Most milk produced in developed countries is Grade A. To be Grade A the milk:
(1) must be produced at a dairy farm that is registered and regularly inspected
(2) must be chilled promptly after collection (to 45°F within 2 hours) and maintained at that temperature
(3) must be free of gross defects in appearance, smell and taste. This includes chunks of non-fat solids that may indicate mastitis.
(4) must have less than a specified cutoff for bacteria and somatic cells (<= 100,000 bacteria per mL; <= 1,000,000 somatic cells per mL)
(5) must be handled and processed according to specified sanitary guidelines
Any milk that is fit to use and that is not Grade A is termed Grade B. Grade B is primarily used in production of commercial foods such as cheese. Grade B milk must meet guidelines for sanitary handling, cutoffs for bacteria (<= 300,000 per mL), etc.
Milk that is unfit for use may be:
(1) contaminated by pathogenic bacteria or in numbers that cannot be made safe by pasteurization or other processing
(2) contaminated by a poisonous or deleterious product
(3) contaminated by any substance unfit for human consumption, which may include drugs used to treat the cows
(4) contains an additive that is used to make the milk appear to be of higher quality than it actually is
(5) produced, handled or processed in an unsanitary manner
Milk may not be sold to the public if it has not been processed to eliminate pathogenic bacteria, usually by pasteurization. Pasteurized products must meet specified criteria to maintain a Grade A rating.
