Field-flow fractionation of cationic cellulose derivatives

The asymmetric flow field-flow fractionation (AF4) method was developed for cationic cellulose derivatives. AF4 is the method of choice especially for high-molar mass samples, which are challenging to characterize with conventional chromatographic techniques such as size-exclusion chromatography (SEC). The cationic charge of macromolecules also complicates the size-based separations where no interaction between the analytes and the column stationary phase (SEC) or membrane (AF4) should occur. However, many column matrices and membranes carry negative charge and thus preventing interactions between cationic analytes and negatively charged separation support should be taken into consideration when doing method development. In this study, two eluent compositions, neutral and acidic, were tested for AF4 separation of cationic hydroxyethyl celluloses with varying charge densities. The eluent composition with a pH below the isoelectric point of regenerated cellulose membrane, which was used in this AF4 study, enabled the size-based separation with close to 100% analysis recovery. Macromolecular parameters (molar mass and radius of gyration) and conformation were investigated by coupling a multi-angle light scattering detector and differential refractometer to the AF4 system.Peer reviewe

The effect of structure on the dilute solution properties of branched polysaccharides studied with SEC and AsFlFFF

Cereal arabinoxylans, guar galactomannans, and dextrans produced by lactic acid bacteria(LAB) are a structurally diverse group of branched polysaccharides with nutritional and industrial functions. In this thesis, the effect of the chemical structure on the dilute solution properties of these polysaccharides was investigated using size-exclusion chromatography(SEC) and asymmetric flow field-flow fractionation (AsFlFFF) with multiple-detection. The chemical structures of arabinoxylans were determined, whereas galactomannan and dextran structures were studied in previous investigations. Characterization of arabinoxylans revealed differences in the chemical structures of cereal arabinoxylans. Although arabinoxylans from wheat, rye, and barley fiber contained similar amounts of arabinose side units, the substitution pattern of arabinoxylans from different cereals varied. Arabinoxylans from barley husks and commercial low-viscosity wheat arabinoxylan contained a lower number of arabinose side units. Structurally different dextrans were obtained from different LAB. The structural effects on the solution properties could be studied in detail by modifying pure wheat and rye arabinoxylans and guar galactomannan with specific enzymes. The solution characterization of arabinoxylans, enzymatically modified galactomannans, and dextrans revealed the presence of aggregates in aqueous polysaccharide solutions. In the case of arabinoxylans and dextrans, the comparison of molar mass data from aqueous and organic SEC analyses was essential in confirming aggregation, which could not be observed only from the peak or molar mass distribution shapes obtained with aqueous SEC. The AsFlFFF analyses gave further evidence of aggregation. Comparison of molar mass and intrinsic viscosity data of unmodified and partially debranched guar galactomannan, on the other hand, revealed the aggregation of native galactomannan. The arabinoxylan and galactomannan samples with low or enzymatically extensively decreased side unit content behaved similarly in aqueous solution: lower molar mass samples stayed in solution but formed large aggregates, whereas the water solubility of the higher-molar-mass samples decreased significantly. Due to the restricted solubility of galactomannans in organic solvents, only aqueous galactomannan solutions were studied. The SEC and AsFlFFF results differed for the wheat arabinoxylan and dextran samples. Column matrix effects and possible differences in the separation parameters are discussed, and a problem related to the non-established relationship between the separation parameters of the two separation techniques is highlighted. This thesis shows that complementary approaches in the solution characterization of chemically heterogeneous polysaccharides are needed to comprehensively investigate macromolecular behavior in solution. These results may also be valuable when characterizing other branched polysaccharides.Erilaisia analyysimenetelmiä hyödyntämällä luotettavaa tietoa haaroittuneiden polysakkaridien liuosominaisuuksista Arabinoksylaanit, galaktomannaanit ja dekstraanit ovat joko kasvi- tai mikrobiperäisiä polysakkarideja. Viljoissa esiintyvät arabinoksylaanit muodostavat yhdessä beetaglukaanin kanssa pääasiallisen ravintokuidun lähteen ravinnossa. Galaktomannaania saadaan guar-kasvin paloista ja sitä käytetään yleisesti elintarviketeollisuudessa sakeutusaineena (guarkumi E 412). Dekstraanit ovat puolestaan maitohappobakteerien tuottamia eksopolysakkarideja, joilla on paljon sovelluksia. Dekstraaneja käytetään esimerkiksi lisäaineina kosmetiikassa, kliinisissä sovelluksissa plasman laajentajina ja standardiaineina kromatografiassa. Lisäksi dekstraaneja käytetään elintarviketeollisuudessa emulgaattoreina, sakeuttajina ja stabilaattoreina. Näiden jo mainittujen sovellusten lisäksi näitä kaikkia uusiutuvia biopolymeerejä voitaisiin hyödyntää vieläkin tehokkaammin mm. selluloosan ja tärkkelyksen rinnalla, joilla on selkeästi enemmän käyttösovelluksia. Polysakkaridien kemiallinen rakenne ja sekä fysikaaliset ominaisuudet tulee kuitenkin tuntea tarkasti, jotta uusia sovelluksia voidaan kehittää. Tässä työssä tutkittiin polysakkaridien rakenteen vaikutusta niiden liuosominaisuuksiin laimeissa liuoksissa, jolloin voidaan saada tietoa yksittäisten molekyylien ominaisuuksista. Eri viljoista peräisin olevien arabinoksylaanien rakenteet olivat luontaisesti erilaiset. Lisäksi polysakkaridien rakenteita muokattiin spesifisillä entsyymeillä. Haaroittuneiden polysakkaridien liuosominaisuuksien tutkiminen on haastavaa, sillä kemiallisen rakenteen vaihtelu on suurta näytemolekyylien välillä. Lisäksi, suurin osa haaroittuneiden polysakkaridien tutkimuksesta on toistaiseksi keskittynyt amylopektiiniin, joka on tärkkelyksen rakennekomponentti, sekä glykogeeniin. Polymeerien karakterisointi on kehittynyt paljon viime vuosikymmeninä, mutta sovellukset on kehitetty lähinnä synteettisille polymeereille. Tässä tutkimuksessa hyödynnettiin kokoekskluusiokromatografiaa (SEC) ja asymmetristä poikittaisvirtauskenttävirtausfraktiointia (AsFlFFF). Molemmissa erotusmenetelmissä käytettiin useita detektoreita moolimassan, molekyylikoon, konformaation ja rajaviskositeetin määrittämiseksi kunkin näytteen kokojakaumalle. Kemiallinen rakenne vaikutti tutkittujen polysakkaridien liuosominaisuuksiin. Vaikka arabinoksylaanien ja galaktomannaanien rakenne on samankaltainen, niiden liuoskäyttäytymisessä havaittiin eroja. Dekstraaneissa on myös pidempiä haaroja, toisin kuin arabinoksylaaneissa ja galaktomannaaneissa, jotka hallitsevat molekyylien käyttäytymistä liuoksessa. Tämän tutkimuksen tulokset osoittavat, että rakenteellisesti heterogeenisten biopolymeerien liuosominaisuuksista voidaan saada luotettavaa tietoa kahta erotusmenetelmää vertaamalla, eri liuottimia hyödyntämällä, sekä eri detektiomenetelmiä yhdistämällä

Enzymatic modification of oat globulin enables covalent interaction with procyanidin B2

The effect of enzyme treatment on protein-tannin interactions was investigated using up-to-date analytical approaches for improving their physical properties. The formation of ligands between procyanidin B2 and native oat globulin (OG) was observed to be affected by the ratio of procyanidin B2 to OG and the availability of tryptophan. For the transglutaminase-treated OG, the results obtained from circular dichroism (CD) and size exclusion chromatography (SEC) revealed that procyanidin B2 acted as an acyl acceptor in the process of OG deamidation. Procyanidin B2 also inhibited the non-covalent protein-protein interactions occurring between the aromatic side-chains or sedimentation of tryptophan aggregates. For trypsin-treated OG, procyanidin B2 interacted with phenylalanine and the tryptophan side-chain of OG. The inhibition of procyanidin B2 towards protein-protein aggregation was proved by the observation of CD, SEC and asymmetric flow field-flow fractionation.Peer reviewe

Safety considerations of plant polysaccharides for food use: a case study on phenolic-rich softwood galactoglucomannan extract

A growing population and concern over the sufficiency of natural resources for feeding this population has motivated researchers and industries to search for alternative and complementary sources of food ingredients and additives. Numerous plant species and parts of plants are explored as raw materials for food production. An interesting example is wood; to date, few wood-based additives or ingredients are authorized for food use. Wood hemicelluloses, such as softwood galactoglucomannans (GGM), constitute an abundant bioresource that shows a highly potential functionality in edible materials. Spruce GGM—“spruce gum”—acts as a multi-functional emulsion stabilizer, and it could be used in various processed food products, replacing less effective, conventional emulsifiers. Before new materials can be released onto the food market, their safety must be evaluated, according to the Novel Food regulation. This review focuses on the safety aspects that must be considered before polysaccharide- and phenolic-rich plant extracts can be awarded the status of authorized food ingredients. In this review, GGM is presented as a case study and examples are given of plant-based polysaccharides that are already authorized for food purposes. The legislation regarding Novel Food ingredients in Europe is also briefly reviewed.Peer reviewe

The Solution Interaction of Tetrathionate Ions and Sodium Isobutyl Xanthate and Its Effect on the Flotation of Galena and Chalcopyrite

Tetrathionates have been found in significantly high concentrations in recycled process waters from massive sulphide ore processing plants. These polythionates react with xanthate added to flotation pulps thus reducing xanthate dosages in solution potentially affecting flotation performance. The current study focused on the effect of the tetrathionate-xanthate reaction on sulphide mineral recoveries. Ore dissolution studies confirmed the generation of tetrathionates by copper-lead-zinc ores. In 20 min, the tetrathionates consumed more than half of the xanthate in solution at pH 7. Rest potential measurements and Fourier transform infrared spectroscopy (FTIR) showed that the degree of collector-mineral interactions of xanthate and both galena and chalcopyrite was greatly reduced in the presence of a 2000 mg/L tetrathionate solution. Microflotation tests showed that chalcopyrite recovery was less sensitive to tetrathionates as indicated by small changes in mineral recoveries. Galena was sensitive to the action of tetrathionates on the mineral surface as the galena recovery significantly declined when floated with xanthate as a collector in both a 500 mg/L tetrathionate solution and a 2000 mg/L tetrathionate solution. These fundamental results lay a sound base on which more discussion into the significance and the effect of tetrathionates on flotation performance of sulphide ores can be developed

A Value-Based Steering Model for Healthcare

This article aims to answer how a commissioning body can steer health services based on value in an environment where the commissioner is responsible for the health services of a population with varying health service needs. In this design science study, we constructed a value-based steering model consisting of three parts: (1) the principles of steering; (2) the steering process; and (3) Value Steering Canvas, a concrete tool for steering. The study is based on Finland, a tax-funded healthcare system, where healthcare is a public service. The results can be applied in any system where there is a commissioner and a service provider, whether they are two separate organizations or not. We conclude that steering can be done based on value. The commissioning body can start using value-based steering without changes in legislation or in the present service system. Further research is needed to test the model in practice.Peer reviewe

Colloidal features of softwood galactoglucomannans-rich extract

Development of a sustainable bioeconomy requires valorization of renewable resources, such as wood hemicelluloses. The intra- and inter-molecular associations of hemicelluloses within themselves or with other wood components can result in complex macromolecular features. These features exhibit functionality as hydrocolloids, however macromolecular characterization of these heterogeneous materials are challenging using conventional techniques such as size-exclusion chromatography. We studied galactoglucomannans (GGM) -rich softwood extracts at two grades of purity—as crude extract and after ethanol-precipitation. Asymmetrical flow field-flow fractionation (AF4) was optimized and utilized to fractionate size classes in GGM extracts, and subsequent characterization was performed with light scattering and microscopy techniques. Both GGM extracts contained polysaccharides of around 10,000 g/mol molar mass, and colloidal assemblies and/or particles in sub-micron size range. The optimized AF4 method facilitates the characterization of complex biomass-derived carbohydrates without pre-fractionation, and provides valuable understanding of their unique macromolecular features for their future application in food, pharmaceuticals, and cosmetics.Peer reviewe

The Resistome of Farmed Fish Feces Contributes to the Enrichment of Antibiotic Resistance Genes in Sediments below Baltic Sea Fish Farms

Our previous studies showed that particular antibiotic resistance genes (ARGs) were enriched locally in sediments below fish farms in the Northern Baltic Sea, Finland, even when the selection pressure from antibiotics was negligible. We assumed that a constant influx of farmed fish feces could be the plausible source of the ARGs enriched in the farm sediments. In the present study, we analyzed the composition of the antibiotic resistome from the intestinal contents of 20 fish from the Baltic Sea farms. We used a high-throughput method, WaferGen qPCR array with 364 primer sets to detect and quantify ARGs, mobile genetic elements (MGE), and the 16S rRNA gene. Despite a considerably wide selection of qPCR primer sets, only 28 genes were detected in the intestinal contents. The detected genes were ARGs encoding resistance to sulfonamide (sul1), trimethoprim (dfrA1), tetracycline [tet(32), tetM, tetO, tetW], aminoglycoside (aadA1, aadA2), chloramphenicol (catA1), and efflux-pumps resistance genes (emrB, matA, mefA, msrA). The detected genes also included class 1 integron-associated genes (intI1, qacE?1) and transposases (tnpA). Importantly, most of the detected genes were the same genes enriched in the farm sediments. This preliminary study suggests that feces from farmed fish contribute to the ARG enrichment in farm sediments despite the lack of contemporaneous antibiotic treatments at the farms. We observed that the intestinal contents of individual farmed fish had their own resistome compositions. Our result also showed that the total relative abundances of transposases and tet genes were significantly correlated (p = 0.001, R-2 = 0.71). In addition, we analyzed the mucosal skin and gill filament resistomes of the farmed fish but only one multidrug-efflux resistance gene (emrB) was detected. To our knowledge, this is the first study reporting the resistome of farmed fish using a culture-independent method. Determining the possible sources of ARGs, especially mobilized ARGs, is essential for controlling the occurrence and spread of ARGs at fish farming facilities and for lowering the risk of ARG spread from the farms to surrounding environments.Peer reviewe

Knoevenagel condensation for modifying the reducing endgroups of cellulose nanocrystals

Peer reviewe