How Does a Coffee Bean Mixture Affect Latte Art Foam?

Lasting latte art foam comes down to two things: the milk and how it is steamed. Chilled whole milk outperforms shelf-stable and skim milk because its fat and protein build fine, dense bubbles, and steaming it to roughly 60 to 65 degrees Celsius keeps the texture stable long enough to pour a clean pattern.

Whole milk is easier to steam than skim, which turns watery and flattens the flavor, while shelf-stable milk lasts six months unopened but gives a slightly weaker taste and texture than pasteurized chilled milk. Tapping the pitcher on the counter and swirling it before the pour breaks up larger bubbles. A coffee bean mixture chosen for espresso also affects how well the foam holds.

Many people find that their milk foam never seems to turn out right when learning latte art. In fact, the quality of the milk and the way it is steamed both directly affect how fine and how long-lasting the foam will be. This article starts with the types of milk, analyzing the differences between shelf-stable and chilled milk, and between whole milk and skim milk. It then uses Front Street Coffee's recommended Vitasoy whole fresh milk to explain in detail the temperature control, technique, and milk-to-foam ratio involved in steaming milk foam. It also shares methods such as tapping out bubbles and controlling the heating temperature to make the foam more stable and longer-lasting, helping coffee lovers achieve better results in latte art and when making lattes and cappuccinos.

Many friends, when they first start practicing latte art and steaming milk foam, always find it hard to get the foam right. In reality, the quality of the milk itself has a big impact on how difficult it is to steam. Front Street Coffee will now recommend a few milks that make it easier to produce ideal foam.

From a barista's perspective, milk can be divided by storage method into shelf-stable milk and chilled milk, or by fat content into whole milk and skim milk. For latte art, chilled whole milk is the best choice—it performs best in both flavor and ease of steaming.

Shelf-stable milk: It undergoes high-temperature sterilization, which achieves near-total sterilization, so it can be stored at room temperature for a long time, usually with a shelf life of 6 months, but its taste and nutrition are slightly inferior.

Chilled milk: It uses pasteurization, which kills most bacteria, and can only be stored at low temperatures for about 7 to 12 days. Its shelf life is shorter, but its nutrients and flavor are better.

Whole milk: Fat content is an important standard for judging whether milk is easy to steam. Whole milk steams relatively easily and more readily forms fine, dense foam.

Skim milk: Skim milk is made by processing milk to remove the fat, and is suitable for people with allergic conditions or high blood pressure. But Front Street Coffee must emphasize again that skim milk simply cannot compare with whole milk in flavor—it tastes watery and the milky flavor is clearly lacking.

How to steam milk foam Front Street Coffee uses Vitasoy whole fresh milk. Before steaming with the steam wand, be sure to let the machine preheat fully and confirm that what comes out is steam, so that the pressure is strong enough. If you are using a professional commercial machine, this is not an issue.

Many cheap espresso machines on the market lack sufficient pressure and spray out only water and a little steam. If the steam wand has a plastic tip, one end of that tip draws in air—be careful not to let it go below the milk surface.

Steaming time is usually limited, so do not steam too long. Generally, you can stop once the temperature reaches about 60 degrees Celsius. You can try touching the bottom of the pitcher with your hand—when it feels hot to the touch and you can smell the milky aroma, it is time to stop.

The last step is very important: after the foam has formed, place a thick cloth on the table and lightly tap the milk pitcher on the table to shake the air out of the foam. This makes the foam firmer, so that even if you do not drink it right away, it will not disappear quickly.

It is best to steam milk that has just been taken out of the refrigerator—the result is the best.

Place the steam tip right in the center of the stainless steel pitcher, keeping it about one centimeter below the surface of the milk. If the sound is too loud, that means the angle needs adjustment.

You can practice with a thermometer first. Turn off the steam before the temperature rises to the target temperature, because after that the temperature rises very quickly.

Well-steamed milk should be semi-paste-like, with a bit of thickness. Basically, it should not be fully cooked through, but the proper temperature must be controlled.

After turning off the steam, tap the stainless steel pitcher on the table once, and you will see the foam on top become fine and silky.

If the foam is too coarse or has bubbles, it means the milk temperature was too high—either because the temperature was not controlled well, or because the steam was turned off too late.

Many factors are involved in making milk foam last.

The temperature to which milk is heated There are two ways to form milk foam: one is steaming with a steam wand, and the other is pumping with a French press.

Let's start with steam-steamed foam. The temperature must not be too low, otherwise the foam will not form densely enough and naturally will not last long. Too high a temperature is even worse, because the milk will boil, and the foam will no longer be dense—instead, boiling creates large bubbles that break easily.

So what temperature is most suitable for milk foam? Roughly around 75 degrees Celsius. However, a very stylish barista told me that he never uses a thermometer when steaming milk. Instead, he feels the temperature with the thinnest part of his palm—the thick fleshy part beside the thumb—which is the most sensitive to temperature, until it feels hot.

To make a good cup of coffee, you must try many whole milks before you can determine which one is better. It should also be noted here that different coffee beans pair well with different milk flavors. Milk that is too rich may instead overpower the mellow body of the coffee itself, so even if a certain milk produces very good foam, it is not necessarily the best choice for pairing with that coffee bean. As for foam made with a French press, basically any chilled milk can be used. The faster and more frequently you pump, the better the quality of the bubbles. This kind of foam is usually used for cold drinks.

Milk-to-foam ratio Simply put, with 500 milliliters of milk, you can produce 1000 milliliters of a milk-and-foam mixture, or you can produce 600 milliliters of the mixture. This depends entirely on what coffee you are making—for example, what latte art you are pouring, or whether you are making a latte or a cappuccino. Relatively speaking, the greater the proportion of milk, the denser the foam. Of course, this is closely tied to personal skill.

Personal skill This area is even more complex. How you operate the steam wand, when to turn the steam up high, when to turn it down, how deep to insert the steam wand into the milk, and how much force to use when swirling—all of these matter. The lower the initial temperature of the milk, the more steaming time you have available, and the more time you have to adjust the quality of the foam. The steam wand uses steam to rapidly mix air and milk, so how you form bubbles on the surface of the milk and then turn those bubbles into the densest possible foam matters a great deal. This requires years of practice. To save money, Front Street Coffee often practices with water instead of milk.

After steaming, you also need to work the milk in your pitcher. Front Street Coffee usually taps the pitcher hard on the table a few times. "Hard" here does not mean extremely hard—the force is quite particular: too light, and the large bubbles in the milk will not be shaken out; too hard, and new large bubbles will be shaken in. Of course, this is a personal habit, and some people do not use this trick at all.

Standing time Normally, steamed milk is made into coffee very quickly. Otherwise, the longer it sits, the fewer the bubbles, and it is no longer dense and silky.

The above content is compiled by CoffeeHunters, a coffee news website.