Bringing milk to a simmer is a cooking technique that involves gently heating milk until small bubbles start to break the surface. This is done to achieve certain results in recipes that call for scalded or simmered milk. Understanding what simmering milk entails and how it affects milk can help you successfully execute recipes.
What Temperature is a Simmer?
A simmer occurs between 180°F and 190°F. This is below the boiling point of 212°F. As milk heats up, the proteins and sugars begin to break down. When the temperature reaches a simmer, small bubbles will start forming and slowly rising to the surface without actively boiling. The surface of the milk will also begin to show some gentle movement.
Why Simmer Milk?
There are a few reasons to simmer milk:
- It extends the shelf life by denaturing milk proteins and killing bacteria.
- It concentrates flavors as some water content evaporates.
- It alters textures and consistency.
- It facilitates dissolving solid ingredients like chocolate.
- It activates yeast in recipes when making bread.
How to Simmer Milk
Here is a simple process for bringing milk to a simmer on the stovetop:
- Pour milk into a saucepan – stainless steel or nonstick work well.
- Heat the milk over medium heat, stirring occasionally with a wooden spoon or heat-safe spatula.
- Bring the milk to temperature right below a boil, between 180°F-190°F.
- Once small bubbles start breaking the surface, reduce heat to keep at a gentle simmer.
- Let simmer for specified time in recipe, typically 2-3 minutes.
- Remove from heat and use milk immediately as recipes direct.
How Simmering Affects Milk
Simmering causes some key changes to milk:
- Denatures proteins – Casein and whey proteins unfold from heat, altering texture.
- Evaporates water – Up to 10% water can evaporate, concentrating flavor and nutrients.
- Kills bacteria – Pasteurization kills pathogens, extending shelf life.
- Changes taste – Maillard browning can lead to slightly sweeter flavor.
- Alters consistency – Thickens texture due to protein denaturing and water loss.
Denaturing Milk Proteins
Heating milk causes the proteins to unravel or “denature” from their natural state. The casein proteins that contribute to the white color will coagulate or clump together from this exposure to heat. The whey proteins also become denatured. This alters the viscosity and texture of the milk.
Concentrating Flavor
As milk heats, some of the water will evaporate. This causes the components like sugars and proteins to become more concentrated. For every 100mL of milk, simmering can result in a loss of up to 10mL of water. This leaves behind a milk with a more pronounced flavor.
Pasteurization
Heating milk to the simmering point of 180°F essentially pasteurizes it by killing any pathogenic bacteria that may be present. This eliminates dangerous organisms and increases the shelf life of the milk.
Maillard Reactions
The sugars in milk can undergo Maillard reactions from simmering, which causes browning. This results in the development of nutty, toasted, caramelized flavors. It brings a complexity and slight sweetness to simmered milk.
Thickened Texture
The denaturing of proteins and reduction of water makes simmered milk take on a thicker, richer consistency. Recipes like hot chocolate, custards, and sauces utilize this ability of simmering to improve mouthfeel and texture.
Tips for Simmering Milk
Here are some tips to properly simmer milk:
- Stir often to prevent scorching on the bottom of the pan.
- Use low to medium heat to gently bring milk to a simmer.
- Add any spices, chocolate, or other flavorings before simmering.
- Do not let the milk come to a full rolling boil as this can scald it.
- Simmer for recipe specified time, typically just 2-3 minutes.
- Remove pan from heat as soon as simmering to prevent overheating.
Conclusion
Simmering is heating milk to just below the boiling point so that small bubbles break the surface gently. This technique can extend shelf life, intensify flavors, alter texture, dissolve ingredients, and activate yeast in recipes. Follow proper protocol by stirring over medium heat and reducing once bubbles appear. Simmer milk briefly before using as desired in both savory and sweet recipes to achieve optimal results.