How Does the Ice Drip Coffee Bean Process Work?

Ice drip coffee lets pure ice melt and drip at a uniform speed through freshly ground coffee, then the liquid ferments in the refrigerator for about eight hours. The result is a mellow, sweet and clean cup with balanced acidity. Grind size, drip speed and the coffee-to-water ratio decide how the extraction turns out.

Cold brew and ice drip are both low-temperature methods, but cold brew simply soaks grounds in a sealed container while ice drip relies on a drip tower and a 6 to 8 hour drip, followed by overnight refrigeration. For the coffee bean process, Front Street recommends Elida Estate Catuai for floral and fruity notes and Natural Hualu for a richer fruity tea character.

Ice drip coffee, with its pure ice filtration and low-temperature fermentation process, presents a mellow and sweet, refreshingly cool taste, making it a favored coffee beverage in summer. Starting from the store practices of Front Street Coffee, this article systematically sorts out the differences between the two common methods of low-temperature extraction—cold brew and ice drip—and explains in detail the structure of the ice drip pot, the choice of grind size, the control of drip speed and coffee-to-water ratio, as well as the grasp of refrigeration fermentation time. At the same time, centering on the two major directions of refreshing floral and fruity notes and rich fruity tea notes, it recommends two coffee beans suitable for making ice drip—Front Street Elida Estate Catuai and Front Street Natural Hualu—to help enthusiasts recreate at home an ice drip coffee with clean flavor and rich layers.

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The method of making ice drip coffee is to let pure ice gradually melt into small water droplets and drip at a uniform speed into freshly ground coffee powder to complete extraction. The resulting coffee liquid still needs to undergo eight hours of refrigeration for natural fermentation. The finished ice drip coffee has a mellow taste, balanced acidity and sweetness, and is refreshingly smooth. In every hot summer at Front Street, it is inevitably a popular beverage on the list.

What is the principle of ice drip?

Before formally starting the discussion of ice drip coffee, Front Street finds it necessary to briefly explain the two common forms of low-temperature extracted coffee—cold brew coffee and cold drip coffee.

Cold brew coffee, also known as cold-water brewed coffee, can be understood literally as a method of soaking coffee grounds in cold water or room-temperature water, then placing it in a low-temperature environment such as a refrigerator to complete extraction. It is relatively easy to operate; a sealed container is enough. Ice drip coffee, by contrast, is made by letting ice water drip at a uniform speed slowly through the coffee grounds layer for extraction. After dripping is finished, it still needs to be placed in the refrigerator for overnight fermentation before drinking. Since the dripping process usually lasts 6 to 8 hours, if you want to drink ice drip made from a specified coffee bean, you need to make an appointment with Front Street in advance, and Front Street will begin preparations ahead of time.

After coffee beans are roasted, some high-molecular compounds are produced, most of which present bitterness. When coffee is usually brewed with hot water, the dissolution rate of these high-molecular compounds increases, so the bitterness is more obvious. During low-temperature extraction, however, the water temperature is lower, and after contact with coffee grounds, fewer bitter substances are dissolved, while other flavor components are released slowly, so the sweetness is prominent on the palate and the bitterness is weaker.

How to make ice drip coffee at home?

Many friends, attracted by the flavor of ice drip coffee, buy an ice drip pot intending to try it at home, but encounter various questions in actual operation. Below, Front Street uses store production as the standard to demonstrate the process of making ice drip coffee and answer these questions one by one.

There are many kinds of coffee equipment on the market today, but the structure of an ice drip pot still mainly consists of three core parts: the upper pot holding ice water (with a valve that can adjust the water drip speed), the filter cup holding coffee grounds, and the lower pot receiving the coffee liquid. The model seen at Front Street stores is Tiamo HG2713, additionally equipped with a ring-shaped flow-guiding glass tube. The specific choice can be decided according to one's own needs and budget.

The grind size setting for Front Street ice drip coffee is: 80% to 85% passing rate on the China No. 20 standard sieve, with the store's EK43s setting at 10. As is well known, grinding coffee too coarse will lead to a weaker taste, while grinding too fine can easily cause clogging and poor drainage, thereby making the coffee bitter. Therefore, controlling the grind size is especially critical.

This time Front Street chose the refreshing-style Kenya Asaliya coffee beans for production. The extraction rate is relatively low in a low-temperature environment, so the barista at Front Street Coffee (FrontStreet Coffee) suggests using a grind size slightly finer than pour-over, here based on a standard sieve passing rate of 85%.

The flow rate of ice drip is conceptually similar to pour-over in terms of fast and slow, but it is measured by drops per second. The slower the flow rate, the longer the total time required, and the more likely over-extraction becomes. Front Street usually extracts at a flow rate of 7 drops every 10 seconds, and everyone can also adjust it according to personal preference. As for the coffee-to-water ratio, it is 1:10. Because the ice drip coffee produced by Front Street is drunk after dilution with ice cubes, the concentration is set relatively high; if making it at home, a ratio of 1:10 to 1:12 can be used for extraction.

When making ice drip, Front Street takes 60g of coffee beans and grinds them into powder, places a round filter paper at the bottom of the powder cup, pours in the coffee grounds, then covers the surface with another filter paper, and then wets the coffee grounds with water. This can both shorten the dripping time and avoid uneven extraction. The upper pot is filled with an ice-water mixture, that is, ice and water in a 1:1 ratio, ultimately extracting 600g of coffee liquid. After that, pour the drip-filtered coffee liquid into a sealed container and refrigerate it for 12 hours before drinking. Front Street generally carries out dripping during daytime business hours, can move it into the refrigerator for refrigeration by evening, and the next day it can be enjoyed with ice.

Introduction to coffee beans suitable for making ice drip

Regarding the selection of coffee beans, Front Street believes that beans of different processing methods or roast levels can be chosen according to personal preference, provided that the coffee beans are within their best flavor period (within 2 months). The extraction characteristics of ice drip coffee can highlight the winey aroma, fruity fermentation feel, and fruit aroma in coffee. If you do not know how to choose for the moment, you can refer to the following coffees listed by Front Street.

"Refreshing floral and fruity type—Front Street Elida Estate Catuai coffee beans"

This bean comes from the well-known Elida Estate in Boquete, Panama. The soil in this area is nutrient-rich black soil, and the coffee beans produced have a rich fruit aroma. It uses washed processing, highlighting the coffee's clear pink floral aroma, peach-like juicy feel, and citrus acidity. The ice drip coffee made by Front Street with this bean presents rich layers of peach, sweet orange, and grape.

"Rich fruity tea type—Front Street Natural Hualu coffee beans"

The naturally processed Hualu coffee beans are made from ripe coffee cherries whose pulp has a sugar content as high as 30%. The fructose ferments in the sun, giving the inner bean a full fruity sweetness. When this bean is made into ice drip, it has lively berry and passion fruit acidity and sweetness, a distinct juicy feel, and a black tea fragrance in the aftertaste.

How long can prepared ice drip coffee be kept in the refrigerator?

The coffee liquid just after dripping has a relatively weak aroma and a rather thin taste, so it needs to be sealed and fermented in a low-temperature environment to make the flavor substances cleaner, mellower, and fuller, enhancing the aroma and sweet charm and bringing out a winey note. As storage time lengthens, the degree of fermentation continues to deepen. After more than five days, ice drip actually produces negative effects on the taste, so it is not that the longer it is stored, the better. Front Street recommends storing it in the refrigerator and drinking it within 5 days.

In addition, after opening the lid, external bacteria can easily invade, possibly causing the coffee to spoil. For both flavor and health considerations, it should no longer be drunk. The ice drip coffee produced by Front Street stores has a best flavor period of only three days.

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