Jirat Wongsanittayarak. Production of purified short-chain Fructooligosaccharides from red onion (Allium cepa L. var. viviparum and their in vitro effect on human gut microbiota. Master's degree(Biotechnology). Chiang Mai University. Library. : Chiang Mai University, 2024.
Production of purified short-chain Fructooligosaccharides from red onion (Allium cepa L. var. viviparum and their in vitro effect on human gut microbiota
การผลิตฟรุกโตโอลิโกแซ็กคาไรด์สายโซ่สั้นบริสุทธิ์จากหอมแขก (Allium cepa L. var. viviparum) และผลระดับหลอดทดลองต่อไมโครไบโอตาในลำไส้มนุษย์
Abstract:
Variation of gut microbiota is a cause of obesity and insulin resistance. Several research reveals that a high ratio of Firmicutes to Bacteroidetes is associated with obesity, on the other hand, a low ratio is relative to inflammatory bowel disease (IBD). Yet, improvement of gut microbiota by using prebiotics and probiotics are alternative strategies for prevention and treatment of the mentioned diseases. Red onion or Hom Kaek has a scientific name of Allium cepa L. var. viviparum is a plant that is rich in various structures of fructooligosaccharide as well as inulin as the main constituen, thus being well deserved as prebiotics. Short chain fructooligosaccharides (SCFOSs) have been accepted by their ability to more selectively stimulate growth of probiotics than longer chain fructooligosaccharides but they have been determined at low level. Moreover, the presence of absorbable sugars that are stored in the onion bulb limits application of fructooligosaccharides as prebiotics. The objectives of this research were to prepare purified SCFOSs from red onion and to study the in vitro effect of the purified SCFOSs on human gut microbiota. Red onion extract prepared by direct squeezing using a juicer machine. The red onion extract appeared as pinkish-purple in color and had a dry matter of 16.18% with carbohydrate content of 93.5%, protein content of 5.1%. The extract consisted of (g/L) fructan 129 ± 2, fructose 5.9 ± 0.6, glucose 14.9 ± 0.4, sucrose 14.9 ± 0.6, neokestose 15.6 ± 0.1, kestose 4.4 ± 0.1, nystose 11.5 ± 0.4, fructofuranosylnystose 12.8 ± 0.2 which is calculated to a total SCFOSs of 44.3 g/L. Three different strategies including two-step (TSP), simultaneous (SP), and semi-simultaneous (SSP) production process, were designed for production of purified SCFOSs. In SCFOSs production process, endo-inulinase was used to catalyze the hydrolysis of β-(2,1) glycosidic linkage of long chain fructooligosaccharides and inulin to produce SCFOSs. A yeast strain Candida orthopsilosis FLA44.2 was used for purification process as it is capable of selectively assimilating fructose, glucose, and sucrose with a minimum negative effect on the produced SCFOSs. The results revealed that the SP and SSP processes met the objective criteria in terms of time consuming. Notably, the SP process is considered a much simpler process. The optimal conditions of the SP process were as follows ; 0.4 unit of endo-inulinase/g total fructans, 5% (v/v) C. orthopsilosis FLA44.2, incubation on 120-rpm rotary shaker at 30ºC for 60 h. The condition allowed SCFOSs yield (g/L) of neokestose 42 ± 3, kestose 5.4 ± 0.6, nystose 16.2 ± 0.4, fructofuranosylnystose 17.3 ± 0.1 and total fructans 81 ± 4 with a total fructan recovery of 68.9% and the SCFOSs possessed the purity of 93.5%. Cation and anion exchange resin and activated charcoal column were employed for decolorization and deodorization of the produced SCFOSs, respectively. After these steps, the derived SCFOSs was apparently clear and odorless with the recovery yield of SCFOS of 63.5%, the recovery yield of total fructans of 56.0%, and consisting of ratio of each SCFOSs similar to the former SCFOSs solution.