INTRODUCTION - 3 - MILK QUALITY_Bacterial Quality

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* 1. Enter your First and Last Name

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* 2. The term "milk quality" can refer to the nutritional composition, physiochemical properties, hygienic aspects, and biosecurity of milk.

True

False

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* 3. Select all that apply. High quality milk will:

have low bacterial counts

not have objectionable odors

not contain abnormal substances such as pesticides, added water, antibiotic or antiseptic residues

have low somatic cell counts

be white in appearance

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* 4. Which of the following best describes bacteria counts in milk?

Regardless of the means of milk production, there will always be an initial amount of bacteria in milk resulting from the milking process; the number of bacteria in milk later on reflects microbial contamination during production, collection, and/or handling.

Bacteria counts in milk are required by law to be performed daily on all farms.

Depending on the means of milk production, there might not be bacteria initially present that results from the milking process.

The number of bacteria present in milk later in the milking process does not reflect microbial contamination during production, collection, and/or handling.

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* 5. Select all that apply. Why is the presence of bacteria in milk important to the quality of the milk?

bacteria can break down milk components such as lactose, protein, and fat

bacteria can transmit mad cow disease

bacteria can cause diseases in animals and humans

bacteria can secrete substances that alter milk's characteristics

bacteria can cause deterioration of milk

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* 6. Select all that apply. Classifications for bacteria that are determined based on their optimal growth temperatures include:

mesophilic (grows well at warm temperatures [90°F or 32°C])

psychrophilic (grows well at cool temperatures [55°F or 13°C])

coliforms (grows well at warm temperatures [90°F or 32°C])

listeria (resistant to high temperatures)

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* 7. Mesophils (bacteria in which optimal growth temperature is around 90°F [32°C]) contamination is assessed by Standard Plate Count (SPC).

True

False

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* 8. Independent of their optimal growth temperatures, bacteria can be classified by the temperatures that can or cannot destroy them. Select all that apply

thermoduric bacteria is resistant to pasteurization temperature (145°F or 75°C)

psychrotrophic bacteria stays viable at cold temperatures, but does not grow at cold temperatures

None of the above

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* 9. Select all that apply. Mesophilic bacteria can come from:

within the udder (mastitis organisms)

the exterior of the udder and teats (dirty cows and inadequate pre-milking sanitation)

the environment (bacteria drawn into the milking machine from the milking environment)

milk handling and storage equipment (due to cleaning failures or incubation during long milking periods)

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* 10. Select all that apply

mesophils consumes milk lactose, protein, and fat

psychrophilic produces lipases that cause hydrolysis of fatty acids (rancidity)

thermoduric can cause spoilage of products after pasteurization

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* 11. Select all that apply

psychrotrophic bacteria come from contaminated water

mesophilic bacteria come from the environment (e.g., mud, bedding, and manure)

mesophilic bacteria come from cooling equipment that is not cleaned well and/or sanitized

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* 12. Select all of the correct descriptions of pasteurization.

Pasteurization is a thermal process that kills potentially harmful bacteria in milk.

Pasteurization is a process that kills some bacteria that can cause milk deterioration.

Pasteurization exposes milk to high temperatures (145°F or 60°C for 30 minutes, or 180°F or 75°C for 30 seconds).

Pasteurization is a process that kills some bacteria that can transmit diseases to humans such as tuberculosis or brucelosis.

Pasteurization is a thermal process that improves the nutritional qualities of milk.

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* 13. Select all of the correct descriptions of psychrotrophs.

Some psychrotrophs are thermoduric and will live through pasteurization.

Psychrotrophs that resist pasteurization can multiply in milk that is at the supermarket, which may reduce the shelf life of the milk.

Psychrotrophs that are thermoduric can cause spoilage of cheese, which all thermoduric bacteria has the potential to do.

Psychrotrophs that are thermoduric do not withstand the high temperatures of the pasteurization process and will spoil milk but not cheese.

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* 14. Coliforms are mesophilic bacteria that are present in feces, and Coliform Count (CC) measures the extent of fecal contamination of milk.

True

False

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* 15. Select all of the correct descriptions of thermoduric bacteria.

Thermoduric bacteria can survive at high temperatures.

Thermoduric bacteria are assessed by Laboratory Pasteurized Count (LPC).

Thermoduric bacteria generally cause persistent cleaning problems.

Thermoduric bacteria do not survive high pasteurization temperatures.

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* 16. Lab Pasteurized Count (LPC) is a good indicator of persistent cleaning problems because it kills environmental and mastitis organisms.

True

False

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* 17. When cows enter the milking facility with dirty udders, the adequacy of premilking udder hygiene is the last line of defense against exposure to environmental bacteria and contamination of bulk tank milk with fecal pathogens.

True

False