Molecular Weight Distribution Research Articles

Polycondensation, cyclization and disproportionation of solid Poly(L-lactide) trifluoroethyl esters and the simultaneous formation of extended chain crystals and extended ring crystals

Two poly(L-lactide)s (PLAs) with a degree of polymerization (DP) of 20 or 100 were prepared by trifluoroethanol-initiated ring-opening polymerization (ROP) catalyzed by tin(II) 2-ethyl hexanoate (SnOct2). These PLAs were annealed at 140 °C or at 160 °C in the presence of SnOct2, and the changes in topology and molecular weight distribution (MWD) were monitored by matrix-assisted laser desorption/ionization time-of-flight (MALDI TOF) mass spectrometry and gel permeation chromatography (GPC). For the PLA with a DP 20, the main reaction was polycondensation combined with higher dispersities. In the case of the DP 100, PLA polycondensation was combined with disproportionation and the formation of a new MWD maximum around m/z 3500. In addition, extensive cyclization occurred, and the resulting cyclic PLAs crystallized separately from the linear chains in the form of extended ring crystals. These results also suggest that both extended chain and extended ring crystals posses the same crystal thickness as a result of thermodynamically controlled transesterification in the solid state.

Effect of extraction processes on the physicochemical and functional properties of protein-rich extracts from the red seaweed Pyropia Seriata (Nori)

This study examined the physicochemical and techno-functional properties of protein extracts from the red seaweed (Pyropia seriata). The extraction processes involved variations of some of the following steps: alkaline treatment, milling, freeze drying, neutralisation, heating, and concentration. The extracts had total amino acid contents ranging between 40 and 55 % of the powders with essential amino acids comprising 25–30 % of the powders. The extracts were particularly abundant in aspartic acid and limited in the essential sulphur amino acids. The molecular weight (MW) distribution of the proteins within the extracts ranged from <10 to 50 kDa. All the extracts were soluble, with a solubility of 65–100 % depending on the final pH of the solution. The extracts had significant foaming-producing and emulsifying potential. The foaming stability ranged between 75 and 91 % for solutions between pH 7 and 11 and less than 75 % for solutions with pH of 5 or 3. Alkaline treatment significantly improved foaming capacity (120–160 %). A similar effect was also observed for emulsifying activity (0.29–0.51) and emulsifying stability (15–40 %). Milling enhanced the emulsifying potential and decreased the mg of amino acids per g powder. Neutralisation with hydrochloric acid instead of citric acid and subsequent heating and concentration showed minimal effect on the properties of the extracts and decreased the mg amino acids per g powder. This research highlights the potential of Pyropia seriata as a source of soluble alternative protein for food applications.

Copolymer Randomization by End‐Group Interchain Exchange Reactions

AbstractTheoretical analysis of the kinetic scheme describing formation and randomization of a binary copolymer due to end‐group interchange reactions is presented. Compact analytical expressions are obtained for the transient and equilibrium values of the copolymer degree of blockiness and fractions of active end‐groups of different types. The resulting copolymer is described by the first‐order Markov statistics, which can be rather far from the Bernoullian one. Its structure is determined by the composition of the system and a single combination of the rate constants of four elementary reactions. The kinetics includes fast and slow stages with characteristic time periods independent of and proportional to the average polymerization degree, respectively. During the fast stage, the initial polymers disappear, whereas the copolymer degree of blockiness is still very low. The distribution of units in the copolymer is Markovian, only if the initial polymers possess the most probable molar mass distributions. At the slow stage copolymer randomization gradually progresses, whereas the distribution of end groups may change in the opposite direction compared to the fast stage. The results can be used to analyze the experimental data on the chain structure of condensation, metathesis, and dynamic covalent polymers, where interchange reactions play a significant role.

Disassembly of catechyl lignin from castor shells by maleic acid aqueous and production of single catechols

Catechyl lignin (C-lignin) is recognized as a uniform and straight biopolymer that stands out as an exemplary archetype of what is often referred to as "ideal lignin." This difference is due to its unique ability to efficiently depolymerize into a single catechol product. This remarkable property makes C-lignin suitable for further applications and highlights its potential for the production of chemicals. In this study, a protocol utilizing maleic acid aqueous (MAA) was developed for the effective disassembly of coexisting C-lignin and G/S-lignin in castor shells under mild conditions. Thioacidolysis combined with nuclear magnetic resonance (NMR) spectroscopic analyses revealed a significant enrichment of benzodioxane units, without observation of β-O-4 structures from G/S-lignin. The mechanism underlying selective disassembly of coexisting C-lignin and G/S-lignin in castor shells was comprehensive elucidated by analyzing the chemical structure change of benzodioxane and β-O-4 lignin model compounds. Furthermore, the structural characteristics of the disassembled C-lignin were synthetically evaluated, highlighting its narrow molecular weight distribution (Mw = 2432–2763 Da) and high hydroxyl content (aliphatic OH = 7.7–8.4 mmol/g; catechol OH = 5.7–7.5 mmol/g). Compared with the feedstock containing C-lignin and G/S-lignin, the extracted C-lignin sample showed exceptional catalytic activity and selectivity. The results show that the Pd/C-catalyzed hydrogenation reaction mainly produces catechylpropanol compounds (selectivity as high as 97 %).

A survey of solid form landscape: Trends in occurrence and distribution of various solid forms and challenges in solid form selection

This survey provides a comprehensive analysis of solid form screens for 476 new chemical entities (NCEs) conducted at Pharmaron from 2016 to 2023. The findings from this survey reveal notable trends in polymorphism, salt formation, crystallization behavior and molecular weight (MW) distribution of the NCEs evaluated. Most solid form screens were conducted to select the preferred solid form for Investigational New Drug (IND) enabling projects, others were for candidate selection or late-stage development. Comparison to published historical data was made to show changes in occurrence of counterions/co-formers for salts/co-crystals, polymorphs, and the distribution of MWs over time. Increased complexity in the solid-form landscape and selection of the development form are discussed, including challenges in crystallization and selection of lead forms. The distribution of types of crystal forms and the observation of emerging and disappearing polymorphs are presented. These results highlight the evolving challenges and considerations in solid form screening and form selection and offer insights for future pharmaceutical development and crystallization strategies.

Systematic Characteristics of Fucoidan: Intriguing Features for New Pharmacological Interventions.

Fucoidan, a sulfated polysaccharide found primarily in brown algae, is known for exhibiting various biological activities, many of which have been attributed to its sulfate content. However, recent advancements in techniques for analyzing polysaccharide structures have highlighted that not only the sulfate groups but also the composition, molecular weight, and structures of the polysaccharides and their monomers play a crucial role in modulating biological effects. This review comprehensively provides the monosaccharide composition, degree of sulfation, molecular weight distribution, and linkage of glycosidic bonds of fucoidan, focusing on the diversity of its biological activities based on various characteristics. The implications of these findings for future applications and potential therapeutic uses of fucoidan are also discussed.

Synthesis of miktoarm star-shaped polymers with polyoxazoline arms and macrocyclic calix[8]arene branching center

A novel approach to the synthesis of miktoarm star-shaped poly(2-alkyl-2-oxazolines) with calix[8]arene core was developed using a combination of the “core first” (grafting from) and “grafting onto” methods. The star-shaped polymers of A8B8 type with grafted poly(2-ethyl-2-oxazoline) and poly(2-isopropyl-2-oxazoline) arms were obtained using calix[8]arene based multifunctional branching center with sulfonyl chloride initiating moieties and as well as acyl hydrazide termination ones. The polymer structure has been confirmed by 1H NMR spectroscopy and UV spectroscopy. The molar mass characteristics of the samples were determined by size-exclusion chromatographic and light scattering. It was experimentally confirmed that all synthesized polymers had the target arm number, namely 8 or 16. The obtained miktoarm stars were characterized by narrow molar mass distributions, and the polymerization degree of the arms was 15. The synthesized stars had a high intramolecular density, which increased with the arm number. It is shown that the thermoresponsiveness of the studied stars depends on the number and structure of arms and on intramolecular density, while molecular mass is not a decisive factor determining their LCST behavior.For miktoarm stars, phase separation temperatures do not depend on the grafting configuration of poly(2-ethyl-2-oxazoline) and poly(2-isopropyl-2-oxazoline) on the upper or lower rim of calix[8]arene.

Study on the green extraction of lignin and its crosslinking and solidification properties by geopolymer pretreatment

Different delignification processes lead to significant differences in the structure and activity of lignin. Consequently, complex modifications are necessary before lignin to be applied. In this paper, a green process for the selective catalytic extraction of lignin by geopolymer is proposed based on biomass refining. This process can obtain lignin with ideal performance on activity, crosslink ability and curability. Taking eucalyptus, fir and bagasse as examples, the optimal lignin yields reach 46.5 %, 34.8 % and 48.7 % respectively (mFiber/mGeopolymer = 3, 120 min, and 130 °C). Moreover, lignin isolated with geopolymer (GL) shows a similar narrow molecular weight distribution range to that of Milled Wood Lignin (MWL). Studies on crosslinking solidification mechanisms have demonstrated that the phenolic hydroxyl groups of GL participate in the formation of a multi-stage amine crosslinking and solidification network structure. GL does not rely on flexible chains in the crosslinking and solidification of wood adhesives. Since highly active lignin can condense with phenolic hydroxyl groups on the surface of wood, it provides the adhesive with higher bonding strength (3.8 MPa). This study presents a novel approach to fabricating lignin-based formaldehyde-free wood adhesives.

Synthesis of basic amino acid-grafted lignin for use as a high-performance pigment dispersant

Lignin is a promising dispersant due to its hyperbranched polymer structure, low cost, renewability and abundant availability. However, its use is limited by its broad molecular weight distribution, inhomogeneity, and low content of hydrophilic functional groups. In this work, lignin was functionalized with alkaline amino acids (EHL-AA) to enhance water solubility and molecular weight uniformity. The results showed that EHL-AA significantly improved the dispersion of pigment Red 57:1 (P.R.57:1) in aqueous solutions, reducing the required dosage by 50 % compared to commercial small-molecule dispersants. Additionally, histidine modified lignin (EHL-His) exhibited superior stability for P.R.57:1 compared to commercial lignosulfonate (REAX 85A). Molecular dynamics simulations further revealed that showed that EHL-His had the highest electrostatic potential difference and the largest absolute value of negative ESP. The adsorption of EHL-His onto the P.R.57:1 surface followed the pseudo-second-order kinetic model and the Langmuir model, with EHL-His showing a higher Langmuir constant (b) than REAX 85A, indicating the strongest interaction with the pigment. In summary, this work advances pigment dispersion technology and promotes the high-value utilization of lignin.

Polysaccharides from Gaultheria leucocarpa var. yunnanensis (DBZP) alleviates rheumatoid arthritis through ameliorating gut microbiota

Gaultheria leucocarpa var. yunnanensis (Dianbaizhu) is a traditional Chinese herb for rheumatoid arthritis (RA). However, its macromolecular components have always been overlooked. This study aimed to investigate the chemical composition and effect on improving RA of polysaccharides from Dianbaizhu (DBZP). The results showed the yield of DBZP was 4.07 % ± 0.03 %, and it was composed of Mannose (6.63 %), ribose (1.33 %), rhamnose (4.53 %), glucuronic acid (2.95 %), galacturonic acid (32.29 %), glucose (13.78 %), galactose (22.97 %), xylose (3.94 %) and arabinose (11.59 %), with a large molecular weight distribution range. DBZP treatment could reduce the paws thickness and arthritis scores of collagen-induced arthritis (CIA) mice, and improve inflammatory cell infiltration, synovial hyperplasia, bone erosion, and deterioration. The abundance of several specific bacteria, such as Lactobacillus, Bacteroides, Alistipes, Mucispirillum, and Candidatus_Saccharimonas, and some metabolites in feces or urine, such as 11beta-hydroxytestosterone, pregnanediol 3-O-glucuronide, p-cresol sulfate and several amino acids and peptides, was also altered. The process of DBZP alleviating RA through gut microbiota involves affecting the digestion and metabolism of carbohydrates and protein, altering sex hormones levels, and regulating intestinal immune function, such as the differentiation and signaling of Th17 cells. These findings suggest that DBZP possesses a protective effect on CIA in mice via modulating gut microbiota.

The dual role of mannosylerythritol lipid-A: Improving gelling property and exerting antibacterial activity in chicken and beef gel

Gel meat products are important in the meat market. To develop high-quality meat gel products, mannosylerythritol lipid-A (MEL-A) was added to chicken and beef gels, and their physicochemical and biological properties of the composite gel formed by heating were determined in this study. The results of texture analysis showed that MEL-A could significantly improve the hardness, gumminess and chewiness of meat gels and reduce water loss (P < 0.05). In addition, rheological and differential scanning calorimetry (DSC) analysis showed that MEL-A not only improved the rheological properties of meat gel, but also improved its thermal stability. The results of dynamic rheological analysis also showed that MEL-A improved the gel strength of meat gel, and the gel strength of chicken was the highest after adding 1.5 % MEL-A while the gel strength of beef was the highest after adding 2 % MEL-A. The image of scanning electron microscopy (SEM) and protein molecular weight distribution measurement indicated that MEL-A induced protein aggregation, resulting in fewer pores in the meat gels and a more compact network structure. These results suggest that different meat gels show good gel properties, so MEL-A has a lot of potential for gel product development.

Multidisciplinary structural optimization of polysaccharides preventing alcohol-induced liver disease with computer-aided molecular design

Here, we optimized the active units of polysaccharides and investigated the conformational relationship between the polysaccharides and alcoholic liver disease (ALD) at the molecular level. We used data mining to screen polysaccharide structural parameters for ALD (PSP-ALD). Most ALD-resistant polysaccharides against ALD comprised glucose (Glc), mannose (Man), galactose (Gal), arabinose (Ara), and rhamnose (Rha). Additionally, (1 → 6)-, (1 → 3)-, and (1 → 4)- glycosidic linkages were mainly contained. Polysaccharides against ALD have a wide molecular weight distribution (2.1 × 103 Da - 9.6 × 107 Da). Based on the PSP-ALD analysis, six commercially available oligosaccharides were selected and their structures were built. After molecular docking, the binding affinities between stachyose and the key ALD targets were stronger, indicating that stachyose may be a polysaccharide-active unit against ALD (PAU-ALD). Furthermore, histological examination of liver tissue combined with serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), and triglycerides (TG) showed that stachyose had a significant protective effect against ALD in mice. In summary, we optimized a PAU-ALD and developed a method for studying the structure-activity relationship between polysaccharides and ALD at the molecular level, which provides a new research direction for the development and utilization of polysaccharides and their clinical applications in ALD.

Hydrophobically Modified Polyacrylamide Incorporating Both Hydrophilic and Hydrophobic Units: Enhanced Printability and Stability in Aqueous Ink.

For this research, three hydrophobically modified polyacrylamides, HPAAB, HPAAF, and HPAAS, with multiple hydrophobic monomers were designed, synthesized, and used as thickeners in aqueous ink for digital ink-jet printing. The structures were characterized by Fourier transform infrared (FTIR) analysis and nuclear magnetic resonance (NMR) spectroscopy. The viscosity-average molecular weight was determined by intrinsic viscosity determination and was adjusted according to hydrophobic content. The critical association concentration (CAC) of polymers was measured simultaneously using the apparent viscosity method and the fluorescence spectrum. The formation of a network structure and the mechanism of hydrophobic association are visualized dynamically with a scanning electron microscope (SEM) at different concentrations. Under the same conditions, HPAAB exhibited excellent thickening ability across different pH levels, temperatures, and shear rates, which is caused by the longer hydrophobic side chain and the stronger hydrophobic effect of the behenyl polyoxyethylene ether methacrylate (BEM) group. Furthermore, an aqueous ink using HPAAB as a thickener displays significant printability and stability, functioning much better than a corresponding aqueous ink that uses a commercial thickener. This is the first example of a hydrophobic associating polyacrylamide, incorporating both hydrophilic and hydrophobic units within a single hydrophobic chain, thereby serving as an efficient thickener for aqueous ink.

Catalyzing PET-RAFT Polymerizations Using Inherently Photoactive Zinc Myoglobin.

Protein photocatalysts provide a modular platform to access new reaction pathways and affect product outcomes, but their use in polymer synthesis is limited because co-catalysts and/or co-reductants are required to complete catalytic cycles. Herein, we report using zinc myoglobin (ZnMb), an inherently photoactive protein, to mediate photoinduced electron/energy transfer (PET) reversible addition-fragmentation chain transfer (RAFT) polymerizations. Using ZnMb as the sole reagent for catalysis, photomediated polymerizations of N,N-dimethylacrylamide in PBS were achieved with predictable molecular weights, dispersity values approaching 1.1, and high chain-end fidelity. We found that initial apparent rate constants of polymerization increased from 4.6×10-5 s-1 for zinc mesoporpyhrin IX (ZnMIX) to 6.5×10-5 s-1 when ZnMIX was incorporated into myoglobin to yield ZnMb, indicating that the protein binding site enhanced catalytic activity. Chain extension reactions comparing ZnMb-mediated RAFT polymerizations to thermally-initiated RAFT polymerizations showed minimal differences in block copolymer molecular weights and dispersities. This work enables studies to elucidate how protein modifications (e.g., secondary structure folding, site-directed mutagenesis, directed evolution) can be used to modulate polymerization outcomes (e.g., selective monomer additions towards sequence control, tacticity control, molar mass distributions).

Optimization of extraction for efficient recovery of kenaf seed protein isolates: evaluation of physicochemical and techno-functional characteristics.

Kenaf seeds are a rich source of protein; however, finding the best extraction method is crucial to obtaining high-quality protein from these underutilized seeds. This research devised an optimized extraction process for best recovery of kenaf seeds protein using response surface methodology. The key parameters affecting the yield and protein content were optimized, including extraction pH (2-11), seed:water ratio (5:1-50:1), temperature (30-90 °C), and duration (20-360 min). The physicochemical and techno-functional properties of kenaf seed protein isolates (KSPIs) were examined. A maximum protein yield of 12.05 g/100 g with purity level 91.94 g/100 g was obtained using an optimized extraction with pH 11.0, seed:water ratio 50:1, 360 min duration, and temperature 50 °C. The oil and water retention capacities of KSPI were 1.14 mL g-1 and 1.37 mL g-1 respectively. After 30 min at pH 7, KSPIs demonstrated remarkable emulsion capacity (83.12%) and stability (75.63%), along with high foaming capacity (106%) and stability (18.3%). As per high-performance liquid chromatography analysis, arginine, glutamic acid, leucine, phenylalanine, and lysine were the most abundant amino acids detected in KPSIs. The KSPIs' globular protein structure was successfully verified using analytical approaches, including Fourier transform infrared spectroscopy, protein fraction ratios, and differential scanning calorimetry. Sodium dodecyl sulfate polyacrylamide gel electrophoresis analysis revealed that KPSI has a molecular weight distribution ranging from 10 kDa to 50 kDa. The results of this study support the application of the proposed response-surface-methodology-optimized extraction method for efficient recovery of high-quality kenaf seed proteins that meet the necessary physicochemical and techno-functional requirements. © 2024 Society of Chemical Industry.

Adjustment of Electronic (OMe and NO2) and Steric (CHPh2) Effects in Bis(imino)pyridinyliron Precatalysts for Producing High Molecular Weight Linear PE

AbstractBased on variations in steric and electronic substituents in the N‐aryl unit, a set of five 2‐[1‐(arylimino)ethyl]‐6‐[1‐(2‐benzhydryl‐4‐nitro‐6‐methoxyphenylimino)ethyl]pyridyliron dichloride complexes (where aryl=2,6‐dimethylphenyl (Fe‐Me2), 2,6‐diethylphenyl (Fe‐Et2), 2,6‐diisopropyl (Fe‐iPr2), 2,4,6‐trimethylphenyl (Fe‐Me3), 2,6‐diethyl‐4‐methylphenyl (Fe‐Et2Me)) were synthesized and investigated for ethylene polymerization. Their structures and compositions were confirmed by FTIR, elemental analysis, and X‐ray diffraction analysis (Fe‐Et2 and Fe‐iPr2), revealing a distorted square pyramidal geometry around the iron center. When activated in situ with MAO or MMAO, these iron complexes acted as highly active precatalysts, achieving activity levels up to 29.0×106 gPE molFe−1 h−1 for a 5‐min reaction at 60 °C. A notable characteristic of these precatalysts is their high thermal stability, maintaining significant activity (2.0×106 gPE molFe−1 h−1) at temperatures up to 100 °C. Importantly, the incorporation of strong electron‐withdrawing groups in the ligand structure favored the production of polyethylene with high molecular weights (up to 407.5 kg mol−1) across various reaction conditions, surpassing those of most previously reported iron complexes. Moreover, less hindered iron precatalysts showed higher activity compared to more hindered ones. However, the trend reversed when comparing the molecular weight of obtained polyethylene: more sterically hindered precatalysts yielded higher molecular weight polymers. The molecular weight distributions ranged from monomodal to bimodal with broad dispersity. DSC thermograms and 1H/13C NMR spectra of the polyethylene confirmed its highly linear microstructure, evidenced by sharp endothermic peaks and pronounced singlets for the −(CH2)n− repeating units.

Catalyzing PET‐RAFT Polymerizations Using Inherently Photoactive Zinc Myoglobin

AbstractProtein photocatalysts provide a modular platform to access new reaction pathways and affect product outcomes, but their use in polymer synthesis is limited because co‐catalysts and/or co‐reductants are required to complete catalytic cycles. Herein, we report using zinc myoglobin (ZnMb), an inherently photoactive protein, to mediate photoinduced electron/energy transfer (PET) reversible addition‐fragmentation chain transfer (RAFT) polymerizations. Using ZnMb as the sole reagent for catalysis, photomediated polymerizations of N,N‐dimethylacrylamide in PBS were achieved with predictable molecular weights, dispersity values approaching 1.1, and high chain‐end fidelity. We found that initial apparent rate constants of polymerization increased from 4.6×10–5 s−1 for zinc mesoporpyhrin IX (ZnMIX) to 6.5×10–5 s−1 when ZnMIX was incorporated into myoglobin to yield ZnMb, indicating that the protein binding site enhanced catalytic activity. Chain extension reactions comparing ZnMb‐mediated RAFT polymerizations to thermally‐initiated RAFT polymerizations showed minimal differences in block copolymer molecular weights and dispersities. This work enables studies to elucidate how protein modifications (e.g., secondary structure folding, site‐directed mutagenesis, directed evolution) can be used to modulate polymerization outcomes (e.g., selective monomer additions towards sequence control, tacticity control, molar mass distributions).

Effect of temperature and relative humidity on hydrolytic degradation of additively manufactured PLA: Characterization and artificial neural network modeling

Understanding the long-term durability of 3D-printed polymeric materials under varying temperature and humidity conditions is essential for expanding their industrial applications. Therefore, it is critical to assess the impact of degradation on mechanical properties such as tensile strength. In this study, we manufactured specimens with dual orientations by additive manufacturing-based 3D printing and subjected them to accelerated degradation under various temperature and humidity conditions to evaluate their durability in degradation environments. Mechanical properties significantly decreased under the most severe conditions, with a maximum reduction of 76.7 % observed in molecular weight. The deconvolution of the molecular weight distribution and its correlation with mechanical properties were thoroughly investigated. We derived an equation representing the relationship between the peaks obtained from deconvoluting the molecular weight distribution and the tensile strength. Furthermore, to expedite and simplify tensile strength assessment, we trained an artificial neural network (ANN) model using tensile test results to construct a predictive model. The ANN utilized temperature, humidity, printing angle, and time as input data, with tensile strength as the output. Validation of this model demonstrated the capability to predict tensile strength accurately under different temperature and humidity conditions.

Relationship between Xylene Solubles and Crystallization Elution Fractionation of Polypropylene.

The Xylene Soluble (XS) is one of the most important parameters closely related to the performance of polypropylene (PP) materials. In order to obtain precise and accurate XS data, ASTM D 5492-17, based on the wet chemistry separation mechanism, strictly specifies each and every step of the procedure, such as a glassware setup, heating and cooling rates, etc. Meanwhile, crystallization elution fractionation (CEF), a newly developed technique, is capable of quantifying polyolefin structural regularity and comonomer distribution in a fast and automated manner. There have been a few pieces of preliminary work aiming to provide XS value from the CEF test with a limited number of samples. It is important to gain deep insights into the relationship between XS and the purge fraction of CEF by studying a large number of diverse polypropylene materials. In this paper, close to 300 commercial polypropylene and/or homemade polypropylene, both homopolypropylene (hPP) and propylene-ethylene copolymers (P/E) made with various catalysts under different conditions, were employed. XS values were obtained via CRYSTEX QC calibration. It was found that XS and the soluble fraction (SF) from CEF yielded a linear relationship with R 2 = 0.9942. This linearity is applicable regardless of polymer types, which can differ significantly in terms of molecular weight distribution, tacticity, chemical composition, and melt flow rate. One of the prominent advantages of using the CEF test instead of ASTM D 5492-17 is the elimination of the time-consuming procedure for much-improved precision and high productivity. In addition, the catalytic system was found to have an influence on SF and crystalline fractions of copolymers.

Hydrolysates of mare's milk proteins. Immunochemical and physico-chemical characteristics

In recent years, the attention of specialists has been attracted by a significant increase in allergic diseases, especially among children. Enzymatic hydrolysis with the participation of peptidases is considered the most effective measure to reduce the allergenicity of milk proteins. The study of the features of protein proteolysis by various enzymes, aimed at establishing optimal process parameters, is the subject of research in the production of hydrolysates with specified properties: a certain peptide and amino acid profile, reduced antigenic properties. At the same time, for a correct preclinical assessment of the safety and potential effectiveness of specialized food products, it is not enough only to determine the molecular weight distribution of peptide fractions in the composition. A necessary additional and informative indicator of reducing the potential allergenicity of the hydrolysate is the degree of preservation of the antigenic properties of the initial protein (residual antigenicity), determined by immunochemical methods. The preparation and subsequent comprehensive assessment of enzymatic hydrolysates of mare's milk proteins is of considerable interest, since, according to the results of clinical studies, it was suggested that upon allergy to cow's milk proteins mare's milk can be considered hypoallergenic. The purpose of this work was to obtain enzymatic hydrolysates of mare's milk proteins using domestic enzymes and their further physico-chemical and immunochemical characteristics. The object of the study was mare's milk protein obtained from skimmed mare's milk powder as a protein substrate. Two samples of enzymes from various manufacturers of the Russian Federation were used in the work. The results of the conducted studies show that the peptide profiles of hydrolysates vary greatly depending on the enzyme used, however, the multiplicity of antigenicity reduction practically does not depend on the nature of the enzyme, and does not depend on an increase in the enzyme/substrate ratio. The peptide profile and the multiplicity of reducing the antigenicity of hydrolysates of mare's milk proteins are influenced by ultrafiltration treatment of the obtained hydrolysates, which allows reducing the content of antigenic structures in the final product by several orders of magnitude.