Biopolymer Ratio Research Articles

Comparison of structural and physicochemical properties of lysozyme/carboxymethylcellulose complexes and microgels.

Proteins and polysaccharides can be used to assemble colloidal delivery systems suitable for industrial applications, such as functional foods, supplements, pharmaceuticals, and personal care products. The purpose of this work was to compare the physicochemical and structural properties of colloidal delivery systems prepared from lysozyme and carboxymethyl cellulose (CMC) at different biopolymer ratios, pH values, and salt levels. Specifically, the performance of unheated ("complexes") and heated ("microgels") lysozyme-CMC systems were compared. Isothermal turbidity-pH titrations indicated that the critical pH value for complex formation was lower for microgels than for complexes. Complexes were prone to dissociation when the pH or ionic strength was altered due to weakening of electrostatic interactions between the CMC and lysozyme. Conversely, microgels remained intact when the pH or ionic strength was altered, exhibiting swelling or shrinkage rather than dissociation. These results have important implications for the selection of the most appropriate protein/polysaccharide systems to achieve specific functional requirements. Complexes may be more suitable for pH- or salt-based triggered release whereas microgels may be more suitable for sustained release.

Исследование иммобилизации пробиотиков как метода их защиты и доставки в желудочно-кишечный тракт человека

The relevance of research is the experimental and analytical justification of the effectiveness of the joint use of biopolymers of animal and plant origin as a substrate in the process of immobilization of the association of probiotic cultures. Researches are executed in specialized laboratories of universities: Omsk GAU, Saratov GAU, SKFU. In the form of a substrate were used: gelatin, χ-carrageenan, low-esterified pectin, modified starch; as bioobjects are selected: L. acidophilus, B. Lactis, S. thermophilus. To obtain reliable and complete characteristics, a set of research methods was used in the work: physicochemical, sensory, and microbiological. Investigation of immobilization allowed to determine the optimal ratio of biopolymers as a carrier (substrate): pectin and gelatin, as 2:1; the total concentration of solids of the carrier solution (20.0 ± 0.5)% by weight. The total number of viable cells of probiotic microorganisms in membranes (plates) is an average of lg (11.0 ± 0.55). In order to extend the shelf life, the membranes were dried in a freeze dryer, with parameters: the temperature of the frozen product (–25 °C) and the residual pressure in the sublimate 0.013–0.133 kPa. Immobilization by microencapsulation of the association of probiotic cultures of L. acidophilus, B. Lactis and S. thermophilus into a gel of biopolymers: gelatin food, pectin gene LM 106 AS-YA, starch in a ratio of 5:1:1 was studied by microencapsulation. The obtained microcapsules were studied in imitated gastric and intestinal conditions, while the number of viable probiotic cells was determined at different times of their degradation. It was established that 20–25% of viable cells of probiotics were released from capsules in the "artificial stomach" phase, 75–80% in the "artificial bowel" phase. Innovative biotechnologies of milk based products for specialized nutrition are presented.

Edible Pickering emulsions stabilized by ovotransferrin–gum arabic particles

Abstract: The objective of the present work was to fabricate ovotransferrin–gum arabic particles with desirable properties as Pickering stabilizers. Complexation of ovotransferrin (OVT) with gum arabic (GA) was investigated using turbidimetric titrations, and OVT–GA complexation proved to be an effective method to assemble hardcore food-grade nanoparticles. Preparation of OVT–GA particles was optimized by controlling biopolymer ratios and pH values, and uniform OVT–GA nanoparticles with mean particle size of 175.8 ± 1.3 nm and air-water contact angle of 82.6° were prepared at r = 3:1 and pH 3.2. Involvement of electrostatic interaction, hydrophobic interaction and hydrogen bonding in nanoparticle formation was verified through titrations in the presence of destabilizing agents. Interfacial tension measurements revealed that OVT–GA nanoparticles could effectively reduce interfacial tension. Afterwards, OVT–GA nanoparticles were employed to prepare surfactant-free Pickering emulsions. Visual observation indicated that Pickering emulsions stabilized by OVT–GA nanoparticles possessed superior emulsified phase volume fraction and storage stability. Confocal laser scanning microscopy results indicated that OVT–GA nanoparticles were located at the oil-water interface. Microstructures of emulsions were dependent on the concentrations of applied particles and oil fraction. Rheological measurements of Pickering emulsions demonstrated that increasing either particle concentration or oil fraction could lead to an increase of storage modulus and viscosity.

Immobilization of β-galactosidase by complexation: Effect of interaction on the properties of the enzyme

In the present work, we aimed to explore the molecular binding between alginate and β-galactosidase, as well as the effect of this interaction on the activity retention, thermal stability, and kinetic properties of the enzyme. The impact of pH and enzyme/alginate ratio on physicochemical properties (turbidity, morphology, particle size distribution, ζ-potential, FTIR, and isothermal titration calorimetry) was also evaluated. The ratio of biopolymers and pH of the system directly affected the critical pH of complex formation; however, a low alginate concentration (0.1 wt%) could achieve an electrical charge equivalence at pH 3.4 with 93.72% of yield. The binding between β-galactosidase and alginate was an equilibrium between enthalpic and entropic contributions, which promoted changes in the structure of the enzyme. Nevertheless, this conformational modification was reversible after the dissociation of the complex, which allowed the enzyme to regain its activity. These findings will likely broaden functional applications of enzyme immobilization.

Formation and characterization of the complex coacervates obtained between lactoferrin and sodium alginate

The aim of this study was to evaluate the influence of some parameters (pH, NaCl, and ratio of biopolymers) on the formation of the complex coacervates of lactoferrin and sodium alginate. Different ratios of lactoferrin:sodium alginate were tested (1:1, 1:2, 1:4,1:8, 2:1, 4:1, and 8:1) at pH levels ranging from 2.0 to 7.0 with different concentrations of NaCl (0, 50, 100, 150, and 200 mM). Sodium alginate has a molecular weight of 138 kDa ± 0.07. The ratio of 8:1(lactoferrin: sodium alginate) at a pH of 4.0 with a low salt concentration was the optimal condition for the formation of the complex. The thermodynamic parameters demonstrated that the interaction between lactoferrin and sodium alginate was exothermic and spontaneous with a favorable enthalpic and unfavorable entropic contribution during the interaction. The chemical, thermal and morphological characteristics of the biopolymers and the complex coacervates demonstrated their nature and changes due to electrostatic interactions. The formation of complex coacervates between lactoferrrin and sodium alginate can serve as an alternative to the incorporation of lipophilic functional ingredients sensitive to high temperatures in various food systems.

Influence of process parameters on microcapsule formation from chitosan—Type B gelatin complex coacervates

A series of chitosan/gelatin based microcapsules containing n-hexadecane was synthesized through complex phase coacervation from chitosan (CH) and type-B gelatin (GB), and crosslinked by glutaraldehyde (GTA). This research was conducted to clarify the influence of different parameters on the encapsulation process, i.e., the emulsion formation and the shell formation, using zeta potential and surface tension measurements, attenuated total reflectance (ATR), and thermal analysis such as differential scanning calorimetry (DSC). The optimal values of biopolymer ratios (TBP), crosslinker amount, emulsion time and feeding weight ratio of core/shell polymer (RCS) were identified. The stability of the emulsion was depended on the surface activity and TBP ratio, which also affected the droplet size distribution and the thickness of the shell. Furthermore, core content, encapsulation efficiency and thermal properties of the microcapsules were related to TBP and RCS; with the lowest RCS giving the best microcapsules features.

Lactase (β-galactosidase) immobilization by complex formation: Impact of biopolymers on enzyme activity

In this study, a novel way to immobilize the enzyme β-galactosidase (Kluyveromyces lactis) through complexation with polysaccharides (sodium alginate (ALG) or Ɩ-carrageenan (CA)) was described. The kinetic parameters of the formation of the complexes and the immobilization efficiency of the enzyme as a function of pH and ratio of biopolymers were studied. The temperature profile, thermal stability, and kinetic parameters of the immobilized and free lactase were also analyzed. At pH 4.0, the results for the zeta potential associated with complex yield showed that the highest complex yield (97.14% ± 2.14) was reached for LAC/ALG at a 5:1 ratio, whereas the highest complex yield (95.26% ± 2.44) was reached an 8:1 ratio for LAC/CA. The process of complexation decreased the activity retained by the enzyme after dissociation. However, this decrease was less substantial for the LAC/ALG (83.2 ± 3.7%) complex than for LAC/CA (69.4 ± 7.6%) complex. The Michaelis–Menten constant (Km) increased from 2.91 mM (native enzyme) to 3.43 mM (LAC/ALG complex) and 4.15 (LAC/CA complex), while the apparent turnover number (Kcat) and the specificity constant (Kcat/Km) of both systems were not significantly different. The immobilization of the enzyme by complexation did not increase its thermal stability. However, the activity of the complexed lactase remained higher than that of native enzyme when exposed to low pH (pH 4.0) after 200 and 250 min for the LAC/ALG and LAC/CA complexes respectively. Our findings suggest that complexation can be a useful method for the immobilization of β-galactosidase.

Interpolymeric Complexes Formed Between Whey Proteins and Biopolymers: Delivery Systems of Bioactive Ingredients.

Whey proteins are obtained from dairy industry waste. Studies involving the analysis of the bioactive compounds in whey show health benefits, as it is an excellent source of indispensable amino acids. Milk whey contains principally β-lactoglobulin, α-lactoglobulin, bovine serum albumin, and lactoferrin, proteins with innumerable functional and technological properties. One application of these proteins in food is the formation of interpolymer complexes, along with other proteins or anionic polysaccharides. The formation of complexes occurs mainly through electrostatic interactions between a negatively charged biopolymer and a positively charged biopolymer. This formation is influenced by factors such as pH, ionic strength, and biopolymer ratio. Because they do not use high temperatures and chemical reagents and have additional nutritional and functional value, these complexes have been used as encapsulating agents for bioactive ingredients. Recent studies on their training and applications are addressed in this review to boost new research and applications in the food industry, thus increasing opportunities for utilizing whey proteins.

Pea protein isolate–high methoxyl pectin soluble complexes for improving pea protein functionality: Effect of pH, biopolymer ratio and concentrations

Recently, there is a strong interest in the incorporation of pea protein as a preferred alternative animal protein into protein fortified beverage because of its cheaper price, more sustainable and gluten free that can be claimed in label. However, poor functionality of pea protein such as acidic solubility and thermal stability has limited their applications in dispersed food systems such as beverage. The aim of this study was to enhance the functionality of pea protein isolate (PPI) by forming soluble complexes with high methoxyl pectin (HMP). The effect of PPI–HMP mixing ratio (1:1–20:1) and PPI concentrations (0.05 and 1.00 wt %) on critical pH transition point (pHs), a key parameter differentiating between soluble and insoluble complexes formation, was investigated using turbidimetric analysis, phase diagram, and ζ–potential. Critical pHs decreased to pH 3.5 as PPI–HMP mixing ratio decreased from 20:1 to 1:1. The ζ–potential results showed a shift in net charge neutrality from pH 4.8 in homogenous PPI solutions to pH 3 for PPI-HPM mixtures with 1:1 ratio. However, HMP induced phase separation of PPI–HMP mixtures at both higher biopolymer concentration (>1.50 wt %) and neutral pH values was observed presumably via a thermal incompatibility mechanism. The pH- percentage solubility of PPI–HMP mixtures at fixed PPI concentration (1.00 wt %) was mixing ratio dependent. When increasing HMP concentration, the pH of minimum protein solubility for biopolymer mixture was shifted towards more acidic condition as compared to PPI alone. Apparent viscosity and thermal denaturation temperature of soluble complexes at fixed PPI concentration (1.00 wt %) slightly increased due to the formation of new net structure in the PPI–HMP systems. The findings derived from this research could provide useful information in the design of pea protein fortified beverage with enhanced pea protein stability.

Microrheology and microstructure of water-in-water emulsions containing sodium caseinate and locust bean gum.

The mechanical response on the microscale of phase-separated water-in-water emulsions containing sodium caseinate (SCN) and locust bean gum (LBG) has been monitored by confocal laser scanning microscopy and particle tracking microrheology. Mixed biopolymer systems exhibiting phase-separated micro-regions were enriched in either protein or polysaccharide in the continuous or dispersed phase, depending on the weight ratio of the two biopolymers. Measurements of the tracking of charged probe particles revealed that the local rheological properties of protein-rich regions were considerably lower than that of LBG-rich domains for all the biopolymer ratios examined. At pH 7 in the absence of added salt, the viscosity of the protein-rich regions was little affected by an increase in overall LBG concentration, which is consistent with the phase separation mechanism in the mixed solution of charged (SCN) and uncharged (LBG) biopolymers being dominated by the relative entropy of the counter-ions associated with the charged protein molecules. Addition of salt was found to produce an enhancement in the level of thermodynamic incompatibility, leading to faster and more pronounced phase separation, and altering the micro-viscosity of protein-rich regions. At high ionic strength, it was also noted that there was a pronounced accumulation of incorporated probe particles at the liquid-liquid interface. The microrheological properties of the SCN-rich regions were found to be substantially pH-dependent in the range 7 > pH > 5.4. By adjusting the acidification conditions and the biopolymer ratio, discrete protein-based microspheres were generated with potential applications as a functional food ingredient.

Nanoemulsions From Unsaturated Fatty Acids Concentrates of Carp Oil Using Chitosan, Gelatin, and Their Blends as Wall Materials

This work aimed to study the development of food–grade nanoemulsions containing unsaturated fatty acids concentrates from carp oil, using chitosan, and gelatin as wall materials. The effects of chitosan:gelatin ratio, polymer concentration and homogenization time on the nanoemulsions characteristics were evaluated. Phase separation occurred when the chitosan:gelatin ratio was higher than 50:50. Nanoemulsions using proportion of chitosan over than 70% remained visually stable, with no phase separation, for more of 7 days. The highest homogenization time (20 min) and the lowest biopolymers concentration (1% w/v) resulted in smaller particle sizes for the ratios of 100:0, 90:10, and 70:30 (respectively, 292.0, 52.3, and 34.8 nm). The zeta potential increased with the amount of chitosan (from 26.5 to 31.0 mV), while pH and refractive index were not affected by the biopolymers ratio. After 7 days of storage, the nanoemulsion with 90:10 of chitosan:gelatin ratio was in the acceptable range of the legislation, showing peroxide value of 4.8 meq kg−1, p–Anisidine value of 9.8 meq kg−1, and ToTox value of 19.4 meq kg−1. Chitosan and gelatin provided high stability to the emulsions and also behaved as good wall materials, demonstrating the importance of studying its combination to form food–grade nanoemulsions.Practical Applications: Carp viscera are by–products of the fishery industry, rich in unsaturated fatty acids, which are associated to human health benefits. However, its low solubility in water and oxidative instability difficult the foods enrichment with these unsaturated fatty acids. Nanoemulsions delivery systems can be used to protect and increase its solubility. Edible biopolymers, such as chitosan and gelatin, can increase the physical and oxidative stability of these lipids in food systems through the formation of nanoemulsions, to facilitate the addition these lipophilic active ingredients in aqueous–based foods or beverages.Unsaturated fatty acids (UFA) of fish oil, especially omega‐3 series, are associated with several health benefits. In this work are prepared food–grade nanoemulsions containing UFA concentrates of carp oil, rich in omega‐3, using different proportions of the biopolymers chitosan and gelatin as wall materials.

An optimal window for the fabrication of Edible Polyelectrolyte Complex Nanotubes (EPCNs) from bovine serum albumin (BSA) and sodium alginate

Edible polyelectrolyte complex nanotubes (EPCNs) were assembled with the alternate layer-by-layer (LbL) deposition technique using bovine serum albumin (BSA) as positively charged biopolymer and sodium alginate as negatively charged biopolymers. The specific manufacturing conditions that led to the formation of defined and stable nanotubular structures were studied. Dynamic light scattering (DLS) and isothermal titration calorimetry (ITC) were used to study the ability of a protein and polysaccharide to interact and form nanotubes. These methods also offer insights into the types of interactions occurring between these two biopolymers. ITC measurements indicated that electrostatic interactions between BSA and sodium alginate were predominant at pH 3–4, while a strong electrostatic repulsion occurred at pH 6–7. This was also correlated by zeta potential measurements that showed opposite charges for these two biopolymers at acidic pH and similar charges at neutral pH. The ability of a protein and polysaccharides to interact and form nanotubes were studied with the assistance of polycarbonate (PC) templates (pore diameters: 200, 400, 600 and 800 nm). Other assembly parameters, including ratio and concentration of biopolymers, rates of addition, and stability at different pH values were also studied. It was possible to form stable EPCNs with diameters of 200, 400, 600 and 800 nm-template. The wall thickness that leads to the most stable EPCN is 4 bilayers [(BSA/ALG)4] with a rate of addition of 1.0 ml/min and biopolymers concentrations of 0.8 mg/ml and 0.6 mg/ml for BSA and alginate, respectively. The morphology, outer diameter, thickness of the wall and length of the freeze dried EPCNs were characterized with SEM. The SEM images showed that (BSA/ALG)1 and (BSA/ALG)2 yield a weaker EPCN whereas (BSA/ALG)3 yields a more robust wall thickness.

Complex coacervation between lysozyme and pectin: Effect of pH, salt, and biopolymer ratio

The complexation between lysozyme and pectin was studied by acidification using zeta potential, turbidity measurements and calorimetry titration. The complexes were analyzed in various NaCl concentrations with different ratios. At ratio 1:1 with 0.01M NaCl, is worth mentioning that the insoluble complexes were formed between pH 2.0 and 7.0, which represents a great range to apply this complex to different food matrices. When the ratio was increased from 1:1 to 3:1, the pH range between the pHφ1 and pHφ2 increased even more. When the NaCl concentration was increased from 0.01M to 0.2M, a progressive reduction of turbidity was observed. At 0.4M NaCl, there was total suppression of complex formation at ratio ≤ 3:1. The process of complex coacervate formation occurred in two different steps, presenting favorable enthalpic as well as entropic contributions. The positive entropy change is a strong indication that water molecules have been released from the complex surface, however the positive sign of TΔS suggests that hydrophobic interactions were involved in the interaction between lysozyme and pectin. Microscopy images of the samples revealed that the complexes presented a spheroid-like appearance which may contribute to possible future applications.

Miscibility and Performance Evaluation of Biocomposites Made from Polypropylene/Poly(lactic acid)/Poly(hydroxybutyrate-co-hydroxyvalerate) with a Sustainable Biocarbon Filler.

The incorporation of poly(lactic acid) (PLA) and poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) as a partial biobased polymer substitute for polypropylene (PP) was investigated. The ternary blends were prepared through melt compounding extrusion followed by injection molding techniques with a constant biopolymer ratio of 30 wt %. Further addition of pyrolyzed miscanthus-based carbon was carried out to establish a contrast between talc-filled PP. When the morphology of the biopolymer minor phase was analyzed theoretically using contact angle for interfacial tension and spreading coefficient values along with solubility parameter calculations and via scanning electron microscopy imaging, the core–shell architecture was found with the PHBV encasing the PLA phase. Mechanical testing of the materials showed that only the tensile properties were reduced for all samples, whereas the impact strength was increased above the neat PP. With inclusion of the biobased carbon filler into the blend system, the thermomechanical properties were elevated above that of the PP matrix. The final properties of the multiphase polymeric composites are found to be related to the morphology obtained and inherent properties of the individual constituents.

Biocomposites from (Anadara granosa) shells waste for bone material applications

The overall objective for this study is to determine the effect of biopolymer types and ratio on producing biocomposites derived from cockle (Anadara granosa) shells waste. In this study, two types of biopolymer were used i.e. sodium alginate and carboxymethyl cellulose. These biocomposites are meant for bone material applications. The processes involved in producing the biocomposites were pre-treatment of the cockle shells, formation of CaCO3 in aragonite form and finally the synthesis of biocomposites. All samples have undergone physicochemical and mechanical analyses to determine their crystallinity, purity, functional group, surface morphology, elemental compounds and compressive strength using X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscope (SEM), Electron Dispersive X-ray Analysis (EDX) and Universal testing machine (UTM). The CaCO3-biocomposites have been prepared using different ratio of biopolymer and different types of biopolymers. The physicochemical properties of the biocomposites are not affected by the ratio and types of biopolymers. Yet, the ratio and types of biopolymers have influenced the mechanical properties of biocomposites. The biocomposite with lesser amount of biopolymer has denser structure and greater mechanical strength. Comparison between types of polymers revealed that biocomposite with carboxymethyl cellulose has greater mechanical strength compared to biocomposite with sodium alginate.

Characterization of biopolymers and soy protein isolate-high-methoxyl pectin complex

Abstract This study aimed at characterizing the soy protein isolate and high-methoxyl pectin biopolymers individually, and the complexes formed by both at different proportions and pHs in order to find the most suitable pH and biopolymer ratios to food application as stabilizers. The biopolymers were evaluated through solubility, charges, turbidimetry, and optical microscopy analyses; the systems with the pair of biopolymers were analyzed through turbidimetry and optical microscopy. High-methoxyl pectin showed high solubility at all pHs investigated. The soy protein isolate showed low solubility at pH 4.5, which is close to its isoelectric point, and complete solubility at pH 11.0. The formation of complexes suggested an attractive interaction between the biopolymers, with high absorbance reading values and images of complexes from optical microscopy. These complexes were present in systems with pHs below the soy protein isolate's isoelectric point, with positive charges; the high-methoxyl pectin, however, had negative ones.

Formation of concentrated biopolymer particles composed of oppositely charged WPI and pectin for food applications

ABSTRACTThe application of protein–polysaccharide complexes as potential structure modifier, fat replacer, or emulsifying agents in food dispersions has gained increasing interest amongst scientists and manufacturers. Based on associative complexation, low biopolymer concentrations are typically used to generate particulated complexes. The current study, however, presents results that focused on the formation of concentrated biopolymer dispersions. A simple heat treatment was applied to tailor the overall water content of the biopolymer dispersion. For that purpose, whey protein isolate (WPI) and citrus pectin (DE 71%) solutions were mixed at different pH and biopolymer ratios to induce complex coacervation and subsequently heat-treated (ϑ = 90–95°C). Phase separation behavior, microstructural, rheological, and electrical properties of the complexes were investigated by surface charge, turbidity, particle size, rheometry, and light microscopy measurements. Results revealed that complexation was induced under acidic conditions, whereas high WPI:citrus pectin ratios led to positive surface charges, promoting the formation of large and dense particles. In addition, concentrated complex dispersions with water contents ≥80% could be manufactured and easily re-dispersed, whereas complexes maintained their particulate structures. Results are of importance for future studies where we intend to incorporate concentrated biopolymer particles as structuring agents in complex food matrices.

Effects of biopolymer ratio and heat treatment on the complex formation between whey protein isolate and soluble fraction of Persian gum

ABSTRACTProteins and polysaccharides are the two most important natural ingredients with unique functional properties. Their interactions can be considered as a route to produce new materials of various technological applications. In this study, the effect of pH (3–7) as well as the mixing ratio of whey protein isolate (WPI)/soluble part of Persian gum (PG) (1:3, 1:1, 3:1, 6:1, and 9:1% w/w WPI/PG) on the complex formation behavior of the two polymers were studied using spectrophotometric and dynamic light scattering techniques, soluble protein measurement, and microscopic observations. Investigating the curves of turbidity versus pH showed that pHc and pHϕ1, which are associated with the formation of soluble and insoluble complexes, moved toward higher pH values by increasing WPI:PG ratio. Increased solubility was observed at pHc > pH > pHϕ1 for all biopolymers mixtures. In addition, lowering the pH toward pHϕ1 resulted in a decrease in the size of complexes, while further decrease of pH beyond this point led to larger particles. No significant difference was noticed between pHc and pHϕ1 of heated and unheated WPI/PG mixtures, although the turbidity of heated samples increased due to the formation of larger aggregates.

Effect of coacervation conditions on the viscoelastic properties of N,O-carboxymethyl chitosan - gum Arabic coacervates.

The effects of coacervation acidity, phase separation temperature, ionic strength, and biopolymer ratio on the viscoelasticity of the N,O-carboxymethyl chitosan (NOCC) - gum Arabic (GA) coacervate were investigated by using coacervate yield as the indicator of electrostatic interaction strength. The strongest interaction between NOCC and GA occurred at pH 3.0, whereas the highest modulus values were found in the coacervate separated at pH 6.0. The coacervate yield did not vary with phase separation temperature in the range 4-55°C, but the coacervate viscoelasticity declined as the temperature increased from 25°C to 45°C and then peaked at 55°C. The presence of NaCl weakened the electrostatic interaction between the two polyelectrolytes, but no dose-dependent reduction in viscoelasticity was observed for their coacervates. Besides, the highest electrostatic interaction strength and coacervate viscoelasticity were recorded at different GA to NOCC ratios. It is proposed that the strength of electrostatic interaction is not the only parameter that determines the viscoelasticity of the NOCC - GA coacervate.

Immobilization of Lipase Inhibitor on the Biopolymers from Agaricus bisporus Cell Walls.

One of the methods for curing obesity is the inclusion of some substances with the antilipase activity in the diet and thus reducing the uptake of fat components from food. The aim of this research is to provide a stabilized form of lipase inhibitor by immobilization of enzyme on the biopolymers from Agaricus bisporus cell walls. The phenolic compounds extracted from the rapeseed were considered as the lipase inhibitor. The activity of the inhibitor was considerably reduced in the gastric juice, as well as at temperatures above 37 °C and during its storage, which determined the suitability of the inhibitor for stabilization on the matrix. The effectiveness of the phenolic compound stabilization was investigated by means of immobilization on the biopolymers from Agaricus bisporus cell wall matrix. The biopolymers used were β-glucan, chitin, melanin and proteins. A number of samples, which differed both in the content of the inhibitor (from 1 to 16%) and in the ratio of biopolymers in the matrix composition, was obtained. The conditions of immobilization (temperature, duration of the process) were also varied. The expediency of obtaining the sample with the inhibitor content of 12% and matrix containing 47.9% of glucan, 18.8% of chitin, 18.8% of melanin and 11.1% of proteins was shown. The best immobilization was carried out at 20-25 °C for 30 min. Thermal analysis and infrared spectroscopy data confirmed that immobilization of the lipase inhibitor on the matrix was due to the hydrogen bonds. The immobilized inhibitor had higher pH stability and higher thermal stability than the original one. The remaining activity of the immobilized inhibitor was higher than the original one after incubation in the gastric acid and bile. The immobilized inhibitor was characterized by a low loss of activity after 12 months of storage.