Carrageenan Research Articles

Carrageenan/Chitin Nanowhiskers Cryogels for Vaginal Delivery of Metronidazole.

The development of polymeric carriers based on partially deacetylated chitin nanowhiskers (CNWs) and anionic sulfated polysaccharides is an attractive strategy for improved vaginal delivery with modified drug release profiles. This study focuses on the development of metronidazole (MET)-containing cryogels based on carrageenan (CRG) and CNWs. The desired cryogels were obtained by electrostatic interactions between the amino groups of CNWs and the sulfate groups of CRG and by the formation of additional hydrogen bonds, as well as by entanglement of carrageenan macrochains. It was shown that the introduction of 5% CNWs significantly increased the strength of the initial hydrogel and ensured the formation of a homogeneous cryogel structure, resulting in sustained MET release within 24 h. At the same time, when the CNW content was increased to 10%, the system collapsed with the formation of discrete cryogels, demonstrating MET release within 12 h. The mechanism of prolonged drug release was mediated by polymer swelling and chain relaxation in the polymer matrix and correlated well with the Korsmeyer-Peppas and Peppas-Sahlin models. In vitro tests showed that the developed cryogels had a prolonged (24 h) antiprotozoal effect against Trichomonas, including MET-resistant strains. Thus, the new cryogels with MET may be promising dosage forms for the treatment of vaginal infections.

Preparation and adsorption behavior of dodecyltrimethylammonium bromide modified carrageenan hydrogel beads with remarkable removal efficiency and thermostability in water

AbstractIn this study, water‐soluble polymer carrageenan (CAR) was cross‐linked by dodecyltrimethylammonium bromide (DTAB) in an aqueous solution for the preparation of gel beads, which can be used for removal of methylene blue (MB). The combination of DTAB and CAR was validated by Fourier transform infrared (FTIR) spectroscopy, while the folded surface was characterized by scanning electron microscope. DTAB can be used as a modifier of CAR for promoting the hydrophobicity and stability of hydrogel beads, which even withstood 70°C in water for 24 h without dissociation. The best removal efficiency was achieved 99.6% in 100 mg L−1 MB aqueous solution by CAR‐0.5DTAB, and the maximum adsorption capacity of CAR‐1.5DTAB at 30°C reached 38.6 mg g−1 by wet weight (weight of gel beads in wet condition) in 2000 mg L−1 MB aqueous solution. The CAR‐DTAB adsorption behavior was best fitted with pseudo‐first‐order and Langmuir equations, respectively. The exothermic nature and spontaneity of adsorption process were proved by thermodynamic experiment. Reusability studies revealed that the adsorption performance displayed almost no change after 10 cycles of adsorption/desorption process. The properties of CAR‐DTAB in this research proposed a facile way to prepare stable CAR composite by cross‐linking with quaternary ammonium surfactant.

Cultivable seaweeds eliminate the lethal effects of the harmful alga, Margalefidinium polykrikoides, on early life stage fish

Margalefidinium polykrikoides (aka Cochlodinium polykrikoides) is a harmful algal bloom (HAB)-forming dinoflagellate that is well-known for its ichthyotoxic properties, causing economically significant fish kills globally during bloom events. In this study, we evaluate the ability of seaweeds, including Ulva spp., Gracilaria sp., Chondrus crispus, and Grateloupia turuturu to mitigate the ichthyotoxicity of cultured and bloom populations of M. polykrikoides towards early life stage forage fish (Menidia menidia, Menidia beryllina, and Cyprinodon variegatus). In assays with both cultured and wild M. polykrikoides, live seaweed thalli – particularly Ulva spp. – significantly extended fish survival in all cases, with higher concentrations of seaweed resulting in a greater protective effect. In some cases, seaweeds completely mitigated fish mortality, resulting in survival not statistically different from the control. DMSP, an antioxidant compound produced by seaweeds, significantly reduced the ichthyotoxic effects of M. polykrikoides (p < 0.005) with no Ulva present, suggesting that the antioxidant properties of seaweeds and seaweed metabolites may be partly responsible for the protective effects. Partition chamber survival assays demonstrated that close physical proximity between the fish and Ulva was necessary for a protective effect to occur. Finally, we show that over longer timescales, very low concentrations of Ulva (0.2 g L-1) can significantly reduce (68–92% reduction) bloom populations of wild M. polykrikoides compared to control (p < 0.05). Collectively, the results of this study demonstrate that (1) aquaculture of Ulva spp. may be a viable strategy to protect caged fish farms from M. polykrikoides blooms, (2) existing beds of Ulva and other seaweeds may provide a refuge for vulnerable fish populations during M. polykrikoides blooms, and (3) the protective effects of seaweeds from M. polykrikoides ichthyotoxicity is due to a localized antioxidant-rich microenvironment around the surface of the seaweed, neutralizing short-lived reactive oxygen species produced by M. polykrikoides.

Network interpenetrating slow-release nitrogen fertilizer based on carrageenan and urea: A new low-cost water and fertilizer regulation carrier

Modern agriculture presents new requirements of low cost, high water retention and degradability for superabsorbent and slow-release fertilizers. In this study, carrageenan (CG), acrylic acid (AA), N, N ‘-methylene diacrylamide (MBA), urea and ammonium persulfate (APS) were used as raw materials. A kind of high water absorption, water retention, nitrogen slow release and biodegradable carrageenan superabsorbent (CG-SA) was prepared by grafting copolymerization. The optimal CG-SA was obtained with a water absorption rate of 680.45 g/g by orthogonal L18(3)7 experiments and single-factor experiments. The water absorption behavior of CG-SA in deionized water and salt solution were studied. The CG-SA was characterized before and after degradation by FTIR, SEM. The nitrogen release behavior and kinetic characteristics of CG-SA were investigated. In addition, CG-SA degraded 58.33 % and 64.35 % in soil at 25 °C and 35 °C after 28 days. All the results indicated that the low-cost and degradable CG-SA can achieve simultaneous slow release of water and nutrients, which is expected to be widely used as a new water-fertilizer integration technology in arid and poor areas.

Different Chondrus crispus Aquaculture Methods and Carrageenan Extraction

With the notable scarcity of Chondrus crispus on the Portuguese coast, and interest in exploiting compounds such as carrageenan, this study focuses on investigating different aquaculture methods and recording the yield of carrageenan from specimens grown by different methods. We compare the growth of Chondrus crispus in aquaculture using Free Floating, Cages, Attempted Fixation on Rock, and Fixed Line similar to Long Line. The best method was Free Floating where Nursery 0 had a 24-day Specific Growth Rate (SGR) of 2.08 ± 0.47%/day. The worst method in terms of growth was Nursery 2 (Attempted Fixation on Rock) where the SGR at 28 days was 0.33 ± 0.69%/day, and no fixation was observed. In terms of carrageenan extraction, all culture methods gave rise to biomass that had a lower extraction yield than wild specimens, at 50.95 ± 4.10%. However, the Free-Floating method from Nursery 1 showed an acceptable carrageenan content (31.43 ± 7.00%). Therefore, we demonstrate that the concept of C. crispus cultivation may be key to promoting the sustainability and stability of this species.

Quality improvement of plant-based meat alternatives by addition of iota carrageenan to pea protein–wheat gluten blend

In this study, the influence of iota carrageenan (IC) addition at different steps to the protein blends based on pea protein isolate (PPI) and wheat gluten (WG) as well as hydration mixing time and temperature of IC on the quality attributes of plant-based meat alternatives was studied. In more detail, IC was added before (B, in water with mixing times of 15 or 30 min and temperatures of 25 or 75 °C) or after (A, in powder form) the addition of PPI to the mixture with or without calcium chloride (Ca) in the formulation. The results showed that the addition of IC after PPI, especially combination with Ca resulted in the products with the most visible fibers, which can be considered as a quality improvement. IC addition to the formulations with or without Ca also increased the browning index, water holding capacity, tensile stress, and air bubble numbers compared to the PPI.WG formulation. However, no considerable difference in these parameters was found regarding the addition order of IC (before or after the addition of PPI). As the addition of IC after PPI hydration needs less energy for mixing, and, thus, less time for preparation, this order of addition can be recommended for improving the quality of plant-based meat alternatives containing IC. Therefore, hydration of IC in water, especially at high temperatures, is not necessary for the production of plant-based meat alternatives produced in the high-temperature shear cell (HTSC).

Dose response effects of Himanthalia elongata, Chondrus crispus, Alaria esculenta and Fucus vesiculosus macroalgae on in vitro rumen fermentation and methane production compared against Asparagopsis taxiformis

Dose response effects of Himanthalia elongata, Chondrus crispus, Alaria esculenta and Fucus vesiculosus macroalgae on in vitro rumen fermentation and methane production compared against Asparagopsis taxiformis

N-methyl-d-aspartate receptors induce M1 polarization of macrophages: Feasibility of targeted imaging in inflammatory response in vivo

BackgroundN-methyl-d-aspartate receptors (NMDARs) are considered to be involved in several physiological and pathophysiological processes in addition to the progression of neurological disorders. However, how NMDARs are involved in the glycolytic phenotype of M1 macrophage polarization and the possibility of using them as a bio-imaging probe for macrophage-mediated inflammation remain unclear.MethodsWe analyzed cellular responses to NMDAR antagonism and small interfering RNAs using mouse bone marrow-derived macrophages (BMDMs) treated with lipopolysaccharide (LPS). An NMDAR targeting imaging probe, N-TIP, was produced via the introduction of NMDAR antibody and the infrared fluorescent dye FSD Fluor™ 647. N-TIP binding efficiency was tested in intact and LPS-stimulated BMDMs. N-TIP was intravenously administered to mice with carrageenan (CG)- and LPS-induced paw edema, and in vivo fluorescence imaging was conducted. The anti-inflammatory effects of dexamethasone were evaluated using the N-TIP-mediated macrophage imaging technique.ResultsNMDARs were overexpressed in LPS-treated macrophages, subsequently inducing M1 macrophage polarization. Mechanistically, NMDAR-mediated Ca2+ accumulation resulted in LPS-stimulated glycolysis via upregulation of PI3K/AKT/mTORC1 signaling. In vivo fluorescence imaging with N-TIP showed LPS- and CG-induced inflamed lesions at 5 h post-inflammation, and the inflamed lesions could be detected until 24 h. Furthermore, our N-TIP-mediated macrophage imaging technique helped successfully visualize the anti-inflammatory effects of dexamethasone in mice with inflammation.ConclusionThis study demonstrates that NMDAR-mediated glycolysis plays a critical role in M1 macrophage-related inflammation. Moreover, our results suggest that NMDAR targeting imaging probe may be useful in research on inflammatory response in vivo.

Non-toxic and biodegradable κ-carrageenan/ZnO hydrogel for adsorptive removal of norfloxacin: Optimization using response surface methodology

Antibiotic resistance is increasing globally due to increased prescription and easy dispensing of antibiotic drugs universally. Hence, to mitigate this effect, efficient, biodegradable, and non-toxic adsorbents are required to be developed. Carrageenan (CG), a natural polymer, having multiple functional groups, provides a backbone for crosslinking with borax and incorporation of ZnO nanoparticles that formed borax-cross-linked κ-carrageenan (CG/Bx/ZnO) hydrogel which is used for efficient adsorption of norfloxacin from water. Surface morphology of as-synthesized hydrogel revealed the rough surface, which was determined by FESEM. Surface area of CG/Bx/ZnO hydrogel was found to be 22.90 m2/g with 3.41 nm pore radius. Systematic batch adsorption studies revealed that 99.4 % removal efficiency could be achieved at a dosage level of 20 mg/L of norfloxacin with 10 mg of hydrogel at pH of 4 in 8 h at room temperature. Experimentally optimized key parameters affecting the overall efficiency of adsorption matched well with the results assessed from ANOVA using Box-Behnken composite design model. The adsorption process was well fitted with the pseudo-second-order model and Langmuir isotherm with 1282.05 mg/g adsorption capacity. Thermodynamic study results show that adsorption is spontaneous and endothermic. The CG/Bx/ZnO hydrogel demonstrated excellent repeatability with minimal loss in norfloxacin adsorption for seven cycles.

Cover

On the Cover: Celebrating the 50th anniversary of Journal of Biogeography, the cover is comprised of five circles representing the journal’s five decades and papers in the current issue. Centre: Phyteuma hemisphericum from the Sierra de Villabandín, Cantabrian Mountains, Spain; photograph by Borja Jiménez-Alfaro; pp. 743–754. Top right: Chondrus crispus Stackhouse (commonly known as Irish moss) is a middle intertidal to subtidal red algae that inhabits European and American Atlantic rocky shores, including the Vigo estuary, Galicia (Spain); photograph by Sandra Hernández; pp. 780–791. Top left: Cauliflower corals (Pocillopora spp.) encounter multiple environmental conditions across the Indo-Pacific and have diverse microbial communities (including bacteria, photosymbiotic dinoflagellates, viruses) that are implicated in health and bleaching outcomes under climate change; illustration by Victoria Marie Glynn; pp. 669–684. Bottom left: A stream in the Tibet Plateau, the world’s third pole; photograph by Gong Zheng; pp. 792–804. Bottom right: The cover of the first issue (March 1974) and initial 14 volumes of the Journal of Biogeography were graced by this circular logo; the golden text celebrates the journal’s 50th year.

Attenuation of COX-2 enzyme by modulating H2O2-mediated NF-κB signaling pathway by monoamine oxidase inhibitor (MAOI): a further study on the reprofiling of MAOI in acute inflammation.

This study aims to investigate the anti-inflammatory mechanism of monoamine oxidase inhibitor (MAOI) in carrageenan (CARR) induced inflammation models to reprofile their use. We also aimed to explore the role of monoamine oxidase (MAO)-mediated H2O2-NF-κB-COX-2 pathway in acute inflammation. In vitro anti-inflammatory activity and hydrogen peroxide (H2O2) scavenging activity were performed according to the established procedure. Inflammation was induced using CARR in BALB/c mice at the foot paw and peritoneal cavity. Hourly measurement of paw swelling was performed. The level of nitric oxide (NO), myeloperoxidase (MPO), cyclooxygenase-2 (COX-2), prostaglandin E2 (PGE2) and nuclear factor κB (NF-κB) was determined using enzyme-linked immunosorbent assay (ELISA). Peritoneal fluid was collected to investigate total count, differential count of leukocytes, and capillary permeability. In vitro anti-inflammatory evaluations revealed the potential role of MAOI to inhibit heat-induced protein denaturation and human red cell membrane destabilization. H2O2 inhibition activity of MAOI also proved their powerful role as an H2O2 scavenger. Treatment with MAOI in CARR-induced mice significantly reduced paw edema, leukocyte extravasation, and total and differential leukocyte count. The result of ELISA showed MAOI effectively reduce the level of COX-2, PGE2 and NF-κB in inflamed tissue. In short, this study demonstrates that inhibition of H2O2 by MAOI alleviates CARR-induced paw edema possibly by inhibiting the H2O2-mediated NF-κB-COX-2 pathway. The present investigation identifies MAOI might reprofile for the treatment of acute inflammation also, the MAO enzyme may use as a novel therapeutic target to design and develop new class of anti-inflammatory agents.

Injectable hybrid hydrogels physically crosslinked based on carrageenan and green graphene for tissue repair

Injectable and biocompatible novel hybrid hydrogels based on physically crosslinked natural biopolymers and green graphene for potential use in tissue engineering are reported. Kappa and iota carrageenan, locust bean gum and gelatin are used as biopolymeric matrix. The effect of green graphene content on the swelling behavior, mechanical properties and biocompatibility of the hybrid hydrogels is investigated. The hybrid hydrogels present a porous network with three-dimensionally interconnected microstructures, with lower pore size than that of the hydrogel without graphene. The addition of graphene into the biopolymeric network improves the stability and the mechanical properties of the hydrogels in phosphate buffer saline solution at 37 °C without noticeable change in the injectability. The mechanical properties of the hybrid hydrogels were enhanced by varying the dosage of graphene between 0.025 and 0.075 w/v%. In this range, the hybrid hydrogels preserve their integrity during mechanical test and recover the initial shape after removing the applied stress. Meanwhile, hybrid hydrogels with graphene content of up to 0.05 w/v% exhibit good biocompatibility for 3T3-L1 fibroblasts; the cells proliferate inside the gel structure and show higher spreading after 48 h. These injectable hybrid hydrogels with graphene have promising future as materials for tissue repair.

The Role of Protein-Rich Extracts from Chondrus crispus as Biostimulant and in Enhancing Tolerance to Drought Stress in Tomato Plants.

The application of seaweed extract-based biostimulants is a promising approach for achieving sustainable agriculture, with an enormous potential of improving crop yield and mitigating climate change effects. Abiotic stressors, such as drought, are major factors resulting in tomato (Solanum lycopersicum L.) yield losses and seaweed-based biostimulants have been proposed as an eco-friendly strategy to counteract this negative impact. Chondrus crispus is a common red seaweed widely used as source of carrageenans, not yet explored as a plant biostimulant. In this study, a protein hydrolysate-rich C. crispus extract, by-products of the carrageenan extraction, was tested on tomato plants under well-watered condition and water shortage. The foliar application of the protein-rich C. crispus extract conferred drought tolerance to tomato plants resulting in less noticeable visual stress symptoms. Treated plants showed higher shoot height and biomass under both well-watered and water deficit conditions, evidencing the double effect exerted by this new biostimulant, as plant growth promoter and drought stress protector. The treatment with the biostimulant had an effect on levels of abscisic acid and proline, and triggered the expression of Solyc02g084840, a drought marker gene. Finally, a label-free mass spectrometric approach allowed us to identify phycoerythrins and phycocyanins as major bioactive proteins contained in the extract. Altogether, these results indicate that the foliar application of protein hydrolysate-rich extracts from C. crispus improved tomato plant growth and tolerance to drought stress, suggesting a new opportunity for further applications in the agriculture and horticultural sectors.

Enhancing solid-like characteristics of porcine plasma protein-carrageenan-based high internal phase emulsion: As solid fat alternative of loading curcumin

This study explored the feasibility of a novel solid-like fat stabilized by porcine plasma protein (PPP) and carrageenan (CG) coupling emulsifier as curcumin delivery vehicle. The combination of 2.0% (w/v) PPP and 0.3% (w/v) CG successfully stabilized the oil of 80% (v/v) volume fraction at solid-like state, and the increasing of oil phase led to the increase in droplet size, storage modulus (G′) and apparent viscosity. Compared with free oil, oxidation of PPP-CG-stabilized solid-like fat could be significantly inhibited. The results from in vitro simulated digestion showed that the release rate of free fatty acids and bioaccessibility of curcumin in the solid-like fat were significantly higher than those in free oil, and curcumin was almost not released in simulated gastric fluid, but mainly released in simulated intestinal fluid. Therefore, PPP-CG-stabilized solid-like fat could be used as an effective nutrient delivery vehicle for food and pharmaceuticals, and the work provided some new insights into the structure design of functional food.

Role of polysaccharide structure in the rheological, physical and sensory properties of low-fat ice cream

Polysaccharides can be used as fat replacers in ice cream, as they contribute to an increase of viscosity. However, no research has clarified the exact role of viscosity from that of the structure of the polysaccharides on the properties of ice cream. In this study, the effect of polysaccharide structure on different properties of low-fat ice cream was investigated. The polysaccharides taken into consideration varied from flexible (locust bean gum and guar gum) to rigid (xanthan gum and iota carrageenan). Relationships between rheological properties of ice cream mixes and microstructural characteristics and sensory perception of the final ice cream were established. To separate the effect of the polysaccharide structure from that of viscosity, two series of ice cream were prepared: one in which the mix viscosity of the various samples was similar (approximately 68.3 mPa· s), and one in which the serum phase viscosity was similar (approximately 15563 mPa· s). Flexible polysaccharides showed a lower degree of shear-thinning and a more liquid-like viscoelastic behavior compared with rigid polysaccharides. In addition, flexible polysaccharides led to higher overrun (47–58%) than other samples (approximately 30%), which resulted in lower hardness of the ice cream (<3.2 MPa). Rigid polysaccharides caused gelation of the serum phase, which made the ice cream more difficult to scoop. Based on the results of the sensory evaluation, flexible polysaccharides could provide higher softness and creaminess-related properties, while rigid polysaccharides resulted in higher coldness and grittiness. Therefore, polysaccharides with a flexible structure are a better choice for improving the textural and sensory properties of low-fat ice cream.

A highly conductive gel electrolyte with favorable ion transfer channels for long-lived zinc-iodine batteries.

Aqueous rechargeable zinc-iodine batteries (ARZIBs), as a powerful energy alternative, have inherent advantages, such as low cost, good safety and environmental friendliness. Unfortunately, uneven Zn deposition with dendrite growth and undesirable side reactions seriously compromises the safety and stability of ARZIBs. Herein, a novel strategy is demonstrated to fabricate highly conductive iota-carrageenan (IC) gel electrolyte. The unique double helix structure with good mechanical properties provides favorable Zn2+ channels guided by sulfate groups, which enables confinement effect and orderly guidance of Zn deposition. Additionally, the activity of water molecules confined in the gel electrolyte is reduced, thus inhibiting the corrosion reactions of the zinc electrode. As a result, the gel electrolyte with remarkable ionic conductivity (42.95 mS cm-1) showed a good cycling stability over 1000 h. Importantly, the Zn-I2 batteries with the IC-Zn gel electrolyte demonstrated remarkable reversibility with an impressive capacity retention (91.9%) over 5000 cycles and high average coulombic efficiency (99.86%). This work provides a reliable strategy to develop natural polymer gel electrolytes to regulate the Zn deposition for advanced rechargeable Zn-I2 batteries.

Novel mannich-based derivative of 2-mercaptobenzimidazole (AK7): a new candidate for the treatment of inflammatory arthritis owing to its NF-κB1 inhibitory potential.

This study investigated the anti-arthritic potential of novel mannich-based derivatives of 2-mercaptobenzimidazole (AK7 and AK9) in rats. The compounds were characterized by NMR and FTIR spectroscopies and their acute anti-inflammatory effects were measured by carrageenan (CRG)-induced paw edema model. The most potent doses of AK7 and AK9 were subsequently evaluated in the complete Freund's adjuvant (CFA)-induced inflammatory arthritis model. AK7 and AK9 inhibited CRG-induced inflammation in a dose-dependent fashion and a similar reduction in CFA-induced paw inflammation was observed. Moreover, X-ray and histopathological analyses of AK7-treated animals displayed normal joint structure whereas AK9, despite of its anti-inflammatory effects, failed to protect against cartilage destruction. Interestingly, biochemical analysis revealed a better safety profile for AK7 than for AK9 and methotrexate. Both compounds suppressed mRNA levels of pro-inflammatory mediators (IRAK1, NF-κB1, TNF-α, IL1B) while only AK7 reduced the transcript levels of interstitial collagenase (MMP1). Molecular docking analysis of AK7 and AK9 with TNF-α and MMP1 also supported the experimental data. These findings clearly highlight the beneficial effects of AK7 in the prevention and/or treatment of inflammatory arthritis.

Compositional and rheological analysis of carrageenan from the gametophyte phase of the red seaweed Chondrus crispus neutrally extracted at varying temperatures and time

Carrageenan-rich precipitate (CRP) was extracted from gametophyte Chondrus crispus at varying temperatures (22 °C, 45 °C, 90 °C) and time (0.25 h, 2 h, 8 h) at neutral conditions (i.e. without addition of alkali). Lower levels of 3,6-anhydrogalactose were detected in CRPs extracted at room temperature (22 °C) compared to extractions at 45 °C and 90 °C, suggesting a lower proportion of gelling units. Meanwhile, the CRPs obtained during the first period of extraction (0.25 h, at 45 °C and 90 °C) showed a higher amount of sulphate as compared to extractions for 2 or 8 h, suggesting a higher proportion of precursor units. These compositional differences were also supported by rheological studies. Gels made from CRP extracted at 22 °C had lower shear elastic modulus (G’) compared to gels made from CRP extracted at higher temperatures (45 °C, 90 °C). This was likely due to the lower 3,6-anhydrogalactose content in the extraction made at room temperature. In addition, the viscosity of gels made from CRP extracted at 0.25 h were higher compared to gels made from CRP extracted at 2–8 h for the same temperature (45 °C or 90 °C). This could be due to the higher amount of sulphate detected in the CRP of the former. Since 3,6-anhydrogalactse is an indicator of transformed (gelling) units, this result suggested that carrageenan chains with higher proportion of precursor units are more extractable under mild conditions. This knowledge may lead to the possibility for selective carrageenan extraction. • There are various carrageenan fractions in the seaweed cell walls that differ in terms of extractability in water. • Carrageenan fraction extracted at 22 °C contains lower amounts of 3,6-anhydrogalactose. • Gels made from carrageenan fraction extracted at 22 °C exhibits lower G’ values. • Carrageenan fraction obtained during the first period of extraction (0.25 h, at 45 and 90 °C) contains higher proportion of sulphate units. • Gels made from carrageenan obtained during the first period of extraction (0.25 h, 45 and 90 °C) exhibits lower viscosity values.

Ultrasound combined with carrageenan and curdlan addition improved the gelation properties of low-salt chicken meat paste

Excess Na+ intake can easily lead to chronic diseases, whereas the sodium salt plays very important role in maintaining meat product quality. To overcome the low-salt induced deterioration, the ultrasound treatment (UT) was coupled with polysaccharide addition (PS) to improve the gelation properties of low-salt chicken meat product. Carrageenan (CAR) and curdlan (CUD) were chosen as PS sources. The application of UT, CAR, CUD could all effectively decrease cooking loss, and CUD group showed lowest cooking loss. However, CUD and CUD-UT treatment both reduced the gel hardness significantly, while CAR and CAR-UT showed greatly positive effects on texture. CAR/CUD decreased the whiteness of gels, while the corporation with UT diminished the negative impact. UT could improve gel quality of CAR group by lowering the particle size, making polymers more evenly distributed and increasing viscosity. UT showed different influence on CAR and CUD samples, which is probably induced by various water distribution population in these groups. Overall, CAR-UT showed the best quality, which provides important information for development of low-salt meat products.

Microrheological properties and local structure of ι-carrageenan gels probed by using optical tweezers

Iota carrageenan (IC) is one of the most important gelling carrageenans in food and biotechnological applications; however, some of its potential applications have been constrained by its weak gelation ability. In order to better understand the origin of the weak mechanical response of IC gels, the hierarchical network structure based on meso- and microrheological properties of IC gels at 20 °C were probed via passive and active microrheology both performed by using optical tweezers (OT). Passive microrheology captures a wide spectral content of IC viscoelastic properties, revealing a rubbery plateau of the elastic modulus at relatively high frequencies for all IC concentrations; thus, uncovering the dynamics of the network. Moreover, different microstructures of IC gels were inferred by analyzing the concentration-dependent stress response when applying large deformation to the network. At low IC concentration, yielding was observed as indicated by the stress-independent response vs. strain, implying the structural rearrangement and disentanglement. As the IC concentration increased, the yielding diminished with increasing strain rate due to increased entanglement density, which limits the rearrangement of clusters. Therefore, this study presents novel insights into the meso- and microscale properties of IC gels that otherwise would not be accessible by conventional bulk rheology and submicroscopic probe diffusion measurements.