Original: The first technique , called '' batch pasteurization '' , involves heating large batches of milk to a lower temperature , typically 63 ° C ( 145 ° F ) for 30 minutes , followed by quick cooling to about 4 ° C ( 39 ° F ) .
Simplified: The first technique , called '' batch pasteurization '' , involves heating large batches of milk to a lower temperature , typically 155 ° F ( 68 ° C ) .