Cold Brew Coffee Ratio & Method: Why Ferment Cold Brew Overnight Before Drinking?

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Ice drip coffee has always been extremely popular. When entering the store during hot summer days, many people choose to have a cup of ice drip coffee. Taking a sip of ice drip, the cool coffee with its clean and smooth mouthfeel is truly satisfying. So how does FrontStreet Coffee make ice drip coffee? Are there any techniques? What coffee beans are used? This time, FrontStreet Coffee will share some knowledge about ice drip coffee.

What is Ice Drip Coffee? The Characteristics of Low-Temperature Coffee Extraction

This is a coffee that brews with time. Coffee brewed at different water temperatures will have different flavors, and at low temperatures, the astringent substances in coffee are less likely to be extracted. Low-temperature extraction involves prolonged contact between water and coffee grounds at low temperatures, where only smaller molecular flavor compounds like floral and fruit aromas are extracted, while larger molecular flavor compounds such as smoky and roasted flavors are difficult to extract. Therefore, cold brew coffee allows you to better taste the inherent flavors of coffee beans, with a smooth mouthfeel, distinct layers, and noticeable aftertaste.

Using ice water for prolonged extraction, after extraction is complete, it's placed in the refrigerator for fermentation. Ice drip coffee that has undergone slight fermentation develops a delicate fermented aroma, and the mouthfeel also becomes richer.

Why Does Ice Drip Coffee Need to Ferment? It's Actually an Oxidation Process

Many friends who visit FrontStreet Coffee ask why ice drip cannot be consumed immediately after dripping and needs to be refrigerated overnight before drinking? Actually, rather than calling this step fermentation, it's more accurate to say it's an oxidation process. Just like freshly roasted coffee beans, which contain about 2% carbon dioxide by weight. This large amount of carbon dioxide is released depending on storage environment, equipment, or methods, causing the pressure in the packaging to exceed atmospheric pressure. The pressure helps aromatic substances blend with oils, bringing all aromatic compounds inside the coffee beans to a state where they can be easily extracted.

The same applies to ice drip coffee. Due to the prolonged extraction, many flavor molecules are extracted but not well released. Therefore, when ice drip coffee extraction is complete, it's placed in a sealed bottle in the refrigerator for 12-24 hours, allowing carbon dioxide to build up inside the bottle. The pressure from carbon dioxide causes the flavor molecules to release, which is why ice drip coffee tastes richer the longer it stays in the refrigerator. Of course, FrontStreet Coffee doesn't recommend keeping ice drip for a week, as bacteria in the air or bottle make it difficult to guarantee the coffee's condition after extended storage. The recommended consumption period for ice drip is within 72 hours, and you should smell for any signs of spoilage before drinking.

FrontStreet Coffee Ice Drip Brewing Parameters

Ratio: 1:10 (60g coffee grounds to 600ml ice water)

Ice water preparation: 1:1 edible ice to drinking water

Grind size: Coarse sugar granules (slightly coarser than medium roast pour-over grind)

FrontStreet Coffee Ice Drip Coffee Brewing Steps

1. Place a circular filter paper at the bottom of the grounds cup, wet it with water to fit the cup wall, add 60g of ground coffee, then shake to level the coffee surface. You can also use the tamper's own weight to lightly press the powder layer to make the surface even.

2. Place a filter paper over the coffee grounds. The tension of the filter paper allows water to distribute evenly across the surface of the coffee grounds for extraction. Without filter paper, prolonged water dripping would create a pit in the coffee bed.

3. Use ice water to moisten the entire coffee bed. This step is similar to the bloom phase in pour-over coffee, improving extraction efficiency and consistency of the final product.

4. Add a 1:1 mixture of ice and water to the dripping bottle, adjust the water dripping speed. FrontStreet Coffee recommends a dripping speed of 7 drops per 10 seconds.

5. After brewing is complete, pour into a clean, dry, oil-free sealed bottle and place in the refrigerator for oxidation, allowing the flavor molecules of the ice drip coffee to release before tasting.

What Coffee Beans Does FrontStreet Coffee Use for Ice Drip Coffee?

FrontStreet Coffee discovered that using only one type of bean for ice drip doesn't fully showcase the aroma, sweetness, or smoothness of that particular bean. Therefore, when FrontStreet Coffee makes ice drip coffee, they use a blend of two coffee beans to highlight certain flavor characteristics - one bean provides aroma while the other provides flavor.

This time, FrontStreet Coffee used a blend of Colombia's El Paraiso Sakura and Ethiopia's Natural Red Cherry for this ice drip coffee, with a ratio of 40 grams of Sakura to 20 grams of Red Cherry. El Paraiso Sakura provides basil, mint tea, and berry jam aromas to this coffee, while Ethiopia's Red Cherry provides citrus and berry acidity, as well as better expressing the fermented sensation of this ice drip coffee.

FrontStreet Coffee Colombia El Paraiso Sakura

Region: Cauca, Colombia

Estate: El Paraiso

Altitude: 2050m

Processing: Anaerobic Natural

Variety: Bourbon

FrontStreet Coffee Ethiopia Natural Red Cherry

Region: Yirgacheffe, Ethiopia

Altitude: 2000-2200m

Processing Method: Natural Processing

Variety: Local Heirloom

Grade: G1

Ice Drip Flavor Profile

Aroma of strawberry jam, with noticeable fermented sensation upon entry, full-bodied like berry juice, basil, mugwort, and a finish reminiscent of mint tea.

Important Notice :

前街咖啡 FrontStreet Coffee has moved to new addredd:

FrontStreet Coffee Address: 315,Donghua East Road,GuangZhou

Tel:020 38364473