What is COD Sperm? An In-Depth Look at This Exotic Delicacy
Cod milt, or shirako as it‘s known in Japanese cuisine, refers to the sperm sacs harvested from male codfish and other species. While the notion of eating fish semen may seem strange to most Westerners, this ingredient has been prized in Asian cooking for centuries. As an adventurous foodie, I decided to dive in and get the full scoop on cod milt – its culinary uses, nutrition, history and how it goes from sea to table. Here‘s the deep dive on this intriguing delicacy.
A Taste of the Sea
My first bite of cod milt was at a sushi restaurant in Vancouver. The raw shirako was served atop rice tempura-style, with a sweet soy glaze. The texture was soft and creamy, almost custard-like. The mild fish flavor had a pleasant sweetness balanced by the salty soy. It was easier to eat than I expected! Served cooked, milt takes on a firmer, flaky texture similar to fish cakes. Frying gives the exterior a crispy breading that contrasts the rich interior.
In Japan, cod milt is often enjoyed boiled in hot pots during the winter months. Chef Morihiro Onishi says shirako nabe is comforting yet delicate: "The cod milt cooks to a custard-like softness that pairs beautifully with vegetables, tofu and seafood." Beyond sushi and hot pots, cod milt also shines when sautéed or added to soups and stews. From my tastings, its flavor pairs well with ginger, scallions, garlic, mushrooms and light sauces like ponzu and soy.
Nutritional & Anti-Aging Effects
What makes cod milt so coveted? These sperm sacs pack a powerful nutritional punch. A 100 gram serving provides 116 calories and 16 grams of protein, plus ample Vitamin B12, selenium and phosphorus [1]. Compared to a fillet of cod, milt contains nearly five times as much protein! This makes it more nutritionally dense than regular fish meat. Research suggests cod milt may also have anti-aging properties thanks to proteins that benefit skin [2].
In many Asian cultures, foods that promote youth and vigor are highly valued. Cod milt‘s high protein content resembles that of bone broth, also prized for its collagen. Its richness provides decadent flavor in small servings. For these reasons, cod milt has been enjoyed by everyone from Japanese emperors to modern day foodies.
A Japanese Delicacy with History
So how did cod milt become a delicacy in Japan? Its long history in Japanese cuisine dates back to the Edo period. During this time, cod was heavily fished from northern Pacific waters. The milt was salted or boiled and eaten largely by the upper class [3]. The texture and creamy flavor made it a treasured food. Later, cod populations declined from overfishing. But migratory Atlantic cod replaced the Pacific populations, and cod milt remained a winter delicacy.
Today, shirako is served at high-end restaurants and fish markets in Japan from December to February. While expensive, a serving of milt is seen as a special treat. It also shows up in home cooking. Keiko Nakamura, a Osaka-based chef, says "I make miso soup with shirako for my family every winter. The flavor is amazing with tofu, wakame and scallions." For centuries, Japanese diners have relished this seasonal delicacy.
Global Demand & Sustainability
Beyond Japan, cod milt is also enjoyed in Korea, China and Russia. Portugal has become the #1 consumer of cod globally, eating on average 35kg per person each year [4]! Most milt still goes to Japan though, where it commands exorbitant prices. In 2019, a single pair of cod milt sacs sold for 1 million yen – equivalent to nearly $10,000 USD [5].
With such popularity, is cod fishing sustainable enough to support milt harvests? On the sustainability front, Atlantic cod stocks are scientifically managed under quotas. In the Pacific, U.S. and Canadian cod fisheries are certified by the MSC as sustainable [6]. While cod collapsed 30 years ago, they have strongly rebounded thanks to careful management. This allows cod to still grace tables, milt and all.
From Sea to Sashimi: The Harvesting Process
So how does cod milt actually get harvested and prepared? Milt sacs are located alongside the fish‘s belly and kidneys. Chefs are specially trained to extract the milt while keeping it intact. It must be carefully separated from the membrane and any urine residue to avoid contamination [7]. Once extracted, the sacs are placed on ice and rushed to market. Freezing and extended storage will ruin the taste and texture. That‘s why fresh milt commands a premium price.
Proper handling is crucial, as Liz Palmer of True World Foods told me: "The key is to transport the milt overnight on ice to fish markets. Milt is highly perishable – any mishandling ruins the eating experience." Top sushi restaurants even examine milt under a microscope to ensure quality before serving. It‘s an intricate art to deliver optimal milt to diners.
My Take: An Exotic Experience Worth Trying
For most Westerners, cod milt is something seen on fear factor-esque reality shows. But setting aside the gross-out factor reveals a legitimately unique delicacy. My first impressions of shirako changed from squeamish to impressed. The mild, creamy taste makes cod milt approachable and satisfying. While expensive, it‘s an interesting splurge for sushi fans or the culinarily curious.
Does the notion still seem strange? Sure, slurping down fish semen may never sound "appetizing." But an open mind and adventurous palate can discover marvelous new flavors. Cod milt has brought joy to Japanese gourmets for centuries. By sourcing it sustainably, we can keep enjoying this exotic delicacy well into the future. In my book, that makes cod milt worth a taste. Give it a shot – you might be surprised!