is not done yet.

Also, when a fermenting setup is shaken, it may produce some bubbles, some fizz or foam. This doesn’t mean fermentation has just halted and is re-starting. It’s only that there’s CO2 in the setup itself (as in most brewed setups such as beer) and it was only disturbed by shaking it.

9. To guarantee that fermentation has ended, measure with the hydrometer the specific gravity of the fermenting setup. Mark this as the final or finishing gravity (F.G.). Compute for apparent attenuation. Mark this as A.A. Apparent attenuation is the difference between the specific gravities before and after fermentation divided by the specific gravity before fermentation, and multiplied by 100.

To illustrate:

((O.G. – F.G.) / O.G.) x 100 = A.A.

Usual apparent attenuation of a complete fermentation is 70-75 percent.

10. If apparent attenuation of 70-75 percent is not capped, repeats steps 1 to 9.

11. Tabulate data.

VI. Results and Discussions

A. Chart on Rate of Fermentation of Mangifera indica, Annona muricata, and Citrofortunella microcarpa juices

Fruit Juice
Date Fermentation Started
Original Gravity
(at 31°C)
Final Gravity
(at 31°C)
Apparent Attenuation
(in Percent)
Date Fermentation
Number of Days of Fermentation
Mangifera indica
Jan. 14, 2013
Jan. 27, 2013
13 days
Annona muricata
Jan. 14, 2013
Jan. 24, 2013
10 days
Citrofortunella microcarpa
Jan. 14, 2013
Jan. 18, 2013

B. Discussions

Juices of Mangifera indica, Annona muricata, and Citrofortunella microcarpa completed fermentation at different dates. Mangifera indica completed fermentation last at 13 days, while Annona muricata at 10 days, and Citrofortunella microcarpa, the fastest, at only 3 days. The researchers deemed this difference in fermentation rate a result of the apparent amount of fructose, which are broken down by the yeast cells, in the fruits where the juices came from as can easily be induced from the sweetness of the fruits.

It was, thus, determined that more fermented product can be made from the juice of Citrofortunella microcarpa in less amount of time, than from the juices of Mangifera indica and Annona muricata.

VII. Implications

The researchers have found fruits viable for fermentation and, hence, for making liquor such as wine.

With the development of the fermentation of fruit juices for the latter purpose, so will the growth of income opportunities for the people of this island province. The manufacture of fruit juice-fermented beverage can easily be operated even in small homes.

Using these fruits might also provide for a substitute for beer, gin and other alcoholic beverages, which come from less healthful raw materials.

Backyard fruit growing would be also encouraged, which not only would provide necessary raw materials but would also somehow help lessen the effect of air pollution and global warming.

VIII. Recommendations

Verifying studies are highly recommended. Different fruits are recommended for experimentation. Different and varying factors such as temperature, pressure, more yeast cells, can also be tried on.

IX. Selected References:

Katarzyna Chojnacka. Chemical Engineering and Chemical Process Technology,
Volume V.,
Encyclopedia of Life Support Systems, UNESCO, 2008.

Shurtleff, W. and Aoyagi, A. A Brief History of Fermentation, East and West, Soyinfo Center,
Daniel I.C. Wang. Fermentation and Enzyme Technology, Wiley, 1979. Rene J. Dubos. “Louis Pasteur: Free Lance of Science, Gollancz.” Trends in Biotechnology,
Volume 1, Cell Press, 1951.
Merriam-Webster Collegiate Dictionary, 11th Ed, Merriam-Webster, Inc, 2010. Guimaras Quickstat, National Statistics Coordinating Board, 2007. http://www.nobelprize.org/nobel_prizes/chemistry/laureates/1907/buchner-bio.html, November

2, 2012.
http://www.nobelprize.org/nobel_prizes/chemistry/laureates/1929/press.html, November 2, 2012. http://www.beer100.com/history/winehistory.htm, November 26, 2012. http://en.wikipedia.org/wiki/Cider, October 12, 2012.

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