Carbohydrate Matrices Research Articles

The Influence of Oligosaccharides when Measuring Lactose and Total Carbohydrates in Human Milk and Comparison of Methods

BackgroundUnderstanding how human milk impacts growth requires valid analytical methods for quantifying the composition. Lactose, the most abundant constituent in human milk and a predominant source of energy, is often assessed using methods borrowed from the bovine dairy industry. However, the carbohydrate matrices of bovine and human milk are quite different, especially as they relate to human milk oligosaccharides (HMOs), each with a terminal lactose unit that may influence analytical methods. ObjectivesOur goals were to determine the extent to which HMOs influence common analytical methods for measuring carbohydrates in human milk and to compare common methods for measuring lactose. MethodsTwo sets of experiments were performed. In the first set, native and HMO-spiked human milk samples (n = 16 each) were assessed and compared using 4 methods: AOAC 2006.06 (based on the Megazyme enzymatic assay), BioVision enzymatic assay, ultraperformance LC with MS, and infrared analysis. In the second set, human milk samples (n = 20) were assessed using 2 methods approved for measuring lactose in bovine milk: AOAC 984.22 that uses high-performance LC and refractive index detection and AOAC 2006.06 prepared using both volume and weighted dilutions. ResultsNative and HMO-spiked samples were not significantly different in lactose using AOAC 2006.06 and ultraperformance LC with MS but were significantly different using BioVision (mean difference = 0.2 g/dL; 95% CI: 0.1, 0.4; P = 0.005). Total carbohydrate measurements assessed using infrared were also higher after HMO spiking (mean difference = 0.4 g/dL; 95% CI: 0.3, 0.6; P < 0.001). Only AOAC methods 984.22 and 2006.06 for measuring lactose were very highly correlated (r > 0.90, P < 0.001). ConclusionsAOAC methods 984.22 and 2006.06 are comparable for measuring lactose in human milk and are not influenced by HMOs. HMOs influence other enzymatic methods as well as infrared analysis, which leads to an overestimate of energy values. J Nutr 2023;x:xx.

Effect of temperature shocks on the caking of moisture-sensitive amorphous powders

Caking in amorphous powders is frequently caused by sintering at particle contacts. The molecular mobility and hence viscosity at these contacts depends delicately on temperature and concentration of plasticizers and specifically for carbohydrate matrices, water is a very effective plasticizer. In scenarios with rapid temperature changes, drying at particle surfaces reduces plasticization whereas it is promoted by the elevated temperature itself. In this paper, we combine particle-based simulations, experiments, and a percolation analysis to study the effect of sudden temperature rise on the caking of amorphous food powders. We show how and when a sudden change in temperature may lead to rapid percolation and hence powder caking, where caking time depends not only on the matrix properties, but also strongly on the particle size distribution. • Caking of amorphous powders is studied using a particle-based model. • An abrupt temperature increase changes the humidity and viscosity of the particles. • Particle sintering is affected by competing particle drying and bridge formation. • The phase plot of the caking time agrees qualitatively with experiments.

Green synthesis and chemometric characterization of hydrophobic xanthan matrices: Interactions with phenolic compounds

Polysaccharides such as xanthan, locust bean gum or chitosan are easily crosslinked and purified using citric acid in an ecofriendly process. In order to achieve an improved sorption capability towards hydrophobic solutes, β-cyclodextrin, a cyclic oligosaccharide, and lignin, a natural aromatic polymer, are incorporated in the same process. Once crosslinked, the influence of these on the sorption capacities towards model solutes has been assessed by comparing the sorption isotherms of matrices with or without the hydrophobic modifications. The sorption capacities of these materials for different phenolic compounds have also been tested to ascertain their efficiencies as a function of their affinities to β-cyclodextrin cavities and/or their partition coefficients. In addition, these functionalized carbohydrate matrices were successfully characterized by principal component analysis, which is a useful tool to select the most appropriate polymers to interact with a specific molecule.

Association of antioxidant monophenolic compounds with β-cyclodextrin-functionalized cellulose and starch substrates

Polysaccharide substrates loaded with antioxidant and antimicrobial compounds, effectively protected by cyclodextrin moieties, can be a long-lasting solution to confer certain properties to fabrics, paper and other materials. β-Cyclodextrin was attached to α-cellulose, bleached pulp and starch by a two-step esterification with a tetracarboxylic acid. The resulting derivatives were characterized by spectroscopy, thermal degradation analysis and capability of phenolphthalein inclusion. The carriers, containing between 89 and 171 μmol of β-cyclodextrin per gram, were loaded with carvacrol, cuminaldehyde, cinnamaldehyde and hydroxytyrosol. From a stoichiometric addition, the percentage of compound retained ranged from 49% (hydroxytyrosol in pulp–cyclodextrin) to 92% (carvacrol in starch–cyclodextrin). Finally, the release rate to aqueous ethanol was measured over eight days and fitted to kinetic models. From the analysis of the mean dissolution time, it can be concluded that inserting β-cyclodextrin units enhanced the long-term holding of phenolic active compounds in carbohydrate matrices.

Encapsulation of the Natural Product Tyrosol in Carbohydrate Nanosystems and Study of Their Binding with ctDNA

Tyrosol, a natural product present in olive oil and white wine, possesses a wide range of bioactivity. The aim of this study was to optimize the preparation of nanosystems encapsulating tyrosol in carbohydrate matrices and the investigation of their ability to bind with DNA. The first encapsulation matrix of choice was chitosan using the ionic gelation method. The second matrix was β-cyclodextrin (βCD) using the kneading method. Coating of the tyrosol-βCD ICs with chitosan resulted in a third nanosystem with very interesting properties. Optimal preparation parameters of each nanosystem were obtained through two three-factor, three-level Box-Behnken experimental designs and statistical analysis of the results. Thereafter, the nanoparticles were evaluated for their physical and thermal characteristics using several techniques (DLS, NMR, FT-IR, DSC, TGA). The study was completed with the investigation of the impact of the encapsulation on the ability of tyrosol to bind to calf thymus DNA. The results revealed that tyrosol and all the studied systems bind to the minor groove of ctDNA. Tyrosol interacts with ctDNA via hydrogen bond formation, as predicted via molecular modeling studies and corroborated by the experiments. The tyrosol-chitosan nanosystem does not show any binding to ctDNA whereas the βCD inclusion complex shows analogous interaction with that of free tyrosol.

Synthesis, properties and applications of self‐repairing carbohydrates as smart materials via thermally reversible DA bonds

Self‐healing carbohydrate polymers were synthesized by Diels‐Alder reaction. Intermediate products and the carbohydrate matrices were characterized by Fourier transform infrared spectroscopy (FT‐IR) and 1H NMR, while the thermally reversible properties were assessed by FT‐IR and differential scanning calorimetry. The mechanical properties, water absorption, and enzymatic degradation of starch/PVA/modified carbohydrate films were examined, as well as the relationship of the properties to the DA and rDA reactions. These results showed that DA bonds were introduced into the carbohydrate polymers successfully and endow the material with self‐healing thermal recyclability. The mixed films exhibited alternating strong and weak mechanical properties upon cycling through the DA and rDA reactions. Water absorption was limited and the films demonstrated good water resistance. The status of the DA bonds was found not to affect the enzymatic degradation rates of the various carbohydrate films.

Use of sulfated cellulose membrane adsorbers for chromatographic purification of cell cultured-derived influenza A and B viruses

Influenza virus particles can be purified by pseudo-affinity chromatography using sulfated carbohydrate matrices. In this study, we compared the binding capacity and the purification performance of two bead-based resins and one membrane adsorber for three influenza virus strains (H1N1, H3N2 and B) produced in MDCK suspension cells in a chemically defined medium. The dynamic binding capacity for the sulfated cellulose membrane adsorbers was consistently higher than for the resins (8 to 22-fold). Confocal microscopy demonstrated, that while virus particles uniformly covered the complete surface of the membrane, the virus particles only bound to the external surface of the sulfated beads. Overall, recovery of virus varied between 66% and 81%. Total protein and DNA removal were >74% and >96%, respectively. Statistically significant differences in the purification performance were more often observed between strains than between matrices. In particular, H3N2 influenza virus particles could only be purified using the sulfated membrane adsorbers. Due to the higher operating flow rate and binding capacity, the productivity with the membrane adsorbers was on average 25-times higher than with the resins.

Water Diffusion in the Semi-Liquid State during Industrial Candy Preparation

In the domain of production of flavor delivery systems based on carbohydrate matrices, Hot Melt Extrusion (HME) is one of the processes used which implies a relatively slow water evaporation step compared to Spray Drying or other common processes. The HME process of generating liquid syrup is stable only at industrial scales. The drying kinetic associated to the syrup formation is followed by collecting the vapored water. This experiment is exploited to estimate the diffusion coefficient of liquid water in a continuously concentrating carbohydrate melt ranging from 30.4 to 10.2%w/w water content and at temperatures ranging from 100 to 116 °C. A combination of Fick, Arnold and Vogel-Tammann-Fulcher models was used to derive the viscosity of the solution, the gradient thickness at the surface of the stirred solution and the diffusion coefficient of water in the liquid under boiling conditions. It is here demonstrated that under continuous boiling conditions, the water concentration gradient depth from the surface of the solution has a dimension that is comparable to the size of the hydrated carbohydrate molecules and the diffusion coefficient of water in boiling carbohydrate solutions ranges from 5.10−9 cm.s−2 for low temperature and high water content to 10−11 cm.s−2 for high temperature and low water content.

Novel ionic liquid matrices for qualitative and quantitative detection of carbohydrates by matrix assisted laser desorption/ionization mass spectrometry

Analysis of carbohydrates based on matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is still challenging and researchers have been devoting themselves to efficient matrices discovery. In the present study, the design, synthesis, qualitative and quantitative performance of non-derivative ionic liquid matrices (ILMs) were reported. DHB/N-methylaniline (N-MA) and DHB/N-ethylaniline (N-EA), performing best for carbohydrate detection, have been screened out. The limit of detection for oligosaccharide provided by DHB/N-MA and DHB/N-EA were as low as 10 fmol. DHB/N-MA and DHB/N-EA showed significantly higher ion generation efficiency than DHB. The comparison of capacity to probe polysaccharide between these two ILMs and DHB also revealed their powerful potential. Their outstanding performance were probably due to lower proton affinities and stronger UV absorption at λ = 355 nm. What is more, taking DHB/N-MA as an example, quantitative analysis of fructo-oligosaccharide mixtures extracted and identified from rice noodles has been accomplished sensitively using an internal standard method. Overall, DHB/N-MA and DHB/N-EA exhibited excellent performance and might be significant sources as the carbohydrate matrices.

Effect of the glass transition temperature on alpha-amylase activity in a starch matrix

This study optimises a protocol for the estimation of α-amylase activity in a condensed starch matrix in the vicinity of the glass transition region. Enzymatic activity on the vitrified starch system was compared with that of a reference substrate, maltodextrin. The activity was assayed as the rate of release of reducing sugar using a dinitrosalicylic acid procedure. The condensed carbohydrate matrices served the dual purpose of acting as a substrate as well as producing a pronounced effect on the ability to enzymatic hydrolysis. Activation energies were estimated throughout the glass transition region of condensed carbohydrate preparations based on the concept of the spectroscopic shift factor. Results were used to demonstrate a considerable moderation by the mechanical glass transition temperature, beyond the expected linear effect of the temperature dependence, on the reaction rate of starch hydrolysis by α-amylase in comparison with the low-molecular weight chain of maltodextrin.

Dynamics in Polysaccharide Glasses and Their Impact on the Stability of Encapsulated Flavors

The aim of this work is to examine the correlation between measured instability of model flavor compounds in glassy matrices with the calorimetric relaxation times of the matrices. Spray-dried carbohydrate matrices were chosen as the model compounds for this study. Enthalpy relaxation times were determined for spray-dried carbohydrate matrices using differential and isothermal calorimetric methods. The losses of the volatile methyl acetate, ethyl acetate and limonene, as well as formation of limonene oxidation products, were measured by gas chromatography. Storage conditions were 30 and 40 °C, with samples equilibrated with 11, 23, 33 and 43 % RH at each temperature. A comparison of the relaxation times for temperatures below Tg was made using Modulated DSC (MDSC) and a Thermal Activity Monitor (TAM). TAM yields significantly lower values for relaxation times implying that it is capturing some of the faster dynamics as well as dynamics that are activated near Tg. However, plots of relaxation times as determined by both techniques versus temperature appear to converge at Tg. An increase in the relative humidity results in moderately higher loss of volatiles (methyl acetate, ethyl acetate and limonene) and greater oxidation rates. In general, there is a good correlation between relaxation time and stability, with greater enthalpy relaxation time associated with better stability. Enthalpy relaxation time appears to be a useful predictor of stability for both loss of volatiles and oxidation of limonene.

Orange terpenes, carvacrol and α-tocopherol encapsulated in maltodextrin and sucrose matrices via batch mixing

Orange terpenes, carvacrol and tocopherol were used as model substances for flavours, essential oils and lipophilic liquid (bio)-active ingredients (AI). They were encapsulated via a batch mixing process in various carbohydrate matrices containing maltodextrin and sucrose. Plasticizing properties of the AIs, independently from their concentration (4.5–8.8%), on the matrices were not obtained. Furthermore the AIs did not affect the solid state properties, especially the crystalline content, of the carbohydrate matrix. An AI retention between 6% and 100% correlated inversely with the vapour pressure of the pure AI. At a mixing time of 5min a vapour pressure of higher than 70kPa led to a almost completely loss of the AI. The AI retention and the solid state of the matrices were not affected by applying different cooling conditions. These results can be used to adjust the parameters of an extrusion process to receive high AI retention.

Solid state of processed carbohydrate matrices from maltodextrin and sucrose

Various mixtures of maltodextrin, sucrose, and water, as typical compounds of food matrices used for flavour encapsulation via extrusion, were processed in a batch mixing process. Plasticization, melting and caramelization just as the formation of amorphous sucrose were studied. All matrices were plasticized within 2min, resulting in a loss of crystalline sucrose. Melting occurred due to water loss higher than 55%. Caramelization could be correlated to a specific mechanical energy input higher than 300Wh/kg. The glass transition temperature of the caramelized matrices could not be fitted with the Gordon Taylor equation, based on the used compounds. Increasing sucrose content in the preblended powder mixture combined with increasing sample water content increased the crystalline fraction within the matrix. These findings enable a systematically investigation of matrices for encapsulation of flavours within the batch mixing process, which can help to transfer the flavour encapsulation to an extrusion process.

Hydrogen bonding in maltooligomer–glycerol–water matrices: Relation to physical state and molecular free volume

We use Fourier Transform Infra Red (FTIR) Spectroscopy to explore the effects of water and glycerol on the hydrogen bonding of low water content maltooligomer matrices by monitoring the shifts in the position of the peak associated with the fundamental stretching vibration of the hydroxyl groups, νOH. Changes in hydrogen bonding are investigated in relation to the physical state and the molecular packing of the maltooligomer matrices, which are measured by Positron Annihilation Lifetime Spectroscopy (PALS). In the concentration range studied (0–20wt.%), glycerol acts as an anti-plasticizer whereby it reduces the average molecular hole size, vh, while modulating the hydrogen bond network of the carbohydrate matrices. Depending on the level of hydration, water can cause anti-plasticization or plasticization of the maltooligomer–glycerol matrices. For water contents below ∼5wt.%, water acts as an anti-plasticizer, whereby it reduces vh and we measure a reduction νOH. At higher water contents, water acts as a plasticizer, causing a systematic increase in vh, while νOH continues to decrease as a function of increasing water content.

Ethoximation-silylation approach for mono- and disaccharide analysis and characterization of their identification parameters by GC/MS

The qualitative and quantitative analysis of complex carbohydrate mixtures is a challenging problem. When tackled by GC/MS, close retention times and largely similar mass spectra with no specific features complicate unambiguous identification, especially of monosaccharides. An optimized pre-capillary ethoximation-silylation GC/MS method for determination of monosaccharides and disaccharides was applied to a wide range of analytes (46 compounds). The two-step derivatization resulted in a pair of syn and anti peaks with specific retention and intensity ratio. The resulting dataset of mass spectra was subjected to a PCA-based pattern recognition. An oxime peak identifier (OPI) of the carbohydrate analytes, based on the combination of an internal standard and the corresponding syn/anti peak ratios, increased the reliability of the identification of reducing carbohydrates. Finally, the introduced EtOx-TMS derivatization method was applied to four different carbohydrate matrices (agave sirup, maple sirup, palm sugar, and honey).

Structural and functional stabilization of phage particles in carbohydrate matrices for bacterial biosensing

Infections associated with health care services are nowadays widespread and, associated to the progressive emergence of microorganisms resistant to conventional chemical antibiotics, are major causes of morbidity and mortality. One of the most representative microorganisms in this scenario is the bacterium Pseudomonas aeruginosa, which alone is responsible for ca. 13–15% of all nosocomial infections. Bacteriophages have been reported as a potentially useful tool in the diagnosis of bacterial diseases, since they specifically recognize and lyse bacterial isolates thus confirming the presence of viable cells. In the present research effort, immobilization of these biological (although metabolically inert) entities was achieved via entrapment within (optimized) porous (bio)polymeric matrices of alginate and agar, aiming at their full structural and functional stabilization. Such phage-impregnated polymeric matrices are intended for future use as chromogenic hydrogels sensitive to color changes evolving from reaction with (released) intracytoplasmatic moieties, as a detection kit for P. aeruginosa cells.

Effect of a glassy gellan/polydextrose matrix on the activity of α-d-glucosidase

An investigation of the ability of the enzyme α-d-glucosidase to act on the substrate 4-nitrophenyl α-d-glucopyranoside (pNPG) while embedded in glassy carbohydrate matrices (deacylated gellan with polydextrose and polydextrose alone) is presented. Physicochemical characterisation of the matrices was achieved using the techniques of modulated differential scanning calorimetry, small deformation dynamic oscillation on shear, Fourier transform infra-red spectroscopy, wide angle X-ray diffraction and scanning electron microscopy. A UV–vis spectrophotometric procedure was adapted for the analysis of the activity of α-d-glucosidase in hydrolysing pNPG in the condensed carbohydrate systems. In order to derive a relationship between the structural properties of the matrix and the enzymatic activity, mechanical spectra were recorded using the combined framework of the Williams, Landel and Ferry equation with the time–temperature superposition principle. Theoretical modelling and experimental observations strongly argue for a pronounced effect of the gelling polysaccharide/co-solute mixture on enzymatic activity near the mechanical Tg of the matrix.

Both stereo-isomers of glucose enhance the survival rate of microencapsulated Lactobacillus rhamnosus GG during storage in the dry state

This study investigates the protective effects of a metabolizable and a non-metabolizable stereoisomer of glucose on encapsulated Lactobacillus rhamnosus GG (LGG) bacteria in the dry state. Separate experiments confirmed that the probiotic strain metabolizes only d-glucose. Encapsulated LGG formulations (2wt.% LGG, dry basis) were prepared by freeze drying a mixture of the freshly cultured bacteria within various whey protein–carbohydrate matrices. The encapsulant matrices used were (i) a 1:2 mixture of protein:maltodextrin, (ii) a 1:1:1 mixture of protein:maltodextrin:d-glucose and (iii) a 1:1:1 mixture of protein:maltodextrin:l-glucose. The partial substitution of maltodextrin with either d-glucose or l-glucose in the encapsulant matrix significantly enhanced the survival of LGG powders stored at a relative humidity of 33% RH and 25°C over 35days. In comparison, there was a protective effect afforded by partial substitution of maltodextrin with either stereoisomer of glucose during storage of LGG powders at relative humidity of 70% RH and 25°C over 7days only. However, on longer term storage at relative humidity of 70% RH and 25°C over 14–35days, the viability of LGG was similar for all formulations. The results suggest that the protection afforded to LGG by the incorporation of d-glucose or l-glucose in the encapsulant matrix was primarily due to the physico-chemical effect of the glucose molecules rather than d-glucose being a metabolizable sugar. These experiments allowed discrimination between the physico-chemical and nutritional roles of glucose on LGG viability.

Evaluation of different derivatisation approaches for gas chromatographic–mass spectrometric analysis of carbohydrates in complex matrices of biological and synthetic origin

Gas chromatographic analysis of complex carbohydrate mixtures requires highly effective and reliable derivatisation strategies for successful separation, identification, and quantitation of all constituents. Different single-step (per-trimethylsilylation, isopropylidenation) and two-step approaches (ethoximation–trimethylsilylation, ethoximation–trifluoroacetylation, benzoximation–trimethylsilylation, benzoximation–trifluoroacetylation) have been comprehensively studied with regard to chromatographic characteristics, informational value of mass spectra, ease of peak assignment, robustness toward matrix effects, and quantitation using a set of reference compounds that comprise eight monosaccharides (C5–C6), glycolaldehyde, and dihydroxyacetone. It has been shown that isopropylidenation and the two oximation-trifluoroacetylation approaches are least suitable for complex carbohydrate matrices. Whereas the former is limited to compounds that contain vicinal dihydroxy moieties in cis configuration, the latter two methods are sensitive to traces of trifluoroacetic acid which strongly supports decomposition of ketohexoses. It has been demonstrated for two “real” carbohydrate-rich matrices of biological and synthetic origin, respectively, that two-step ethoximation–trimethylsilylation is superior to other approaches due to the low number of peaks obtained per carbohydrate, good peak separation performance, structural information of mass spectra, low limits of detection and quantitation, minor relative standard deviations, and low sensitivity toward matrix effects.

Water sorption properties, molecular mobility and probiotic survival in freeze dried protein–carbohydrate matrices

The moisture uptake and molecular mobility of freeze-dried powders containing whey protein isolate-carbohydrate matrices (1WPI:2maltodextrin; 1WPI:1maltodextrin:1d-glucose; and 1WPI:1maltodextrin:1l-glucose) and encapsulated Lactobacillus rhamnosus GG (LGG) in these matrices were investigated at 25 °C and 33% and 70% relative humidity (RH). The inactivation rate constant for probiotics in freeze-dried matrices were positively correlated (R(2) = 0.98) to moisture uptake and molecular mobility measured by NMR relaxometry. The stability of probiotics in glassy protein-carbohydrate matrices was dependent on the composition of the matrix. The partial substitution of maltodextrin with glucose (d- or l-) which improved microbial survival at 33% RH was related to the reduced molecular mobility and lower water uptake of the matrix. This study suggests that moisture uptake properties and molecular mobility of the matrix composition, as opposed to the relative humidity of the environment, are better determinants of probiotic viability during storage. Dynamic vapour sorption and NMR relaxometry are promising tools to assist in the selection of protein-carbohydrate matrices for enhancing probiotic viability during storage.