## 1 Introduction  
Dandelion (_Taraxacum sect. Taraxacum F.H. [PERSON]_, _syn. Taraxacum officinala_) is a medicinal and edible plant that belongs to the genus Taraxacum, subfamily Cichorioideae, Asteraceae family, and occurs in New Zealand, Australia, Eurasia, Africa, and North and South America. It is widespread in subarctic and Northern temperate regions as a common perennial weed growing in roadsides, fallow fields, meadows, and lawns [1; 2; 3]. Because of its medicinal properties, it is predominantly produced as a cultivated plant in Bulgaria, Romania, Hungary, and Poland [4; 5]. Dandelion roots and their herb extracts have been \"generally recognized as safe\" according to the Food and Drug Administration, and they are applied for dietary supplements, medicinal use, and food purposes [1; 4]. Dandelion is traditionally used for bacterial infections, kidney diseases, diuretic diabetes, liver, and spleen disorders. The root can be utilized as an anti-inflammatory agent, and also for the treatment of hepatitis, dysppesia, heartburn, liver complaints, spleen, anorexia, and for the prevention of renal gravel and loss of appetite [1; 2; 3; 4; 5; 6; 7]. The mentioned effects are due to the numerous bioactive substances in its roots [1; 2; 3]. Among them, dandelion polysaccharides deserve special attention. _Tarasacum officinal_ roots contain polysaccharides [3], mainly inulin-type fructans [1; 2; 5]. Inulin and fructooligosaccharides are fructans that consist mainly of \(\beta\)-(2\(\rightarrow\)1)-fructosyl fructose units (Fm), with one \(\alpha\)-glucopyranosyl unit (1\(\rightarrow\)2) (GFn) usually, but not always [2; 8]. Inulin possesses many bioactive properties, such as prebiotic and immunomod addition activity, improves mineral absorption and glucolipid metabolism, lowers blood sugar, and represses obesity, osteoporosis, and cancer. Its healthy effect is connected mainly to the action of short-chain fatty acids that result after inulin fermentation in the large intestine (colon) by bifidobacteria [2; 4; 5; 6]. Inulin in dandelion roots is situated in parenchyma cells in colorless lumps and clumps [9]. Its content in dandelion roots varies from 2 to 40% depending on the season and location [4; 5; 10; 11; 12], and as usual for Bulgarian representatives total fructans do not exceed 20% dw, while inulin content was found to be 11% [5]. Many studies have demonstrated that dandelion polysaccharides exhibit anti-inflammatory, anti-complement, antioxidant, antibacterial, antitumor, hypoglycemic, anticoagulant, and other effects [3; 4; 6; 7]. It was shown that the two polysaccharides from dandelion roots could protect the liver from hepatic injury, while the fructan fraction showed good antioxidant activities in DPPH, hydroxyl free radical-scavenging abilities, and good hypoglycemic activities [6]. Many different extraction approaches have been performed for the extraction of inulin-type fructans from different plants: classical extraction, enzyme-assisted extraction, pressure liquid extraction, accelerated solvent extraction, microwave-assisted extraction, and ultrasound-assisted extraction [6; 13; 14; 15; 16; 17]. It was reported that dandelion polysaccharides, especially inulin, were obtained mainly by classical extraction [5; 10; 11; 12; 18], and only one study mentioned ultrasound-assisted extraction [6]. In most cases, the classical extraction of dandelion inulin is connected mainly to its content determination, structure elucidation, or physicochemical evaluation, but its functional properties were not listed at all. Moreover, no studies have been conducted on the isolation of inulin from dandelion roots by microwave-assisted extraction. Therefore, an investigation into the impact of ultrasound-assisted and microwave extraction on the physicochemical properties of dandelion inulin remains a challenge. It was reported earlier that the physicochemical properties of polysaccharides (mainly chemical composition and molecular weight distribution) were strongly influenced by the used extraction processes [19].