Alternative protein potential from seafood industry “waste” process waters

05 Nov 2018 --- Process waters that are continuously pumped out as waste from the seafood industry contain valuable nutrients that could be used in food or aquaculture feed, a Chalmers University of Technology, Sweden, study has found. These side stream waters contain proteins, peptides, fats and micronutrients, which could be recycled and used as an ingredient.

During the preparation of herring, shrimps and mussels, large amounts of process water are continuously pumped out as waste by the seafood industry. The water is used when boiling shrimps or mussels, or when filleting, salting and marinating herring, for example.

“It's very important to help the industry understand that the side streams don't need to be wasted. Instead, they should be treated as really exciting raw material,” says Professor Ingrid Undeland of the Department of Biology and Biological Engineering at Chalmers University of Technology.

“The backbone of our project is a circular approach. In the past, we had a more holistic view on the handling of food raw materials, but today so much is lost in side streams. Furthermore, we are in the middle of a protein shift, and there's a huge demand in society for alternative protein sources,” she adds.

The research team recovered up to 98 percent of the protein and 99 percent of the omega 3-rich fats from the waste streams. The process resulted in a semi-solid biomass and a nutrient-rich liquid. After dehydration, biomass from shrimp boiling water was shown to contain 66 percent protein and 25 percent fat. Two tests were made, together with the University of Gothenburg and Skretting ARC, using this new biomass as an ingredient in feed for salmon, and the results were said to be encouraging.

The nutritious liquid was used for glazing frozen fish to protect it from going rancid. It proved to be more protective than water, which is currently used for such glazing. The fluid was also tested as a substance for mi the croalgae-cultivation and was shown to enhance the growth of two types of algae. The algae biomasses can subsequently be used as sources of protein or pigment.

Regarding consumer attitudes to new ingredients coming from “non-conventional” raw materials such as this, Undeland tells NutritionInsight, “We think the choice of words and the way it is communicated is super important, e.g., stressing sustainability issues and the fact that we need to use all of the raw material we are harvesting. We have better processing possibilities though and can make a larger variety of new products. In this context, it is important to stress that we only work with side streams that are still food grade. Thus, we start to process them while they are still treated as food raw materials, beforepoint they start being handled as waste.”

“A major challenge is to get the industry to manage the water side streams as food, beyond the stage when they are separated from the seafood product. Today, that is the point where the side streams start being handled as waste. This means there's a need for new routines for cooling and hygiene,” says Undeland.

Indeed, a big challenge ahead will be making the protein recovery process cheaper, Undeland tells NutritionInsight, and to find mild ways of dewatering the initial protein biomass recovered.

“I am quite positive on the fact that related industries, sooner or later, will be implementing these techniques. With ever increasing awareness on the value of recycling nutrients, this facilitates industrial processes to adopt feasible approaches towards a circular economy,” she concludes.

The work now continues within the new project AquaStream, funded by the European Maritime and Fisheries Fund.

By Laxmi Haigh and Lucy Gunn