BioSci information – Lab Section 810 QUANTITATIVE PLATING PURPOSE The objective of this research laboratory is to see the effects of pasteurization while emphasizing the process intended for serial dilutions. PROCEDURE Find references (1) RESULTS Because the dilution factor increased for both the organic milk (unpasteurized) and pasteurized milk selections, the number of groupe decreased. The quantity of cells/mL in the pasteurized milk sample is considerably less than the number of cells/mL in the organic milk sample.
RAW (UNPASTEURIZED) SAMPLE Dilution Factor| Quantity of Colonies| Volume 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, 500, 000 cells/mL| | AVERAGE| 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 Pasteurization, a process named after scientist Louis Pasteur, requires the application of temperature to eliminate the majority of man pathogens in foods.
Inside the dairy market, pasteurization requires the “heating of every molecule of milk or milk product into a specific temperature for a specified period of time without allowing recontamination of that milk or dairy product throughout the heat treatment process. ” (2) Intended for public health reasons, pasteurization is definitely the process of making milk and milk products safe for man consumption by destroying almost all bacteria that may be harmful to health. (2) A serial dilution is a clinical technique where a substance is decreased in concentration in a series of proportionate amounts. Dilutions are usually made in multiples of 10. 3) The practical plate count procedure allowed for live cellular material in the dairy samples to become analyzed. The raw dairy (unpasteurized) test demonstrated a lot of colony creating units to count in the first three dilutions of 10-3, 10-4, and 10-5. The 10-6 dilution shown 284, 500, 000 cells/mL and the 10-7 dilution demonstrated 440, 500, 000 cells/mL. This demonstrates that organic milk consists of a lot of bacteria even after multiple serial dilutions. In the 10-3 pasteurized sample, the plate displayed 71, 000 cells/mL. The results of the additional dilution samples included too few nest forming devices to count number.
However , inside the 10-7 dilution, although the platter demonstrated 12 colonies, generally there should have been no colony forming models on this platter. The reasons for this could have been this sample was contaminated by “double-dipping” the sample before dispensing this onto home plate or with all the pipette, it mistakenly was inserted within a higher attention sample and after that immediately to a lower focus sample prior to it was distributed onto home plate. The results suggest that pasteurization kills the majority of pathogens in milk by brief contact with relatively temperature.
This was exhibited most beneficially with the 10-6 and 10-7 dilutions wherein the uncooked milk exhibited 284, 1000, 000 cells/mL and 440, 000, 500 cells/mL respectively and the pasteurized milk had too few cellular colony creating units to even depend. Unpasteurized milk is unhealhy for people to consume. For example , within a study performed in 12 , of 2001, the bacterias Campylobacter jejuni, a microaerophilic bacteria frequently found in dog feces, was found in unpasteurized milk in an organic milk farm in Wisconsin and caused seventy five people, age range 2 to 63, to be ill. 4) Therefore , pasteurized milk is vital for making sure good quality, practically bacteria-free standable milk. SOURCES 1 . BioSci 101, Section 810 – PowerPoint Lab 9A 2 . http://www. foodsci. uoguelph. ca/dairyedu/pasteurization. html three or more. BioSci 101, General Review of Microbiology Laboratory Product Fall 2012 4. http://foodsafety. ksu. edu/articles/1138/Raw_Milk_Outbreak_Table. pdf
