FOOD MICROBIOLOGY
MICROORGANISMS IN FOOD
|
Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
|
|
|
By adding a known volume of original sample to an equal volume of diluent
|
|
|
By heating the sample
|
|
|
By freezing the sample
|
|
|
By centrifuging the sample
|
Detailed explanation-1: -To perform serial dilution, for example, 1 ml of the starting sample is added to 9 ml of Dilution Blank Tube 1. This is then followed by the same procedure, where 1 ml from Tube 1 is added to 9 ml of Tube 2, 1 ml from Tube 2 is added to 9 ml from Tube 3, and so on until the desired concentration is reached.
Detailed explanation-2: -We use serial dilutions to create decreasing concentrations of the original sample that are then plated so that a plate will be created with a low enough number of bacteria that we can count individual colonies. From that number, we can calculate the original cell density in the broth.
Detailed explanation-3: -In serial dilutions, you multiply the dilution factors for each step. The dilution factor or the dilution is the initial volume divided by the final volume. For example, if you add a 1 mL sample to 9 mL of diluent to get 10 mL of solution, DF=ViVf = 1mL10mL=110 .