Dairy and Milk Science Flashcards
What is pasteurization
invented by Louis Pasteur. a process which uses heat to destroy all pathogenic bacteria from milk and other juices.
Does pasteurization kill all bacteria?
no, many non-pathogenic bacteria remain
What is one of the most heat resistant pathogenic bacteria in milk? and what temperature is it destroyed at
Q fever bacteria (coxiella burneti) destroyed at 145F at 30 minutes
What does milk loose it’s flavor and consistency if cooked too hot?
because the albumin coagulates which changes the sugars, fats and salts in the milk.
What are the 5 pasteurization methods
the VAT (Batch) Method HTST High Temp Short Time Method High Heat Short Time Method Ultra High Temperature Method Instantaneous Method
What is the VAT (Batch) Method
145 for 30 minutes typically used for cultured dairy products such as sour cream and yogurt
What is the HTST Method (name the three common temperatures and times)
Milk goes through a continuous flow process where it is carefully heated.
161 for 15 seconds
166 for 15 seconds (if Q fever in product)
175 for 25 seconds for high fat products such as ice cream
What is the high heat short time method of pasteurization
similar to ultra high temp.
between 191 and 212 for a second or less
What is the ultra high temperature method
in a vacuum chamber 194 for 3/4 second
used for high sugar/fat products such as half and half and whipping cream
What is one of the benefits of ultra high temp pasteurization
gives a product a very long storage life. some products can even be stored at room temperature
What is the instantaneous method of pasteurization
280 for a fraction of a second. not really used because it’s hard to maintain consistent temperature. it is used for some shelf stable dairy creamers
Which method has been found to product the best results
high temperature short time
What are some of the downfalls of the VAT method
bubbles in the vat can cool the milk resulting in improper pasteurization
to counter act something hot air is blown over the vat
What are some downfalls to the HTST method
milk must be preheated first
What happens if the milk does not get hot enough as it passes through the coils in the HTST method
it is automatically recirculated back through
What are the names of the 5 standards for bacteria in milk
grade A raw milk grade A pasteurized milk grade b raw grade b pasteurized certified raw milk
grade A raw milk
less than 50,000 bacti per ml
grade A pasteurized
less than 15,000 bacti per ml (standard plate count)
grade b raw
less than 1,000,000 bacti per ml
grade b pasteurized
less than 50,000 bacti per ml
typically used for industrial processes (where it will be heated further)
not direct to consumer
certified raw milk
same stds as grade a
less than 15,000 bacti per ml
how much vitamin D is added to most milk products
400 ius
What two vitamins does pasteurization destroy in milk
vitamin D and C
What is homogenized milk
milk that has been centrifuged so the fat globules break up into a non settling liquid
Name 10 diseases that may be found in milk
brucellosis bovine tuberculosis staphylococcus typhoid salmonella streptococcus septic sore throats hep a q fever scarlet fever
how long before the birth and after the birth must milk from a calving cow be disposed of
15 days prior and 5 days after
How often are most cows examined
every 6 years
milking cows are testing every year for what?
tuberculosis
Can milk pails be used?
NO, milk is now collected and stored in bulk storage tanks
The average milking cow produces __ to __ gallons of milk per day
5 to 7
What is bovine mastitis
aka scarlet fever
a streptoccus infection of the cows udder
What would a leucocyle count tell you about a cows health?
it’s a white blood cell count, it will tell you if they have an infection
What are 4 foreign substances that can be found in milk?
antibiotics
insecticides
radioactivity
milkstone
what are two radioactive materials that have been found in milk?
radioactive strontium and iodine isotopes
What are milkstones
build up of calcium and magnesium from milking equipment that can get into milk
What is the phosphatase test used for?
to test for the phosphatase enzyme which if present in milk indicates improper pasteurization
What is the ring test (blue ring test)
tests for brucellosis in cows. a blue ring will form in the test bottle
The methylene blue test is aka as ________ and tests what about milk?
the milk reduction test
tests overall quality of milk, mainly checking to see fi there is a large number of bacteria in the milk sample
