Adventures in Fermentation Part II: Shio-koji

Hiroko Shimbo on  shio-koji.

As I mentioned in an earlier post, I’ve been learning a lot about fermentation, Japanese style. After learning about the healthy properties of miso, I attended a talk by Japanese food expert, chef-instructor, cookbook author and consultant Hiroko Shimbo on the topic of shio-koji, the ingredient Japanese have fallen in love with for its flavor enhancing and tenderizing abilities.

Shio-koji is the miracle marinade, seasoning and tenderizer that’s made from a simple mixture of a substance called koji, sea salt and water It's the enzymes in shio-koji--protease, lipase and amylase—that act as tenderizers.

To understand shio-koji, you first need to understand koji, the mold-innoculated rice integral to making Japan’s favorite fermented grain products: soy sauce, miso, mirin (rice wine vinegar) and saké. Koji plays the key role of breaking down the starch of grains and converting it to glucose, and has been commercially available in Japan since the 14^th century. You can find it at most good Japanese food markets. Even in small doses, koji teams with life; a teaspoon of koji contains about 100 million yeast cells.

Make shio-koji isn’t hard, that is if you don’t mind stirring your batch 100 times a day and letting it develop for five to ten days (it takes longer to ferment in the winter). At the recent International Restaurant and Food Service Show in New York City earlier this month, where she was a featured speaker, Shimbo demonstrated how to do it by mixing together koji  sea salt and water in a ratio of 3:1:5. Check out Shimbo’s shio-koji recipe, for details.  Since New York City has even softer water than Kyoko or Tokyo, she noted, we're lucky to be able to use water straight from the tap.

The possible uses of shio- and shoyu-koji boggle the mind.

If audience members had any doubts that this whole shio-koji thing is for real, Shimbo banished them with a parade of delectable sample dishes made using commercially available shio-koji and shoyu-koji from Marukome (the latter essentially made by substituting soy sauce for the salt and water). While shio-koji is best for fish, chicken and vegetables, shoyu-koji, explained Shimbo, is great with more robust meat or fowl such as pork, beef or chicken.

             

She passed out tender and umami-infused morsels of chicken that had been marinated overnight in shio-koji. Whole chickens should be marinated overnight, but if you’re working with small piece of chicken, a quick 30-minute marinade will do the trick; for white fish, an hour will suffice. Shimbo likes to use three parts shio-koji to one part mirin for her marinade. Since it’s salty, there’s no need for additional seasoning. Shimbo dressed a delicious Brussels sprouts and petit tomatoes salad with a mixture of shio-koji, mustard, rice vinegar, honey, canola oil.

The general rule for marinating, Shimbo instructed, is that the marinade should amount to 10 percent of the total weight of the food you are preparing.

We also tried a salty, thick and creamy tofu-yo, an Okinawan regional specialty that I first tasted at David Bouley’s Brushstroke, in which tofu is marinated in red koji, malt, and a type of local distilled rice alcohol, awamori. Shimbo improvised her version of tofu-yo by keeping it submerged in a  3:1:1 ration of shiokoji, mirin and sake for two weeks. The tofu-yo was the exception to the 10 percent rule, resulting in an umami bomb with the texture of cream cheese and the funky saltiness of blue cheese.

The possible uses of shio-koji boggle the mind: you can use it with olive oil to dress cold pasta, tomato, and red onion, for dipping sauces or in stir frys, Shimbo suggests, or as she did, to tenderize and pump up the flavor of Turkish-style lamb meatballs. Happy experimenting!