Browsing by Subject "oligosaccharides"

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  • Koivistoinen, Mia (Helsingin yliopisto, 2019)
    Oligosaccharides and dextran can both be produced from sucrose during sourdough fermentation when using dextran producing lactic acid bacteria (LAB). Both dextran and oligosaccharides increase the softness and volume of bread. Since they both are produced simultaneously, the exact effects of dextran and oligosaccharides in sourdough cannot be differentiated. The production of oligosaccharides and dextran can, however, be affected by modifying the concentrations and ratio of sucrose and acceptor and changing the used pH and temperature. The aim of this master’s thesis was to improve the functionality of syrups used in baking by optimizing the production of maltosylisomaltooligosaccharides (MIMO) by oligosaccharides and dextran producing LAB Weissella confusa. The used fermentation temperatures were 20℃ and 30℃. Sucrose concentrations in syrups were 0%, 10% and 20%. Native syrup was used as a control sample. The optimized, functionalized syrup with 20% added sucrose was further used in bread production to evaluate its ability to increase volume and decrease hardness of bread. Breads with added optimized and functionalized syrup, syrup with 0% added sucrose and native syrup as well as control wheat bread were baked. The volume of functionalized syrup containing bread was expected to increase and hardness to decrease compared to other breads. The oligosaccharide production in syrups was qualitatively whereas mono- and disaccharides quantitatively evaluated by high performance anion exchange chromatography with pulse amperometric detection (HPAEC-PAD). Dextran content was evaluated after enzymatic degradation using HPAEC-PAD. The technological impact in bread was evaluated by measuring of the specific volume and texture profile analysis (TPA) of breads containing dextran and MIMO. The results were compared to the breads containing syrup with 0% added sucrose, native syrup and control wheat bread. An increased production of MIMO was obtained by increasing sucrose concentration from 10% to 20%. The peaks of short-chain MIMO decreased, and long-chain MIMO increased as sucrose concentration increased. Temperature did not affect MIMO production. Unlike expected, the volume of functionalized syrup containing bread decreased, and the hardness increased compared to control, bread containing syrup with 0% sucrose or bread with native syrup. This could be due to decreased yeast activity due to increased osmotic pressure, which was caused by a low water amount and yet high sugar content. In further studies, the baking conditions of functionalized syrup containing bread should be optimized to increase the activity of yeast and also the use of functionalized syrup fermented with 10% sucrose should be evaluated in baking.
  • Lensu, Sanna; Pariyani, Raghunath; Mäkinen, Elina; Yang, Baoru; Saleem, Wisam; Munukka, Eveliina; Lehti, Maarit; Driuchina, Anastasiia; Linden, Jere; Tiirola, Marja; Lahti, Leo; Pekkala, Satu (2020)
    Understanding the importance of the gut microbiota (GM) in non-alcoholic fatty liver disease (NAFLD) has raised the hope for therapeutic microbes. We have shown that high hepatic fat content associated with low abundance of Faecalibacterium prausnitzii in humans and, further, the administration of F. prausnitzii prevented NAFLD in mice. Here, we aimed at targeting F. prausnitzii by prebiotic xylo-oligosaccharides (XOS) to treat NAFLD. First, the effect of XOS on F. prausnitzii growth was assessed in vitro. Then, XOS was supplemented or not with high (HFD, 60% of energy from fat) or low (LFD) fat diet for 12 weeks in Wistar rats (n = 10/group). XOS increased F. prausnitzii growth, having only a minor impact on the GM composition. When supplemented with HFD, XOS ameliorated hepatic steatosis. The underlying mechanisms involved enhanced hepatic beta-oxidation and mitochondrial respiration. Nuclear magnetic resonance (H-1-NMR) analysis of cecal metabolites showed that, compared to the HFD, the LFD group had a healthier cecal short-chain fatty acid profile and on the HFD, XOS reduced cecal isovalerate and tyrosine, metabolites previously linked to NAFLD. Cecal branched-chain fatty acids associated positively and butyrate negatively with hepatic triglycerides. In conclusion, XOS supplementation can ameliorate NAFLD by improving hepatic oxidative metabolism and affecting GM.
  • Juvonen, Minna (Helsingfors universitet, 2011)
    The aim of the present study was to implement a tandem mass spectrometry (MS/MS) method for determining glycosidic bond linkage positions of neutral isomeric glucooligosaccharides. The methods for structural analysis and the fragmentation mechanisms of oligosaccharides in MS/MS-analysis was reviewed. The MS/MS-spectra of oligosaccharide contains glycosidic bond and cross ring cleavage fragment ions. The linkage position can be determined by cross ring cleavage fragment ions of cationized or anionized oligosaccharides. The study started by analyzing the typical MS/MS-spectra of model isomeric disaccharides with different linkage positions. The data was then used to assess the MS/MS-spectra of model tri- and tetrasaccharides. The similarity of MS/MS fragmentation patterns of the model disaccharides and the tri- and tetrasaccharides would enable the linkage position analysis by the applied MS/MS method. The MS/MS-analyses were carried out by using electron spray ionization with ion trap mass spectrometer in both positive and negative mode. In positive mode the oligosaccharides were analyzed as sodium and lithium adduct ions while chloride adduct ions were used in negative mode analysis. The different linkage positions of disaccharides were characterized by the different MS/MS fragmentation profiles in positive and negative ionization methods. The reducing end linkage positions of tri- and tetrasaccharides were easily identified by comparing their MS/MS fragmentation patterns with the MS/MS-spectra of model disaccharides. The other linkages in the tri- and tetrasaccharide were identified by using negative mode. In positive mode the identification of other linkages was not possible because the cross ring cleavage fragment ions were formed mostly from the reducing end. The linkages of tri- and tetrasaccharides could not be identified by MS3-analysis due to formation of isomeric glycosidic bond fragment ions as the charge can be retained in the reducing or non-reducing end. The results indicated that the applied MS/MS method was suitable for determing the glycosidic bond linkages of oligosaccharides in negative mode. In positive mode only the reducing end linkage can be determined.