What Does Milk Frothing Do For Coffee? (All You Need To Know)

Have you ever wondered what does milk frothing do for coffee? Why does it matter if it’s frothed or not before it is added to your coffee? 

Before we press on, in my blog post regarding Milk Steaming Vs Milk Frothing we define milk frothing and milk steaming as:

Milk Frothing: Foaming up milk with a handheld or electric frother.

Milk Steaming: Creating milk with microfoam with a steam wand.

However, to most people in the coffee industry including baristas, milk frothing and milk steaming essentially involve the use of the steam wand; rarely and most often not handheld frothers.

So for common understanding, I will refer to it as milk frothing from this point forward.

In this blog post, we will deep dive into everything about milk frothing for coffee; the whys, whats, and hows. 

Disclosure

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At a glance: What Does Milk Frothing Do For Coffee?

Why Froth Milk For Coffee?

There are four main goals to achieve when a barista froth milk for coffee; 

• Change the milk texture
• Produce microfoam for latte art
• Raise the temperature of the milk
• Bring out the milk sweetness

1. Milk Texture

You may not be consciously aware of it but an espresso topped with frothed milk is unmistakably creamier than an espresso topped with just milk itself.

And the magic happens when the milk is frothed with a steam wand.

First off, the action of milk frothing aerates the milk. In other words, you are introducing air into the milk itself. The steam wand injects hot steam into the milk and folds it evenly across the whole mixture. 

This results in a light velvety milk texture which reflects in the mouthfeel of the coffee beverage.

Secondly, it is the exposure of the milk molecules to heat. The milk components react and form different molecules that make the milk texture creamier.

That said, the whole milk chemistry stuff needs a whole section for itself. If you are interested to know more about how it works, jump straight below where I talk about the milk chemistry during milk frothing.

Barista Tip: Besides hot lattes, you can texture some milk and layer the foamy part on an Iced Latte for texture and aesthetics!

2. Latte Art

Frothing milk for latte art is almost a basic requirement for all cafes today. Personally, the ability to pour latte art was at the top of my list when I first snooped into the world of coffee. 

From the above section, we know that milk frothing aerates the milk by folding air bubbles into the milk which creates microfoam. And microfoam is the key component when it comes to latte art pouring. 

I have lost count of the number of times where customers requested to have a nice latte art for their coffee. Nonetheless, it pulls the crowd and gets more people posting about your cafe on social media.

Without a doubt, it is an important factor when it comes to business. So for aspiring baristas, other than coffee brewing skills, work on your latte art too!

3. Temperature

A freshly extracted espresso topped with cold milk will definitely get you an unpleasant cup of lukewarm milk coffee. Hence, it is essential to raise the temperature of the milk to palatable levels before mixing it with the espresso base.

You can definitely heat up milk on a stovetop or with a microwave but these two methods give you very little control over the temperature of the milk. One distraction will overcook your milk, leaving you with curdled milk. Yuck!

So, the third reason to froth coffee is to heat up the milk to the perfect temperature for a hot coffee beverage. By using a steam wand, baristas can aerate the milk and heat it up in a milk pitcher. While doing so, the palm will be placed at the bottom of the milk pitcher to gauge if the milk has reached the desired temperature. 

The perfect temperature we are talking about here is 55^oC and 65^oC (139–149°F). This is because at this temperature the coffee beverage is just nice and warm for the tongue.  

Besides that this temperature is where the milk tastes the sweetest. And that brings us to our next point.

4. Milk Sweetness

Milk is frequently paired with coffee to prepare a variety of drinks. Milk can be used to balance out coffee flavor profiles or can be frothed to provide a different texture and ultimately alter the whole coffee-drinking experience. However, one lesser-known fact is that one can actually make milk taste sweet naturally.

And the question is how?

The answer is by simply frothing (with a steam wand) or simply heating up the milk. Yes, by introducing heat to your milk, you can bring out the natural sweetness of the milk. But, do not expect sugary sweetness instead the perceived sweetness of the milk is definitely more evident.

However, the specific range of temperature at which the milk exhibits such sweetness is only between 55^oC and 65^oC (139–149°F). Frothing your milk to that sweet spot leaves you with the sweet velvety goodness that you want in a latte or a cappuccino. 

Any lower, the milk will just taste just like warm milk, and overheating the milk exceeding 70^oC (158^oF) will cause the milk to be burnt and taste unpleasant. So, every time you ask for your latte or cortado to be extra hot, be prepared to watch your barista die a little inside.

Nonetheless, it is ultimately your choice. I am sure your barista will gladly comply if you want scalding hot milk for your coffee.

What Happens When You Froth Milk?

When you froth milk, there are a lot of things that are happening simultaneously to create that smooth velvety warm milk. 

First, the steam wand aerates the milk by injecting hot steam into the milk. At the same time, the steam heats up the milk. While this is happening, the milk molecules react to the heat and change their properties. See what I mean?

So, to understand the science behind how all this magic works, we need to know a little bit more about milk chemistry. Bear with me, I will try to keep it simple! 

Milk Chemistry

Milk is a complex liquid mixture of multiple components.

But for the sake of simplicity, we can mainly categorize the major components that makeup milk into Lactose, Fat, and Protein. 

When we expose these molecules to heat when we froth the milk with a steam wand, the properties change and they do wonders for the coffee.

In a nutshell:

Lactose: Lactose, a sugar component in nature, is not readily soluble in water. Introducing heat allows the lactose to dissolve and increases the perceived sweetness of the milk.

Fat: Fat molecules become more stable and voluminous under heat. That is why frothed milk gives that thick creamy texture.

Protein: Proteins in the milk help keep the microfoam stable after milk frothing. Without it, your latte art will quickly disperse and the layer of foam will disintegrate pretty soon.

If I have not lost your interest yet, read on to know how milk reacts when we froth milk.

Lactose

In this context, we are interested in lactose as it is the sugar component that is naturally found in cow’s milk. But lactose has only approximately 30% of the sweetness of sucrose. So we cannot really taste the sweetness of milk right off the bat. 

A common misconception was that during milk steaming, lactose is broken down into simpler sugars and hence giving it a sweeter taste. In reality, lactose needs to be exposed to high heat over an extended period of time to denature it. Steaming milk with a steam wand for a minute simply will not break down lactose. If not, lactose intolerant folks are able to enjoy a toasty cup of latte by just steaming the milk!

So why does steamed milk taste sweeter? It’s merely how the human tongue perceives flavor which is influenced by a variety of factors and in this case temperature. Studies show that we seem to perceive lactose to be the sweetest when it is between 55^oC and 65^oC (139–149°F).

A simple way to imagine this is to compare having an iced cold soda and a warm room temperature soda. The warm soda will definitely taste cloyingly sweet! The concentration of sugar in both cans of soda is constant. What’s different is the perceived sweetness of the soda at different temperatures!

The next time you drop by your favorite cafe to have your latte, take a sip and appreciate the science that has contributed to that cup!

Fat

If you enjoy the mouthful of creamy mouthfeel when you have your cappuccino, you will have the fat in the milk to thank. 

Inversely, if I use skim milk to make your cappuccino, you will get a flat and thin milk coffee instead. This is because there simply isn’t any fat present in the skim milk. 

The other role of fat in the milk is to help stabilize the layer of foam on your milk-based coffee beverage. The fat exposed to heat will melt at 40^oC and this action creates a layer of film that prevents air bubbles from coalescing together.

Protein

Proteins in milk single-handedly contribute to the milk’s ability to froth up into a beautiful velvety foamy milk. 

Without diving too deep into the science-y stuff that happens when you froth milk, you should know the two main proteins present in milk are caseins and whey proteins. 

In this case, we are interested in whey proteins.

Whey proteins “unfold”, also known as denatures, when exposed to heat. This changes its structure and the way it reacts with other components in the milk. 

As you aerate the milk with a steam wand, the denatured whey protein easily grabs onto the air bubbles in the milk and this causes these air bubbles to be fairly stable. In the end, you will have millions of stable microbubbles and this is known as the microfoam.

So the next time you notice that your latte art is stable and does not disperse easily, you know that it is well-frothed milk. 

Additional Note: There is some misconception that adding to milk to coffee reduces the caffeine content. Truth is, adding milk to coffee absolutely does not reduce the caffeine content in coffee. All it does is dilute the coffee!

Personal Note On What Does Milk Frothing Do For Coffee?

Here is my take on what does milk frothing do for coffee. On the basic level, milk frothing enhances the coffee beverage’s mouthfeel and allows the barista to pour latte art. 

But to me, it is a little more than that. 

The art of milk frothing trains your focus and discipline. To be able to froth milk consistently at the perfect temperature for different kinds of coffee beverages requires experience and skill which is honed over time.

There is no shortcut in learning this art. 

Furthermore, it is also an avenue for creativity to flourish. Just looking at the latte art presented at the World Latte Art Championship year after year, the latte art styles are improving tremendously. 

How To Froth Milk For Espresso Drinks?

Frothing milk for espresso drinks using a steam wand can be fairly tricky for beginner baristas and home brewers alike.

Here’s a quick step-by-step guide to froth milk using a steam wand. 

Does The Type Of Milk Matters?

For lactose-intolerant folks, you might be wondering if this applies to other milk alternatives.

Let’s dive into the other milk alternatives commonly used.

Lactose-Free Milk

TL;DR lactose milk tastes sweeter compared to regular full-cream milk. But why?

Little did you know that lactose is a naturally occurring sugar found in cow’s milk. To produce lactose-free milk, the lactase enzyme is added to milk which breaks down lactose into simpler sugars (i.e. glucose and galactose). Both glucose and galactose have higher perceived sweetness levels compared to lactose. 

So, don’t be surprised when you switch from your usual full cream milk latte to a lactose-free milk latte, your coffee drink will taste slightly sweeter!

However, methods to mechanically filter out lactose from milk via filtration technique have been developed. 

Doing so completely removes the sugary element from milk and you may not get the enhanced sweetness. But this seems to preserve the natural taste of the milk.

Oat Milk, Almond Milk, And Soy Milk

All these three types of milk are made by blending them with water and then filtered to get the final creamy milk. As these are plant-based derivatives, no lactose is naturally present in these alternative milk. 

With low naturally occurring sugars in almonds, milk-based coffee beverages with these milk alternatives will not taste as sweet as the full cream milk-based coffee beverages. 

Since there is no sugar component present in these alternative milk, the perceived sweetness will be comparatively low compared to whole milk. Hence, raising the temperature will not change the perceived sweetness levels anyway. Excellent alternative for folks who are lactose intolerant and also watching their sugar intake!

That said, manufacturers of store-bought alternative milk may have added sugar to extend shelf life and enhance the flavors of these products. For example, certain production processes for oat milk were known to cause the production of maltose as a sub-product. So do check the fine prints on the product!

Types Of Milk	Calories	Carbohydrates (total)	Sugars	Fat (total)	Protein
Cow’s Milk (whole)	150	12 g	12 g	8 g	8 g
Cow’s Milk (1%)	110	12 g	12 g	2 g	8 g
Cow’s Milk (Skim)	80	12 g	12 g	0 g	8 g
Almond Milk (Unsweetened)	40	1 g	0 g	3 g	2 g
Soy Milk (Unsweetened)	80	4 g	1 g	4 g	7 g

FAQ On What Does Milk Frothing Do For Coffee?

Does froth make coffee better?

Yes, frothing milk makes coffee better as frothing milk makes the milk taste sweeter. Milk by itself is naturally sweet due to the presence of lactose. The act of frothing the milk heats up the milk. This is why the perceived sweetness of the milk is higher and hence enhances the taste of the coffee too.

Does frothing milk make a difference?

Frothing milk makes a whole load of difference for coffee drinks. Frothed milk has a creamier mouthfeel and higher perceived sweetness which balances out the bitterness of the coffee. The best milk to use here is whole milk. When whole milk is frothed it’s more stable than skim milk, but it will be less voluminous.

What is the point of froth on coffee?

The main point of having froth on coffee is for the added creaminess. By frothing milk, you introduce air bubbles into the milk known as microfoam. During the frothing process, the milk is also heated up which allows the fat molecules to bind these air bubbles. This creates milk that is light and creamy. 

Is it better to froth milk hot or cold?

It is better to froth milk cold so that you have enough time to create microfoam without overheating the milk. Also, make sure to use fresh milk as the fresher the milk the better it froths. The combination of cold fresh milk allows you to froth the milk to create a velvety smooth and creamy milk. 

Conclusion

The next time someone asks you what does milk frothing do for coffee, you should know that it is more than just making your coffee beverage foamy. 

Milk frothing improves milk texture, increases perceived sweetness, raises the milk temperature steadily, and creates microfoam for latte art. All things that make milk-based espresso a crowd favorite in most cafes across the world. 

In a nutshell, milk frothing adds a creamy, airy mouthfeel to your coffee drinks.

If you have found this piece of blog post beneficial to you, do share it around with your fellow baristas and coffee lovers.