Although this thick, versatile seasoning paste originated in China twenty-five hundred years ago, miso is most commonly associated with Japan, where it is one of the hallmarks of traditional Japanese cuisine.
It is made from cooked soybeans mixed with water and koji, which is cooked grain or soybeans inoculated with a mold that starts the fermentation process. Depending on the type of miso being produced, the aging process may range between two months and three years. Each variety of miso reflects the microorganisms native to the area in which it is made, giving it a unique flavor and sometimes a unique appearance.
The fermentation process enhances the fifth flavor, umami, explaining why miso is widely recognized for its ability to enhance flavor in soups, with classic miso soup being the most familiar. It also sets the stage for exceptional sauces, stews, gravies, salad dressings, dips, spreads, and marinades, and can even serve as a stand-in for Parmesan cheese for a new spin on pesto.
Miso and Health
An additional bonus of miso is its healthful, probiotic properties, arising from the “friendly” lactobacillus bacteria that proliferate during the process of making miso. Probiotics can help support the body’s own native friendly bacteria, effectively providing a boost to the immune system, helping protect against disease, and aiding in digestion of food and absorption of nutrients.
Since pasteurization is designed to kill microbes, unpasteurized miso has the best probiotic activity. This type of miso will always be sold refrigerated in glass jars or plastic containers. While pasteurized miso is fine in terms of flavor and easier to ship, the pasteurization process reduces the health benefits of miso, trading nutrition for convenience.
Studies have also shown that frequent consumption of miso soup is associated with decreased risk of stomach cancer and breast cancer. Other studies indicate that miso consumption can reduce the effects of radiation exposure and increase survival rates from cancer, particularly dark miso that has been fermented for a long time.
How Miso Is Made
The thick texture of miso and its inherent complexity of flavors result from a unique production process involving alternating cycles of fermentation and aging. The process begins by steaming grain, typically rice or barley, or cooked soybeans, and inoculating them with Aspergillus oryzae, the type of mold most widely used in Japan for initiating food-related fermentation processes.
After a two-day incubation period, the mixture, now called koji, is mixed in with cooked, mashed soybeans or garbanzo beans, sea salt, and water. During the subsequent aging process, the enzymes in the koji, along with natural microorganisms in the environment, break down the complex carbohydrates, fat, and protein in the beans and grains into more easily digested sugars, fatty acids, and amino acids, including glutamic acid, which is responsible for miso’s umami flavor-enhancing properties.
Because fermentation requires warm temperatures, this phase occurs during the warmer months. Cold temperatures during the winter aging phase slow enzyme activity and kill undesirable bacteria that could otherwise taint the flavor and character of the miso. Both cycles are essential to the process of making miso. One-year miso has been fermented at least one summer, while “two-year” miso has gone through two summer fermentation seasons and at least one full summer-to-winter cycle. Similarly, “three-year” miso has gone through at least three summer fermentation seasons and at least two full summer-to-winter cycles, which accounts for its deeper flavors and thicker texture.
Varieties of Miso
Differences among the various types of miso are based on the specific type of koji used, proportions of each of the ingredients, and the total fermentation time. There are two fundamental categories of miso based on color and taste: light miso and dark miso.
Light miso includes all one-year misos, which are typically labeled generically as “mellow miso” or “sweet miso,” or by the type of grain used in the koji, such as shiro (sweet rice miso). Misos in this category are less salty, lighter in color (white, yellow, or beige), and higher in carbohydrates than are dark misos. To achieve these characteristics, light miso is made with a high proportion of grain koji, along with a low percentage of salt (ranging from 4 to 6 percent) to speed up fermentation. Since the high protein content of soybeans naturally requires a longer fermentation time to break down the protein, fewer soybeans are used in light miso than dark.
Sweet miso varieties have even less salt and more koji than does mellow miso, producing a smooth, creamy texture and a flavor that’s mild, slightly tart, somewhat sweet, and cooling. It’s a good choice for use in soups, sauces, dips, spreads, and dressings in warmer seasons and climates. Using sweet miso can be as simple as mixing a small amount into mashed avocado and tofu for a fusion-style guacamole, or blending it with pureed cooked beans and fresh herbs for a quick spread. The creamy texture of light miso also makes it an effective substitute for dairy in soups, spreads, dressings, and even mashed potatoes, though you’d use only a moderate amount.
Try making a miso glaze by combining light miso with oil, honey, and vinegar, and brushing it on roasted vegetables or grilled fish, chicken, or tofu near the end of cooking. Miso marinades are yet another way to explore light miso; combine it into a pastelike mixture with ingredients such as mirin (sweet rice wine), lemon juice, or sake. It’s an especially good way to prepare tofu or fish; not only does the marinade help accentuate flavors, but it also serves as a natural tenderizer. Marinate tofu for 2 to 24 hours in the refrigerator. Firm fish like salmon or sablefish (also known as black cod) can be marinated in the refrigerator for as little as 4 hours or up to a couple days prior to cooking.
Dark miso includes two- and three-year misos made with rice (red, kome, genmai, or brown rice miso), barley (mugi miso), soybeans (hatcho miso), or buckwheat (soba miso), with colors ranging from russet red to deep brown. Proportions used to make dark miso are largely the opposite of those used in light miso, with a lower percentage of koji, more soybeans, and more salt (ranging from 10 to 12 percent). Fermented longer, and richer in flavor, dark miso is more warming to the body and is therefore more appropriate for colder seasons and climates. In addition to complementing hearty root vegetables, onions, winter squash, nuts, and nut butters, dark miso provides an excellent foundation for cooked beans, stews, tomato sauces, and soup of all varieties, not just miso soup.
Miso tahini sauce is a classic and delicious all-purpose sauce. To make it, combine one part red miso with four parts tahini in a saucepan and thin with broth or water, adjusting the amount of water depending on whether you’d like to make a spread or a sauce. Stir constantly over low heat for 2 to 3 minutes before serving; don’t allow the mixture to boil. It’s even better topped with a bit of grated fresh ginger or freshly chopped parsley.