Research system turns kitchen waste into fish-feed protein

A restaurant kitchen’s scraps could take a different route from landfill: into a two-stage system built by Chinese researchers at the Tianjin Institute of Industrial Biotechnology, where they have developed a way to turn food waste into protein for aquaculture and livestock feed. The process also produces oils, giving the same waste stream two higher-value outputs.

The system works in two stages. Microaeration or heat first pretreats the kitchen waste, which is then fermented into organic acids and made easier to biodegrade. In the second stage, Schizochytrium, a marine-derived microorganism, consumes lactic acid and converts it into single-cell protein while producing intracellular lipids.

The researchers report that Schizochytrium can consume 90 percent of the organic acids within 48 hours. After optimization, the system is expected to yield 258.23 kilograms of organic acids per ton of kitchen waste. Those figures describe the research team’s process, which is expected to move toward real-world deployment.

The practical payoff is a possible substitute for fishmeal and soybean meal, whose supply chains also face environmental and resource pressures. The protein is aimed at aquaculture and livestock feed, while the DHA-rich lipids could be used in functional foods, nutritional supplements and feed additives.

And then what? If the technology moves toward real-world deployment, it could turn difficult-to-manage food waste into a source of feed protein and oils. The researchers say it could lower greenhouse-gas emissions and energy use, but they describe real-world deployment as a next step, not a service already operating.