Comparative viscoelasticity studies: Corn fiber gum versus commercial polysaccharide emulsifiers in bulk and at air/liquid interfaces

A multi-scale approach to arabinoxylan-based emulsions: From molecular features, interfacial properties to emulsion behaviors

Arabinoxylan (AX) is well-known for its emulsification and beneficial biological activity, but the roles of AX's molecular features and interfacial properties in AX-based emulsion behaviors were unknown. We first used a multi-scale approach to correlate molecular, interfacial, droplet characteristics, and bulk emulsion of AXs from corn and wheat bran (CAXs and WAXs). Our results showed that among CAXs and WAXs solution (1 %, 2 % and 3 %, w/v), 0.25 M NaOH-treated CAX and WAX showed smaller particle sizes (493 nm and 8621 nm), lower interfacial tension and stronger interfacial layer, whose emulsion exhibited smaller initial droplets (541 nm and 660 nm) and better stability. Moreover, WAXs had bigger particle sizes, lower interfacial tension and stronger interfacial layer than CAXs, but CAXs exhibited better emulsifying and emulsion-stabilizing properties than WAXs. There is a satisfactory correlation among CAXs' or WAXs' molecular features, interfacial properties and emulsion behaviors. However, a good correlation from different grains AXs cannot be established.

Investigation of physicochemical and sensory characteristics of low calorie sponge cake made from flaxseed mucilage and flaxseed flour

This research aimed to extract flaxseed mucilage (FM) and investigate its rheological properties (static and dynamic tests) compared with animal oil. In the next stage, the D-optimal design was applied to investigate the effect of FM (0-60%) and FF (0-30%) replacements with animal oil and cake flour, respectively on the sponge cake's physicochemical, textural, and sensory properties. According to the flow behavior test, FM showed Newtonian behavior while animal oil had pseudoplastic behavior. The results of the dynamic test showed with an increase in frequency, the loss modulus (G״) and storage modulus (G') of samples increased. However, G' was higher than G״ in all samples. By replacement of FM and FF, the moisture content, water activity, antioxidant capacity, crumb hardness, and cohesiveness of the samples increased while springiness, crust hardness, and specific volume decreased (P < 0.05). Lightness of samples with replacement of FF decreased (P < 0.05). The overall acceptance score was enhanced with an increase in FM substitution while it was decreased with the replacement of FF (P < 0.05). The amounts of fat, calories, and peroxide values were decreased in sponge cake with the incorporation of FF and FM (P < 0.05). In general, the substitution of FM (60%) and FF (28%) in the cake formulation as an optimized sample to make new products with low-calorie content is possible without significant decreases in product quality.

Ultrasound-assisted extraction of tamarind xyloglucan: an effective approach to reduce the viscosity and improve the α-amylase inhibition of xyloglucan

BACKGROUND

Water extraction (WE) is the classical extraction method for tamarind xyloglucan (XyG), but its low yield, high viscosity and poor dispersion in aqueous solution are not conducive to the industrial applications. To promote the industrial application of tamarind XyG, an ultrasonic-assisted extraction (UAE) method for extracting low-viscosity XyG from tamarind kernel powder was proposed.

RESULTS

The yield of UAE-XyG was higher (502.33 ± 0.036 g kg^-1 ) than that of WE-XyG (163.43 ± 0.085 g kg^-1 ). UAE reduced the molecular weight, monosaccharide content and apparent viscosity of XyG. The hypoglycemic experiment in vitro showed that UAE-XyG had a stronger inhibitory effect on α-amylase activity than WE-XyG, but its glucose dialysis retardation index was lower.

CONCLUSION

In sum, UAE is a type of extraction method that could effectively improve the yield of XyG and reduce its viscosity to expand its application without reducing its physiological activity. UAE exhibits an excellent potential in the extraction of XyG. © 2022 Society of Chemical Industry.

Pickering Emulsion Stabilized by Fish Myofibrillar Proteins Modified with Tannic Acid, as Influenced by Different Drying Methods

A novel food-grade, particles-based Pickering emulsion (PE) was prepared from a marine source. Yellow stripe trevally is an under-utilized species. The use of its muscle protein as solid food-grade particles for the preparation of a Pickering emulsion can be a potential means of obtaining the natural nutritive emulsifier/stabilizer. Fish myofibrillar proteins (FMP) were modified with tannic acid (TA) at varying concentrations (0.125, 0.25, and 0.5%) followed by freeze-drying (FD) or spray-drying (SD). Physicochemical characteristics and emulsifying properties of obtained FMP-TA complexed particles were assessed for structural changes and oil-in-water emulsion stabilization. The addition of TA caused a reduction in surface hydrophobicity and total sulfhydryl content values for either FD-FMP or SD-FMP. Conversely, disulfide bond content was significantly increased, particularly when TA at 0.5% was used (p < 0.05). FTIR, spectrofluorometer, and the protein pattern also confirmed the cross-linking between FMP and TA. SD-FMP modified with 0.5% TA (SD-FMP-0.5TA) rendered the highest emulsifying stability index but had a lowered emulsifying activity index (p < 0.05). Confocal microscopic images, droplet size, and rheological properties revealed that a SD-FMP-0.5TA-stabilized emulsion had higher stability after 45 days of storage than an FD-FMP-0.5TA-stabilized emulsion. Therefore, the SD-FMP-0.5TA complex could be used as a potential food-grade stabilizer/emulsifier for PE with enhanced emulsifying properties.

Correlation between interfacial layer properties and physical stability of food emulsions: current trends, challenges, strategies, and further perspectives

Emulsions are thermodynamically unstable systems that tend to separate into two immiscible phases over time. The interfacial layer formed by the emulsifiers adsorbed at the oil-water interface plays an important role in the emulsion stability. The interfacial layer properties of emulsion droplets have been considered the cutting-in points that influence emulsion stability, a traditional motif of physical chemistry and colloid chemistry of particular significance in relation to the food science and technology sector. Although many attempts have shown that high interfacial viscoelasticity may contribute to long-term emulsion stability, a universal relationship for all cases between the interfacial layer features at the microscopic scale and the bulk physical stability of the emulsion at the macroscopic scale remains to be established. Not only that, but integrating the cognition from different scales of emulsions and establishing a unified single model to fill the gap in awareness between scales also remain challenging. In this review, we present a comprehensive overview of recent progress in the general science of emulsion stability with a peculiar focus on interfacial layer characteristics in relation to the formation and stabilization of food emulsions, where the natural origin and edible safety of emulsifiers and stabilizers are highly requested. This review begins with a general overview of the construction and destruction of interfacial layers in emulsions to highlight the most important physicochemical characteristics of interfacial layers (formation kinetics, surface load, interactions among adsorbed emulsifiers, thickness and structure, and shear and dilatational rheology), and their roles in controlling emulsion stability. Subsequently, the structural effects of a series of typically dietary emulsifiers (small-molecule surfactants,proteins, polysaccharides, protein-polysaccharide complexes, and particles) on oil-water interfaces in food emulsions are emphasized. Finally, the main protocols developed for modifying the structural characteristics of adsorbed emulsifiers at multiple scales and improving the stability of emulsions are highlighted. Overall, this paper aims to comprehensively study the literature findings in the past decade and find out the commonality of multi-scale structures of emulsifiers, so as to deeply understand the common characteristics and emulsification stability behaviour of adsorption emulsifiers with different interfacial layer structures. It is difficult to say that there has been significant progress in the underlying principles and technologies in the general science of emulsion stability over the last decade or two. However, the correlation between interfacial layer properties and physical stability of food emulsions promotes revealing the role of interfacial rheological properties in emulsion stability, providing guidance on controlling the bulk properties by tuning the interfacial layer functionality.

Effects of in vitro digestion and fecal fermentation on physico-chemical properties and metabolic behavior of polysaccharides from Clitocybe squamulosa

The aim of this study was to establish a human digestion model in vitro to explore the degradation characteristics of a novel high-purity polysaccharide from Clitocybe squamulosa (CSFP2). The results showed that the content of reducing sugars (C_R ) of CSFP2 increased from 0.13 to 0.23 mg/mL, the molecular weight (Mw) of CSFP2 decreased significantly during the saliva-gastrointestinal digestion. The constituent monosaccharides of CSFP2, including galactose, glucose, and mannose, were stable during in vitro digestion, but their molar ratios were changed from 0.023: 0.737: 0.234 to 0.496: 0.478: 0.027. The surface of CSFP2 changes from a rough flaky structure to a scattered flocculent or rod-shaped structure after the gastrointestinal digestion. However, the apparent viscosity of CSFP2 was overall stable during in vitro digestion. Moreover, CSFP2 still maintains its strong antioxidant capacity after saliva-gastrointestinal digestion. The results showed that CSFP2 can be partially decomposed during digestion. Meanwhile, some physico-chemical properties of the fermentation broth containing CSFP2 changed significantly after gut microbiota fermentation. For example, the pH value (from 8.46 to 4.72) decreased significantly (p < 0.05) after 48 h of fermentation. the OD ₆₀₀ value increased first and then decreased (from 2.00 to 2.68 to 1.32) during 48-h fermentation. In addition, CSFP2 could also increase the amounts of short-chain fatty acids (SCFAs) (from 5.5 to 37.15 mmol/L) during fermentation (in particular, acetic acid, propionic acid, and butyric acid). Furthermore, the relative abundances of Bacteriodes, Bifidobacterium, Catenibacterium, Lachnospiraceae_NK4A136_group, Megasphaera, Prevotella, Megamonas, and Lactobacillus at genus level were markedly increased with the intervention of CSFP2. These results provided a theoretical basis for the further development of functional foods related to CSFP2.

Determination of the Emulsion Stabilization Mechanisms of Quaternized Glucan of Curdlan via Rheological and Interfacial Characterization

Interfacial-active quaternized glucan of curdlan (QCD) with different degrees of substitution (DS) was prepared and used as stabilizers of oil-in-water (O/W) emulsions at different concentrations. The adsorption behavior of QCDs, rheology of bulk emulsions and interfacial films, emulsion morphology, and stability were investigated. The emulsifying capacity of QCD was essentially related to the viscoelastic features of the interfacial film and the continuous phase and the electrostatic repulsion among oil droplets. QCD molecules with different DS form structurally different interfacial films. The high-DS QCD formed a viscously predominant interfacial film with certain hydrophobicity, whereas the low-DS QCD molecules formed an elastically predominant film characterized by hydrogen bonds among adsorbed chains. The structuralization of low-DS QCD molecules through physical cross-linking in bulk and interfacial films at high concentrations was conducive to emulsion stability. Excess QCD chains in the bulk formed a weak gel-like network, further hindering the movement of droplets in the emulsions. Relevant emulsification and stability mechanisms were proposed. Finally, the stability of curcumin encapsulated in O/W emulsions was evaluated.

Systematic evaluation on the physicochemical characteristics of a series polysaccharides extracted from different edible lilies by ultrasound and subcritical water

A series polysaccharide samples extracted from three edible lilies (Lilium davidii var. willmottiae, Lilium brownii var. viridulum, and Lilium lancifolium) by subcritical water and ultrasound-assisted extraction were systematically compared. The results showed that extraction method was a more important factor than lily species. Subcritical water extracted lily polysaccharides (S-LP) with higher yield, molecular weight, neutral glucose and uronic acid content as well as apparent viscosity. Ultrasound-assisted extracted lily polysaccharides (U-LP) with higher reducing sugars and protein content. Moreover, due to the degradation of glycosidic bonds, ultrasonic extraction was easier to obtain lower molecular weight polysaccharides. In addition, the extraction method significantly affected the monosaccharide proportion of polysaccharides, but had no effect on type. Glucose was the main component in S-LP, and glucose and mannose were the main components in U-LP. The micromorphology of different polysaccharide samples was similar, and the scanning electron microscope (SEM) images showed regular/irregular particle clusters with different particle sizes. Overall, the relationships between extraction methods, lily species and polysaccharide properties were preliminarily elucidated, providing a reference for the targeted extraction of specific lily polysaccharides (LP).

Two Novel Polysaccharides From Clitocybe squamulosa: Their Isolation, Structures, and Bioactivities

The crude polysaccharides from the fruiting bodies of Clitocybe squamulosa (CSFP) were isolated by hot-water extraction. Two novel polysaccharides, CSFP1-β and CSFP2-α, were further purified by DEAE-52 anion exchange and Sephacryl S-400 gel filtration chromatography, and the purities reached 98.44 and 97.83%, respectively. The structural characteristics and bioactivities of CSFP, CSFP1-β, and CSFP2-α were identified by the combination of chemical and instrumental analysis. Results showed that CSFP was formed by the aggregation of honeycomb spherical materials; CSFP1-β and CSFP2-α were interwoven by reticular and fibrous structures, respectively. Purified components of both CSFP1-β and CSFP2-α showed typical infrared absorption peaks of polysaccharides, and contents of nucleic acid and protein decreased significantly. Simultaneously, CSFP with a molecular weight (Mw) of 1.948 × 10⁴ Da were composed mainly of glucose, mannose, galactose, and rhamnose. CSFP1-β was composed mainly of glucose, galactose, and mannose, while CSFP2-α was composed of glucose, and both their Mw distributions were uneven. Compared with CSFP, the antioxidant activities of CSFP1-β and CSFP2-α were significantly improved (p < 0.05), and they both showed good abilities to bind free cholesterol and bile acid salts in vitro. The binding abilities of the two compounds were found to be 68.62 and 64.43%, and 46.66 and 45.05 mg/g, respectively. CSFP, CSFP1-β, and CSFP2-α had good bacteriostatic effects with a linear increasing relationship to increasing concentration. In addition, CSFP promoted the growth of RAW264.7 cells and has potential immunomodulatory, anti-inflammatory, and anti-tumor activities.

Combined effect of chitosan and bovine serum albumin/whey protein isolate on the characteristics and stability of shrimp oil-in-water emulsion

The effect of bovine serum albumin (BSA) or whey protein isolate (WPI) at various concentrations (0.5%, 1.5%, and 3%; w/v) on the properties of shrimp oil-in-water emulsion was investigated. Both proteins at 1.5% showed the highest emulsifying properties. Moreover, the combined impact of chitosan (CS) at different levels (0.25%, 0.50%, 0.75%, and 1%; w/v) and 1.5% BSA or 1.5% WPI on emulsion properties was also studied. For the same protein used, those stabilized by BSA and WPI in conjunction with CS solution at 0.5% and 0.25% had the highest emulsion stability index, respectively. During storage for 28 days, the BSA-CSstabilized emulsion had higher turbidity, a*, b* but the lowest L* values compared to the WPI-CS counterpart (p < 0.05). Emulsion stabilized by the BSA-CS complex showed higher stability, as witnessed by lower d₃₂ and d₄₃ and lower flocculation factor and coalescence index, but it had a lower negative charge than those stabilized by the WPI-CS complex (p < 0.05). Oil droplets of the BSA-CS-stabilized emulsion showed a lower extent of size enlargement after storage. Rheological studies revealed viscous, shear-thinning, and non-Newtonian behavior of emulsions. Overall, emulsion stabilized by the BSA-CS complex had higher stability than that stabilized by the WPI-CS complex, and the former could maintain the stability of pigment in shrimp oil to some extent. PRACTICAL APPLICATION: Oil from shrimp hepatopancreas is a rich source of both astaxanthin and polyunsaturated fatty acids with health benefits. It can be used for the preparation of food emulsion, such as mayonnaise, with nutraceutical properties. However, emulsion stability determines the quality of the emulsion. The use of protein (bovine serum albumin) in conjunction with polysaccharides, especially chitosan at appropriate concentrations, was proven to improve shrimp oil-in-water emulsion during extended storage. Additionally, chitosan can act as an antioxidant to prevent the degradation of astaxanthin to some extent. This finding could be potentially beneficial to produce emulsion with high stability using protein-chitosan complexes.

Physicochemical, Rheological, Structural, Antioxidant, and Antimicrobial Properties of Polysaccharides Extracted from Tamarind Seeds

In this study, the polysaccharides were firstly extracted from the tamarind seeds in which the crude polysaccharides have been extracted once by hot water extraction. The structure was characterized by FTIR, SEM, and X-ray diffraction after removing protein and small molecule impurities. Furthermore, the rheological and bioactivity of tamarind seed polysaccharides (TSP) were also investigated. The results indicated that the yield of the obtained polysaccharide was 3.42%. TSP was mainly composed of glucose (45.09%), galactose (22.80%), and xylose (28.89%), while it contained characteristic structure of polysaccharides, such as –OH, pyranose, and uronic acid at 3,418, 1,150, and 1,040 cm−1 respectively, which demonstrated that it was a uronic acid heteropolysaccharide. Moreover, the XRD pattern revealed the amorphous behavior of TSP, and it was found to consist of films or “sheets” reflected by SEM. The flow behavior testing confirmed its pseudoplastic character, and the flow behavior index (n) was between 0.4539 and 0.9201. The DPPH radical scavenging activity of TSP was 40.34% at 10 mg/mL. Furthermore, TSP displayed moderate hydroxyl radical scavenging and anti-bacterial activities, owing to its special structure and composition. Overall, our results suggested that TSP could be used as a food ingredient with anti-oxidative and antibacterial activities, which provides useful information on the potential utilization of TSP in the food industry.

In Situ Room-Temperature Cross-Linked Highly Branched Biopolymeric Binder Based on the Diels-Alder Reaction for High-Performance Silicon Anodes in Lithium-Ion Batteries

Silicon (Si) is an auspicious anode material in next-generation lithium-ion batteries due to its exceptional theoretical gravimetric capacity, environmental friendliness, and high natural abundance. However, the practical application of Si anodes remains a "must-solve" challenge because of its drastic capacity fading that results from the inherent property of drastic volume expansion of Si during repeated lithiation and delithiation. Developing binders employed in robust electrodes has been considered an economical and practical method to affect the electrochemical performance of Si-based electrodes. Some natural polymers have demonstrated good adhesive properties with Si-active materials. However, they have limited capacity to keep the structural integrity of electrodes because the network structures solely based on weak hydrogen bonds are susceptible to deformation during cycling. Herein, we develop an in situ covalently cross-linked three-dimensional (3D) supramolecular network and apply it to the Si electrode to improve cycling performance. This network architecture is constructed using furan-modified branched arabinoxylan of corn fiber gum (CFG) and an ionically conductive cross-linker of maleimido-poly(ethylene glycol) (PEG) through the Diels-Alder reaction. The maleimide groups in PEG can react spontaneously with the furan groups in CFG at room temperature without any other stimulation, thus forming strong covalent bonds in the network. The cross-linked CFG-PEG binder has demonstrated robust adhesive properties with Si-active materials and the current collector. The branching of CFG and functional groups of PEG are conducive to improving the lithium-ion conductivity in the silicon anode, resulting in excellent rate performances. The Si anode with a cross-linked CFG-PEG binder exhibits superior cycling stability. As a result, an in situ cross-linking 3D network as a novel binder has a great potential for fabricating an advanced Si anode in next-generation Li-ion batteries.

Interfacial self-assembled behavior of pH/light-responsive host-guest alginate-based supra-amphiphiles for controlling emulsifying property

Soft emulsifiers with relatively suitable structural controllability are necessarily required for the preparation of multifunctional Pickering emulsions. Herein, a β-cyclodextrin-grafted alginate/azobenzene-functionalized dodecyl (Alg-β-CD/AzoC. 12) polymeric supra-amphiphile was designed based on the host-guest interfacial self-assembly. As compared with Alg-β-CD amphiphilic polymers, the interfacial tension of Alg-β-CD/AzoC12 supra-amphiphilic assemblies reduced from 29.57 mN/m to 0.18 mN/m, indicating the great amphiphilicity derived from Alg-β-CD/AzoC12 supra-amphiphilic assemblies. With the increase of pH, the interfacial microstructures transformed from flocculated structures, spherical structures into deformed structures. Especially, the spherical microstructures with the highest interfacial viscoelasticity and thickness demonstrated the highest emulsifying efficiency due to the steric hindrance mechanism. Moreover, the interfacial elastic modulus of adsorbed layers exhibited ~4 times of that upon the ultraviolet illumination. These results disclosed that the interfacial microstructures could be readily regulated by the tunable amphiphilicity of Alg-β-CD/AzoC12 assemblies, which would be useful for the applications of Pickering emulsions in numerous fields.

Development of emulsion gelatin gels for food application: Physicochemical, rheological, structural and thermal characterization

The current work aimed to prepare emulsion gels based on European eel skin gelatin (ESG). The results revealed that the ESG exhibited interesting antioxidant and functional properties in a dose-dependent manner. The ESG has a gel strength of 354.86 g and high gelling and melting temperatures of about 33 and 43 °C, respectively. Hence, based on its interesting gelling ability, the ESG-based gel was employed to stabilize European eel oil (EO) emulsions. In this context, two emulsions were prepared by homogenization or homogenization followed by sonication at EO:ESG weight ratios of 1:2 and 1:4. The physicochemical, textural, structural and thermal properties of emulsion gelatin-based gels (EGGs) were evaluated. The EGGs had a rigid and a cohesive gel network, according to the textural and microstructural analysis. Structural and thermogravimetric analyses showed the effective entrapment of EO in the ESG gel network.

Depletion and bridging flocculation of oil droplets in the presence of β-glucan, arabinoxylan and pectin polymers: Effects on lipolysis

The aim of this study was to investigate the influence of food polysaccharides from different sources on microstructural and rheological properties, and in vitro lipolysis of oil-in-water emulsions of canola oil stabilised by whey protein isolate. The polysaccharides used were β-glucan (BG) from oat, arabinoxylan (AX) from wheat, and pectin (PTN) from apple. All polysaccharides added at 1 % w/v increased the viscosity of emulsions and promoted flocculation but with different mechanisms, BG and AX by depletion flocculation and PTN by bridging flocculation. Depletion flocculation was associated with an increase in viscosity of BG or AX-stabilised emulsions compared with BG/AX alone, whereas bridging flocculation with PTN caused a decrease in viscosity. All three polysaccharides reduced lipid digestion rate and extent, but the bridging flocculation induced by PTN had the greatest effect. This study has implications for better understanding the influence of carbohydrate polymers from cereals and fruits on lipid digestibility.

Interfacial rheology, emulsifying property and emulsion stability of glyceryl monooleate-modified corn fiber gum

The present work aims to develop novel glyceryl monooleate (GMO)-modified corn fiber gum (CFG) emulsifiers (GMO-CFG) and investigate the role of the interfacial properties on emulsion stability. GMO-CFG with different degrees of substitution (DS) were prepared, and their interfacial rheology and emulsification were appraised for potential applications in stabilizing oil/water emulsions. Various oil/water interfacial properties (i.e., adsorption kinetics, viscoelasticity, and adsorbed amount) were determined as a function of DS by using interfacial shear rheology and quartz crystal microbalance with dissipation monitoring techniques. Hydrophobically modified CFG provides an increased capacity to produce fine droplets and stable emulsions. Esterification and its degree exert non-negligible effects on the critical micelle concentration, interfacial tension, interfacial adsorbed amount, and viscoelasticity of the interfacial layer. The rheological properties of the interfacial layers play an important role in macroscopic emulsion stability.

Ultrasonic-Assisted Extraction, Structural Characterization, Chain Conformation, and Biological Activities of a Pectic-Polysaccharide from Okra (Abelmoschus esculentus)

The purpose of this study was to better understand the chemical characteristics and chain conformation of okra polysaccharides extracted by ultrasonic-assisted extraction. A pectic-polysaccharide, named OPP-D, was obtained, which was mainly composed of rhamnose, galacturonic acid, and galactose with a molar ratio of 1.01:1.00:2.31. Combined with NMR analysis, -4)-α-d-GalAp-(1,2,4)-α-l-Rhap-(1- were identified as the backbone with galactan side chains substituted partly at O-4 of Rhap. Molecular weight and radius of gyration of OPP-D were determined as 2.19 × 10⁵ Da and 27.0 nm, respectively. OPP-D was determined as an air-core sphere with branching chains in 0.9% NaCl solution by high-performance size-exclusion chromatography coupled with multi-angle laser light scattering and dynamic light scattering for the first time. Moreover, OPP-D exhibited typical shear-thinning behavior. In addition, OPP-D exhibited remarkable in vitro antioxidant activities and prebiotic activities, while the relatively high molecular weight, high degree of esterification, high content of uronic acids, and highly branched globular conformation of OPP-D might contribute to its in vitro anti-diabetic activities and binding capacities. Results can contribute to a better understanding of the structure–bioactivity relationship of OPPs, and OPP-D has great potential applications in the functional food and pharmaceutical industries.

Polysaccharides from loquat (Eriobotrya japonica) leaves: Impacts of extraction methods on their physicochemical characteristics and biological activities

Impacts of hot water extraction (HWE), pressurized water extraction (PWE), high-speed shearing homogenization extraction, microwave assisted extraction (MAE), ultrasound assisted extraction (UAE), ultrasound assisted enzymatic extraction, and ultrasound-microwave assisted extraction (UMAE) on physicochemical characteristics and bioactivities of polysaccharides from loquat (Eriobotrya japonica) leaves (LLPs) were investigated. Results showed that the degrees of esterification, contents of phenolics and uronic acids, constituent monosaccharides, apparent viscosities, and molecular weights of LLPs varied by different extraction methods. Bioactivities of LLPs were also significantly affected by different extraction methods. The high molecular weight and high degree of esterification of LLP-W and LLP-P extracted by HWE and PWE, respectively, might contribute to their strong binding capacities. The strong antioxidant activities and inhibitory effects on α-amylase and α-glucosidase were found in LLP-M and LLP-U extracted by MAE and UAE, respectively, which might be attributed to their contents of uronic acids, contents of total phenolics, and molecular weights. The low molecular weights and viscosities of LLP-U and LLP-UM extracted by UMAE might contribute to their strong prebiotic effects. These findings could provide scientific foundations for selecting appropriate extraction methods to obtain LLPs with desired bioactivities for applications in the pharmaceutical and functional food industries.

Comparison of structural characteristics and bioactivities of polysaccharides from loquat leaves prepared by different drying techniques

In the present study, freeze drying, hot-air drying, vacuum drying, and microwave drying at the microwave powers of 400, 600, and 800 W, respectively, were utilized to dry loquat leaves for evaluating the effects of different drying techniques on the physicochemical structures and bioactivities of polysaccharides extracted from loquat leaves (LLPs). Results demonstrated that the physicochemical structures and bioactivities of LLPs significantly affected by different drying techniques. The degrees of esterification, molar ratios of constituent monosaccharides, contents of uronic acids, apparent viscosities, and molecular weights of LLPs were varied by different drying techniques. Additionally, LLPs, particularly LLP-M4 which extracted from loquat leaves prepared by microwave drying at the power of 400 W, exerted remarkable in vitro binding capacities, strong inhibitory effects on α-amylase and α-glucosidase, and obvious antioxidant activities. Results indicated that the microwave drying could be an efficient drying technique before extraction of bioactive LLPs, and LLPs had great potential applications in the functional food and pharmaceutical industries.

Structural characteristics, rheological properties, and biological activities of polysaccharides from different cultivars of okra (Abelmoschus esculentus) collected in China

In order to well understand the physicochemical characteristics and biological activities of polysaccharides (OPPs) from different cultivars of okra collected in China, the chemical characteristics, rheological properties, antioxidant activities, in vitro binding properties, and in vitro inhibitory effects on α-glucosidase of polysaccharides from five representative okra cultivars, including 'Lvjian', 'Kalong8', 'Shuiguo', 'Taiwanwufu', and 'Kalong3', were investigated and compared. Results showed that the constituent monosaccharides of OPPs were similar, which composed of rhamnose, galacturonic acid, galactose, and arabinose. However, their weight-average molecular weights varied from 2.76 × 10³ to 4.20 × 10³ kDa, and from 0.11 × 10³ to 0.90 × 10³ kDa, respectively. The uronic acids and degrees of esterification of OPPs ranged from 39.32% to 61.68%, and from 21.66% to 30.02%, respectively. OPPs exhibited typical shear-thinning behavior and viscoelastic properties. Furthermore, OPPs exhibited remarkable antioxidant activities, in vitro binding capacities, and inhibitory effects on α-glucosidase, which might be attributed to their relatively high content of uronic acids, high degrees of esterification, and high molecular weights. Results are helpful for better understanding of the physicochemical structures and bioactivities of OPPs, and OPPs had good application prospects as functional food ingredients for industrial applications.

Polysaccharides at fluid interfaces of food systems

Fabrication of next generation polysaccharides with interfacial properties is driven by the need to create high performance surfactants that operate at extreme environments, as for example in complex food formulations or in the gastrointestinal tract. The present review examines the behaviour of polysaccharides at fluid food interfaces focusing on their performance in the absence of any other intentionally added interfacially active components. Relevant theoretical principles of colloidal stabilisation using concepts that have been developed for synthetic polymers at interfaces are firstly introduced. The role of protein that in most cases is present in polysaccharide preparations either as contaminant or as integral part of the structure is also discussed. Critical assessment of the literature reveals that although protein may contribute to emulsion formation mostly as an anchor for polysaccharides to attach, it is not the determinant factor for the long-term emulsion stability, irrespectively of polysaccharide structure. Interfacial performance of key polysaccharides is also assessed revealing shared characteristics in their modes of adsorption. Conformation of polysaccharides, as affected by the composition of the aqueous solvent needs to be closely controlled, as it seems to be the underlying fundamental cause of stabilisation events and appears to be more important than the constituent polysaccharide sugar-monomers. Finally, polysaccharide adsorption is better understood by regarding them as copolymers, as this approach may assist to better control their properties with the aim to create the next generation biosurfactants.