Jan J Enghild_Developing a Sustainable Agriculture Production | Carlsbergfondet
Til projektoversigt

Developing a Sustainable Agriculture Production

Andet forskningsprojekt | 29/01/2018

Potato protein: The Danish production of potato starch generates a protein-rich side stream of potato juice. If the proteins in the side-stream can be upgraded to food quality, the juice has the potential of generating 10,000 ton of potato protein on an annual basis.

As the human population continues to grow, an increase of the global food production while simultaneously shrinking the agriculture’s environmental footprint is desirable. The goal of Jan J. Enghild's Propotato-project is to convert the current side-stream of potato starch production into a high-value protein product useful for human nutrition. The Carlsberg Foundation has supported the project with essential research infrastructure.

By Professor Jan J. Enghild, Department of Molecular Biology and Genetics, Aarhus University and Assistant Professor Carsten Scavenius, Department of Molecular Biology and Genetics, Aarhus University 

The human population continues to grow and is expected to plateau at some 9 billion people by the middle of this century resulting in an increased global demand for food. At the same time agriculture is a major force, driving the environmental impact beyond the “planetary boundaries”. Therefore, an increase of the global food production while simultaneously shrinking the agriculture’s environmental footprint is desirable. 

The challenge is that more food will have to be produced on the same amount of land, a daunting task as the reality is that already today, one in seven are not getting sufficient protein and energy from their diet. The conversion efficiency of plant material into animal matter is approximately 10 percent. 

Thus, one efficient way to feed more people is to reduce the consumption of meat and increase the consumption of plant-based products. In the search for a sustainable protein source, the Innovation Fund Denmark have funded the project Propotato - a private/public research collaboration between the Danish potato starch industry, University of Copenhagen and Aarhus University. 

The goal of Propotato is to convert the current side-stream of potato starch production into a high-value protein product useful for human nutrition. The Carlsberg Foundation has supported Propotato with essential research infrastructure.

Potato Protein as a Sustainable Protein Source

Denmark has a large potato production, and the companies KMC and AKV Langholt receive more than 1.2 million tons of potatoes a year, used for the production of starch. During the manufacturing, a side-stream of potato juice is produced which mainly is utilised as low-cost animal feed and fertiliser products. 

The side-stream potato fruit water production typically contains 0.7-1.8 w/w % of protein where raw potato contains around 1.8 w/w %. The successful use of the protein-rich potato starch side-stream will not only increase the availability of nutritional proteins it will also reduce waste generation and result in a more sustainable production of protein.


"The majority of us are still eating too much meat. If you, for example, feed a pig with 100 kg of potato protein, you only get 10 kg of pig protein out of it, which means that most of it is wasted. But if we eat more plant-based proteins instead of meat, it will benefit both the environment and our health," says Professor Jan J. Enghild from Aarhus University.

The conversion efficiency of plant material into animal matter is approximately 10 percent. Thus, one efficient way to feed more people is to reduce the consumption of meat and increase the consumption of plant-based products. Propotato will contribute to this dietary shift by exploiting the proteins in potato fruit juice, a side-stream from the production of starch. 

News on Propotato (in Danish)


DR.dk:
Kartoffelaffald kan fylde fremtidens flødeboller op

Food-supply.dk:
Kartoffelprotein kan blive guld værd

Vafo.dk:
Virksomhed satser på kartoffelprotein - ny fabrik og flere ansatte er planen

However, due to anti-nutritional components, vegetable proteins typically need to be refined before they are suitable for human consumption. 

This is also the case for potato protein fractions where the value is decreased due to toxic glycoalkaloids (GA) and the enzyme polyphenol oxidase (PPO) responsible for a colour formation causing the final products to have a brown hue and a negative impact on solubility and digestibility. 

It is thus essential to eliminate this enzymatic reaction during purification of the potato protein fraction.

GA is part of the potato plants natural defence and can in high amounts cause several gastrointestinal and neurological problems in humans like vomiting, diarrhoea, headache, and hallucinations. In addition, GA adds an unwanted bitter taste to potato protein products. 

Consequently, these components must be removed from the potato protein fractions before it is suitable for human consumption. Therefore, this side product is currently predominantly used for animal feed. 

With the project Propotato, the partners intend to change that by developing new and healthy potato protein-based ingredients and food.

Industrial Cross-flow Filtration Used in Laboratory Scale


Production of potato starch generates a side stream of protein containing potato juice with an annual production of 10,000 ton of potato protein. During full-scale production, the factories will process around 100,000 litres of potato juice an hour. The large amount of raw material naturally limits the number of techniques available for removing glycoalkaloids. One promising technique is cross flow filtration. 

Cross flow filtration is a technique in which the starting solution passes along the surface of a membrane-filter. A pressure difference across the membrane pushes components, which are smaller than the pores through the filter. Components larger than the filter pores are retained. The technique can handle the large amounts of liquid often seen in industrial food production. In the potato project, the significant size difference between glycoalkaloids and proteins are exploited.


Cross flow-filtration is a high capacity method used industrially for separation and purification of biomolecules and is a central technology in biotechnological production and in isolation of functional food fractions. The Carlsberg Foundation has supported the acquisition of an advanced laboratory scale cross-flow filtration system for this project

“The cross-flow filtration system has given us the possibility to screen conditions in a laboratory scale before setting up a pilot plant. This can save us a lot of time and money in the development of a new potato protein-based product,” says Assistant Professor Carsten Scavenius, Project Manager of Propotato.

A major advantage of this system is the easy scaling between laboratory and production scale. This means that once the optimal settings for any cross-flow protocol are identified these settings are easily implemented in the production. In relation to the potato protein production, it is therefore possible to optimise the condition for removing the glycoalkaloid both in relations to efficiency but also for best use of resources such as clean water and energy. 

A major issue with the glycoalkaloids is the affinity for the proteins in the potato-fruited juice. Consequently, conditions for optimal separations were the interaction is low needs to be identified prior to establishing a pilot plant. 

The Opening of New Possibilities for Supporting Industrial Research

Most of the laboratory's projects involve protein purification that forms the basis for further experiments and analyses. It is therefore crucial that we have equipment that can assist this time and labour-intensive discipline. In addition, the equipment supported by the Carlsberg Foundation expands the possibilities we have to establish additional collaborative projects with industry as exemplified by the Propotato-project. 

With the cross-flow filtration setup, we have the possibility to support research within food production and biotechnology that is especially relevant for small and medium sized enterprises, which do not have access to this kind of research infrastructure.

“With the new cross flow filtration instrument, we have an infrastructure which allows us to participate in new private/public collaborations and thereby expanding the technological capabilities of the industrial sector,” says Professor Jan J. Enghild from Aarhus University.