Can stainless steel ice cubes be used in coffee? Which cools better: stainless steel ice pellets or homemade ice cubes?

Recently, while FrontStreet Coffee was talking iced pour-over with friends, we noticed that most coffee shops chill their drinks with ordinary ice cubes. By the time you reach the last few sips, the coffee has usually warmed to room temperature and lost the richness it had at the start, sometimes turning watery. That raised a question for FrontStreet Coffee: why not use stainless steel ice cubes?

What Are Stainless Steel Ice Cubes?

Stainless steel ice cubes, also called stainless steel ice stones, usually have an outer shell of 304 or 316 stainless steel. They are not hollow: each one holds a colorless, odorless liquid, and if you shake one at room temperature you can hear the liquid sloshing inside. Two types dominate the market, one filled with a water-and-alcohol mixture and the other with a water-and-glycerin mixture.

Judged purely on structure, stainless steel ice cubes do offer several advantages over traditional edible ice. First, they do not melt as the drink warms, so they can stay in the glass from the first sip to the last. As long as the steel is colder than the liquid, it keeps drawing heat out of the drink.

These non-melting ice stones are also convenient and save time. Traditional edible ice needs 4-6 hours in a mold to freeze, whereas stainless steel cubes need only about an hour in the freezer before they are ready. Afterwards you simply wash them and put them straight back in the freezer for next time.

But since they are called "ice cubes," what matters most is cooling power and practicality. To answer our friend's question, FrontStreet Coffee bought four stainless steel ice stones. What follows is a comparison from several angles, to see whether this much-talked-about tool really works in the world of coffee.

Volume, Weight and Cooling Speed Compared

For daily service, FrontStreet Coffee's shop normally uses larger edible ice cubes: small cubes 2.5 centimeters wide, each weighing about 30 grams. Stainless steel ice cubes look more compact, shaped as dice 1.5 centimeters wide, and each weighs about 29.7 grams, roughly the same as our homemade ice.

Following the merchant's recommendation of one stainless steel cube for 50 ml of beverage, FrontStreet Coffee prepared two identical glasses, each holding 100 ml of drinking water. At room temperature the water measured 27°C. One homemade ice cube went into the first glass and two stainless steel cubes into the second, while both were watched and measured.

Within the first two minutes both glasses cooled, but the homemade ice cube cooled noticeably faster. At 2 minutes 30 seconds the homemade ice group had dropped to 12°C, while the stainless steel group had only reached 19°C. Because the metal ice is so dense it sank straight to the bottom, so the water beneath cooled first while the surface water stayed warm. After five minutes the edible ice cube had almost fully absorbed heat and melted, taking the water down to 8.1°C. The stainless steel group held the same liquid volume but remained at 16°C.

When FrontStreet Coffee swapped the drinking water for room-temperature cola and milk, the cooling effects shifted only slightly, and stainless steel ice cubes were still far behind homemade ice in cooling speed.

So while metal ice cubes have the advantage of never melting into the drink, their mediocre cooling performance makes them hard to use during the chilling stage of coffee extraction. After all, our iced pour-over has another name: rapid-cooling pour-over. That left a different question: could they hold the low temperature of an already-brewed iced coffee?

Trying an Iced Pour-over

Given the limited number of stainless steel cubes and their slow cooling, FrontStreet Coffee made a small tweak to the standard iced recipe to get better chilling and flavor. Two transparent ice cubes were swapped for four stainless steel cubes.

This served two purposes: to cut the watery taste caused by excess melting ice, and to help the coffee cool quickly while keeping the flavor concentrated.

Coffee beans: Sidamo - Guji 8.0
Dose: 16 g
Coffee-to-water ratio: 1:10 (160 g hot water)
Ice: 180 g (2 homemade ice cubes + 4 stainless steel ice cubes)
Grind size: Ek43s setting 9.5
Water temperature: 92°C
Dripper: V60
Pouring technique: Three-stage method

For comparison, FrontStreet Coffee also brewed a regular iced pour-over with the same parameters and beans, using 120 g of ice cubes, or 4 pieces. Both pots were then poured into pre-chilled glasses.

In terms of taste, the mixed-ice pour-over had a drinking temperature of 18.9°C. It was not ice-cold on entry but pleasantly cool, with aromas of raisins, sweet oranges and black tea. The texture was smooth, and it held for about 17 minutes before it began to warm.

The second pot, chilled only with homemade ice, dropped to an ice-cold 6.9°C almost instantly after a gentle stir, with aromas of citrus, blueberries and cranberries and a clearer fruit acidity. Once the ice melted completely into water, the coffee started warming after 11 minutes and the flavors faded slightly.

Weighing everything, as a reusable alternative ice, stainless steel cubes struggle to replace traditional edible ice on cooling effectiveness, flavor contribution, practicality and even safety, since they can easily crack glassware. Applied to coffee brewing, the role of ice becomes obvious. FrontStreet Coffee suspects this is why so few coffee shops use stainless steel ice cubes in their drinks.

FrontStreet Coffee Recommendation

Since ice-forward coffee lives or dies by the bean, an iced pour-over rewards a bright, clean lot. The FrontStreet Kenya Cherry Tomato is a strong choice: a washed Kenyan coffee from the Sika region grown at 1,550-1,750 meters from the classic SL28 and SL34 varieties, given 72 hours of double fermentation and a light roast, it brings cherry tomato and smoked plum with a lively, juicy acidity that stays crisp over ice.

If you want the deep, fruit-forward style that suits a slow chilled brew, the FrontStreet Mozart is a natural fit. Grown in Costa Rica and given a raisin honey process, it shows blueberry, black grape and a gentle fermented note, and it stays refreshing and clean when served cold.

For a lighter, tea-like iced coffee, FrontStreet's Yirgacheffe is the answer, with white florals, citrus and honey sweetness that cup cleanly over ice without turning bitter as the temperature rises.