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Fermentation lab record essay

Through this experiment milk was fermented into Kefir, then a number of tests had been used to state that fermentation actually occurred. The tests used to confirm the fermentation were a gas creation test, pH test, Gram stain, and turbidity test. The effects showed throughout the conversion of milk to Kefir there was gas made, a decrease in pH, even more bacteria present, and an increase in absorbency. The results turned out that fermentation occurred with three great confirmatory comes from the gas production, pH, and turbidity tests, while the Gram stain test acted as a adverse confirmatory test.


The key goal on this experiment was going to successfully ferment milk into a yogurt-like product called Kefir. The fermentation is completed with a symbiotic combination of diverse bacteria and yeasts. The main type of bacterias found in the fermentation of milk to Kefir is usually Lactobacillus. Lactobacilli ferment the lactose found in milk and produces lactic acid, leading to the bad taste, attribute of Kefir.

The fermented item, Kefir, is usually not know only for it is taste, but more so intended for the many health benefits if may have pertaining to the body.

Trial and error Procedures

The first step in this research was to associated with fermented kefir product as well as a control. Two bottles had been filled with dairy; kefir grain were included with the 1st bottle to do something as the experimental sample, and the second bottle, which in turn contained only milk, utilized as the control test. A plastic glove was placed on the top of each bottle of wine to act as being a gas extractor, and the two bottle had been allowed to take twenty-four several hours.

The initial test accustomed to confirm the occurrence of fermentation was to check for the existence of Carbon dioxide. It was carried out by exploring the gas lovers, on the top of each bottle, for the presence of carbon dioxidegas. The second test performed used sign paper to look for the pH of both examples. Two bits of indicator paper were dipped in each of the samples, and the color change was written. The third test performed was a gram staining of the two samples to look for the presence of bacteria (“Gram Stain Protocols.  ASM Microbelibrary). The fourth test performed was a turbidity test to look for the absorbance of each sample. Five microliters of each sample was placed in a test pipe and diluted with 500 microliters of water. The test tubes were then put into a spectrophotometer and the absorbance was recorded.


Gas Development







pH Test out




5. 5







Bacterias present


Bacteria present






Gas Production Observations:

The Kefir sample had an inflated gas collector

The dairy sample had a deflated gas collector

(Figure 1)

pH Observations:

The indicator paper dipped in the Kefir recently had an orange color, correlating with a pH of 4. five The indicator paper drizzled with the dairy had a yellowish color, correlating with a pH of 7 (Figure 2)

Gram-stain Observations:

The presence of bacterias was seen in the Kefir sample.

The presence of bacteria was seen in the milk sample, but was a lower in amount than that of the Kefir test.

Turbidity Findings:

The Kefir sample was noticed to have a bigger absorbency compared to the milk test. The dairy sample was observed to experience a lower absorbency compared to the Kefir sample.


The gas creation test showed the Kefir sample created gas while the milk sample did not. It was interpreted while an indication of fermentation, mainly because carbon dioxide is a direct merchandise of fermentation.

The ph level test demonstrated that the kefir sample was more acidulent than the milk sample, which is exactly what was expected. This confirms the existence of fermentation due to the bacteria making several different stomach acids when fermenting the sugars in milk. The ph level of the milk was natural asexpected.

The turbidity test out showed the Kefir sample to have a larger absorbance than the milk sample. This proceeded to go exactly how we all expected, and is also used because confirmation of fermentation considering that the fermented merchandise would have even more bacteria present.

The Gram stain check showed that there were bacteria present in the Kefir and milk examples, which was no expected consequence. Before performing the research, milk was believed to have no bacterias due to the pasteurization process. After further analysis the group came to the realization that bacteria was present in milk due to the all-pervasive nature of bacteria. This can be a test that is certainly considered the unfavorable confirmatory test out.


This experiment was funded by selfless charitable contributions of Chip Fiore and Michael Ahrens, with further funding from your University of Kansas. Meters. A., In. F., G. H., and M. C. designed and performed the experiment. Meters. A. wrote the survey. No clashes of interest had been reported.


1) Ahrens, Micheal L. Figure 1 . 2014. Micheal Ahren’s Mobile phone, Lawrence, KS.

2) Cullom, Melissa. Figure installment payments on your 2014. Melissa Cullom’s Telephone, Lawrence, KS. 3) Johnson, Ann C., and Marise A. Hussey. “Gram Discoloration Protocols.  Gram Discoloration Protocols. ASM Microbelibrary, 40 Sept. june 2006. Web. twenty-three Oct. 2014.


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Published: 01.27.20

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