Sake

Discover how Sake Kasu Can Be Used As a Mayo Substitute

Saki Kimura

February 18, 2023

Last October, American food professionals visited fermented food producers to deepen their knowledge of Japanese fermentation culture during the “Hakko Tourism in Japan” tour campaign. As part of the tour, organizers held a tasting session where guests gave candid advice from the perspective of the American market to food product manufacturers looking to enter the United States market.

Ine to Agave Brewery, located on the Oga Peninsula in Akita Prefecture, northwestern Japan, is restoring an aging country town through fermented products, especially sake.

Part 1 introduced the founder, Shuhei Okazumi and his diverse projects. Here, we’ll focus on their new product, Koji Mayo, which will be distributed in the U.S. as well.

Sake kasu: a treasure trove of nutrients

The main ingredient of Koji Mayo is sake kasu (sake lees), a byproduct of the sake production process at the Ine to Agave Brewery. As sake is made from rice, it becomes a white pulpy mash during the alcoholic fermentation stage. Once this is pressed, the liquid extracted becomes sake, while the remaining solids become sake lees.
A bowl of sake kasu

Sake kasu

Sake kasu, while a byproduct of brewing, still has the aroma and umami of sake. By taking advantage of this flavor, sake lees has been used in cooking in Japan. It’s leaned on for pickling vegetables, marinating grilled fish and meat and for dissolving in miso soup. Not only for Japanese cuisine, it also lends a savory aroma when kneaded into bread dough and baked.

More noteworthy than the flavor, however, is its nutritional profile. It is often used in health and beauty food products and other products for its rich vitamin B complex, which regulates the skin and mucous membranes. Rich in dietary fiber, it helps regulate the intestinal environment. Also, it is said to prevent obesity because of its components that suppress the absorption of sugar and eliminate fat and cholesterol. Studies show it prevents serious diseases like cerebral infarction and arteriosclerosis.

Despite such nutritional treasures, sake kasu is increasingly thrown away since it does not fit into the modern Japanese diet. Ine to Agave is trying to rediscover the value of sake kasu in a quest for zero-waste operations.

The healthiest vegan mayo

Koji Mayo is like a mayonnaise with its pale yellow color and texture, but contains no eggs. It has a distinct umami, which is actually derived from sake kasu. Its tartness and unique aroma expands the variety of recipes it can be used in beyond Japanese cuisine. With no animal ingredients, vegans and people with egg allergies can also eat it. The sake kasu is made from naturally grown rice and contains no additives. But the appeal of this paste is that it is healthier than other mayonnaise, including vegan ones. Containing less oil and only half the calories of the average mayonnaise, it contains four times as much protein. In addition, it is high in heat-killed probiotics, which the latest science is focusing on for its ability to activate intestinal bacteria and improve gut biome. With Hakko Lab, a strategic co-brand launched with several food manufacturers, this new condiment promises to reach American consumers, where vegan products serve a thriving vegan community.
Hakko Lab logo

Sake kasu for sustainability

Okazumi aims to revive Oga as a major tourist destination, but the means to achieve this goal are not limited to the brewing business. By transforming vacant properties around the peninsula into processing factories and restaurants, he aims to provide opportunities for people to make a living in Oga. Koji Mayo will be produced at the Sanaburi Factory, a food processing plant that will open this April. Sanaburi is the name of a custom passed down in Akita farms for a feast at the end of rice planting season. In the area, farmers used to grow rice and make sake from it, then distill the sake kasu to make a spirit called shochu. Finally, they would spread the remaining sake kasu as fertilizer on the rice fields for the next cultivation. Historically, the Sanaburi feast was held at the end of the rice planting season, when townspeople drank the shochu they had made while giving thanks to the God of rice paddies.
Rendering of Sanaburi Factory

Rendering of Sanaburi Factory

Ine to Agave’s sake kasu will create not only a nutritious foodstuff, but also new jobs in rural areas. This project will introduce a circular economy, like the lees that farmers spread in the paddy have grown the rice to make sake again. “I want to create the future of Oga after we die,” Okazumi says. The story of the hero of fermentation will continue until the foundation is laid for a future where the peninsula is teeming with people and full of vitality.

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Saki Kimura
SAKETIMES | + posts

Saki Kimura is an accomplished journalist specializing in sake. With a journalism certificate from UCLA, she's reported on sake consumption worldwide. Currently the director of SAKETIMES International, she writes, translates, and promotes sake, focusing on overseas distribution and international breweries. Her expertise has made her a respected figure in the industry.