What is cold brew?
Cold brew is a kind of new and trendy style of coffee that's become popular in the recent few years. It's basically a cold black coffee that is brewed with cold water for approximately 8-12 hours. Not like other coffees such as iced long black or iced/chilled filter coffee, cold brew has less acidity and caffeine content as this is a cold water brewed coffee.
So, how it works?
There are two major ways to make cold brew coffee - drip tower and steeping. Drip tower is a tool that has a hopper holds cold water inside and let water drip at a slow dripping speed. This slowly soaks the coffee particles and then slowly extracts coffee. Steeping method is that putting ground coffee inside the filter and putting the filter inside a big bucket with cold water. Like a French press brewer, the coffee is directly contacting water and is being brewed for the period of time. This allows a slow and gradual extraction. Also, as the temperature of the water is cold, it extracts less acidity and caffeine than hot brews.
What kind of coffee works well for cold brew?
It truely depends on coffee and preference, but I would say light roasted coffee, coarse grinding size, 1:16-18 brewing ratio work well. This is because, as the contact time is long, it needs to be preventing over-extraction. If over-extraction happens, this makes the taste bitter, astringent and dry. So, by adjusting the other elements, we need to make the taste balance good. Light roasted coffee allows the cold brew to have a good amount of acidity and light flavours, coarse grinding size makes the coffee to be extracted at a right extraction yield.
What do we recommend?
It depends on preference. If you like fruity coffee, maybe natural processed single origin coffees. If you like something chocolaty or heavy, blends would be good. And if you like something mild, clean and balanced, washed coffees are a good option. After you choose the coffee, then you need to grind the coffee at a right size, and brew the coffee with your preferred brewing ratio.