Food Microbiology Laboratory Notes

These flashcards cover key concepts and procedures from the Food Microbiology laboratory, focusing on enumeration of bacteria in food products, particularly meat and milk.

What was the main objective of Laboratory #15 in Food Microbiology?

To successfully enumerate the number of bacteria found in meat and milk.

What is a microbiome?

It refers to the collection of microorganisms living in a particular environment, including food products.

What type of bacteria can be present in ground beef?

Harmful E. coli and other bacteria from the animal and production facilities.

Why is it important to cook meat properly?

To eliminate harmful bacteria like E. coli.

What process helps eliminate bacterial burden in milk?

Pasteurization.

Name two beneficial bacteria found in milk.

Lactobacillus and Streptococcus.

What materials were used in the microbiology lab exercises?

Milk and meat samples, manual pipettes, serological pipets, plate count agar, and water blanks.

What does a 1:10 dilution mean?

1 ml of sample mixed with 9 ml of diluent.

When performing a dilution, how much sample is transferred to the agar plate?

0.1 ml.

What is the first step in the procedure for Exercise 15A: Microbes in Milk?

Form groups of 4 and assign a 0hr or 24hr milk sample.

How many plates are labeled for each dilution in Exercise 15A?

4 plates labeled 101, 102, 103, and 104.

What is added to the first dilution tube in the milk exercise?

1ml from the milk stock into a 9ml water blank.

What is the dilution factor for the second dilution in Exercise 15A?

1:100 or 102.

How is the mixture of the dilution done?

By rotating it between your hands.

What is added to the agar plate after making a dilution?

0.1ml of the diluted sample.

What must be done after all plates are prepared in the exercises?

Place all plates into the incubation pan.

In Exercise 15B, what is the first step in the procedure?

Form groups of 4 and assign a 0hr or 24hr meat sample.

How many agar plates are labeled for meat samples?

4 plates labeled 101, 102, 103, and 104.

What is the procedure for transferring from the meat stock to the dilution tube?

Transfer 1ml from meat stock into a 9ml water blank.

What is the label for the fourth dilution in the procedure for meat?

(1:10,000 or 104).

What should happen after incubating the plates?

They will be observed for bacterial growth.

What kind of facilities can contribute bacteria to meat?

Production facilities.

Why is the grinding of meat significant?

It increases the surface area, which can lead to a higher contamination risk.

What kind of samples were used in this laboratory exercise?

Milk and meat samples.

How many water blank tubes are utilized in the exercises?

8 tubes, each containing 9ml of water.

What is the dilution series used in the procedures?

101, 102, 103, 104.

What is the preparation step before making the dilutions?

Label the agar plates with team name and sample type.

What crucial step is performed after adding the sample to the agar plates?

Spread it with a sterile hockey stick.

What type of bacteria could be considered harmful from dairy products?

Pathogenic bacteria present before pasteurization.

What diluent is used for the microbiology assays?

Water.

What is the mixture process described in the procedure?

Rotating the tubes between hands.

What type of agar is used for counting bacteria in this lab?

Plate count agar.

What are the incubation conditions for the plates?

Typically warm and moist to encourage bacterial growth.

What happens to beneficial bacteria during pasteurization?

Some beneficial bacteria may be eliminated.

What is a key health concern associated with unprocessed meat?

Presence of harmful bacteria like E. coli.

How is the dilution of 1:1000 labeled in the meat procedure?

It is labeled as 103.

What is indicated by the term '0hr' in the lab notes?

It refers to the fresh sample time point.

What is indicated by the term '24hr' in the lab notes?

It indicates a sample taken after 24 hours.