Fructan β-fructosidase (, ''exo-β-D-fructosidase'', ''exo-β-fructosidase'', ''polysaccharide β-fructofuranosidase'', ''fructan exohydrolase'') is an

enzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

with

systematic name A systematic name is a name given in a systematic way to one unique group, organism, object or chemical substance, out of a specific population or collection. Systematic names are usually part of a nomenclature. A semisystematic name or semitrivi ...

''β-D-fructan fructohydrolase''. It catalyses the

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

of terminal, non-reducing (2→1)- and (2→6)-linked β-D-fructofuranose residues in

fructan A fructan is a polymer of fructose molecules. Fructans with a short chain length are known as fructooligosaccharides. Fructans can be found in over 12% of the angiosperms including both monocots and dicotyledon, dicots such as agave, artichokes, a ...

s. Fructans are also a type of fructoside.

Industrial use and safety

Fructan β-fructosidase is used in the food industry to hydrolyze

sucrose Sucrose, a disaccharide, is a sugar composed of glucose and fructose subunits. It is produced naturally in plants and is the main constituent of white sugar. It has the molecular formula . For human consumption, sucrose is extracted and refined ...

and also

fructans A fructan is a polymer of fructose molecules. Fructans with a short chain length are known as fructooligosaccharides. Fructans can be found in over 12% of the angiosperms including both monocots and dicots such as agave, artichokes, asparagus, l ...

such as

inulin Inulins are a group of naturally occurring polysaccharides produced by many types of plants, industrially most often extracted from chicory. The inulins belong to a class of dietary fibers known as fructans. Inulin is used by some plants as a ...

and levan into

fructose Fructose (), or fruit sugar, is a Ketose, ketonic monosaccharide, simple sugar found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. It is one of the three dietary monosaccharides, along with glucose and gal ...

, which is useful in the production of fructose syrups and other food ingredients. One such enzyme preparation is produced using a genetically modified strain of ''Trichoderma reesei'' (strain AR-577), which has been evaluated for safety by the European Food Safety Authority (EFSA).Zorn, H.; Barat Baviera, J. M.; Bolognesi, C.; et al. (2024). "Safety evaluation of the food enzyme fructan β‐fructosidase from the genetically modified ''Trichoderma reesei'' strain AR‐577". ''EFSA Journal''. 22 (12): e9124. https://doi.org/10.2903/j.efsa.2024.9124 According to EFSA's 2024 report, the genetic modifications in the production strain do not give rise to safety concerns, and the final enzyme preparation is free from viable ''T. reesei'' cells and its DNA. Toxicological studies, including a 90-day oral toxicity test in rats and genotoxicity assessments, revealed no adverse effects. Additionally, an allergenicity assessment based on amino acid sequence comparison found no significant similarity to known allergens, suggesting a low likelihood of allergic reactions under the intended conditions of use.

Biological function and natural occurrence

Fructan β-fructosidase enzymes occur naturally in various plant species, where they play a key role in mobilizing carbohydrate reserves. A study on ''Helianthus tuberosus'' (Jerusalem artichoke) tubers demonstrated that the activity of fructan β-fructosidase varies seasonally, with the highest activity observed during the sprouting period when carbohydrate mobilization is most critical for growth. The same study also characterized a β-(2-1)-linkage specific fructan β-fructosidase (FEH), which preferentially hydrolyzed inulin-type fructans rather than levan-type substrates. This specificity highlights the existence of distinct isoforms of FEH enzymes that vary by substrate preference.

Applications in food fermentation and nutrition

Fructan β-fructosidase enzymes are also applied in food biotechnology, particularly for modifying dietary carbohydrate content during fermentation. A study on ''

Lactobacillus paracasei ''Lacticaseibacillus paracasei ''(commonly abbreviated as ''Lc. paracasei'') is a gram-positive, homofermentative species of lactic acid bacteria that are commonly used in dairy product fermentation and as probiotic cultures. ''Lc. paracasei'' i ...

'' identified a β-fructosidase known as FosE, which actively degrades fructans during sourdough fermentation. This enzymatic activity significantly reduces the levels of fermentable oligosaccharides, disaccharides, monosaccharides, and polyols ( FODMAPs), which are commonly associated with gastrointestinal symptoms in individuals with

irritable bowel syndrome Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder characterized by a group of symptoms that commonly include abdominal pain, abdominal bloating, and changes in the consistency of bowel movements. These symptoms may ...

(IBS). By reducing FODMAP content, the use of fructan-degrading enzymes like FosE in fermentation improves the digestibility of baked products such as steamed bread. This demonstrates the enzyme's role not only in carbohydrate metabolism but also in enhancing the nutritional profile of fermented foods for sensitive populations.

References

External links

* EC 3.2.1 {{Enzyme-stub