Extracting more value from spent grains: a brewery-backed blueprint

Brewer’s spent grain (BSG), the solid waste generated from beer production, is composed of fiber (70%), protein (20%) and other nutritional compounds, including vitamins, minerals, and polyphenols. Despite being an abundant source of protein, at present, BSG is underutilized. It is mainly used for the production of biogas, as a fertilizer and as cattle feed - either fed immediately in its wet stage or processed and dried.

Numerous scientific papers have identified the potential to extract and valorize the protein fraction of BSG as a plant-based ingredient, but, to date, there has been little evidence of these findings being successfully adopted and advanced by industry.

There are some exceptions to this, and one company that has achieved a market-ready solution for upcycling BSG is Duynie Group. The company, which has long been recovering residual potato starch from the processing of potatoes, has developed a patented mechanical separation process for breaking BSG down into its component parts, which are then repurposed for various applications.

First scaled-up separation​

Bas Weren, commercial director at Duynie Group subsidiary, Duynie Ingredients, told us that Duynie Group is the first company to have developed the capabilities to separate BSG into proteins and fibers in this way.

“There are examples of initiatives that are processing BSG for certain applications but no-one else is doing what we are doing, and on the scale that we are doing it,” he said.

Scale is everything when it comes to rolling out new technologies, and in this case, commitment from a major brewery group will provide the volumes of BSG that are needed for Duynie Ingredients to guarantee security of supply for its customers.

For the brewery in question, this project is part of its commitment to sustainability goals and will feed into its ambition of achieving net zero carbon emissions across its entire value chain by 2040. The first phase of the project is being implemented at a pilot site, with full operation expected by 2025.

It involves the installation of a processing plant at the brewery for separating BSG into proteins and fiber. The protein will then be refined to over 70% concentration for food- and feed-related uses, while fibers will be used to produce renewable energy on site. Once this pilot site is up and running, the plan is to roll out the technology across six further sites by 2027.

Food and feed outlets​

In the interests of value, the majority of the protein concentrate will be destined for human consumption, with baked goods and plant-based and hybrid meat products some of the applications. In the interests of volume and diversity, Duynie Ingredients also intends to supply some protein concentrate to the pet food and aquafeed industries, where Weren said it can be used in regular compound feed or as an alternative to soy protein concentrate in premixes.

In this project, the fiber will be used to generate renewable energy, contributing to the brewery’s Scope 1 reductions, however, Bas said that the fiber fraction could just as easily be repurposed for use in plant-based meats or nutritional bars, for example.

“We take each project on a case-by-case basis, looking at the demand from the market and the objectives of the customer and fitting the two together,” he explained.

Taking a holistic approach​

This process is a notable example of upcycling, but Weren was keen to emphasize that creating a more sustainable value chain - not upcycling in itself - is Duynie Group’s objective.

“The goal is to create a more sustainable value chain; the creation of upcycled ingredients is a means of achieving that goal…It’s important to evaluate each project on its own merits because in some cases the amount of energy that is needed to process the recovered material means that in the end, the upcycled ingredient isn’t actually sustainable,” he noted.   

The collaboration with the brewery is the first step in creating a complete value chain for BSG; the next steps will involve securing buy-in from feed and food processors, retailers, and food service operators - and Duynie Group is already rising to this challenge.

“We have the backing of a major brewery; now we need to create a ‘pull’ from the market. We are in discussions with retailers who want to make their product portfolios more sustainable and with food manufacturers who want to reduce their emissions. We strongly believe the creation of more sustainable ingredients requires a whole value chain approach,” said Weren.