Browsing by Autor "Lars Nilsson"

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Application of asymmetric flow field-flow fractionation (AF4) and multiangle light scattering (MALS) for the evaluation of changes in the product molar mass during PVP-b-PAMPS synthesis
(Springer Science+Business Media, 2018) Catalina Fuentes; Joel Castillo; José Vila; Lars Nilsson
Characterization of a water soluble, hyperbranched arabinogalactan from yacon (Smallanthus sonchifolius) roots
(Elsevier BV, 2016) Alejandra Castro; Francisco Vilaplana; Lars Nilsson
Characterization of molecular properties of wheat starch from three different types of breads using asymmetric flow field-flow fractionation (AF4)
(Elsevier BV, 2019) Catalina Fuentes; Rossio Castañeda; Fanny Rengel; J. Mauricio Peñarrieta; Lars Nilsson
Characterization of non-solvent precipitated starch using asymmetrical flow field-flow fractionation coupled with multiple detectors
(Elsevier BV, 2018) Catalina Fuentes; Hisfazilah Saari; Jaeyeong Choi; Seungho Lee; Malin Sjöö; Marie Wahlgren; Lars Nilsson
Chemical composition, antioxidant capacity and content of phenolic compounds in meals collected in hospitals in Bolivia and Sweden.
(National Institutes of Health, 2013) Leslie Tejeda; Magdalena Dębiec; Lars Nilsson; J. Mauricio Peñarrieta; Juan Alvarado
The objective of this study was to evaluate the proximal composition, as well as Total Antioxidant Capacity (TAC) and Total Phenols (TPH) in meals that represent a complex food matrix, from different hospitals in Bolivia and Sweden. Protein, fat, ash, dietary fiber and carbohydrate contents were measured in 29 samples: 20 from two Bolivian hospitals and 9 from the university hospital in Lund, Sweden. The antioxidant capacity was measured by three spectrophotometric methods: the ferric reducing antioxidant power (FRAP) method, the 2, 2'- azinobis-3-ethylbenzotiazoline-6-sulfonic acid (ABTS) method and Total Phenolic Compounds (TPH) using the Folin-Ciocalteu reagent. The results show that fat, protein, carbohydrate and dietary fiber in Bolivian and Swedish hospital meals are following internationally established recommendations. Regarding the main courses, TPH contents in both countries were in the same range. However, TAC and dietary fiber content were higher in Swedish meals than in Bolivian meals and the TAC was far lower, in both cases, in comparison with the value obtained from individual food items reported from literature. The results show that antioxidant levels can be easily overestimated by considering only individual uncooked ingredients. An interesting consideration is, the fiber content in the meals, which can be an important source of antioxidants and non-extractable phenolic compounds.
Co-elution effects can influence molar mass determination of large macromolecules with asymmetric flow field-flow fractionation coupled to multiangle light scattering
(Elsevier BV, 2017) Daysi Perez‐Rea; Claudia Zielke; Lars Nilsson
Co-elution phenomena in polymer mixtures studied by asymmetric flow field-flow fractionation
(Elsevier BV, 2017) Claudia Zielke; Catalina Fuentes; Lennart Piculell; Lars Nilsson
Comparison between conventional and frit-inlet channels in separation of biopolymers by asymmetric flow field-flow fractionation
(Royal Society of Chemistry, 2019) Catalina Fuentes; Jaeyeong Choi; Claudia Zielke; J. Mauricio Peñarrieta; Seungho Lee; Lars Nilsson
Asymmetric flow field-flow fractionation (AF4) is a separation technique in which a focusing/relaxation step is used after the sample is injected onto the separation channel. During the focusing/relaxation step, the sample is focused by two counter-directed flows. This allows sample components to establish a diffusion-dependent equilibrium concentration profile. The focusing step may, in some cases, cause a loss of sample due to adsorption into the accumulation wall (i.e. the membrane) or due to aggregation of the sample. In addition, the increase in sample concentration during the focusing step may prevent complete relaxation and cause overloading effects. In this study, a modified AF4 channel equipped with a frit inlet (FI-AF4) is utilized, where the sample is relaxed hydrodynamically as it enters to the channel through the frit. The main advantage of the FI-AF4 channel is to omit the focusing step. The FI-AF4 channel could also allow higher injection mass than in a conventional channel while still avoiding overloading. The purpose of the present study is to compare two channels (conventional and FI-AF4 channels) in terms of the plate height (H), resolution (Rs) and the mass recovery for analysis of a mixture of glycogen and pullulan. In addition, waxy maize (WM) starch was used to compare the mass overloading of the two channels. The results show that the type of relaxation method (i.e. focusing or hydrodynamic relaxation) had no significant effect on mass recovery. The resolution (Rs), was higher in the conventional AF4 channel than in the FI-AF4 channel for the separation of glycogen and pullulan. The results also show that it was possible to inject a higher mass of WM starch (i.e. twice the mass) onto the FI-AF4 channel, compared to a conventional AF4 channel, without observing an overloading effect.
Comparison of molecular and emulsifying properties of gum arabic and mesquite gum using asymmetrical flow field-flow fractionation
(Elsevier BV, 2011) Johan Alftrén; J. Mauricio Peñarrieta; Björn Bergenståhl; Lars Nilsson
Development and evaluation of methods for starch dissolution using asymmetrical flow field-flow fractionation. Part II: Dissolution of amylose
(Springer Science+Business Media, 2015) Daysi Perez‐Rea; Björn Bergenståhl; Lars Nilsson
Enzymatic hydrolysis of Canna indica, Manihot esculenta and Xanthosoma sagittifolium native starches below the gelatinization temperature
(Wiley, 2012) Daysi Perez‐Rea; Cinthia Carola Rojas; Sergio Carballo; Wilson Aguilar; Björn Bergenståhl; Lars Nilsson
Abstract The susceptibility to enzymatic hydrolysis of starch extracted from raw roots of Canna indica , Manihot esculenta and Xanthosoma sagittifolium , grown in Bolivia, were studied below the gelatinization temperature. The granule size and amylose content were as followed: C. indica > M. esculenta > X. sagittifolium . The hydrolysis showed a rapid rate at the initial stage, followed by a progressive decrease thereafter. At 30, 40 and 50°C, during the initial stage, the rate of hydrolysis was observed to be influenced by the size of the granules, being the highest for the small sized granules X. sagittifolium , followed by the medium sized granules M. esculenta and the lowest rate was for the large sized granules C. indica starch. During the slow phase, A‐type M. esculenta and B‐type C. indica showed higher hydrolysis rates than A‐type X. sagittifolium . At 60°C, a positive correlation was found between the amylose content and the rate of hydrolysis among the starches. Microscopic observations showed a pattern of attack by the enzyme towards C. indica starch granules, suggesting that high amylose content is concentrated around the hilum.
Erratum to: Development and evaluation of methods for starch dissolution using asymmetrical flow field-flow fractionation. Part II: dissolution of amylose
(Springer Science+Business Media, 2015) Daysi Perez‐Rea; Björn Bergenståhl; Lars Nilsson
Evaluation of copper content in beers obtained from retail in Sweden
(Academic Journals, 2017) Daniel E. Osorio-Macías; Mauricio Peñarrieta J.; Lars Nilsson
A quantitative study of copper (Cu) content in 19 different beer brands produced in mainly European countries and consumed in Sweden were measured using atomic absorption spectrophotometer without sample digestion. Results showed that the Cu content in beers is below the permissible levels concentrations for potable drinking water recommended by World Health Organization. In addition, the studies indicated that there is no correlation between the amount of Cu content in beers and their respective hops Cu content.   Key words: Atomic absorption, beer, copper, hops.
First Evidence of Acyl-Hydrolase/Lipase Activity From Human Probiotic Bacteria: Lactobacillus rhamnosus GG and Bifidobacterium longum NCC 2705
(Frontiers Media, 2020) Panagiotis Manasian; Atma‐Sol Bustos; Björn Pålsson; Andréas Håkansson; J. Mauricio Peñarrieta; Lars Nilsson; Javier A. Linares‐Pastén
Lactobacillus rhamnosus GG (ATCC 53103) and Bifidobacterium longum NCC 2705 are among the most studied probiotics. However, the first evidence of acyl hydrolase/lipase of two annotated proteins, one in each genome of these strains, is reported in this work. Signal peptide analysis has predicted that these proteins are exported to the extracellular medium. Both proteins were produced in Escherichia coli, purified and characterized. Molecular masses (without signal peptides) were 27 and 52.3 kDa for the proteins of L. rhamnosus and B. longum, respectively. Asymmetrical flow field-flow fractionation analysis has shown that both proteins are present as monomers in their native forms at pH 7. Both have shown enzymatic activity on pNP-laurate at pH 7 and 37°C. The enzyme from L. rhamnosus was characterized deeper, showing preference on pNP-esters with short chain fatty acids. In addition, a computational model of the 3D structure has allowed the prediction of the catalytic amino acids. The enzymatic activities using synthetic substrates were very low for both enzymes. The investigation of natural substrates and biological functions of these enzymes is still open.
Fractionation and characterization of starch granules using field-flow fractionation (FFF) and differential scanning calorimetry (DSC)
(Springer Science+Business Media, 2019) Catalina Fuentes; In Byeong Kang; Jangjae Lee; Dongsup Song; Malin Sjöö; Jaeyeong Choi; Seungho Lee; Lars Nilsson
Starch is one of the main carbohydrates in food; it is formed by two polysaccharides: amylose and amylopectin. The granule size of starch varies with different botanical origins and ranges from less than 1 μm to more than 100 μm. Some physicochemical and functional properties vary with the size of the granule, which makes it of great interest to find an efficient and accurate size-based separation method. In this study, the full-feed depletion mode of split-flow thin cell fractionation (FFD-SF) was employed for a size-based fractionation of two types of starch granules (corn and potato) on a large scale. The fractionation efficiency (FE) of fraction-a for corn and potato granules was 98.4 and 99.4%, respectively. The FFD-SF fractions were analyzed using optical microscopy (OM) and gravitational field-flow fractionation (GrFFF). The respective size distribution results were in close agreement for the corn starch fractions, while they were slightly different for the potato starch fractions. The thermal properties of FFD-SF fractions were analyzed, and the results for the potato starch showed that the peak temperature of gelatinization (Tp) slightly decreases as the size of the granules increases. Additionally, the enthalpy of gelatinization (ΔH) increases when the granule size increases and shows negative correlation with the gelatinization range (ΔT).
Fractionation of Nanoparticle Matter in Red Wines Using Asymmetrical Flow Field-Flow Fractionation
(American Chemical Society, 2020) Daniel E. Osorio-Macías; Dongsup Song; Johan Thuvander; Raúl Ferrer‐Gallego; Jaeyeong Choi; J. Mauricio Peñarrieta; Lars Nilsson; Seungho Lee; Björn Bergenståhl
The particle matter of wine is mainly composed of wine colloids and macromolecules. The present work develops a methodology using asymmetrical flow field-flow fractionation coupled with multi-angle light scattering, differential refractive index detector, and ultraviolet detector (AsFlFFF-MALS-dRI-UV) for the fractionation and determination of the molar mass, the hydrodynamic radius, and the apparent densities of the aggregates and macromolecules present in wine samples. The results from a set of six Argentinian high-altitude wines showed two main populations: the first population composed of wine colloids with higher UV-specific absorptivity and the second population composed of polysaccharides, such as arabinogalactans. The conformation results showed that population 1 consists of small and dense particles, while population 2 showed high molar masses and lower densities. The results demonstrated the use of AsFlFFF as a new, effective method for the fractionation and characterization of wine colloids and wine macromolecules in red wines with further potential applications.
Interaction between Myricetin Aggregates and Lipase under Simplified Intestinal Conditions
(Multidisciplinary Digital Publishing Institute, 2020) Atma‐Sol Bustos; Andréas Håkansson; Javier A. Linares‐Pastén; Lars Nilsson
Myricetin, a flavonoid found in the plant kingdom, has previously been identified as a food molecule with beneficial effects against obesity. This property has been related with its potential to inhibit lipase, the enzyme responsible for fat digestion. In this study, we investigate the interaction between myricetin and lipase under simplified intestinal conditions from a colloidal point of view. The results show that myricetin form aggregates in aqueous medium and under simplified intestinal condition, where it was found that lipase is in its monomeric form. Although lipase inhibition by myricetin at a molecular level has been reported previously, the results of this study suggest that myricetin aggregates inhibit lipase by a sequestering mechanism as well. The size of these aggregates was determined to be in the range of a few nm to >200 nm.
Interaction between myricetin aggregates and lipase under simplified intestinal conditions
(2019) Atma‐Sol Bustos; Andréas Håkansson; Javier A. Linares‐Pastén; Lars Nilsson
Abstract Myricetin, a flavonoid found in the plant kingdom, has previously been identified as a food molecule with beneficial effects against obesity. This property has been related with its potential to inhibit lipase, the enzyme responsible of fat digestion. In this study we investigate the interaction between myricetin and lipase under simplified intestinal conditions from a colloidal point of view. The results show that myricetin form aggregates in aqueous medium and under simplified intestinal condition, where it was found that lipase is in its monomeric form. Although lipase inhibition by myricetin at a molecular level has been reported previously, the results of this study suggest that myricetin aggregates inhibit lipase by a sequestering mechanism as well. The size of these aggregates was determined to be in the range of a few nm to >200 nm.
Interaction Between Phenolic Compounds and Lipase: The Influence of Solubility and Presence of Particles in the IC 50 Value
(Wiley, 2018) Atma‐Sol Bustos; Andréas Håkansson; Javier A. Linares‐Pastén; J. Mauricio Peñarrieta; Lars Nilsson
Obesity is one of the principal human health problems and one of the main treatments against it is the inhibition of pancreatic lipase, the main responsible enzyme of lipid digestion. For that purpose, previous studies have tested several phenolic compounds against lipase, without considering their aggregation behavior in aqueous solutions. Because of this, the present study focuses on understanding how the solubility and the presence of particles affect the IC50 value of the interaction between lipase and phenolic compounds present in beverages like fruit juices and teas. Therefore, the inhibitory capacity against pancreatic lipase and the aggregate formation of 9 phenolic compounds (quercetin, rutin, myricetin, catechin, epigallocatechin gallate, cyanidin, caffeic acid, chlorogenic acid, and vanillic acid) were analyzed. The results obtained together with the solubility data from literature were treated by principal component analysis and indicate that the IC50 value does not correlate with the solubility or aggregate formation of the phenolic compounds. However, the IC50 values of phenolic compounds which aggregate during the assay conditions have low reproducibility. This study shows that the aggregate formation of phenolic compounds plays an important role during in vitro assays for pancreatic lipase inhibition and should be considered in future experiments as it can lead to false positive results. In terms of particle formation, the flavonoids investigated in this study are more prone to aggregation compared to the phenolic acids.
Interaction of Quercetin and Epigallocatechin Gallate (EGCG) Aggregates with Pancreatic Lipase Under Simplified Intestinal Conditions
(2019) Atma‐Sol Bustos; Andréas Håkansson; Javier A. Linares‐Pastén; J. Mauricio Peñarrieta; Lars Nilsson
Abstract Diets rich in flavonoids have been related with low obesity rates, which could be related with their potential to inhibit pancreatic lipase, the main enzyme of fat assimilation. Some flavonoids can aggregate in aqueous medium suggesting that the inhibition mechanism could occur on both molecular and colloidal levels. This study investigates the interaction of two flavonoid aggregates, quercetin and epigallocatechin gallate (EGCG), with pancreatic lipase under simplified intestinal conditions. The stability and the morphology of these flavonoid aggregates were studied in four different solutions: Control (water), salt, low lipase concentration and high lipase concentration. Particles were found by optical microscopy in almost all the solutions tested, except EGCG-control. The results show that the precipitation rate decreases for quercetin and increases for EGCG in salt solution and that lipase stabilize quercetin aggregates. In addition, both flavonoids were shown to precipitate together with pancreatic lipase resulting in a sequestering of the enzyme.