A guilty conscience often accompanies ice cream. However, the substitution of the “problematic” sugar often fails due to consumer acceptance, because the ice cream should taste sweet and fruity, be creamy and create a pleasant mouthfeel.

By Dr. Jörg Häseler

Food technologists and food chemists at the Technical University of Berlin (TUB) and the Karlsruhe Institute of Technology (KIT) want to obtain dietary fibres from fibre-rich by-products of food production, which can be used to replace sugar in ice cream. Side effect: The process helps to avoid waste.

“Sugar not only sweetens ice cream,” explains Prof. Stephan Drusch from the Faculty of Process Sciences at the TUB's Department of Food Technology and Food Materials Sciences, “sugar plays an important technological role in its production and is thus partly responsible for its structure and creaminess.” Thus, a reduction in the sugar content leads to a perceptible change in the mouthfeel. Therefore, the goal of nutritional improvement of ice cream competes with consumer acceptance. The scientists see a possible solution in dietary fibres from by-products of food production. The conversion of carbohydrates from leftovers from peas, carrots and fruits could reduce sugar and maintain mouthfeel.

The insoluble fibre materials of pea shells, carrot fibres and fruit residues from juice production such as cellulose, hemicelluloses and pectin contain complex carbohydrates. In the project “Replacement of sugars in ice cream by potentially prebiotic oligo- and/or polysaccharides from sustainable sources”, the scientists want to convert these components to oligosaccharides by special processes, which changes their functional properties. “It is known that such materials can positively influence the structure and mouthfeel of various foods via improved water binding, thus enabling a reduction in sugar,” says Stephan Drusch. “From a nutritional point of view, they are still considered dietary fibres because of their pre-biotic effect.”

Despite these basic findings, there is still a lot of work ahead of the scientists and before the first ice cream can be enjoyed without regret, because each fibre material has a different carbohydrate profile according to its botanical origin. Thus, the process of producing the oligosaccharides – a combination of enzyme treatment and mechanical high-pressure treatment – must be specifically adapted. The aim of the TUB working group is to make a wide range of plant by-products usable for use in ice cream by understanding this process.

A great opportunity lies in the heterogeneous composition of the fibre materials. This results in very different oligosaccharides with a broad pre-biotic activity. Characterizing these precisely is the task of the food chemistry expertise of the working group of Prof. Mirko Bunzel, Department of Food Chemistry at KIT: “Harnessing existing by-products of the food industry helps to avoid waste in food production. And ice cream can become healthier if sugar is reduced and replaced by dietary fibres.”