High lipase breastmilk is a common issue for parents who store their expressed milk, often resulting in a distinct soapy or metallic taste and smell. This change in flavor is not a sign of spoilage or contamination; the milk remains completely safe and highly nutritious for your baby to consume. The challenge arises when a baby refuses to drink the stored milk due to the altered taste, which can be frustrating when a freezer stash has been built. Fortunately, there are proactive steps to prevent this flavor change and reactive strategies to manage milk that has already been affected.
Understanding Lipase Activity in Breastmilk
Lipase is a natural enzyme present in all human milk, playing an important role in infant nutrition. Its primary function is to break down the complex fats, known as triglycerides, into simpler free fatty acids and glycerol. This process begins immediately after the milk is expressed, making the fats easier for a baby’s developing digestive system to absorb.
The phenomenon called “high lipase” means the enzyme is highly active, not necessarily that there is an excessive amount. When the milk is stored, this enzyme continues its work of fat breakdown at a faster rate than usual. The resulting free fatty acids cause the off-flavor, which is often described as soapy, metallic, or sometimes fishy. The milk’s nutritional components are still intact, meaning the only problem is palatability for some babies.
Preventing Flavor Changes Through Heat Treatment
The most effective strategy to prevent the flavor change is to deactivate the lipase enzyme shortly after pumping. This is achieved through a controlled heating process called scalding, which uses heat to denature the enzyme. Scalding must be performed on freshly expressed milk before the off-flavor has a chance to develop, as the process cannot reverse a taste change that has already occurred. The time window for scalding can vary from mother to mother, sometimes needing to be done within hours or sometimes after a day of refrigeration.
To scald the milk, gently heat it in a clean saucepan over medium heat, avoiding the use of a microwave which can create uneven hot spots. The goal is to bring the milk to a temperature of \(180^\circ\text{F}\) (\(82^\circ\text{C}\)). Using an instant-read thermometer is helpful to ensure accuracy and prevent overheating. You will observe small bubbles forming around the edges of the pan as the milk approaches the correct temperature, but it should never reach a full, rolling boil.
Once the milk reaches the target temperature, it must be immediately removed from the heat source. Rapid cooling is necessary to minimize any further heat exposure and preserve the milk’s beneficial properties. An ice bath, which involves placing the container of warm milk into a bowl of ice and water, is the quickest way to bring the temperature down. After the milk has cooled completely, it can be safely transferred to storage containers for refrigeration or freezing.
Strategies for Handling Already Affected Milk
If you discover a freezer stash of milk with the soapy or metallic taste, scalding the thawed milk will not remove the flavor, but these affected batches do not need to be discarded. A primary strategy is to dilute the strong flavor by mixing the high lipase milk with freshly pumped milk. Start by blending a small amount of the affected milk with a larger volume of fresh milk, then gradually increase the ratio of the stored milk to see what ratio your baby will accept.
For babies who are already eating solids, the stored milk can be mixed into purees, oatmeal, or baby cereals to mask the taste. This incorporates the milk’s nutritional value into food where the flavor is less noticeable. In some cases, adding a single drop of non-alcoholic vanilla extract to a bottle before feeding may help to improve palatability, but this should be discussed with a pediatrician first.
Beyond feeding, high lipase milk can be repurposed for external uses, taking advantage of its beneficial properties for skin health. The milk can be added to a baby’s bath water, which can be soothing for conditions like eczema, cradle cap, or dry skin. The milk can also be used to make breastmilk soap or lotion. Additionally, some milk banks may accept high lipase milk for donation, often for use with babies who are tube-fed and unaffected by the taste.