What are chicory root fibres?
Chicory root fibres are soluble dietary fibres, naturally present in the chicory root. They are well-recognized ingredients in the food industry, due to their proven prebiotic effect, while also improving taste and texture.
Chicory root fibres
In the roots of the chicory plant carbohydrates are present, which serve as energy storage for the plant to grow in the next year. These carbohydrates are characterized by linear chains of fructose units with or without an end-standing glucose unit, all linked by a ß(2-1) linkage. This linkage cannot be split by human enzymes, which means these carbohydrates are not digestible. The chain length varies between 2 and more than 60 units, all of them present at the same time in the root. During harvesting the number of shorter chains increases. This occurs due to enzymes active in the root, splitting the longer chains into shorter chains to prepare for the next year’s growth.
The storage carbohydrate as such with its full variety of chain lengths is called inulin. The shorter chains are called oligofructose or fructooligosaccharides. Oligofructose can also be produced outside the root. With the help of the same type of enzyme present in the root, inulin can be split into shorter chains. Due to its non-digestibility and the physiological properties related to it, inulin and oligofructose are dietary fibres.
Inulin-type fructans
Chicory root fibres (inulin and oligofructose) belong to the group of inulin-type fructans. Inulin-type fructans are naturally present in many plant roots, tubers, vegetables and fruits such as onions, leek, bananas, garlic and many others. Therefore, they have a long history as safe and natural ingredients of human diets.
Due to the high content of inulin in chicory roots these plants are used for commercial harvesting of inulin. Other agricultural sources for commercial use next to chicory root are for example agave and Jerusalem artichoke (also called topinambour). However these inulin-type fructans have different structures and/or linkages and chain lengths compared to those of chicory roots. Additionally, oligofructose is also not to be confused with Short-chain fructooligosaccharides (scFOS) which are not occurring in nature but are produced from sugar.
Prebiotic properties
Chicory root fibres are not digested in the small intestine, but reach the large intestine intact where they are selectively fermented by the microbiota. Unlike many other dietary fibres, chicory root fibres are preferred feed for some beneficial bacteria, in particular bifidobacteria. Those bacteria are specialized in splitting the ß(2-1) linkage that characterises chicory root fibres. This gives those beneficial bacteria a competitive advantage compared to others and therefore they grow selectively. The selective fermentation leads to multiple health benefits. Taking both into account the selective fermentation and the health benefits of chicory root fibres, they are defined as prebiotic, complying with the view of the scientific experts in the field, represented by ISAPP (International Scientific Association for Pro- and Prebiotics).
After more than 20 years of nutrition and health related research, nowadays chicory root fibres are well-recognised food ingredients known for their benefits. They are used for their prebiotic properties combined with the fibre enrichment aspect in a substantial variety of foods and drinks with specific nutritional and health properties. In addition, they are increasingly used as a sugar and fat replacer to keep products tasty while improving the nutritional profile. Chicory root fibres have a neutral to mild sweet taste. They are able to enhance the taste, mouthfeel and texture.
Terminology and definitions
While definitions are not used consistently in the literature, the following provides commonly used descriptions:
Fructans
Fructans are major storage carbohydrates of certain plants. They are linear or branched polymers of fructose, with or without an end-standing glucose unit. Different types of fructans exist and are commonly classified according to linkage type.
Inulin-type fructans
Inulin-type fructans are the general term to cover all β(2-1) linked fructans. They are naturally present in many plant roots, vegetables and fruits, like in chicory roots.
Chicory root fibres
Chicory root fibres are linear β(2-1) inulin-type fructans. As such they are non-digestible carbohydrates and dietary fibres. Chicory root fibres cover both inulin and oligofructose from chicory.
Inulin
Inulin is a natural component of numerous fruits and vegetables where it functions as storage carbohydrate or energy source in the roots or tubers of the plants. Inulin from chicory describes chicory root fibres with a chain length between 2 and 60 units and more.
Oligofructose/Fructooligosaccharides (FOS)
Oligofructose describes the shorter chain chicory root fibres. These shorter chains naturally increase during harvesting in the chicory root. Outside the root this process can be copied by splitting inulin into shorter chains.