Upcycling soy sauce lees into smoking chips in food circularity

A Japanese upcycling project is transforming a traditional byproduct into a tool for culinary needs. Soy sauce lees, the residual paste left after extracting soy sauce, are being repurposed as smoking material, offering an upcyling method to reuse the material.

Soy sauce lees, rich in nutrients but previously limited to animal feed under the Food Recycling Act, can now be used in the product, “Smoke Piece”. The inventor was inspired by how the lees’ aroma was similar to wine and whisky, and collaborated with four established soy sauce manufacturers in Saitama for this upcycling partnership.

The partners faced certain technical challenges when trying to adapt these lees for smoking material. The lees’ high moisture, salt content, and sticky consistency after pressing required a year-long development process to optimise pulverisation and drying techniques. Expert advice from a seasoned smoking artisan helped calibrate the process, ensuring that the final product not only replicates the desirable aroma of traditional wood chips but also delivers an appealing smoked colour through the Maillard reaction at 100℃.

The project, led by Smoke-i-freet representative Kentaro Tsuji, has multiple environmental benefits. Upcycling soy sauce lees diverts material that would otherwise have limited use. This supports a circular economy, as the upcycling efforts reduces waste. Local business awards have recognised the project’s potential, too, awarding them the special prize for their potential in shaping food production.

The endeavour converts waste into a high-value product. It shows a collaboration between traditional industry and innovative start-ups, offering an economic viability in daily sustainability.