If you haven’t tried it dry-aged meat is amazing and certainly worth buying when you can afford it. You could shell out $75 for a 45-day dry-aged rib eye or you try this.
Koji Rice History
Koji is a rice grain that has been introduced with a live culture (Aspergillus oryzae for those of you in the know, bless you) and is one of the main ingredients in making soy sauce and miso paste. When koji is mixed with cooked beans like soy, the live culture helps break down the carbohydrates, amino acids, simple sugars, and proteins in the soybeans.
In theory, if the live culture is used to break down beans, why can’t it be used to help break down meats? Dry-aging happens when meat has been left to hang out in a temperature- and moisture-controlled environment. Over time, the meat’s natural enzymes begin to break down the connective tissue and rid the meat of moisture, which results in a rich, nutty, and tender piece of beef. Yes, your pricey steak is essentially starting to decompose. Science!
The science behind koji is less well-known. Its spores are fond of hot and humid environments (what spore isn’t?), and grows on cooked rice. As they get bigger, they release biochemical agents-protease enzymes that break down protein and amylases that digest starch. When mixed with, say, soybeans, the ensuing culture helps transform the concoction into soy sauce.
But when applied to steak, koji does something amazing. Its powerful enzymes slowly tenderize the meat. Innovative chefs have found that in just 48 hours, koji can turn a fresh-cut piece of beef into something that resembles, in texture and taste, a 45-day-aged steak. A koji-aged New York strip, properly cooked, will offer up the same nutty and funky flavor as one that’s been professionally cured, and with a touch of miso sweetness.
How To Create Amazing Steaks (See Video Below)
I decided to try rubbing a cheap and lean steak with some koji rice that I turned into powder using a high-powered blender. Koji, which looks like white rice hiding under a dusty, powdery shell, can be bought online or at most Asian or Japanese supermarkets.
Rub all sides of the meat (like sirloin or something thin and grainy like skirt or flank steak) generously and then let it sit uncovered on a wire rack in the fridge for 2-3 days. Don’t go too long or the meat starts to get too tough and begins to almost cure. After 12 hours, the meat starts to look like a moist, snow-covered slab of steak (see top photo). The scent is just as rich, nutty, and acorn-like as a steak that’s been dry-aging for over a month, with a touch of sweetness.
Before cooking, rinse the meat thoroughly in cold water to remove all the koji rub that has become a paste, then pat dry. Next, season the meat with salt and sear it in a cast-iron pan. I often will sear the steak quickly and finish it in the oven—basting the steak with melted butter never hurts. You will notice that the steak will caramelize and pick up color much faster than a normal steak.
The meat has a very distinct flavor and picks up a slight miso sweetness. That sweetness is the biggest difference between the real dry-aged meat versus the koji hack, and that’s likely what causes the meat to brown or caramelize faster. The koji steak is also a little less tender than the 45-day one, but I’m not complaining.