Friday, June 12, 2015
Friday, June 7, 2013
I have a suggestion for a way to reduce lipase activity in breast milk, but I need as many of you as possible to try it and see if it works. This is an on-line recruitment for an informal clinical trial.
Right now, the recommended method is to scald the milk to destroy lipase activity. I have also suggested trying to keep the milk as cold as possible starting with time of collection, to minimize the lipase activity.
Scalding the milk destroys the lipase, which is a protein, and this works. The problem is that it also destroys many beneficial proteins, like Antibodies, and it destroys many vitamins, like Vitamin C. Another, easier way, to destroy only the proteins is to shake the milk up so that it foams. Proteins are denatured (stretched out and destroyed) on the surfaces of air bubbles and oil/water interfaces. A textbook says that lipase is also destroyed at these interfaces. What I don't know is whether the lipases are such tough proteins that they can refold and regain their activity. Will you help find out if lipase activity can be reduced just by shaking the milk?
The experiment: collect your milk as you normally do and set aside two small amounts. Shake one fraction vigorously up and down for half a minute. Sniff both fractions to make sure they smell fine. Put both fractions in the refrigerator overnight. The next day, smell them both. Did the shaking prevent the shaken fraction from smelling bad, while the unshaken fraction smells rancid? (When lipase digests fat, free fatty acids are produced. The fatty acids smell this way. Note that these free fatty acids are okay for baby to eat and the milk is not really spoiled. Milk banks in hospitals will gladly take it and very young babies will drink it.)
If this works, it is an easier method than either scalding or keeping everything very cold. While shaking destroys the protein antibodies, just the way scalding does, at least it preserves the vitamins, and is much simpler to do. It is a trade. The feedings that use the stored milk will have fewer of the beneficial antibodies, but they will at least have all the other benefits of maternal milk over formula. There could still be other direct feedings to provide the baby with mom's antibodies.
Just collect milk into cold containers, shake them vigorously, then freeze. If the lipase is inactivated, you can warm the milk for feeding. If not, keep the milk cool.
Please let me know if this works for you.
Wednesday, June 5, 2013
DEALING WITH BREAST MILK LIPASES
Some mothers have the experience that their baby will not accept their breast milk that has been pumped in advance and stored. Most breast milk will taste fine if pumped and then stored even at room temperature overnight, or refrigerated for a few days, and subsequently frozen. For some mothers, however, the milk may taste bad after it has been allowed to sit at room temperature for just a few minutes.
This can have several important financial consequences. A working mother anxious to provide only breast milk to her baby may decide to give up pumping, and stay home to nurse her baby. We have one friend who quit her law practice so that she could stay home and nurse her baby after it rejected her bottled breast milk that had been pumped in advance.
Another consequence occurs in the Neonatal Intensive Care Unit (NICU). If a baby is born prematurely and spends time in the NICU, and the mother plans to pump her milk so she can go back to work, the nurses will not release the baby to go home until it demonstrates that it is strong enough to finish a whole bottle of milk. Even if they had scalded the milk, if the milk had already gone rancid, the baby will not drink beyond the point of being ravenous. The baby may have to stay in the NICU a much longer time than is necessary. Not only is this a great expense to the parents or insurance company, it is an unhappy time for the family that wants to take the baby home.
The culprit is the breast milk lipase enzymes. These lipases are more active in some women for an unknown reason. These enzymes are beneficial for the baby, as they will convert the milk fats to sugar and free fatty acids, assisting in their digestion. The fatty acids are neutralized to salts, and that is the definition of a soap (a salt of a fatty acid) and the milk tastes soapy. With further digestion to fatty acids the milk will taste rancid. It is not spoiled but just tastes bad. According to several mothers, the baby will not usually reject soapy-tasting milk until a good fraction of the lipid has been broken down. Some babies may be fussier about the taste than others.
Several solutions have been tried to reduce or remove the lipase activity. One solution is to scald the milk to inactivate the lipases. However, this reduces some of the beneficial immunoglobulins and vitamins in the milk. Freezing the milk in household freezers will slow the lipase activity, but will not eliminate it, and the milk will taste bad with time. However, it is the best solution for your milk if it can be used within a few days. You will need to check it periodically to see how long your milk will stay good under your home conditions.
Reasoning that the lower the temperature, the slower an enzyme works,we have found that keeping the milk as cold as possible at all times will sufficiently reduce the lipase activity so the milk will not taste bad. This means cooling the milk while pumping, getting it frozen as quickly as possible, storing it in as low a temperature as possible, quick-thawing the milk, and serving it cold in a thermos baby bottle.
Here is a procedure for keeping everything cold:
For pumping the milk, have the collection bottle and all components that may contact the milk pre-cooled. Keep the pumped milk cold during collection. The collection bottle can be wrapped with a commercially available cold pack or cold wrist wrap and secured by Velcro. The collection bottle can also be kept in an ice-water bath, consisting of ice cubes floating in a tub or jar of water. You may have to place the water bath on a table, and adjust your seat height so the bottle rests in the ice water bath. You may need to weigh the bottle down with a wrist or ankle weight, or an adjustable weighted bottle cape (photo). Finally, you can cut a hole in a fitted top to a plastic tub so that the top will hold down the empty bottle.
You can store the milk in the collection bottle or transfer it to pre-cooled storage containers or bags that are commercially available for frozen breast milk storage.
Move the milk to a freezer as soon as possible. Ideally, you would have a separate chest freezer that is not opened too often. Standard freezers operate around -20 degrees centigrade, but the lower you can set the temperature the better. Some low level lipase activity continues even in the freezer, unless it gets down to -70 degrees centigrade. Commercial freezers are available that cool to -70. These are expensive, but a NICU could have one of these for the breast milk they store. At home, avoid if possible a freezer with an automatic defrost cycle, because the lipases can work faster if the milk warms up, or thaws, while the freezer defrosts. Don't store the milk in the door of an upright freezer, where the temperature warms up every time the door is opened.
When the milk is needed, thaw it quickly by holding the container under the faucet with lukewarm water running, gently twirling and swirling. Do not shake the milk, as this will produce bubbles which destroy many of the beneficial proteins (enzymes and antibodies, for instance).*
Transfer the still cool milk to a pre-chilled baby thermos bottle, which is commercially available (photo). Our baby accepted the cold milk, but this may take some getting-used-to for your baby.
Everyone's milk is a little different in the amount of lipase activity it contains, and you will learn just how long your milk can be stored in your freezer before it tastes too bad for your baby to drink. Experts say your milk composition changes with your baby's needs, and with time your baby may not require as much help with its digestion, and your milk's lipase activity will decrease. Expect the problem to go away with time.
In spite of the taste, the milk is still completely nutritious, and milk banks or local NICUs will accept the milk that you can no longer use because of the taste. They can use it for infants that are fed by tubes. Please donate it.
*The high surface tension at the gas-liquid interface of an air bubble will cause proteins to denature, and to lose activity that depends upon their structural integrity. Some refolding may occur, but much activity is lost.
On my other blog on this site I ask you to participate in an experiment to see if shaking will reduce lipase activity in pumped milk, since lipases are protein enzymes.