If you love a strong, simple brew over a fussy one, you need to hear about the Rumble Jar. The cold brew coffee maker basically strips down the process of making cold brew into a few simple steps involving a professional-quality filter that minimises the amount of effort you usually out for a good cup of coffee. Recipient of Kickstarter’s 2018 Project of the Year award, Rumble Jar essentially is a dent-resistant stainless steel filter that has a cap made from food-grade silicone that seals your cold brew into an airtight chamber.
Pour coffee grounds into the stainless steel filter, secure the silicone cap onto the metal filter and place the filter into the empty mason jar. Pour cold or lukewarm water into the jar (it will flow through the channels into the body of the jar). Fill the jar with water completely up to its neck. Screw on the jar's lid and simply rotate the jar horizontally twice. You'll hear the water swoosh inside; this activates the brewing process. Let it sit overnight and your cold brew will be ready in the morning. The Rumble Jar is currently priced at $20 (Rs 1665) and is already available online.
The Superstar Filter
The Rumble Jar's main component is its steel filter, which unlike mesh filters wasn't designed for making hot brews. The filter has been etched out of a single sheet of 18/8 (Type 304) stainless steel and its 200-micron hole size allows water to circulate at an ideal rate for steeping coarse coffee grounds that have been ground coarsely (medium-sized grounds are also okay). The cap keeps the coffee grounds sealed inside the filter, while also working as a shock absorber that prevents rattling and protects the filter.
Since cold brew involves steeping coffee grounds in water for 12-18 hours, some coffee lovers get some things wrong in terms of ratio, timing and temperature. The Rumble Jar basically makes it possible for beginners to make a professional-grade cold brew since the equipment does not need any expertise or know-how about coffee-making. The other USP is the quantity it produces in one go.
One mason jar can last one person for at least two days. Moreover, it minimises waste and it is easy to clean the equipment, simply pull the filter out, dump the grounds, rinse the filter, cap and jar or wash them with soap. There is no refillable component in the brewing equipment and it's a breeze to clean.