'Quantitave Plating\r'

'BioSci 101 †Lab role 810 QUANTITATIVE PLATING PURPOSE The purpose of this testing ground is to see the effects of pasteurization while emphasise the process for nonparallel dilutions. PROCEDURE See references (1) RESULTS As the dilution factor increased for both the lovesome milk (un pasteurise) and change integrity milk samples, the number of colonies decreased. The number of cells/mL in the pasteurized milk sample is substantially less than the number of cells/mL in the cutting milk sample. RAW (UNPASTEURIZED) SAMPLE Dilution mover| number of Colonies| Number of cells/mL| 10-3| TMTC| TMTC| 0-4| TMTC| TMTC| 10-5| TMTC| TMTC| 10-6| 284| 284,000,000 cells/mL| 10-7| 44| 440,000,000 cells/mL| | medium| 362,000,000 cells/mL| PASTEURIZED SAMPLE Dilution Factor| Number of Colonies| Number of cells/mL| 10-3| 71| 71,000 cells/mL| 10-4| 9 (TLTC)| TLTC| 10-5| 6 (TLTC)| TLTC| 10-6| 1 (TLTC)| TLTC| 10-7| 12 (TLTC)| TLTC| | AVERAGE| 71,000 cells/mL| DISCUSSION/CONCLUSIONS Pasteu rization, a process named after scientist Louis Pasteur, involves the application of heat to destroy the majority of serviceman pathogens in foods.In the dairy farm industry, pasteurization involves the â€Å"heating of every(prenominal) particle of milk or milk return to a specific temperature for a specified menses of time without allowing recontamination of that milk or milk yield during the heat treatment process. ” (2) For public health purposes, pasteurization is the process of making milk and milk products arctic for human consumption by destroying all bacterium that may be harmful to health. (2) A serial dilution is a laboratory technique in which a substance is decreased in concentration in a series of proportional amounts. Dilutions are unremarkably made in multiples of 10. 3) The viable scale leaf work out procedure allowed for live cells in the milk samples to be analyzed. The rude milk (unpasteurized) sample demonstrated as well as many settlement forming units to count in the first base three dilutions of 10-3, 10-4, and 10-5. The 10-6 dilution demonstrated 284,000,000 cells/mL and the 10-7 dilution demonstrated 440,000,000 cells/mL. This demonstrates that raw milk contains a lot of bacteria all the same after multiple serial dilutions. In the 10-3 pasteurized sample, the plate exhibited 71,000 cells/mL. The results of the additional dilution samples contained too few habituation forming units to count.However, in the 10-7 dilution, although the plate demonstrated 12 colonies, in that location should do been no colony forming units on this plate. The reasons for this could have been that this sample was contaminated from â€Å"double-dipping” the sample in the beginning dispensing it onto the plate or when using the pipette, it mistakenly was inserted in a higher concentration sample and then outright to a lower concentration sample before it was dispensed onto the plate. The results suggest that pasteurization kills most pathogens in milk by brief exposure to comparatively high temperature.This was demonstrated most beneficially with the 10-6 and 10-7 dilutions wherein the raw milk exhibited 284,000,000 cells/mL and 440,000,000 cells/mL respectively and the pasteurized milk had too few cell colony forming units to even count. Unpasteurized milk is not estimable for people to drink. For example, in a study performed in December of 2001, the bacteria Campylobacter jejuni, a microaerophilic bacteria commonly found in animal feces, was found in unpasteurized milk at an organic dairy farm in Wisconsin and caused 75 people, ages 2 to 63, to bring about ill. 4) Therefore, pasteurized milk is essential for ensuring good quality, tight bacteria-free drinkable milk. REFERENCES 1. BioSci 101, Section 810 †PowerPoint Lab 9A 2. http://www. foodsci. uoguelph. ca/dairyedu/pasteurization. hypertext markup language 3. BioSci 101, General Survey of Microbiology Laboratory Supplement get down 2012 4. http://foodsafety. ksu. edu/articles/1138/Raw_Milk_Outbreak_Table. pdf\r\n'