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Efficient processing of vegetable by-products can turn costs into profits for farmers.

“One person’s waste is another person’s ingredient”, was the conclusion of the Natural Resources Institute Finland’s researchers after listening to food producers’ experiences of one of the most widely shared problems of the industry.

Various by-products are generated by the cleaning, chopping, and processing of vegetables, some of which are edible or have other uses.

Making use of these by-products is an exciting prospect for both large and small food producers, for whom wasted by-products can be a substantial extra cost. Producers of different sizes, however, require very different solutions.

Making use of vegetable by-products is not a new idea.

Tutkimusprofessori Marketta Rinne mittaa lasipulloihin säilötystä porkkanarehusta muodostuvien käymiskaasujen määrää. (Kuva: Taina Jalava)
Research Professor Marketta Rinne measures the volume of fermentation gases produced by carrot-based feed preserved in glass bottles. (Photo: Taina Jalava)

Vegetable by-products can be used as compost on farms or taken to various kinds of treatment facilities. Vegetable producers who also have livestock often use their by-products as animal feed.

Today, vegetable by-products are used both as livestock feed and as game feed.

“Vegetable producers would prefer to use their by-products to add value. Their main aim is to avoid incurring extra costs from by-products and to make use of them instead”, explains Senior Research Scientist Minna Kahala from the Natural Resources Institute Finland.

This also prevents the nutrients contained in vegetable by-products from ending up in the wrong place and damaging the environment.

Lasipulloihin säilötystä porkkanarehusta mitataan käymiskaasuja. (kuva: Marketta Rinne)
Measurement of fermentation gases produced by carrot-based feed preserved in glass bottles. (Photo: Marketta Rinne)

The Natural Resources Institute Finland is studying how carrot waste can be turned into animal feed or used efficiently as compost.

Carrot waste contains high volumes of water and sugars. What makes it difficult to use as animal feed is high transport costs and short shelf life. Using vegetable by-products as animal feed is a tempting option, as it has more economic potential than using by-products as compost.

Organic waste can no longer be taken to landfill sites but must be disposed of as compost, if no other use can be found for it. Composting often generates extra costs.

“If more value can be extracted from by-products and provided that there are potential customers, it is possible that this waste will ultimately begin to generate a profit”, says Professor Marketta Rinne from the Natural Resources Institute Finland.

Researchers have been experimenting with fermenting carrot waste and testing the suitability of different kinds of preservatives for carrot-based animal feed. The initial findings are promising.

“Our preservative tests revealed that preservatives in fact improve the quality of animal feed”, Rinne says.

The analyses also suggest that the shelf life and other properties of fermented carrot waste make it suitable for use as a component in animal feed, especially for cattle. The feed trade is a highly regulated industry, and no slip-ups are allowed in the production chain.

“Feed producers can face serious liability if animals get sick. This is why we want to test different preservatives to also ensure that their products are hygienic enough to be used as feed”, Rinne explains.

Approximately 30% of a carrot harvest is lost during storage and sorting, and peeling can remove as much as half of the bulk of a carrot. The Natural Resources Institute Finland wants to give vegetable producers tangible advice on how to make use of their by-products.

“We are working on a booklet of best practices for processing vegetable by-products. The booklet will be made available to all businesses, and it will also address legal requirements and costs”, Rinne explains.

Project Sivuhyöty (“Useful Waste”), which is financed by the Ministry of the Environment’s RAKI (“Nutrient Recycling”) programme, will be hosting a workshop for vegetable producers and other interested parties in Jokioinen on 13 October. For more information about the event, visit


Text: Johanna Leppänen

Photo: Pixabay

Published in Finnish in Maaseudun Tulevaisuus 19 of September 2016.

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