This review covers the preparation, characterization, properties, and applications of methylcelluloses (MC). In particular, the influence of different chemical modifications of cellulose (under both ...heterogeneous and homogeneous conditions) is discussed in relation to the physical properties (solubility, gelation) of the methylcelluloses. The molecular weight (MW) obtained from the viscosity is presented together with the nuclear magnetic resonance (NMR) analysis required for the determination of the degree of methylation. The influence of the molecular weight on the main physical properties of methylcellulose in aqueous solution is analyzed. The interfacial properties are examined together with thermogelation. The surface tension and adsorption at interfaces are described: surface tension in aqueous solution is independent of molecular weight but the adsorption at the solid interface depends on the MW, the higher the MW the thicker the polymeric layer adsorbed. The two-step mechanism of gelation is confirmed and it is shown that the elastic moduli of high temperature gels are not dependent on the molecular weight but only on polymer concentration. Finally, the main applications of MC are listed showing the broad range of applications of these water soluble cellulose derivatives.
•Quinoa protein secondary structure and solubility are influenced by pH.•Heat-set gelation of quinoa protein isolate produces high strength gels (above 4kPa).•Gelation of quinoa protein isolate ...occurs in acid pH (3.5) and neutral pH (7.0).•Gelation of quinoa protein isolate is modified by divalent ions such Ca2+ and Mg2+.•Gel microstructure is modulating by the pH and divalent salt addition.
This work aimed to study the influence of pH (3.5 and 7.0) and CaCl2 and MgCl2 addition on heat-set gelation of a quinoa protein isolate at 10% and 15% (w/w). The protein isolate obtained was composed mainly of 11S globulin as was observed by electrophoresis and mass spectrometry analysis. Heat-set gelation occurred at both pH values studied. Nevertheless, the gels formed at pH 3.5 were more viscoelastic and denser than those formed at pH 7.0, that was coarser and presented syneresis. The CaCl2 and MgCl2 addition increased the gel strength during rheological analysis at pH 3.5, possibly due to the formation of fiber-like connections in the gel network. At pH 7.0, the divalent salts resulted in weaker gels formed by agglomerates, suggesting a neutralization of the protein surface charges. The differences in quinoa protein gelation were attributed to solubility, and the flexibility of proteins secondary structure at the pH studied.
► Lasiodiplodia theobromae MMLR was cultivated for secretion of a β-(1→6)-d-glucan. ► The polymer was derivatized by sulfonation and its structure investigated using UV–vis, FT-IR and 13C NMR ...spectroscopy. ► The 13C NMR spectra showed that sulfonyl groups were inserted mainly on C-2 and C-4. ► The sulfonated β-(1→6)-d-glucan presented anticoagulant activity.
An exocellular β-(1→6)-d-glucan (lasiodiplodan) produced by a strain of Lasiodiplodia theobromae (MMLR) grown on sucrose was derivatized by sulfonation to promote anticoagulant activity. The structural features of the sulfonated β-(1→6)-d-glucan were investigated by UV–vis, FT-IR and 13C NMR spectroscopy, and the anticoagulant activity was investigated by the classical coagulation assays APTT, PT and TT using heparin as standard. The content of sulfur and degree of substitution of the sulfonated glucan was 11.73% and 0.95, respectively. UV spectroscopy showed a band at 261nm due to the unsaturated bond formed in the sulfonation reaction. Results of FT-IR and 13C NMR indicated that sulfonyl groups were inserted on the polysaccharide. The sulfonated β-(1→6)-d-glucan presented anticoagulant activity as demonstrated by the increase in dose dependence of APTT and TT, and these actions most likely occurred because of the inserted sulfonate groups on the polysaccharide. The lasiodiplodan did not inhibit the coagulation tests.
Pressurized hot water extraction (PHWE), known as a “green” extraction technique, was used to obtain polysaccharide from the pulp of gabiroba (Campomanesia xanthocarpa Berg) fruits. The effects of ...pressure, temperature, and flow rate on pectin yields were analyzed through a full factorial design experiment 23. The optimal extraction conditions to achieve maximum pectin yield (5.70 wt%) were pressure of 150 bar, temperature of 120 °C, and flow rate of 1.5 mL min−1. The high pressure (100 bar) promoted an increase in galacturonic acid content (36.0%) compared to conventional hot water extraction (CEGP) with 25.7%. Differences in the proportion of homogalacturonan (HG) and rhamnogalacturonan (RG-I) domains ranging from 16.3 to 35.4% and 61.7 to 80.1%, respectively, were observed for each pectin sample according to the extraction conditions. The mono-dimensional (13C-NMR) and bi-dimensional (1H/13C HSQC-NMR) analyses confirmed the presence of HG and RG-I regions and indicated the presence of arabinogalactans type I (AG-I) and arabinogalactans type II (AG-II) in the PHWE pectin samples, which was not found for pectins from gabiroba pulp obtained by CEGP. The results showed that PHWE proved to be a promising method for extracting pectins from gabiroba fruits.
Pectins from Araçá (Psidium cattleianum Sabine) fruit pulp were extracted, purified and isolated, obtaining the Araçá Purified Pectin (APP) under its sodium form. Yield was found 3.5% w/w of the ...initial dried material. From titration, monosaccharide analysis after total hydrolysis and 1H and HSQC NMR analyses, it was established that the pectins are formed of long galacturonic acid blocks (HG) partially methylated (degree of methyl-esterification – DM = 55.9 mol%) and acetylated (2 mol%) and RG-I blocks with side chains containing mainly arabinose and galactose. No gelation was observed in presence of calcium for the unmodified APP. Then, pectins were treated in alkaline conditions to de-esterify progressively the initial sample down to DM = 0 after 60 min of treatment. Each sample obtained was characterized by SEC and NMR demonstrating the stability of the main chains, where Rha, GalA and Mw remained unchanged independently of the length of alkaline treatment. One of this sample (APP-15) was selected to test the gelling ability and rheological behavior. The gel was formed by dialysis against 1 mol L−1 CaCl2 and its rheological study allows to conclude that a homogeneous physical gel is formed stabilized by cooperative GalA−-Ca+2 junctions.
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•Fine structure of Araçá pectin is established for the first time .•De-esterification is performed in alkaline conditions without any change in Mw.•Initially, it is non gelling pectin (DM ~ 60%) in acid and calcium excesses.•The critical gelation concentration (~2 g L−1) is determined when DM decreases.•Demethylated pectin form a strong gel as shown by rheological measurements.
•A HM pectin from the gabiroba was obtained by an eco-friendly method.•HG and RG-I were isolated and characterized for the first time from gabiroba pulp.•A homogeneous pectic fraction (GWP-TEP) with ...68.1% of GalA was obtained.•5% GW pectin had same shear thinning behavior in water and in the 0.1 mol L−1 NaCl.•5% GW pectin showed a gel behavior by dynamic rheological measurements.
The pulp of gabiroba fruits was submitted to a hot water extraction, giving rise to a crude pectin named GW. GW was shown to be composed mainly of arabinose (54.5%), galacturonic acid (33.5%), galactose (7.6%), and rhamnose (1.6%). GW was characterized by chromatographic and spectroscopic methods indicating the presence of homogalacturonans (HG) with a degree of methyl-esterification (DM) of 60% and rhamnogalacturonans I (RG-I). HG domain represents 31.9% and RG-I domain 65.3%. Furthermore, GW was submitted to sequential fractionation methods, giving rise to GWP-TEP fraction, structurally characterized by the predominance of HG regions, and confirmed by NMR analysis. The rheological behavior of GW was analyzed at 1%, 3%, and 5% (w/v) concentration with 0.1 mol L−1 NaCl. All samples showed shear thinning behavior. In the oscillatory measurements, the 1% GW showed a liquid-like behavior, while the 3% presented a concentrated solution behavior and the 5% GW a gel behavior.
In this study, pectins from commercial citrus and isolated from gabiroba (Campomanesia xanthocarpa) fruits, were obtained with different degrees of methyl-esterification (DM) and applied in the ...films. The DM ranged from 0 % to 62.5 % and the gradual de-esterification process was confirmed by mono-dimensional analysis (1H NMR). In order to investigate the influence of DM values in pectin film properties, PCP (DM: 62.5 %); PCP-5 (DM: 37.4 %); PCP-15 (DM: 19.1 %), and a fully de-esterified sample PCP-35 (DM: 0 %) were selected. The functional properties of the films clearly showed that the DM and cross-linking process are necessary to obtain a material with water resistance. Furthermore, pectin isolated from the fruits of gabiroba was purified (GW-Na, DM: 51.9 %) and partially de-esterified (GW-Na-5, DM: 37.1 %). These pectins were used, for the first time, in development of films and the physical and mechanical properties were compared with films made with PCP and PCP-5 samples. GW-Na and GW-Na-5 films presented suitable properties, with reduced solubility reduced (57.1 and 26.2 %), high degree of swelling (2.14 and 2.26), low flexibility (18.05 and 6.11 MPa), respectively. High strength and rigidity (99.36 and 1040.9 MPa), for both films (GW-Na and GW-Na-5) were demonstrated, similar to that obtained by analyzed citrus pectin.
•The degree of methyl-esterification plays a decisive role in determining the final properties of pectin films.•Pectins with different chemical structures have the ability to form films using the casting method.•Cross-linking with calcium is an essential step in achieving pectin films with water resistance.
The galactomannan from
Mimosa scabrella Bentham was extracted on a pilot plant scale and dried either by vacuum oven (GVO) or by spray-drier (GSD) to evaluate the effect of the drying technique on ...the powder quality and its applicability as excipient in solid dosage forms. The analysis by high performance size exclusion chromatography (HPSEC) coupled to multiangle laser light scattering (MALLS) suggests that both products behave as semi-flexible polymers, although the GSD showed more aggregation at molecular level (∼10%) and higher chain stiffness (Lp 9.1
nm). TG and DSC analysis showed weight loss event with peak at 299.7 and 311.9
°C to GVO and GSD, respectively, as well and higher ash content for GSD sample, in both inert and oxidant atmosphere. The X-ray diffraction confirmed the amorphous nature of both galactomannans although GVO showed high crystallinity. The GSD showed lower density (1.009
g/cm
3), higher cohesiveness (repose angle 35.5°, compressibility 32.2% and absence of flow), smaller and more spherical particles than GVO sample, both with high polydispersion. As vacuum oven-drying resulted in a like fibrous material, spray-drying appears as an alternative method easy to extrapolate in industry, requiring a glidant incorporation to improve the powder flowability.
•A purified pectin (GWP-FP-S) with low molar mass was obtained from gabiroba fruit.•GWP-FP-S is represented by 57.7% HG and 42.0% RG-I, with long neutral side chains.•Low concentrations of GW and ...GWP-FP-S exhibited cytotoxicity against U251-MG cells.•No cytotoxicity of GW and GWP-FP-S was observed to normal (NIH-3T3) cells.
A new source of pectin with a cytotoxic effect on glioblastoma cells is presented. A homogeneous GWP-FP-S fraction (Mw of 29,170 g mol−1) was obtained by fractionating the crude pectin extract (GW) from Campomanesia xanthocarpa pulp. According to the monosaccharide composition, the GWP-FP-S was composed of galacturonic acid (58.8%), arabinose (28.5%), galactose (11.3%) and rhamnose (1.1%), comprising 57.7% of homogalacturonans (HG) and 42.0% of type I rhamnogalacturonans (RG-I). These structures were characterized by chromatographic and spectroscopic methods; GW and GWP-FP-S fractions were evaluated by MTT and crystal violet assays for their cytotoxic effects. Both fractions induced cytotoxicity (15.55–37.65%) with concomitant increase in the cellular ROS levels in human glioblastoma cells at 25–400 μg mL−1, after 48 h of treatment, whereas no cytotoxicity was observed for normal NIH 3T3 cells. This is the first report of in vitro bioactivity and the first investigation of the antitumor potential of gabiroba pectins.
► More stable emulsions had inversion interval with less water concentration. ► Emulsions prepared with soy-lecithin presented strong gel behavior. ► Emulsions prepared with Tween 80 presented ...concentrated solution behavior.
Emulsions inversion occurs in many industrial processes and may be influenced by the formulation conditions, composition and emulsification protocols. In this work, the influence of emulsifiers and stirring on catastrophic inversion (O/W to W/O) was evaluated. Emulsions were prepared with different stirring rates, using soy lecithin and Tween 80, at 2 and 5wt%. The aqueous phase was distilled water with 1wt% NaCl and the oil phase was soy oil. These emulsions were analyzed by conductivity, stability, microscopy and rheology assays. The most stable emulsions presented inversion with a smaller amount of the external phase. Rheological analysis showed that, with a higher concentration of emulsifier, it is better to use Tween 80 when lower viscosity is desired, while soy lecithin is more appropriate for higher viscosity products. The oscillatory tests showed that while the emulsions prepared using Tween 80 exhibited concentrated solution behavior, those prepared with soy lecithin exhibited strong gel behavior.
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