Κ-carrageenan Solutions Research Articles

Synthesis and Characterization of Peppermint Oil Loaded Complex Coacervates of Chitosan Phosphate/κ-Carrageenan and Evaluation of their Antibacterial Activity

Peppermint oil has been in use as traditional medicine for several common ailments besides being used as flavourings in foods and beverages. Like other essential oils it is also susceptible to oxidative degradation on exposure to oxygen, light and heat, which results in its decreased shelf life. Complex coacervation is a commonly used technique to encapsulate essential oils to give protection against degradation as well as providing a carrier vehicle for sustained release. In present work, the peppermint oil was encapsulated in a complex coacervate from a chitosan derivative, chitosan phosphate and κ-carrageenan in the presence of glutaraldehyde as crosslinking agent. The reaction conditions were optimized .The highest yield of the coacervate was recorded at pH 4.6 of the reaction medium and at a ratio of 2:4 by volume of 0.3% (w/v) solution of chitosan phospahate and κ-carrageenan. The effect of the variation of amount of crosslinker on the morphology and swelling property of the coacervate was also investigated and both the properties were found to be affected. A maximum loading efficiency of 84.19% was observed. The swelling and release studies revealed that both were pH dependent and release of peppermint oil from the coacervate showed a sustained release profile over a period of 72 h. The peppermint oil loaded coacervates were investigated for their antibacterial activities against Micrococcus luteus, Staphylococcus epidermidis, Escherichia coli, Klebsiella pneumonia and Proteus vulgarus and found to be mildly effective against all of them.

Mangiferin loaded carrageenan/chitosan core-shell hydrogel beads: Preparation, characterization and proposed application

In this work, an investigation on the use of mangiferin, a bioactive compound, in a controlled release hydrogel system was carried out. Mangiferin isolated from mango leave waste was tested for its antibacterial activities by disc diffusion, agar well and agar dilution methods. The results confirmed effective antibacterial effects against Vibrio parahaemolyticus and Vibrio cholerae, the common species found in fresh seafood that can cause acute diarrheal illness. However, application of this polyphenolic natural compound is limited by its poor water solubility resulting in low bioavailability. To overcome is limitation, biopolymeric core-shell hydrogel beads incorporated with mangiferin were fabricated by a one-step gelling method. The core particles loaded with mangiferin were prepared from κ-carrageenan solution which were subsequently ionic-crosslinked and encapsulated with the chitosan shells. The formation of core-shell morphology was verified by light microscope observation and confirmed that the κ-carrageenan core was completely covered with the uniform shell of chitosan. The composition of microsphere beads was also examined with Fourier transform infrared spectroscopy and scanning electron microscopy equipped with energy dispersive X-ray analysis. The core-shell hydrogel was able to encapsulate mangiferin with the optimum loading efficiency of 85%. The release kinetics was evaluated at different temperatures and Korsmeyer-Peppas was the most appropriate model to represent the release profiles of mangiferin from hydrogel beads. Biocompatibility test performed on all of the hydrogel samples exhibited a good viability for the L929 and Vero cells with low cytotoxicity. Investigations on the microsphere hydrogels revealed that they could regulate the release of bioactive mangiferin and possessed promising potential to be utilized for quality protection of fresh seafood.

Kinetics of acid hydrolysis of k-Carrageenan by in situ rheological follow-up

Water based solutions of κ-Carrageenan (1.5% weight concentration), a high molecular weight polysaccharide, were subjected to acid-catalyzed hydrolysis under controlled pH (≈3) and temperature (from 40 to 70 °C). The hydrolysis process involves selective attack of the Carrageenan glycosidic bonds α(1–3) and β(1–4), determining changes in the weight average molecular weight of the macromolecule and, as a consequence, on the gelling behavior. In this study we used transient rheological tests to monitor the hydrolysis reaction and its consequences on both the sol-gel transition and the final gel properties. Hydrolysis reaction has been modelled using a bi-exponential kinetics. To this end, a rotational rheometer was equipped with a batch reactor configuration, consisting of a cylindrical vessel and a double helix mixing tool. Both viscous and viscoelastic properties of the samples were measured quantitatively and related to the biopolymer molecular weight, replacing more complex molecular weight determinations by an easier methodology. By using the above experimental approach, kinetic constants and activation energies for the κ-Carrageenan hydrolysis were obtained as a function of the hydrolysis temperature. The latter, along with the hydrolysis reaction time, was also shown to be a relevant parameter in determining the possibility of gel formation and of the gel mechanical strength (in the range 10–600 Pa).

Fabrication of a High-Strength, Tough, Swelling-Resistant, Conductive Hydrogel via Ion Cross-Linking, Directional Freeze-Drying, and Rehydration.

Conductive hydrogels have been in huge demand in biomedical and wearable electronics. However, the application of traditional conductive hydrogels is largely limited due to their poor mechanical properties. Here, a conductive hydrogel with excellent mechanical strength and swelling resistance properties is prepared by ion cross-linking, directional freeze-drying, and rehydration. First, the acrylamide and acrylic acid are polymerized in the κ-carrageenan solution to form the hydrogel. Then, the obtained hydrogel is cross-linked with Fe3+ by soaking in ferric chloride solution. Finally, the ionic cross-linked hydrogels are reinforced by directional freeze-drying and rehydration. The resulting hydrogel has excellent tensile strength (5.67 MPa) and high toughness (7.63 MJ/m3). It is worth noting that the hydrogel also had excellent anti-swelling properties. Its mechanical strength and volume almost show no changes after soaking in deionized water for 40 days. In addition, the hydrogel exhibits good ionic conductivity (0.091 S/m), high sensitivity, and excellent stability when applied as a strain sensor. This work proposes a simple method to fabricate a conductive hydrogel with great mechanical properties and swelling resistance, which displays huge potential in varied fields.

High radiation dose studies of kappa-carrageenan in dilute aqueous solution

Crosslinking or degradation of polysaccharides is one of the most important applications of radiation processing. Kappa-carrageenan (κ-carrageenan), one of the most frequently studied polysaccharides, is known to undergo degradation when exposed to ionizing radiation. In this work, irradiation of 1% κ-carrageenan solution (Mw 1.14 × 106 Da) at high radiation doses of 100–300 kGy resulted in an increase in molecular weight. The average molecular weight (Mw) increased from 5600 to 60,000 Da and 7500 to 69,000 Da with gamma and electron-beam irradiation, respectively. UV analyses of irradiated 1% solution showed an increasing absorbance at 265 nm, while FT-IR spectra still displayed some important functional groups and showed an increasing carbonyl and double bond groups with doses up to 300 kGy. The antioxidant properties also increased with dose but leveled off at 100 kGy. Further irradiation to 500 kGy led to the formation of microgels with a size of <5 μm under SEM, indicating the presence of a crosslinked chain of κ-carrageenan. The lowering of solution pH due to the release of sulfate groups during irradiation and the radical formation on the alkyl group of the side chain may be responsible for the radiation crosslinking of κ-carrageenan. The results of this study would be beneficial in understanding the radiation-induced changes in the structure and properties at different irradiation conditions, which may pave the way for various applications of carrageenan-based materials.

Interfacial viscoelastic moduli in a weak gel

HypothesisThe measurement of interfacial viscoelastic moduli provides information on the ability of surface-active agents to texture the interface. However, the contribution of the bulk rheology cannot be ignored in particular when the continuous phase exhibits a gel-like behavior, even with low modulus. ExperimentsBetween 2 and 6 g/L, κ-carrageenan aqueous solutions have no significant activities at interfaces. At low concentrations or high temperatures, they behave like Newtonian liquids. Upon heating or cooling, a reversible liquid/gel transition appears with a hysteresis where the rheological behavior can be easily modulated by adjusting κ-carrageenan concentration. The frequency dependence of bulk and interfacial viscoelastic moduli are determined using a conventional shear rheometer and a drop tensiometer with a polyisobutene oil, respectively. FindingsThe effect of concentration and temperature is analyzed and the frequency dependence of interfacial moduli is correlated with those of the bulk. In presence of a gelled κ-carrageenan solutions, an elastic behavior of the interface appears and strengthens as the elastic modulus of the suspended phase is high. It turns out that the oscillating pendant drop method could be a sensitive indicator of the presence of very weak gels, even hardly detected by a shear classical rheometry.

Self-assembled κ-carrageenase-inorganic hybrid nanoflowers exerting high catalytic efficiency with stable and recyclable properties

κ-Carrageenan oligosaccharides from κ-carrageenan hydrolysis are important biochemicals with more bioactivity. Enzyme engineering plays a key role in improving κ-carrageenase catalytic efficiency for production of κ-carrageenan oligosaccharides. Effect of metal ions on enzyme activity, especially stability and efficiency, is main factor in catalytic process, but metal ions addition leads to gelation of κ-carrageenan solution. In this study, molecular dynamics simulation was used to explore the interaction between κ-carrageenase CgkPZ and Ca2+, and Ca2+ bonded to D164 and E167 in the catalytic center resulting in the catalytic efficiency increase. Circular dichroism analysis indicated that the secondary structure of κ-carrageenase could change in the presence of Ca2+. Therefore, a novel self-assembly κ-carrageenase-inorganic hybrid nanoflowers CaNF@CgkPZ was synthesized and systematically characterized. The catalytic efficiency (kcat/Km) of CaNF@CgkPZ was 382.1 mL·mg−1·s−1, increased by 292% compared with free κ-carrageenase. Notably, the enzyme activity of CaNF@CgkPZ was not reduced significantly after 19 cycles use, and 70–100% relative activity was still retained when stored at 4–25 ℃ for 15 days. This work provides an efficient approach for κ-carrageenase immobilization with good storage stability, reusability and enhanced catalytic efficiency, which is of great significance in practical applications.

Soft κ-carrageenan microgels stabilized pickering emulsion gels: Compact interfacial layer construction and particle-dominated emulsion gelation

HypothesisThe well-known gelling ability of κ-carrageenan can make aqueous solutions into soft materials, which are crisp and can be mechanically treated into the nano-sized microgel particle (MP) as the building block for constructing the Pickering emulsion gel (PEG). MPs are expected to adhere and further create the network structure in PEGs due to their viscoelastic texture. Herein, properties of PEGs should be possibly altered by using MPs with different pH and ionic strength. ExperimentsMPs were prepared by shearing and gelling κ-carrageenan solutions simultaneously. Effects of pH and ionic strength on MPs were formulated, and physical properties of PEGs prepared from corresponding MPs were investigated. The interaction between κ-carrageenan molecules was analyzed by FTIR, and the formation process of the interfacial layer was traced by the interfacial rheological technique. FindingsThe moderate K+ could increase the flocculation and hardness of MPs to improve the viscoelasticity of PEGs. Prepared MPs were more favorable for forming PEGs when pH was 8 and 9. The oil fraction impacted physical properties of PEGs slightly. MPs constantly moved to the interface from the continuous phase, forming the compact adsorption layer due to the extrusion of MPs.

A green strategy for maintaining intelligent response and improving antioxidant properties of κ-carrageenan-based film via cork bark extractive addition

A multifunctional intelligent film was acquired by casting and drying a mixed solution of κ-carrageenan and hydroxypropyl methylcellulose (HPMC) with Prunus maackii pomace extract (EPM) as the natural pH indicator and cork bark extract (CBE) as the antibacterial agent. The film morphology and structure were evaluated by scanning electron microscopy. With the increasing CBE content from 0% to 1.2%, tensile strength of the films decreased from 10.67 to 9.37 MPa and elongation at break increased from 43.86% to 63.89%. The barrier performance and thermal stability of the films after CBE addition still met the food packaging standards. When more than 0.4% (w/w) CBE was added, the films could effectively shield ultraviolet rays. Besides, CBE addition to the films endowed excellent antioxidant properties and resistance to food-borne pathogens, ensured pH sensitivity, and extended the service life of the intelligent film. The films maintained good responsiveness in monitoring pork freshness, and the chromaticity difference was more obvious. Thus, the present study developed a multi-functional smart film with antioxidant, antibacterial, and pH-indicating functions.

Accurately intelligent film made from sodium carboxymethyl starch/κ-carrageenan reinforced by mulberry anthocyanins as an indicator

An accurately intelligent film was obtained by casting and drying a blend solution of sodium carboxymethyl starch (CMS) and κ-carrageenan with mulberry anthocyanin extract (MAE) as an indicator, which showed different colors at different pHs. The interactions of CMS, κ-carrageenan, and MAE in the film were investigated via Fourier transform infrared spectroscopy. The film morphology and structure were evaluated by using scanning electron microscopy and X-ray diffractometry. The effects of MAE addition on the film properties were discussed. The film remained continuous and had a dense structure with the increased addition of MAE which was well-distributed in the film-forming matrix of CMS and κ-carrageenan and exhibited a good compatibility. MAE addition from 0% to 5%, increased the TS of the film from 17.56 MPa to 25.35 MPa, however, decreased the EB% and the light transmittance at 500 nm from 56.12% to 30.47% and from 62.91% to 35.98%, respectively. The incorporation of MAE made the moisture move through the film more rapidly, but no remarkable effect was exerted on the heat stability of the films. The film was applied to indicate the freshness of fish (Cyprinus carpio var. specularis) and the red film changed to dark-blue as TVB-N of the fish reached 19.12 mg/100 g, which is close to the threshold value of freshness in the Chinese standard, showing an accurate response to the quality change. This study provides a feasible path to monitor fish freshness.

Properties of a commercial κ-carrageenan food ingredient and its durable superabsorbent hydrogels

Physical kappa-carrageenan-based hydrogels are often prepared from dilute aqueous kappa-carrageenan (κ-carrageenan) solutions at the presence of metallic ions or by mixing these solutions with proteins and other polysaccharides. The κ-carrageenan hydrogels have been used for technological purposes; however, there are no reports about the properties of a commercial GENUGEL® κ-carrageenan produced by the CP Kelco. The flame atomic absorption spectrometry shows that the commercial κ-carrageenan comprises a high content of metallic ions (K+ = 216.1 g kg−1, Na+ = 6.3 g kg−1 and Ca2+ = 12.5 g kg−1). The X-ray photoelectron spectroscopy (XPS) indicates the presence of sodium, calcium, and potassium atoms on the as-received κ-carrageenan and its physical hydrogel surfaces. XPS supports the occurrence of a low protein content onto the sample surfaces, as well. The metallic level (especially for K+) in the commercial κ-carrageenan plays an essential role in the preparation of durable hydrogels. These materials are prepared by cooling aqueous κ-carrageenan solutions at 4.0 and 5.0 wt%. The gelation temperature is determined by measuring G′ &G″ as a function of the temperature. The gelation behavior depends on the κ-carrageenan concentration, as well as the metallic content in the commercial sample. Scanning electron microscopy shows that hydrogels have porous and smooth surfaces. The dried materials swell from 2400 to 3100%, while the disintegration/dissolution test confirms that the samples present high stability in distilled water throughout 14 days. These hydrogels are superabsorbent materials and can be applied in agriculture as soil conditioners.

Associative behaviour of κ-carrageenan in aqueous solutions and its modification by different monovalent salts as reflected by viscometric parameters

The viscometric behaviour of κ-carrageenan in aqueous solutions and in the presence of monovalent salts was investigated at 25 °C. Coil, helix or double helix conformations were induced by cooling hot κ-carrageenan solutions under appropriate ionic conditions. A new viscometric approach was used for modeling the behaviour of κ-carrageenan solutions. The intrinsic viscosity, [η], is markedly changed by the presence of different monovalent salts (NaCl, NaI and CsI). In pure water, the intrinsic viscosity amounts to 48 dL·g−1. In 0.1 M NaCl solutions (single helix state) [η] is 6.2 dL·g−1, whereas in 0.1 M NaI (double helix conformation) it is approximately twice as large. In 0.1 M CsI (dissimilar cation and counter-ion) the intrinsic viscosity is three times larger, suggesting the formation of the associated κ-carrageenan helices. Stepwise association of κ-carrageenan helices was followed in presence of NaI/CsI mixtures of different compositions. The value of Smidsrød-Haug stiffness parameter (B) measured for κ-carrageenan in NaCl solutions is 4.47 × 10−2, higher than that of DNA (5.5 × 10−3), but lower than those reported for carboxymethyl cellulose (6.3 × 10−2), indicating that the chain conformation is moderately rigid.

Mixed iota and kappa carrageenan gels in the presence of both calcium and potassium ions

The effect was studied of adding both KCl and CaCl2 on gelation of solutions of ι-carrageenan, κ-carrageenan and mixtures of both types. The gel temperature (Tg) of ι-car was found to be determined by the CaCl2 concentration and Tg of κ-car by the KCl concentration. At a given salt concentration, ι-car was stiffest with pure CaCl2, but κ-car gels and mixed carrageenan gels were stiffer when both KCl and CaCl2 were present. Gelation of κ-car increased the turbidity of mixed carrageenan gels in the presence of KCl or CaCl2, but when both salts were present it led to a drop of the turbidity. In mixed salt, K+ induces formation of a homogeneous κ-car network that causes the mixed network to become more homogeneous. Rheological and structural properties of carrageenan gels can be tuned for a given polymer and salt concentration by adding both KCl and CaCl2 to κ-car/ι-car mixtures.

Effect of pH and Gas Flow Rate on Ozone Mass Transfer of Κ-Carrageenan Solution in Bubble Column Reactor

This research was conducted to calculate the mass transfer coefficient value for ozonation reaction of κ-carrageenan solution in the bubble column reactor. Ozone gas was produced using ozone generator type corona discharge. In this study, operating conditions were regulated at ozone gas flow rate 2- 5 L min-1, pH 4-10, and temperature 29 ± 1 oC. Samples were tested every 5 minutes to determine the dissolved ozone concentration. The results showed that dissolved ozone concentrations increased with increasing ozonation time and ozone gas flow rate. However, a very high gas flow rate can increase turbulence so that the mass transfer coefficient (kLa) value decreased. In alkaline conditions, the formation of free radicals (HO*) increases so that the amount of dissolved ozone decreases. The kLa value of ozone gas in κ-carrageenan solution is slightly lower than the kLa value of the ozone gas in the water. The results of this study indicate that (kLa) ozone gas in water is 0.131 / minute while the value (kLa) in κ-carrageenan solution is 0.128 / minute.Keywords: ozone; mass transfer; pH; flowrate

3D printing in situ gelification of κ-carrageenan solutions: Effect of printing variables on the rheological response

This work reports a successful 3D printing-based in situ temperature-induced gelification procedure of κ-carrageenan aqueous dispersions. 3D printer was modified to handle low viscosity fluid feeding and more efficiently distribute ambient air at room temperature causing forced convection to accelerate the cooling of the printed layer. Thus, obtained gel samples, containing 30 mg/g κ-carrageenan in water, showed self-sustaining capability and a rheological response comparable with a reference conventionally prepared gel. Moreover, the effect of main printing variables, such as temperature of the hotend, printing speed and layer height, on the linear viscoelastic response of the gels was analysed by application of the response surface methodology (RSM). In general, gel strength linearly increases by decreasing printing speed and layer height whereas not noticeable improvement in gel strength was achieved by applying hotend temperatures above 80–85 °C. Based on the results obtained from this analysis, an optimisation method is proposed to minimise the temperature and time needed to 3D print a gel with pre-set rheological properties. Overall, this study demonstrates that it is possible to generate in situ 3D printed gel materials with potential uses in food and pharmaco-nutrition, without the aid of reactive additives or initiators, and using a facile protocol.

Determination of kinetic and thermodynamic parameters of food hydrocolloids/water interactions by means of thermal analysis and viscometry

The aim of this study was to determine thermal properties of pseudoplastic polysaccharides (guar gum, κ-carrageenan and xanthan gum) which find many applications as food hydrocolloids in food industry. There was an obvious relationship between thermal dependency of heats of fusion of hydrocolloids in powder form and activation parameters of hydrodynamic flow in solutions, respectively. Results of thermal analysis confirmed, that powder samples of hydrocolloids as typical foodstuffs of low moisture content less than 15 w% after room conditioning, exhibited varying ability to bind water as depending on their molecular structure. The peak temperature of the endothermic polysaccharide order-disorder phase transition process was found in the temperature range of 50–85 °C. It was influenced simultaneously by the applied heating rate and the samples moisture content. Studied samples moisture content was ranging between 9–40 w.% as was obtained after different conditioning. Observed reaction enthalpy (ΔH) associated with phase transition and water evaporation (proved by appropriate weight loss of the samples Δmw) was ranging from 140 to 670 J/g. Activation energy (Ea) of this process in powder samples was calculated from the kinetic parameters using three kinetic models developed by Friedman, Kissinger and model-free kinetics. The latter kinetic models were compared with the Arrhenius model, which was used to determine Ea of polysaccharide solutions on reflecting sensitivity of their molecular structure to the temperature and the solvent. According to the Arrhenius model, there were obtained the highest values of Ea for κ-carrageenan solutions, indicating the highest resistance of their molecular structure to temperature. This fact can be related to the observed the lowest value of the reaction enthalpy in the case of powder samples, suggesting that energy obtained during the order-disorder transition to change the carrageenan powder structure is limited. On the other hand, xanthan gum was the least temperature dependent sample; activation energy of xanthan solutions was only in the range of 2–6 kJ/mol. Concurrently, ΔH of xanthan powder was determined as the largest of all samples under study. In general, there was found an indirect relationship between activation energy of the solutions determined by viscometry and reaction enthalpy of the powders determined by thermal analysis. Results of the Arrhenius model also indicate that the energy necessary to promote viscous flow of solutions is higher for hydrocolloids in distilled water rather than in 0.07 M KCl aqueous solutions, suggesting the suppression of the polyelectrolyte effect. In both cases, Ea was substantially reduced by application of higher shear rate.

Thermal, conformational and rheological properties of κ-carrageenan-sodium stearoyl lactylate gels and solutions

Polysaccharide-surfactant blends are widely used in foods. However, their possible mutual interactions have not been extensively studied. The purpose of this work was to examine how the anionic surfactant sodium stearoyl lactylate (SSL) affects different properties of κ-carrageenan solutions and gels. Rheometry, differential scanning calorimetry, asymmetrical flow field-flow fractionation coupled with multiangle laser light scattering, among others, were used to determine the flow and viscoelastic behavior, thermal transitions, and conformation changes, respectively. Interference caused by SSL is postulated as the primary factor to explain the variations in the conformation of κ-carrageenan in gels and solutions. However, electrostatic repulsions between κ-carrageenan and SSL can also be involved. These latter interactions are more important for high SSL concentrations (13 mmol dm−3) without addition of KCl, because of the higher net negative charge density of the system. SSL significantly modifies the properties of κ-carrageenan in aqueous media.

Ultrathin κ-Carrageenan/Chitosan Hydrogel Films with High Toughness and Antiadhesion Property.

Designing tough biopolymer-based hydrogels as structural biomaterials has both scientific and practical significances. We report a facile approach to prepare polysaccharide-based hydrogel films with remarkable mechanical performances and antiadhesion property. The hydrogel films with a thickness of 40-60 μm were prepared by mixing aqueous solutions of κ-carrageenan (κ-CG) and protonated chitosan (CS), evaporating the solvent, and then swelling the casted film in water to achieve the equilibrium state. The obtained κ-CG/CS gel films with a water content of 48-88 wt % possessed excellent mechanical properties with a breaking stress of 2-6.7 MPa and a breaking strain of 80-120%, superior to the most existing biopolymer-based hydrogels. The extraordinary mechanical properties of gel films obtained over a wide range of mass ratio of κ-CG to CS should be rooted in the synergistic effect of ionic and hydrogen bonds between the κ-CG and CS molecules. In addition, the tough gel films showed good self-recovery ability, biocompatibility, and cell antiadhesion property, making them promising as an artificial dura mater and diaphragm materials in the surgery. The design principle by incorporating multiple noncovalent bonds to toughen the biopolymer-based hydrogels should be applicable to other systems toward structural biomaterials with versatile properties.

АКТИВНІСТЬ СУПЕРОКСИДДИСМУТАЗИ І КАТАЛАЗИ У СТІНЦІ ТОНКОЇ КИШКИ, СЕРЦІ І ПЕЧІНЦІ ПРИ ЕКСПЕРИМЕНТАЛЬНОМУ ЗАСТОСУВАННІ КАРАГІНАНУ

Вступ. Одним з провідних механізмів формування синдрому органних дисфункцій при різних патологіях є гіперпродукція активних форм оксигену, які запускають процеси пероксидного окиснення в органах і тканинах, віддалених від вогнища ураження [6]. Виникнення оксидативного стрессу зумовлене також зниженням ефективності антиоксидантного захисту.Тому, метою нашого дослідження було встановити активність супероксиддисмутази та каталази в тканинах тонкої кишки, серця і печінки тварин при застосуванні 1% розчину κ-карагінану.Матеріали та методи дослідження. Дослідження проведено на 24 білих нелінійних самцях-щурах. Тваринам дослідної групи забезпечували вільний доступ до 1,0 % розчину карагінану у питній воді протягом 1 місяця. У відібраних зразках тонкої кишки, серця і печінки оцінювали активність супероксиддисмутази і каталази.Результати досліджень та їх обговорення. Встановлено, що застосування 1 % розчину κ-карагінану щурам у питній воді зумовлювало активацію ензимної ланки антиоксидантної системи захисту. Встановлено зростання активності СОД в гомогенаті стінки тонкої кишки (в 1,32 раза, р&lt;0,05) і печінці (в 1,30 раза, р&lt;0,05). Підвищувалася також активність каталази у гомогенаті стінки тонкої кишки (в 1,18 раза, р&lt;0,05) і печінці (в 1,13 раза, р&lt;0,05). При цьому коефіцієнт антиоксидантного захисту в стінці кишки становив 1,11 (р&lt;0,05), в міокарді – 1,0 і в печінці – 1,15 (р&lt;0,05).Висновок. Пероральне застосування 1% розчину карагінану щурам веде до статистично значимої активації ензимної ланки антиоксидантного захисту в стінці тонкої кишки і печінці, що характеризується підвищенням, відповідно, активності СОД (на 31,8 % і 29,7 %) і каталази (на 18,3 % і 12,9 %), р&lt;0,05.

Interactions and phase behaviors in mixed solutions of κ-carrageenan and myofibrillar protein extracted from Alaska Pollock surimi

In the present work, we provide insight into electrostatic interactions and phase behaviors in mixtures of myofibrillar protein (MP) and κ-carrageenan (KC) of various pHs (8.0–3.0) and biopolymer weight ratios [R, from 1:1 to 20:1; total concentration=0.05% (w/w)] through turbidimetric analysis, dynamic light scattering (DLS) and zeta potential analysis, and optical microscopy. At R=1: 1, critical pH values (i.e., pHc, pHΦ1, and pHΦ2), which indicate phase transitions interrelated to the formation of soluble or insoluble MP-KC complexes, were observed at pH7.6, 6.8, and 3.6, respectively. As the ratio increased, the pHmax shifted from 4.9 to 5.8. A similar trend was observed for the isoelectric point of MP-KC mixtures, as determined by zeta potential measurements. The maximum interaction indicated by the highest turbidity occurred at pHmax=5.3, at a ratio of 5:1, whereas pHc remained constant during acidification. The changes in electrostatic interactions and transformations of phase behaviors accompanying the complex formation and disassociation processes were further supported by particle size distribution analysis and optical microscopic observations of MP-KC mixtures (R=1:1) at different pH values. This work fills the previous lack of studies on phase behaviors of surimi protein and colloidal polysaccharide in liquid system, and lay the foundation to provide a new way to solve problems of interactions between protein and polysaccharide during the processing of surimi products.