What is Flash Brew? The Difference Between Flash Brew, Cold Brew, Iced Drip, and Iced Pour-Over Coffee

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Flash Brew Coffee: A Rapid Iced Coffee Method

There are numerous methods for making iced coffee, such as cold brew and iced drip coffee, but these two methods require considerable time, averaging between 8-12 hours. However, there's a technique that can extract iced coffee in just minutes—this is flash brew coffee.

Are Cold Brew and Iced Drip Coffee the Same?

Let's first discuss cold brew and iced drip coffee. These two iced coffee preparation methods are quite common, and many coffee shops offer these products during summer.

However, there are significant differences in how these two coffees are made. Cold brew coffee uses immersion extraction, while iced drip coffee uses drip extraction. Of course, both methods share the commonality of using ice water for extraction, resulting in extremely low extraction efficiency and lengthy preparation times.

Iced Drip Coffee Method

Iced drip coffee is typically made using an iced drip tower, which consists of three chambers: an upper chamber (ice water), a middle chamber (coffee grounds), and a lower chamber (coffee liquid). Ice water from the upper chamber drips drop by drop into the coffee grounds in the middle chamber, slowly extracting coffee liquid that flows into the lower chamber. The preparation time generally ranges from 6-8 hours.

FrontStreet Coffee's iced drip recipe uses 60 grams of coffee grounds to extract 600 milliliters of coffee liquid, with a grounds-to-liquid ratio of 1:10. The drip rate is approximately 3 drops every 10 seconds, using an ice-water mixture as the water source in the upper chamber. The extraction takes about 8 hours. After extraction, the coffee liquid is placed in a sealed bottle and refrigerated for 24 hours.

Cold Brew Coffee Method

Cold brew coffee is made by placing ground coffee in a container, then adding the corresponding proportion of cold (ice) water, stirring evenly, and sealing it. It's stored in a low-temperature environment (refrigerator) for 12-24 hours for low-temperature extraction. Then, the coffee grounds are filtered using filter paper, resulting in cold brew coffee.

FrontStreet Coffee's cold brew recipe uses 50 grams of coffee grounds. First, pour in the coffee grounds, then add 400 milliliters of room temperature water and 200 grams of hard ice cubes (totaling 600 grams of ice-water mixture) to the bottle, with a grounds-to-water ratio of 1:12. Then stir the coffee grounds and water evenly with a stir stick, seal, and place in a refrigerator.

After refrigerating for 12-24 hours, use filter paper to filter out the coffee grounds, obtaining clean coffee liquid. Then place the coffee liquid in a clean sealed bottle and refrigerate for about 4 more hours before drinking.

What Are the Flavor Differences Between These Two?

Because iced drip coffee is extracted over a long period with ice water, more small molecular substances (such as floral aromas and acidity) are extracted, while large molecular substances (like the bitter taste of tannic acid) are more difficult to extract. Additionally, after production, it's bottled and fermented at low temperature for 12 hours, resulting in distinct fermented flavors and the inherent sweet aroma of coffee beans, with an ice-cool and refreshing taste.

The liquid produced by cold brew coffee lacks the clarity of iced drip coffee and may have a thin layer of oil floating on the surface. In terms of flavor and mouthfeel, it appears slightly richer and more balanced compared to iced drip coffee.

What is Flash Brew Coffee?

Now that we've distinguished between cold brew and iced drip coffee, let's understand what flash brew coffee is. Flash brew coffee, also known as Flash Brew, is a classic Japanese iced coffee making process that retains the traditional hot coffee preparation method while bringing the advantages of cold brew coffee. It has been enthusiastically embraced by coffee enthusiasts in Japan.

Flash brew coffee is made by quickly extracting coffee grounds with hot water, then adding ice cubes or rapidly cooling it to create a cold coffee beverage, belonging to the hot extraction method. This process cools hot coffee in an extremely short time, effectively "locking in" the aromatic components produced during hot coffee extraction while minimizing oxidation reactions, giving the coffee excellent flavor.

To avoid ice cubes diluting the coffee's flavor, iced pour-over coffee reduces the grounds-to-water ratio during brewing, using less water to obtain a higher concentration of coffee liquid, then adding ice cubes to cool it.

FrontStreet Coffee's method for making flash brew coffee, using 15 grams of coffee grounds as an example, involves grinding the coffee slightly finer than for hot pour-over. For instance, if light roast coffee passes through a #20 sieve at 80%, flash brew would use a grind that passes through at 85%. The ratio of coffee grounds to water to ice is 1:10:5. The water temperature is the same as for hot pour-over: 90-93°C for light roast coffee and 87-89°C for medium-dark roast coffee. After brewing, shake or stir the filter cup to ensure full contact between ice cubes and coffee liquid, achieving rapid cooling while maintaining consistent concentration.

What Are the Characteristics of Flash Brew Coffee?

The greatest characteristic of flash brew coffee is that it can produce a glass of ice-cold, refreshing iced coffee in just a few minutes, significantly reducing time costs compared to iced drip and cold brew. However, flash brew coffee essentially extracts the middle and early-stage coffee substances, then cools and dilutes them with an equal proportion of ice cubes to achieve appropriate temperature and concentration. Therefore, the taste is cleaner and more refreshing, making it easy to highlight the main flavors of the coffee.

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Important Notice :

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