Lipase is an enzyme that is naturally present in human milk. It has several very beneficial dietary functions such as:
– Aids in keeping the milk fat emulsified (or mixed well) with the protein portion of the milk known as the “whey”.
-Keeps the fat globules tiny so that the body can easily digest them
-Helps to break down the milk fat enabling the fat soluble nutrients such as certain vitamins (A&D) and free fatty acids (responsible for protecting the baby’s immunity) become more easily absorbed by the body.
Some mothers may notice their expressed milk will have a “soapy” appearance and taste that becomes rancid rather quickly after being stored. This is a rare condition resulting from an excess of the enzyme lipase in their milk. Lipase is responsible for breaking down the fat in the milk. If there is an excess of this enzyme then the fat gets broken down to quickly after being expressed thus resulting in the change. The milk is not harmful, and most babies are not bothered by the mild change. However, the longer the milk sits the more apparent the taste/smell becomes which then will result in the baby most likely having an aversion to it.
Once the milk has soured or become “soapy” there unfortunately is nothing you can do to reverse the state the milk is in. However, there is something you can do to help prevent the bothersome change with future expressed milk. If you are certain that your milk storing issues are related to an excess of lipase, you can try scalding the milk prior to storing it in the freezer or fridge. Scalding the milk soon after it is expressed with stop the breakdown process of the fat properties resulting from the access enzymes. To scald, heat the milk in a pan on the stove to around 180 degrees F, or until you begin to see bubbles forming around the edge of the pan. DO NOT bring the milk to a rolling boil. Once the proper temperature has been reached, immediately cool the milk down and store in an air tight container.
It is true that scalding the milk at such a high temperature will result in killing some of the antibodies and pro-biotic features of breast milk, however there are still many valuable components to breast milk that will still provide better nutrients to your baby then store bought formula. As long as your baby is receiving breast milk directly from the source a couple times a day, and yes momma that means you, loosing the additional antibodies from the heat treated milk shouldn’t be a problem.
For further information consult with a Licensed Dietitian or Lactation Consultant.
Lawrence R, Lawrence R. Breastfeeding: A Guide for the Medical Profession, 6th ed. Philadelphia, Pennsylvania: Mosby, 2005: 156-158, 203-205, 771, 781.
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