Starch-carrageenan interactions in aqueous media: Role of each polysaccharide chemical and macromolecular characteristics

Preparation and properties of cationic starch-carrageenan‑sodium alginate hydrogels with pH and temperature sensitivity

In this study, cationic starch-carrageenan‑sodium alginate (CAS/CR/SA) hydrogels with different weight ratios of carrageenan and sodium alginate were prepared and their properties such as scanning electron microscopy (SEM), rheological properties, Fourier transform infrared spectroscopy (FTIR), 1H nuclear magnetic resonance (1H NMR), X-ray diffraction (XRD), and methylene blue adsorption test were measured. The results showed that the viscosity and the shear strain resistance of the CAS/CR/SA hybrid hydrogels positively correlated with their sodium alginate contents. The hybrid hydrogels with high carrageenan contents exhibited a high energy storage modulus (G') and a high loss modulus (G"). The swelling and methylene blue adsorption experiments showed that the CAS/CR/SA hydrogels had pH and temperature sensitivity. The hydrogels reached adsorption equilibrium in 12 h (alkaline conditions) and 24-36 h (acidic conditions). The adsorption kinetics of the hybrid hydrogels showed that their adsorption process was mainly controlled by chemisorption and that adsorption was exothermic (ΔH° < 0).

Binary hydrogels constructed from lotus rhizome starch and different types of carrageenan for dysphagia management: Nonlinear rheological behaviors and structural characteristics

This study focused on binary hydrogels constructed from lotus rhizome starch (LRS) and three types of carrageenan (κ-C, ι-C, and λ-C). The enthalpy of LRS gelatinization was reduced by 32.1%-88.4% with the incorporation of carrageenan. Compared with ι-C and λ-C, the conformations of κ-C more facilitated the development of the binary hydrogel network structure. The ability of the LRS/carrageenan binary hydrogel to immobilize water was mainly related to the effect of different types of carrageenan on starch molecular ordering. LRS-based hydrogels were recognized as level 4 in the International Dysphagia Diet Standardization Initiative (IDDSI) framework. Nevertheless, the incorporation of carrageenan significantly reduced the ability of the LRS hydrogel to resist stress under large deformations, which might be favorable to oral processing and swallowing. This research provides preliminary evidence for relevant industries to use carrageenan to adjust LRS hydrogel properties and improve the quality of starch-based foods for dysphagia management.

Anti-colorectal cancer effects of seaweed-derived bioactive compounds

Seaweeds are classified as Chlorophyta, Rhodophyta, and Phaeophyta. They constitute a number of the most significant repositories of new therapeutic compounds for human use. Seaweed has been proven to possess diverse bioactive properties, which include anticancer properties. The present review focuses on colorectal cancer, which is a primary cause of cancer-related mortality in humans. In addition, it discusses various compounds derived from a series of seaweeds that have been shown to eradicate or slow the progression of cancer. Therapeutic compounds extracted from seaweed have shown activity against colorectal cancer. Furthermore, the mechanisms through which these compounds can induce apoptosis in vitro and in vivo were reviewed. This review emphasizes the potential utility of seaweeds as anticancer agents through the consideration of the capability of compounds present in seaweeds to fight against colorectal cancer.

An Overview of Potential Seaweed-Derived Bioactive Compounds for Pharmaceutical Applications

Nowadays, seaweeds are widely involved in biotechnological applications. Due to the variety of bioactive compounds in their composition, species of phylum Ochrophyta, class Phaeophyceae, phylum Rhodophyta and Chlorophyta are valuable for the food, cosmetic, pharmaceutical and nutraceutical industries. Seaweeds have been consumed as whole food since ancient times and used to treat several diseases, even though the mechanisms of action were unknown. During the last decades, research has demonstrated that those unique compounds express beneficial properties for human health. Each compound has peculiar properties (e.g., antioxidant, antimicrobial, antiviral activities, etc.) that can be exploited to enhance human health. Seaweed's extracted polysaccharides are already involved in the pharmaceutical industry, with the aim of replacing synthetic compounds with components of natural origin. This review aims at a better understanding of the recent uses of algae in drug development, with the scope of replacing synthetic compounds and the multiple biotechnological applications that make up seaweed's potential in industrial companies. Further research is needed to better understand the mechanisms of action of seaweed's compounds and to embrace the use of seaweeds in pharmaceutical companies and other applications, with the final scope being to produce sustainable and healthier products.

Effects of two contrasting dietary polysaccharides and tannic acid on the digestive and physicochemical properties of wheat starch

In this study, konjac glucomannan, κ-carrageenan, and tannic acid were selected to study the effects of different combinations on the in vitro digestibility and physicochemical properties of wheat starch. Results showed that the addition of konjac glucomannan, κ-carrageenan, and tannic acid could decrease the digestion of starch and increase the content of resistant starch. Besides, the two polysaccharides weakened the extent of tannic acid on starch digestion. Moreover, although the two polysaccharides had different effects on the in vitro digestion of starch, they had no significant increase in the content of resistant starch. DSC and XRD results demonstrated that the polysaccharides and tannic acid showed synergistic effects on the rebuilding of starch microstructure. FTIR results further manifested that κ-carrageenan and konjac glucomannan could significantly increase the strength of hydrogen bonds in starch. At the same time, the addition of tannic acid would weaken the molecular interaction between polysaccharides and starch. SEM and CLSM results showed that tannic acid added to the polysaccharide-starch mixture not only interacted with starch but also influenced the structure of polysaccharide gel.

Modulating storage stability of binary gel by adjusting the ratios of starch and kappa-carrageenan

This study aimed to investigate the interaction mechanism of the waxy starch and kappa carrageenan (KC) gel with different ratios during co-gelatinization and storage. Water distributions, mobilities and rheological properties of the mixture gels were studied. When KC concentration was low (0.5%KC and 4% starch), the starch dominated the system, and the gel strength was the lowest. When KC concentration increased to 0.75%, the gel had the lowest change rate of fracture force, and the most homogeneous network of the freeze-dried gel was observed. When KC concentration increased to 1.0%, the gel strength was high, but the uneven structure led to the instability of the gel. Overall, the gel with 0.75%KC and 4% starch was the most stable during storage, and the exclusion of the two components to each other was the weakest, resulting in the uniform structure of the gel.

Classification of hydrocolloids based on small amplitude oscillatory shear, large amplitude oscillatory shear, and textural properties

Dynamic rheological and mechanical properties of seven commercial (xanthan [XG], guar [GG], high methoxylated pectin [HMP], κ-carrageenan [κ-Car], agar [AG], alginate [ALG], and carboxymethylcellulose [CMC]) and four emerging hydrocolloids (basil seed gum [BSG], sage seed gum [SSG], Balangu-Shirazi seed gum [BSSG], and cress seed gum [CSG]) were investigated and the classification of the hydrocolloids were carried out based on them. AG belonged to the first class with 0.81 membership function (MF), κ-Car and HMP grouped in the second class with 0.68 and 0.71 MFs, respectively, XG, BSG, and SSG were depended to the third class with 0.61-0.70 MFs, finally, CMC, GG, BSSG, ALG, and CSG related to the fourth class, as the most populated class, with MF > 0.61. The first class contained the highest amount of hardness parameter (43.40 ± 2.76 g), the second class included the highest pseudoplasticity parameter (shear-thinning ratio = -0.54 ± 0.03) and relaxation time (66.25 ± 2.61 s) and the fourth cluster comprised the highest frequency dependency of viscous modulus (exponent of power-law model for viscous modulus vs. frequency = 0.30 ± 0.05). In addition, the results of this study showed that there was a distinct relationship between nonlinear harmonics in the stress wave and fundamental characteristics of hydrogel networks. The investigation of the rheo-mechanical properties of biopolymers in large deformation under shear and normal forces can have an important role in the prediction of the behavior of the material in real processes and application conditions, especially in the food industry. Due to the inconvenience of large deformation mechanical tests, such as Weissenberg effect, the complication of the results analyzing and sampling difficulty of semi-dilute samples; herein, we determined the correlation between large deformation (LAOS and texture analysis) and small deformation (SAOS) tests properties. The studied rheo-mechanical parameters showed high correlation with the four mentioned network parameters (more than 65% similarity index). Using these results, other scientists could rationally design the experiments and avoid experiments with similar parameters.

Effect of Hydrocolloids on the Retrogradation of Lotus Seed Starch Undergoing an Autoclaving-Cooling Treatment

The retrogradation properties of lotus seed starch (LS) blended with the hydrocolloids arabic gum (AG), carrageenan (CG), guar gum (GG), and xanthan (XN) were investigated undergoing an autoclaving-cooling treatment, a model for starch retrogradation acceleration. Compared with LS alone, LS-AG showed the increases in syneresis, tan δ (more solid-like behavior), bound water content and immobile water content, molecular weight, the intensity at 480 cm^-1 in Raman spectra and the ratio of absorbance 1047 cm^-1 /1022 cm^-1 (R_1047/1022 ) in FT-IR spectra. The results suggested that the addition of AG tended to promote the starch retrogradation, which was related to the increased molecular migration of free water, interactions of molecular starch chains, and the formation of ordered structures. The addition of CG, GG, or XN significantly decreased the syneresis, tan δ, the intensity at 480 cm^-1 , and R_1047/1022 values of LS, indicating the prevention of LS retrogradation. The effects of CG and XN on starch retrogradation mainly resulted from competition for water and the increased viscosity, as well as the coating effect on starch. The dominant viscosity of GG was the main factor that influenced starch retrogradation. These results showed not all hydrocolloids would retard starch retrogradation under autoclaving-cooling treatment, for which fine structures altered by different hydrocolloids were the key factors. PRACTICAL APPLICATION: Effects of hydrocolloids on the retrogradation of lotus seed starch were investigated undergoing an autoclaving-cooling treatment. The results will help guide the production and development of starchy foods having desirable properties by specific hydrocolloids during autoclaving-cooling process, especially to control starch retrogradation.

Hydrocolloid clustering based on their rheological properties

In this study, we proposed an objective classification of seven commercial hydrocolloids and four novel hydrocolloids. Total of 74 rheological parameters was generated by steady (flow behavior, hysteresis loop, single shear decay, in-shear structural recovery experiments), dynamic (strain sweep and frequency sweep tests), and transient (creep/recovery and stress relaxation) shear measurements. Subsequently, the parameters were classified into seven categories with more than 60% similarity indexes in each group using agglomerative hierarchical clustering based on those properties related to the number of linkage, strength of linkage, distance of linkage, rupture and flow, rate of destruction, the extent of destruction, and the state of destructured samples in the absence of flow field. Fuzzy c-means classifier used to extract patterns for each class. Our results correspond to four different classes; κ-carrageenan and agar gum were categorized in the first class, high methoxyl pectin, xanthan, sage seed gum and basil seed gum in the second class, alginate gum and Balangu-Shirazi seed gum in the third class, and guar gum, cress seed gum and carboxymethyl cellulose in the fourth class. Using this classification technique, complete rheological patterns can be extracted for each class. This classification provides a map for other researchers to rationally design the best test type which could describe adequately different properties of materials and avoid experiments with a similar type of parameters. The main reason for the frequent use of hydrocolloids in various industries is their ability to modify the rheology. A lot of works have been done to study the rheological behavior of many hydrocolloids in model and food systems. As there is still demand for new sources of hydrocolloids with more specific functionality in foods, probing the similarities among commercial and emerging hydrocolloids could help us to rationally design structural features in different formulations, besides gives insight into the structure-function relationship between them. This object could be attained by clustering, a part of the pattern recognition theory. Contrary to the traditional clustering methods, in which the membership of a product is exclusive for only a class, in constraint clustering by fuzzy logic methods, a partial membership can be shared by two or more classes. In this way, using the fuzzy logic clustering method, we clustered a number of commercial and novel hydrocolloids based on the steady, transient, and dynamic shear rheological properties and found a specific pattern among them. PRACTICAL APPLICATIONS: The main reason for the frequent use of hydrocolloids in various industries is their ability to modify the rheology. A lot of works have been done to study the rheological behavior of many hydrocolloids in model and food systems. As there is still demand for new sources of hydrocolloids with more specific functionality in foods, probing the similarities among commercial and emerging hydrocolloids could help us to rationally design structural features in different formulations, besides gives insight into the structure-function relationship between them. This object could be attained by clustering, a part of the pattern recognition theory. Contrary to the traditional clustering methods, in which the membership of a product is exclusive for only a class, in constraint clustering by fuzzy logic methods, a partial membership can be shared by two or more classes. In this way, using the fuzzy logic clustering method, we clustered a number of commercial and novel hydrocolloids based on the steady, transient, and dynamic shear rheological properties and found a specific pattern among them.

Mixing ratio dependent complex coacervation versus bicontinuous gelation of pectin with in situ formed zein nanoparticles

We report on the competitive phenomenon of complex coacervation versus bicontinuous gelation between pectin (P, a polyanionic carbohydrate, [P] = 0.01-2% (w/v)) and zein nanoparticles (Z, a hydrophobic protein and a weak polyampholyte, [Z] = 0.1 and 0.5% (w/v), in an ethanolic solution of effective concentration 4 and 27% (v/v)), which was studied below (pH ≈ 4), and above (pH ≈ 7.4) the pI (≈ 6.2) of zein at room temperature, 25 °C. The uniqueness of this study arises from the interaction protocol used, where the pectin used was in the extended polyelectrolyte (persistence length ≈ 10 nm) conformation while zein was used as a charged globular nanoparticle (size ≈ 80-120 nm) that was formed in situ. Their mixing ratio, r = [P] : [Z] (w/w), was varied from 0.02 to 4.0 (for [Z] = 0.5% (w/v)), and from 0.1 to 7.5 (for [Z] = 0.1% (w/v)) in the ionic strength range 10-4 to 10-2 M NaCl. Zeta potential data revealed that at pH ≈ 4, the complementary binding condition, r = 1 : 1 (equivalent to 1 : 5 molecule/nanoparticle) demarcated the coacervate from the gel region. The measured rigidity (G0, low frequency storage modulus) of these materials revealed the following: for r < 1, (low pectin content samples, coacervate region) the material had lower values of Gcoac0, whereas for r > 1, an excess of pectin facilitated gelation with Ggel0 ≫ Gcoac0. Above pI, surface patch binding caused associative interactions and complex coacervation though both biopolymers had similar net charge. The network density was used as a descriptor to distinguish between the coacervate and gel samples. Their microstructures were probed by small angle neutron scattering (SANS), and viscoelastic properties by rheology. Simple modeling shows that formation of the interpolymer complex was favored in higher protein containing samples. Mixing ratio dependent selective coacervation (a kinetic process) and bicontinuous gelation (a thermodynamic process) are rarely seen to coexist in biopolymer interactions.