Why You Should Be Using Shio Koji For The Most Tender Meat

There are many ways to tenderize meat — from using a fork on a steak to employing acidic fruits as a deliciously effective way to tenderize meat. But there's one particularly effective ingredient that you might not have tried before, and it goes by the name shio koji. If, like many Americans, you're less familiar with this ingredient, don't worry. Chef and restaurateur Richard Sandoval spoke to Food Republic to give a comprehensive breakdown of the Japanese product and how to use it. "Shio koji is a fermented mixture of rice koji, salt, and water that acts as a natural tenderizer," he said.

But what is rice koji? It's a fermented rice that has been introduced to the mold Aspergillus oryzae, which is a key ingredient in Japanese products like miso and soy sauce and can even be used to replicate the flavor of dry-aging in beef. Salt and water are then added to the rice koji to form a liquidy paste. "On a scientific level, the enzymes in koji — particularly proteases — break down proteins into amino acids, which enhances umami and makes meat more tender," chef Sandoval explained.

Chef Sandoval also noted that the nature of shio koji makes it a better choice for tenderizing than other common ingredients. "Compared to pineapple or yogurt, which also contain natural enzymes like bromelain or lactic acid, shio koji works more gradually, allowing for deeper flavor penetration without the risk of over-tenderizing or making the texture mushy," he informed us.

When it comes to how long to marinate meat in shio koji, chef Richard Sandoval noted that, given the versatility of the ingredient, it depends on what kind of protein you're using. "For lean meats like chicken breast or pork tenderloin, a short marinade of four to six hours improves moisture retention and adds depth," he told us. "For tougher cuts like beef short ribs, a longer marination (up to 24 hours) helps break down connective tissue." 

Because the shio koji dissolves the connective fibers in the ribs, the meat shrinks less during the cooking process, which leaves the protein incredibly juicy and tender. As for the best method for cooking, there are two that chef Sandoval recommended. "[Shio koji] works exceptionally well for grilling and roasting, where it enhances caramelization and imparts a slight sweetness," he said, but with a caveat: "However, because it contains natural sugars, it can burn at high temperatures, so controlled heat is key."

While it's possible to make the whole thing from scratch, for most home cooks looking to make their own shio koji, it's best to start with premade rice koji. Add kosher salt and water, stir until the salt has dissolved, and store it in an airtight jar for at least a week — until the mixture has thickened into a consistency similar to porridge. It's not only good for marinating meat, but also for quick-pickling foods like radishes, cucumbers, and even boiled eggs, which will be ready to eat in 24 hours.