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Polymer-Solvent Interactions in Modified Starches Pastes–Electrokinetic, Dynamic Light Scattering, Rheological and Low Field Nuclear Magnetic Resonance Approach
Starch paste is a very complex dispersion that cannot be clearly classified as a solution, colloid or suspension and many factors affects its properties. As these ambiguities constitute a barrier to technological development, the aim of this study was to investigate the interaction of starch macromolecules with water by analysing the results of rheological properties, low field nuclear magnetic resonance (LF NMR), dynamic light scattering (DLS) and ζ potential analyses. Starch pastes with a concentration of 1%, prepared with distilled water and buffered to pH values of 2.5, 7.0 and 9.5 were analysed. It was proved that the pH buffering substantially decreased the values of consistency index but the pH value itself was not significant. LF NMR studies indicated that the dissolution of starch in water resulted in a reduction in spin-lattice as well as spin-spin relaxation times. Moreover, changes in relaxation times followed the patterns observed in rheological studies. Electrokinetic and DLS analyses showed that potential values are primarily influenced by the properties of the starches themselves and, to a lesser extent, by the environmental conditions. The conducted research also showed complementarity and, to some extent, substitutability of the applied research methods as well as exclusion chromatography (a method not used in this work).
Effects of Heat Treatment Duration on the Electrical Properties, Texture and Color of Polymerized Whey Protein
In this research effects of heat treatment duration on the electrical properties (zeta potential and conductivity), texture and color of polymerized whey protein (PWP) were analyzed. Whey protein solutions were heated for 30 min to obtain single-heated polymerized whey protein (SPWP). After cooling to room temperature, the process was repeated to obtain double-heated polymerized whey protein (DPWP). The largest agglomeration was demonstrated after 10 min of single-heating (zeta potential recorded as −13.3 mV). Single-heating decreased conductivity by 68% and the next heating cycle by 54%. As the heating time increased, there was a significant increase in the firmness of the heated solutions. Zeta potential of the polymerized whey protein correlated with firmness, consistency, and index of viscosity, the latter of which was higher when the zeta potential (r = 0.544) and particle size (r = 0.567) increased. However, there was no correlation between zeta potential and color. This research has implications for future use of PWP in the dairy industry to improve the syneretic, textural, and sensory properties of dairy products.
Wpływ koloidów asocjacyjnych na aktywność antyoksydacyjną natywnych zwiazków fenolowych i stabilność oksydatywną oleju rzepakowego i sojowego
Effect of different oligomerization assemblies of γ-conglutin on its interaction behavior with vitexin
AbstractBACKGROUNDSeveral different factors underlie the molecular mechanisms of phenolic compound‐protein interactions. They include the environmental conditions. In the case of γ‐conglutin, pH conditions translate directly into the adoption of two distinct oligomeric assemblies, i.e. hexameric (pH 7.5) or monomeric (pH 4.5). This paper reports research on the pH‐dependent oligomerization of γ‐conglutin in terms of its ability to form complexes with a model flavonoid (vitexin).RESULTSFluorescence‐quenching thermodynamic measurements indicate that hydrogen bonds, electrostatic forces, and van der Waals interactions are the main driving forces involved in the complex formation. The interaction turned out to be a spontaneous and exothermic process. Assessment of structural composition (secondary structure changes and arrangement/dynamics of aromatic amino acids), molecular size, and the thermal stability of the different oligomeric forms showed that γ‐conglutin in a monomeric state was less affected by vitexin during the interaction.CONCLUSIONThe data show precisely how environmental conditions might influence phenolic compound‐protein complex formation directly. This knowledge is essential for the preparation of food products containing γ‐conglutin. The results can contribute to a better understanding of the detailed fate of this unique health‐promoting lupin seed protein after its intake. © 2023 Society of Chemical Industry.
Heat-induced changes in lupin seed γ-conglutin structure promote its interaction with model phospholipid membranes
Analysis of phytosterols encapsulated in pegylated liposomes
Abstract Dipalmitoylphosphatidylcholine (DPPC) lipids were encapsulated in PEGylated liposomes with free stigmasterol (ST), stigmasterol myristate (ME), and stigmasterol oleate (OE). Their quality was assessed using TEM, zeta potential, and hydrodynamic diameter measurements. The liposomes were heated to 60 °C and 180 °C. The degradation of stigmasterol and fatty acids was considered, as was derivative formation. The results show that the liposomes fulfilled their intended function. The ST liposomes were smallest, while the ME liposomes were similar in size to the OE liposomes. The degree of degradation of the compounds encapsulated in the liposomes depended on their structure. After heating the samples to 60 °C, the extent of stigmasterol degradation ranged from 3.5% in ST to 4.3% in ME and 6.5% in OE. After heating to 180 °C, the lowest level of stigmasterol degradation was observed for OE (7.3%), while degradation in ST and ME reached 13.4% and 10.1%, respectively. The high level of oxyphytosterols in all samples heated to 180 °C raised concerns. The oxyphytosterol (SOP) content of the liposomes heated to 60 °C ranged from 23.2 mg/g in those with free stigmasterol to 6.3 mg/g and 6.4 mg/g in the liposomes with stigmasterol myristate and stigmasterol oleate, respectively. After heating to 180 °C, the total SOP content was significantly higher, ranging from 88.7 mg/g for OE to 7.4 and 29.6 mg/g for ME and ST, respectively.
Interactions of Oleanolic Acid, Apigenin, Rutin, Resveratrol and Ferulic Acid with Phosphatidylcholine Lipid Membranes - A Spectroscopic and Machine Learning Study
Biologically active compounds present in the diet can interact with biological membranes (such as cell membranes), changing their properties. Their mutual interactions can influence their respective activities. In this study, we analyzed the interactions of oleanolic acid and phenolic compounds such as apigenin, rutin, resveratrol and ferulic acid with phosphatidylcholine membranes. Spectroscopic methods (fluorescence spectroscopy, dynamic light scattering) and machine learning were applied. The results of structural studies were compared with the antioxidant activity of the investigated substances in lipid membranes. In liposomes loaded with oleanolic acid, the pro-oxidant activity of resveratrol arises from changes in membrane structure, leading to an increased exposure of its hydrophilic region to external radicals. A similar mechanism may be involved in the pro-oxidant action of oleanolic acid. By contrast, apigenin, rutin and ferulic acid are present at the membrane surface. Their presence in this region protects the bilayer from radicals generated in the aqueous phase. Lower antioxidant activity observed in the case of ferulic aid is probably related to weaker interactions of this compound with the membrane, compared to the investigated flavonoids. Appropriate machine learning models for predicting oleanolic acid and phenolic compounds have been developed for the future application of intelligent predictive systems to optimizing manufacturing processes involving liposomes. The most effective regression model turned out to be the MLP 1:1-100-50-50-6:1, identifying resveratrol with a determination index of 0.83.
Stigmasterol and its esters encapsulated in liposomes: Characterization, stability, and derivative formation
Water content, critical micelle concentration of phospholipids and formation of association colloids as factors influencing autoxidation of rapeseed oil
AbstractBACKGROUNDThe exact mechanism of lipid autoxidation in vegetable oils, taking into account physical aspects of this phenomenon, including the role of association colloids, is still not fully understood. The purpose of this study was to consider changes in moisture content and DOPC phospholipid (1,2‐dioleoyl‐sn‐glycero‐3‐phosphocholine) critical micelle concentration (CMC) in rapeseed oil during autoxidation as well as to find the relationship between these parameters and the accumulation of primary and secondary lipid oxidation products.RESULTSThe experiments were performed at initial oil humidity 220 ppm and 700 ppm, with DOPC below and above CMC. The increase in water concentration was favored by the presence of phospholipids above CMC and, at the same time, high initial water level, which favored oxidation processes and the creation of amphiphilic autoxidation products. At relatively high water level and low amphiphilic DOPC concentration, the growth of water content does not affect the concentration of oxidation products.CONCLUSIONAmphiphilic substances play a significant role in increasing the water content of oil. Autoxidation products may reduce CMC of DOPC, but water is able to compensate for the CMC‐reducing effect of oxidation products. The presence of association colloids and initial water content play a crucial role in the oxidation process of rapeseed oil. The increase in water concentration does not cause a sufficiently large increase in the number of micelles or sufficiently significant changes in their structure to effect an increase in the level of oxidation products. The formation of micelles requires an appropriate content of both water and amphiphilic substances derived from seeds (phospholipids). © 2021 Society of Chemical Industry.
Effect of Antisolvent Used to Regenerate Cellulose Treated with Ionic Liquid on Its Properties
The solvolysis reaction with ionic liquids is one of the most frequently used methods for producing nanometer-sized cellulose. In this study, the nanocellulose was obtained by reacting microcrystalline cellulose with 1-ethyl-3-methylimidazolium acetate (EmimOAc). The aim of this research was to determine the influence of various antisolvents used in the regeneration of cellulose after treatment with ionic liquid on its properties. The following antisolvents were used in this research: acetone, acetonitrile, water, ethanol and a mixture of acetone and water in a 1:1 v/v ratio. The nanocellulose was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), dynamic light scattering (DLS), scanning electron microscopy (SEM) and elemental analysis (EA). The results show that the antisolvent used to regenerate cellulose after the solvolysis reaction with EmimOAc affects its properties. Water, ethanol and a mixture of acetone and water successfully removed the used ionic liquid from the cellulose structure, while acetone and acetonitrile were unable to completely remove EmimOAc from the cellulosic material. The results of the XRD analysis indicate that there is a correlation between the ionic liquid content in the regenerated cellulose and its degree of crystallinity. Among the tested solvents, water leads to the effective removal of EmimOAc from the cellulose structure, which is additionally characterized by the smallest particle size and non-formation of agglomerates.
Hop (Humulus lupulus L.) Phenolic Compounds Profile Depends on Cultivar and Plant Organ Maturity
Hop by-products constitute a significant part of biomass in cones production for the brewing industry. The phenolic compounds (PCs) they contain can be used in the food and pharmaceutical industries but require qualitative and quantitative analysis. The aim of this study was to investigate the extent to which phenolic compounds profiles depend on cultivar, plant organ, and plant level. This paper shows for the first time that for hop, it is not only the plant organ that is important for PC content, but also the level from which it is obtained. Metabolites were investigated in cones, leaves, and stalks at three levels of the plant in Polish hop cultivars (Marynka, Lubelski, and Magnum). The PC content showed a differentiation due to the cultivar of hops, their anatomical part, and position in the plant (level), which reflects the degree of organ maturity. The total PC was the highest in leaves (up to 922 mg/100 g), while lower contents were found in cones (up to 421 mg/100 g) and stalks (up to 105 mg/100 g). The main PCs of leaves were kaempferol-3-glucoside (up to 328 mg/100 g) and rutin (up to 293 mg/100 g), while rutin dominated in cones (up to 209 mg/100 g).