A day in the Pasteurization Room

By Jami Marvin, Pasteurization Technician, Indiana Mothers' Milk Bank

First thing in the morning we come in and clean. Cleaning plays a vital role in keeping the milk safe for babies. After everything is cleaned, it is then time to see what is going on with the milk for that particular day. Most days, there is already thawed milk in the refrigerator that is waiting to be processed. But, let’s start from the beginning.

When the milk first arrives in our building, it is sorted into bins. We sort it by the mom’s names, and then into the months that it was pumped. That milk then gets put into our Raw Milk Freezer until it’s time to be thawed. Once all the milk has been entered into the intake log, it is then the job of the Pasteurization Coordinator to decide which milk will be put together into which batch. A batch is roughly 650-700 ounces of frozen breast milk that has generally been pumped within a three month time frame. It is preferred that the milk comes from 2-5 different moms, so that we can ensure there is a good average of calories per bottle.


Once the milk has been designated to a batch, it is time to pull the milk from the freezer to begin the thawing process. We pull the assigned bags in each batch and arrange the milk into wire racks so that it can thaw evenly.



After the milk has had time to thaw, but while it is still partially frozen, we begin the flasking part of the process. Before we begin, we sanitize all counter tops and hands and put on a clean pair of gloves. We also wear aprons, hair nets and masks. Masks are always worn when there is open milk in the pasteurization room.  We take each bag or bottle out of the rack and wipe down any condensation. It is during this process that we inspect the bag or bottle to make sure it is not leaking and to see if it is still properly sealed. The most common thing we find are holes in bags that cause the milk to leak out. If there is a leak in a bag, we have to throw it out because if milk is coming out, then germs can potentially get in. The end result is what we call a ‘breast milk slushy.’ That ‘breast milk slushy’ goes into the refrigerator until it is ready for the next step.


The milk typically sits in the refrigerator overnight so that the remaining ice can melt and the milk is all liquid the next day. The next step is the pooling, or homogenizing step of the process. To pool the milk, we put the flasks of thawed milk into a table that sits in the middle of the room.  We even out each flask so that there is about 1400 milliliters of milk in each. Then the first flask is picked up, swirled gently, and then half of what is in the flask is poured into the next flask. Each flask must be swirled and poured into the next flask until we have gone around the table ten times.



The next step is bottling. Full term milk is bottled in 4 ounce portions, and Pre-Term milk is bottled into 2 ounce portions. Pre-Term is milk from a mom that had a baby before 36 weeks of gestation. Pre-Term milk has more nutrients, so it is put into smaller portions so that the smallest babies will get just what they need. The bottles are then sealed with an induction sealer. Then we check each bottle to ensure that it properly sealed.


Once every bottle has been checked, the batch gets to go into the pasteurizer for a hot bath. It heats the milk to the designated temperature for the allotted amount of time, and then it is rapidly cooled. When the machine is done with the cycle, it is our job to properly label each bottle and then place them in the freezer. One bottle from each batch is sent to the lab for testing and when the final lab reports come in, we know that it is ok to send out the milk or discard anything if necessary.


So, there you have it! This is what we do in a day, and now you know how we handle liquid gold.