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
