(The Boston Globe is about to let loose a big article on iced coffee so here's our take on it!)
Standard iced coffee: Brew a regular drip brew and refrigerate it. It's the easiest way to make cold coffee by far but the least interesting flavor profile. We recommend glass only for storage containers and consume quickly after brewing due to the short shelf life. Flavor profiles are similar to regular hot coffee but thinner, weaker and often less interesting.
Double strength over ice: This can be made with varying portions of coffee to water and some people even add water after brewing. The idea is to brew straight over iced and drink immediately. While it's fresher, in theory it sounds great, but this type of brew shocks over the ice and acidity is stronger while body and texture are lacking. Varying methods of this have been around for as long as drip coffee has been around. In fact, Starbucks recommends this method as their own suggestion for iced coffee so it has wide acceptance for it's ease in preparation. Doing this as a per cup pour over was also recently misreported by the NYTimes as being 'Japanese Iced' method (we should call regular pour overs 'Japanese Hot Coffee' by that example). It is not however a method we particularly find rewarding across the board for all coffees and is by no means the most complex or absolute ice coffee method available. It tends to work better on coffees that are lighter roasted but not for medium or darker roasts.
Cold drip: There are many versions of this worth trying but the most obvious is what persistently is called Kyoto Style Coffee. The complex version relies on a needle valve where room temperature water drips at rates as slow as one drip per second through the grounds. This may takes several hours to drip through. On the larger scale brewed at room temperature, the resulting brew can change radically as it rests and can turn quickly into less pleasant flavors. This slow drip style results in heavy base notes and winey flavors. We have found that brewing at room temperature yields some unpleasant results so we use a variation of this. We've used a simple medium cupping grind loaded into a pour over or Syphon top with filters in place works well with ice in the refrigerator. Loading ice on top of the grounds and keeping the whole process chilled takes several hours longer to brew but can produce a really interesting cup. The key is not having an excessively coarse grind and brewing cold. This allows more origin character to come through and produces excellent coffee. This method works better for medium and darker roasts.
Cold brew: Much like ice drip, there are versions and caveats to this particular full immersion method. The classic version of toddy is to take a bucket of water and load a large cloth bag full of grounds much like steeping tea. This is typically done with french press grind and at room temperature. With such a coarse grind causing so much under-extraction, very few origin characters come through and the dominant flavors are cocoa, toffee, and caramel. This brew can oxidize, sour, or simply turn while being brewed at room temperatures that are hotter than normal so be advised. The sediment that is a byproduct can be quite acrid so storing for any period of time can also have varying results. We actually disavow this method in that the results are often silty, rancid, and lacking in complexity. We choose to use a variation on this we have experimented with extensively that we think is exceptional:
'full immersion' cold brew (aka Reposo Frio)
For this you will need:
Large Carafe (Glass) or Midzudashi
Burr Grinder with adjustable settings
Bamboo Stirrer or tablespoon
Coffee filter (metal or cloth)
1 liter of clean filtered water
60-80 grams of medium roast whole bean coffee
1. Grind the coffee to a medium grind (cupping grind for professionals). This would be coarser than a drip grind but finer than a french press grind.
2. Load the ground coffee into the carafe.
3. Pour water over the coffee.
4. Stir vigorously.
5. Place in the refrigerator for 18-24 hours.
6. Gently stir the crust of floating coffee and let rest in the fridge again for 20 minutes to let grounds settle.
7. Pour the coffee through a filter. We recommend a cloth filter for the best texture and a pristine sediment free cup. Please ask for cloth care suggestions while in the shop or through email.
This style cold brew has complexity and character with great texture, mouth feel, and body. the key is using cold water and storing cold throughout the process. The choice of coffee is how we tune the flavors we want so you can have fruit, florals, and special character as well so explore the range! The other upside is that it's stable and stores well for several days in glass carafes with lids if cloth filtered. At the resulting strength, it can be diluted with one part water but we recommend drinking it at full strength with smaller portions. A 5oz gibraltar glass with one ice cube being my favorite serving.