Tuesday, November 8, 2011

Considering the crock of kimchi

Onggi photo by Adam Field


It's crazy to try to answer important, thoughtful questions in Twitter's 140-character limit. The microblogging service handles Korean groups of two to four characters as one, so 140 characters could be a short novel. I refuse to butcher English spelling and grammar for the sake of texting: "I need 2 go 2 the store B4 U go home. Can I C U F2F tonight?"

Cat Morrow of NeoHomesteading early one morning tweeted a question to me and a couple of others on where she could find a kimchi fermentation crock, called onggi.

I referred her to Adam Field, an American onggi maker I wrote about for Yonhap News Service in August, and wrote to her:

Right now I'm using a Polish sauerkraut crock with a water seal but I plan to get an onggi too. I might even compare them.

Cat turned the conversation an hour later to fine points of fermentation:

Can something actually ferment if its covered in snow? I thought ferment thrived at 60-90. That's the homebrewing theory at least.
I replied:
When you're fermenting kimchi for the long haul (1 yr +) you need to regulate it as much as possible.
Her follow-up questions made me really despise the character limit:

like with an air lock? And temperature?

My thumbs rapped rapidly across the touchpad:
Korean onggi pots have a lid that overflows the opening of the jar to lock the air out.
Now for the rest of the story, sans text cuffs.

Kimchi, like most fermented products, need to start brewing at room temperature, which is about 68 degrees Fahrenheit. After a few days at that temperature, most kimchi experts recommend continuing the fermentation process in a cooler place, like a refrigerator.

Traditionally, some Koreans would take the clay onggi pots and bury them up to the lid. The lids are very heavy. Once the lid is in place, a hay blanket teepee might be placed on top of that to moderate the temperature even further. The goal is not kimchi popsicles.

In Korea's often harsh winters, when temperatures plunge below freezing for a good part of the season, burying the kimchi jar underground actually kept the kimchi warmer than the outside air temperature. The kimchi inside the buried onggi is percolating at a slow moderate pace. Some kimchis are aged for one to three years. Before refrigeration, burying the crocks mostly underground was an ingenious method of preservation.

Korean onggi don't need lid water seals to regulate airflow. Onggi aren't made of ceramic and heavily glazed like most European sauerkraut crocks. They are made from clay and are somewhat porous, with analogous breathability of oak barrels for wine, whiskey and beer. 

My little Polish sauerkraut crock has a heavy lid, but the lid doesn't cover the whole top as an onggi lid does. Polish and German crocks have a trough around the opening. When filled with water and the lid immersed in the trough, the crock allows fermentation gasses to escape without oxygen and contaminants getting in. Since sauerkraut crocks are stored indoors, the temperatures are much warmer than the Korean onggi pots stored outside. The only maintenance is to periodically check the water level in the lid trough.

This kind of fermentation does resemble beer brewing, which uses a small water lock which is a little glass tube that holds a small amount of water. It's attached to a hole at the top of the tank. It serves the same purpose as the water reservoir in most Polish and German sauerkraut crocks. It allows gases to escape without allowing air to sneak in. Since beer is usually brewed in large, stainless steel tanks, having an outlet for gas to escape in an orderly fashion is imperative. 

Now, how do I effectively dribble out that explanation 140 characters at a time?

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