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Some research activities at Phillips Hydrocolloids Research Centre in Wrexham, Wales and in Wuhan, China have been overviewed. Historical development in both laboratories is described. Most extensively studied topics, the relation between structure and physico-chemical properties of gum Arabic, alginates, konjac glucomannan, carrageenans, beta-lactoglobulins, protein-polysaccharide interactions have been highlighted. [ABSTRACT FROM AUTHOR]

Hydrocolloids can greatly influence the structure and functionalities of modern foods, mainly due to their interactions with other components present in complex food matrices. This review outlines three main categories of hydrocolloid-food component interactions: hydrocolloid-ion, hydrocolloid-small molecule, and hydrocolloid-hydrocolloid interactions. Examples are given to illustrate the impact of the interactions on the structure, stability, functional properties of foods, and their utilizations in food technologies such as separation/purification, gelation, emulsification, and encapsulation etc. [ABSTRACT FROM AUTHOR]

Injectable hydrogels have gained great attentions for cell therapy and tissue regeneration as a result of the applications in minimally invasive surgical procedures with the ease of handling and complete filling of the defect area. Here, a novel biodegradable, thermosensitive and injectable carboxymethyl chitin (CMCH) hydrogel was developed for three-dimensional (3D) cell culture. The obtained CMCH solution remained transparent liquid flowing easily at low temperatures and gelled rapidly at 37 °C. The gelation time of CMCH hydrogels could be easily tuned by varying temperature and the degree of carboxymethylation, which facilitates the cell encapsulation process at room temperature and in-situ forming hydrogel at body temperature. Moreover, the CMCH-14 hydrogels in PBS buffer remained stable and continuous porous structure and could be degraded in the presence of lysozyme or hyaluronidase. HeLa cells proliferated sustainably and self-assembled to form 3D multicellular spheroids with high cell activity on the surface of CMCH-14 hydrogel. Encapsulation of COS-7 cells within the in-situ forming CMCH hydrogel demonstrated that CMCH hydrogels promoted cell survival and proliferation. In vivo mouse study of the CMCH hydrogels showed good in-situ gel formation and tissue biocompatibility. Thus, the biodegradable thermosensitive injectable CMCH hydrogels hold potential for 3D cell culture and biomedical applications. Statement of Significance Biodegradable hydrogels have been widely studied for cell therapy and tissue regeneration. Herein, we report a novel thermosensitive injectable carboxymethyl chitin (CMCH) hydrogel for 3D cell culture, which was synthesized homogeneously from the bioactive natural chitin through the “green” process avoiding using organic solvent. The CMCH solutions exhibited rapid thermoresponsive sol-to-gel phase transition behavior at 37 °C with controllable gelation times, which facilitates the cell encapsulation process at room temperature and in-situ forming hydrogel at body temperature. Importantly, in vitro 3D cell culture and in vivo mouse study of the CMCH hydrogel showed promotion of cell survival and proliferation, good in-situ gel formation and biocompatibility. We believe that such thermosensitive injectable CMCH hydrogels would be very useful for biomedical applications, such as tumor model for cancer research, post-operative adhesion prevention, the regeneration of cartilage and central nervous system and so on. [ABSTRACT FROM AUTHOR]

Abstract: The biological functions as well as physico-chemical properties of hyaluronan (HA), one of the most important and ubiquitous glycosaminoglycan in various organisms, are closely related to its molecular weight, molecular weight distribution and chain conformation. For this reason it is crucially important to make a reliable characterization of these parameters for HA in both chemical and clinical fields. The present work compared the application of different techniques including capillary viscometry, concentration gradient multiangle laser light scattering (CG-MALLS), size exclusion chromatography-multiangle laser light scattering (SEC-MALLS), asymmetric flow field flow fractionation-multiangle laser light scattering (AFlFFF-MALLS) and horizontal agarose gel electrophoresis (AGE), to the characterization of a range of HA samples of bacterial and animal sources. The advantage and limitation of these techniques were discussed in terms of producing accurate and reliable molecular parameters. [Copyright &y& Elsevier]

Abstract: This study investigates how the phase separation induced by the biopolymers gelatin and gum arabic influences the microstructure of alginate beads prepared in CaCl2 solutions and the subsequent rehydration of the air-dried beads. The extent of associative phase separation in mixture gel beads can be controlled via pH. Compared with control beads, alginate/gelatin mixture beads swelled faster at the initial stage of rehydration while slowed down at the late stage, reaching a lower equilibrium swelling ratio. The faster initial swelling kinetics can be attributed to the presence of gelatin which prevents the side-by-side aggregation of egg-box junctions. This conclusion was confirmed using wide angle X-ray diffraction (WAXD) measurements. The lower equilibrium swelling ratio was due to the gelatin network restricting alginate from further swelling. This was evidenced by temperature dependence swelling experiments and comparison with alginate/gum arabic beads where no additional network was formed on top of the alginate network. The varying of pH, correspondingly the change of phase separation extent, had a significant influence on the rehydration of mixture gel beads. The best rehydratability was observed at higher pHs where no phase separation occurred and the components were homogenously mixed. With decreasing pH, the associative phase separation between alginate and gelatin was promoted, and led to local over-concentration of alginate, which gave rise to poor rehydratability. [Copyright &y& Elsevier]

Abstract: The influence of molecular association on the rheological behavior of gum arabic solution was studied. Using time-dependence of transient shear stress a reversible molecular association could be arrested and the thixotropy of gum arabic solution was interpreted. The structural breakdown, buildup and the effect of shear history due to molecular association could be related using the Casson’s equation. Stress jump measurements distinguished the effect of molecular association on the elastic and viscous contributions of shear stress. An elastic-like contribution dominated at low shear rates whereas the viscous component became important at high shear rates. The elastic contribution was strongly affected by the molecular association of gum arabic, with increased molecular association contributing to a larger elastic contribution. The elastic and viscous contributions were also investigated in transient flow. Both of the contributions increased with rest time, indicating a buildup of molecular association. With increasing the rest time the elastic contribution increased much faster than the viscous contribution to the total stress. [ABSTRACT FROM AUTHOR]

Abstract: This study deals with the rheological properties of aqueous solutions of gum arabic, the complex arabinogalactan polysaccharide containing about 2% protein. The flow behavior of control gum and a matured gum (EM2), which have different molecular associations, was investigated at different concentrations in water and added urea (6M) by rheological and dynamic light scattering methods. The influence of molecular association on rheological behavior of gum arabic solutions was studied. It was found that though Newtonian behavior was observed across a wide range of concentrations and at high shear rates, gum arabic solutions showed a pronounced shear thinning in low shear rate ranges. The maximum difference in viscosity between shear rate increasing and decreasing processes was observed at 6% for both control gum and EM2 in water, and at 3% for control gum and 9% for EM2 in urea solutions. The results demonstrated macromolecular association of gum arabic occurring in the solutions, and the observed time-dependent flow behavior reflected microstructural breakdown and re-building in the systems. This phenomenon was understood in view of the relationship between rheological properties and microstructural characteristics. A model was presented to interpret the rheological behavior, which is attributed to the occurrence of shear-induced breakdown and re-formation of gum arabic aggregates. [Copyright &y& Elsevier]

Abstract: Gelation behavior of sodium alginate was investigated in an aqueous system at various CaCO3 doses using two alginate samples of different mannuronate (M)/guluronate (G) ratios but with comparable molecular masses. Macroscopic rheological properties of the polysaccharide were discussed during gelation in relation to microscopic supermolecular structures imaged by atomic force microscopy and Ca2+ binding. At fixed concentrations of the polysaccharide (0.5 w/v%) and glucono-δ-lactone (15mM) as an acidic material, the G-rich sample was higher in elasticity with rod-like molecular assemblies at the highest CaCO3 dose; 15mM, while the M-rich sample was higher in elasticity with network-like molecular assemblies at the lowest CaCO3 dose; 3.75mM. Gelation behavior near the sol-to-gel transition was generally described by the percolation model, except for the M-rich sample at the lowest CaCO3 dose. A critical CaCO3 dose corresponded to 7.5mM at which both alginate samples showed essentially the same gelation kinetics. In an equilibrium state, it was estimated that the G-rich sample was bound to larger amount of Ca2+ at the lowest CaCO3 dose, while the M-rich sample was bound to larger amount of Ca2+ at the highest CaCO3 dose. The amount of bound Ca2+ did not directly relate to elasticity of the system. Based on these results, dominant block structures are suggested for gelation. [Copyright &y& Elsevier]

Abstract: For polyuronates, such as pectin and alginate, the ability to bind calcium and to form gels is the basis of their biological functions and technological applications. In a previous paper [Fang, Y. P., Al-Assaf, S., Phillips, G. O., Nishinari, K., Funami, T., Williams, P. A., & Li, L. B. (2007). Multiple steps and critical behaviors of the binding of calcium to alginate. Journal of Physical Chemistry B, 111, 2456–2462], we investigated the binding of calcium to alginate by using isothermal titration calorimetry and viscometry, and proposed a multi-step model which involves several steps: monocomplexation, dimerization, and lateral association. The present study examines two pectins of low and high methoxyl contents, and compares their behavior with alginate. In contrast to alginate, low methoxyl pectin has a less demarked dimerization step, which starts even when the stoichiometry of the egg-box structure is not achieved. Moreover, low methoxyl pectin shows less dimerization, and no significant lateral association. This behavior can be interpreted in terms of the structural features of the pectin. The random distribution of ester and amide groups along the pectin chain introduces much more defects into the formation of egg-box dimers and even hinders the subsequent lateral association of the dimers. The high methoxyl pectin shows a negligible chain–chain association upon binding with calcium, and its behavior can be simply depicted as a conventional polyelectrolyte without strong specific interactions. [Copyright &y& Elsevier]

It is demanded to supply foods with good quality for all the humans. With the advent of aging society, palatable and healthy foods are required to improve the quality of life and reduce the burden of finance for medical expenditure. Food hydrocolloids can contribute to this demand by versatile functions such as thickening, gelling, stabilising, and emulsifying, controlling texture and flavour release in food processing. Molar mass effects on viscosity and diffusion in liquid foods, and on mechanical and other physical properties of solid and semi-solid foods and films are overviewed. In these functions, the molar mass is one of the key factors, and therefore, the effects of molar mass on various health problems related to noncommunicable diseases or symptoms such as cancer, hyperlipidemia, hyperglycemia, constipation, high blood pressure, knee pain, osteoporosis, cystic fibrosis and dysphagia are described. Understanding these problems only from the viewpoint of molar mass is limited since other structural characteristics, conformation, branching, blockiness in copolymers such as pectin and alginate, degree of substitution as well as the position of the substituents are sometimes the determining factor rather than the molar mass. Nevertheless, comparison of different behaviours and functions in different polymers from the viewpoint of molar mass is expected to be useful to find a common characteristics, which may be helpful to understand the mechanism in other problems. Image 1 • Examples of rheology control by molar mass are shown. • High and low molar mass compounds often show opposite effects. • Effects of lower mass compounds on the properties of food polymers are discussed. • Molar mass effects in physiological function of foods are discussed. • Molar mass effects in flavour release are discussed. [ABSTRACT FROM AUTHOR]

Abstract Utilization of protein-based nanoparticles encapsulating resveratrol is hampered by their instability against the environmental stress including pH, ionic strength and UV light. In this study, we fabricated a sodium alginate (Alg)-shelled soy protein isolate (SPI) nanoparticle for the encapsulation of resveratrol, abbreviated as RSAN. The aim of this study was to investigate the existence of Alg shell on both colloidal and chemical stabilities of RSAN. RSAN, fabricated at pH 3.5 and 0.25 mg/mL of Alg, is 204.5 ± 12.1 nm in diameter, −36.4 ± 1.2 mV in ζ-potential and 91.9 ± 3.3% in encapsulation efficiency of resveratrol. RSAN exhibited consistent solubility from pH 2.0 to 8.0 and was resistant to precipitation in ionic strength of 400 mM NaCl at various pHs. The protein in RSAN was prevented from digestion in gastric. Only 15% trans-resveratrol in RSAN was isomerized after 30 min UV light exposure, which is approximate 30% less than the non-shelled nanoparticle (RSN). Moreover, the encapsulation of resveratrol did not reduce its antioxidant activity. The findings suggest that this Alg-shelled nanoparticle has a potential in encapsulating hydrophobic bioactive compounds for utilization in functional foods. Graphical abstract Image 1 Highlights • Sodium alginate shelled soy protein isolate nanoparticles encapsulating resveratrol were fabricated. • The shelled structure significantly improved the colloidal stability of the nanoparticles. • Trans-resveratrol in the nanoparticles was protected from isomerization against UV. • The nanoparticles are promising for encapsulation of resveratrol for food applications. [ABSTRACT FROM AUTHOR]

Apricot kernel meal is an understudied and underutilized by-product of the apricot industry. In this study, apricot kernel protein (AKP) was obtained from apricot kernel meal by a simple one-step salting-in method, exhibiting high yield (38.4 g AKP/100 g defatted meal), high protein content (91.4%), and high solubility (92.5% at neutral pHs). The possibility and kinetics of AKP fibrillization were further investigated. It was found that apricot kernel protein amyloid fibrils (AKPFs) with twisted nanofibrillar structures were readily formed by heating at pH 2.0 and 90 °C. SDS-PAGE analysis indicated that these AKPFs contained peptide fragments with the molecular weight of around 6.5 kDa. Atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), circular dichroism spectroscopy (CD) and intrinsic fluorescence spectroscopy revealed that the structure, morphology and properties of AKPFs were analogous to other food protein-derived amyloid fibrils. Importantly, AKPF has upgraded foaming characteristics, e.g., AKPF-18h (AKPF formed at 18 h) has 31.7% higher foaming capacity and 30.2% higher foam stability relative to AKP. This is attributed to the formation of a homogeneous interfacial film at the air/water interface of the foam. The DPPH radical scavenging activity of AKPF-18h was also improved, reaching 53.0%, about twice that of AKP (28.4%). In addition, the developed AKP and AKPFs were not cytotoxic in vitro. All these findings suggest that AKPFs have great potential for future food applications. [Display omitted] • Apricot kernel protein (AKP) was prepared with high yield, purity and solubility. • AKP amyloid fibrils (AKPFs) were readily formed under conventional conditions. • The foaming capacity and foam stability of AKPFs were significantly improved. • Antioxidant activity of AKPFs were also significantly enhanced. • AKP and AKPF were not cytotoxic in vitro. [ABSTRACT FROM AUTHOR]

Functions of low molecular-weight polyuronate fractions in the calcium binding and calcium-induced gelation of normal low-methoxyl pectin (LMP) were investigated. The fractions from pectin with two different degrees of esterification (DE) and also from alginate with two different mannuronate/guluronate (M/G) ratios were prepared within the weight average molecular-weight range from ca. 40–65 kg/mol. In the mixtures of LMP and each polyuronate fraction, changes in the relative viscosity ( η r ) of dilute solutions and in rheological properties of gels were examined in the presence of calcium. Different results were indicated between the pectin and the alginate fractions. The addition of the pectin fractions, regardless of its DE, increased η r of dilute solutions and increased dynamic storage modulus ( G ′) of gels with showing greater effects at the lower DE. On the contrary, the addition of the alginate fractions, regardless of its M/G ratio, increased the critical threshold concentration of calcium required for the increase in η r of dilute solutions and decreased G ′ of gels with showing greater effects at the lower M/G ratio (i.e. guluronate rich). Based on the results, molecular associations of the mixtures were presented schematically to compare the functions between the pectin and the alginate fractions. [ABSTRACT FROM AUTHOR]

Gum Acacia Seyal (ASY) is less valued than is gum Acacia Senegal , due to its poor emulsifying ability. The present study investigated the Maillard reaction between ASY and β-lactoglobulin (BLG) and its impact on the emulsifying properties of ASY. The reaction products of BLG/ASY mixture ( r = 1/4), prepared by dry-heating at 60 °C and a relative humidity of 79%, as a function of incubation time, were characterized by SDS-PAGE, GPC-MALLS and DSC. The results showed that 12–24 h of dry-heating under the given conditions was sufficient for conjugation, meanwhile avoiding the formation of deeply coloured and insoluble melanoidins. More than 64% of the protein was incorporated into ASY, resulting in a two-fold increase in arabinogalactan-protein (AGP) content and 3.5 times increase in weight-average molecular mass of ASY. The conjugation with BLG markedly improved the stability of ASY-stabilized emulsions and their resistance against severe conditions, such as low pH and high saline conditions. [ABSTRACT FROM AUTHOR]

The functions of low molecular-weight M w polyuronate on the calcium binding and calcium-induced gelation of normal sodium alginate (ALG) have been investigated. Mannuronate- and guluronate-rich fractions were prepared from ALG at two different M w for each. In the mixtures of ALG and each alginate fraction, changes in the relative viscosity of dilute solutions and rheological properties of the gels were examined after calcium addition. In dilute solutions, the mannuronate-rich fractions did not substantially alter the calcium binding behavior of ALG regardless of M w . On the contrary, the guluronate-rich fractions changed the calcium binding behavior of ALG, and more calcium was required for increase in the relative viscosity relating to the formation of egg-box dimers and subsequent aggregations. These results were more evident when M w of guluronate-rich fractions was lower. Gel rheology was also different between the mannuronate- and the guluronate-rich fractions. In the gels, both fractions decreased the storage modulus in the linear viscoelastic regime with increased yield strain, but these effects of the guluronate-rich fractions were greater than the mannuronate-rich fractions when compared at equivalent M w . These functions of the guluronate-rich fractions were quite different from those of low-methoxyl pectin fraction. By using well-characterized polyuronate samples, calcium-induced gelation for the mixture of ALG and each low M w polyuronate was compared on the molecular level. [ABSTRACT FROM AUTHOR]

The texturization of high-moisture extrudates is crucial for assessing their texture and palatability. Inducing melt elongation flow and controlling cooling temperature are effective strategies for improving protein texturization in the cooling zone. In this study, a multihole die assembly composed of an 89-hole plate and a cooling die was employed for the high-moisture extrusion of soy proteins. The morphology, textural characteristics, and water distribution of the resulting extrudates at different cooling temperatures were investigated. The results showed that the utilization of a multihole die significantly increased the texturization degree of the extrudates by approximately 30%. Extrudates produced at a cooling temperature of 40 °C exhibited anisotropic and fiber-rich structures. These extrudates had superior elasticity and chewiness compared to conventionally extruded proteins, and they also displayed even water distribution in the textured protein matrices. The acquired knowledge would offer valuable insights into the cooling-induced protein texturization facilitated by multihole die technology, which holds significance for the structural design of plant-based meat analogs. [Display omitted] • Cooling temperature and the use of a multihole die affected protein texturization. • Extrudates produced via a multihole die exhibited anisotropic, fiber-rich structures. • Textural characteristics of the extrudates were improved by using a multihole die. [ABSTRACT FROM AUTHOR]

[Display omitted] • Carrageenan effectively masks the bitterness of potassium salts via binding free K+. • Formation of stable double helix structure is basis for bitterness-masking effect. • A highly accurate prediction model is established for saltiness and bitterness. • Created low-sodium salts show favorable sensory properties and application prospect. Potassium citrate (KC) and potassium lactate (KL) are considered as salt replacers due to their saltiness, processing advantages, and health benefits. However, the obvious bitter taste associated with these compounds has limited their use in salt substitutes. Despite this challenge, little attention has been paid to improving their sensory properties. This study provided evidence that dietary polysaccharide carrageenan can effectively mask the bitterness of KC and KL by specifically binding K+ and forming double helix chains. A highly accurate prediction model was then established for the saltiness and bitterness of low-sodium salts using mixture design principles. Three low-sodium salt formulas containing different potassium salts (KC, KL, KCl), NaCl, and carrageenan were created based on the prediction model. These formulas exhibited favorable saltiness potencies (>0.85) without any noticeable odor, preserving the sensory characteristics of high-sodium food products like seasoning powder while significantly reducing their sodium content. This research provides a promising approach for the food industry to formulate alternative low-sodium products with substantially reduced sodium content, potentially contributing to decreased salt intake. [ABSTRACT FROM AUTHOR]

Mixed gels containing κ-carrageenan, ι-carrageenan, konjac glucomannan and xanthan were investigated. In binary mixtures, the only interactions identified from differential scanning calorimetry were between konjac glucomannan and κ-carrageenan or xanthan. The effect of konjac addition on κ-carrageenan-ι-carrageenan mixed gels was similar to that on κ-carrageenan gels, namely, an initial increase of the elastic modulus was observed up to a certain stoichiometric ratio, followed by a plateau of the elastic modulus and a strong increase of the fracture strain when konjac was added in excess. Addition of xanthan led to maxima and minima of the elastic modulus and fracture strain and stress. Interestingly, characteristic features of the elastic modulus appeared at the same concentration of xanthan added to kappa-carrageenan/konjac glucomannan mixtures with or without iota-carrageenan, indicating that xanthan is present in the kappa-carrageenan/konjac phase and absent from the iota-carrageenan phase. Characteristic features of the fracture properties, however, were shifted to higher concentrations of xanthan when iota-carrageenan was added. We tentatively conclude that xanthan chains that are concentrated in the kappa-carrageenan/konjac phase under quiescent conditions achieve homogeneous distribution under large mechanical deformation. [ABSTRACT FROM AUTHOR]

As negatively charged polyelectrolytes, alginate conformation is greatly influenced by ionic environment, which is of critical importance for solution properties and practical applications. To advance our understanding of alginate conformation in the presence of non-specific ions (NaCl, KCl, MgCl 2), high resolution atomic force microscopy, together with statistical analysis, is employed to provide direct structural information. Alginate chains undergo a collapse-reexpansion transition with increasing salt concentration, which is quantitatively evidenced by a nonmonotonic evolution of persistence length (L p). At low salt concentrations, a decrease in L p is caused dominantly by electrostatic screening effect as electrostatic persistence length (L p e ) shows a strong dependence on Debye screening length (κ −1) with a scaling relation of L p e ∼ κ −2, which is in agreement with Odijk-Skolnick-Fixman theory described for semiflexible polyelectrolytes. Above a certain salt concentration, there is a rise in L p , which can be explained by overcharging and ion-ion correlations. The type of salt also affects the change degree of persistence length, with divalent ions (Mg2+) showing the greatest collapse and reexpansion level. Since alginate chains containing higher α-L-guluronate (G) content are more influenced by salts, it can be inferred that non-specific ions have a higher affinity for G units. [Display omitted] • Upon addition of non-specific ions, alginate undergoes a collapse-reexpansion transition. • Corresponding to the conformational transition, the persistence length shows a nonmonotonic evolution. • The chain collapse is caused dominantly by electrostatic screening effect. • Overcharging and ion-ion correlations could account for chain reexpansion. • Non-specific ion types and alginate composition affect the chain conformation. [ABSTRACT FROM AUTHOR]

Pulse proteins are promising components for plant-based food development, yet their diverse subunit compositions, influenced by source origin, result in variable extrusion properties. This study utilized high moisture extrusion (60% moisture content) to prepare extrudates from four pulse proteins: soy, pea, chickpea and mung bean protein isolates (SPI, PPI, CPI, and MPI, respectively). The texture, structure, and in vitro digestion characteristics of extrudates were examined. The results showed that SPI and PPI were mainly composed of 7S and 11S globulins, while CPI and MPI were mainly composed of 7S globulins, and 11S globulins, respectively. SPI extrudates exhibited significantly lower hardness, chewiness, and transverse and longitudinal fracture stresses, while CPI extrudates exhibited a higher anisotropy index. SPI extrudates with a higher β-sheet content (39.08%) exhibited denser structures. The gastrointestinal digestibility (86.65%) of CPI extrudates was higher than other groups. Correlation analysis showed that 7S/11S ratio was positively correlated with the melt viscosity, while negatively correlated with the anisotropy index and in vitro digestibility. This study highlights the distinct extrusion properties of pulse proteins based on their unique subunit composition. The results provide insights for selecting appropriate protein sources and developing plant-based protein products with tailored textural attributes and desirable digestibility. [Display omitted] • Pulse protein subunit composition was correlated with the extrusion properties. • Viscoelastic characteristics affected the texture of extrudates. • 11S-riched pulse exhibited most abundant fibre structure and lowest β-sheet structure. • Chickpea extrudates exhibited the lowest gastric retention and highest digestibility. [ABSTRACT FROM AUTHOR]

Abstract: Emulsification/internal gelation is an effective encapsulation method to protect probiotics from adverse environment. In this paper, microcapsules of Lactobacillus acidophilus CGMCC1.2686 were prepared by emulsification and gelation of alginate solutions with slow release of Ca2+ ions from calcium carbonate (CaCO3) and calcium disodium ethylenediaminetetraacetate (Ca-EDTA). Physical characterization of the two types of microcapsules showed that alginate-Ca-EDTA microcapsule was more uniform in size than alginate-CaCO3, with a span factor of 0.96 and 1.20, respectively. Mechanical measurements demonstrated that alginate-CaCO3 microcapsule was more robust and elastic, which was supported by its denser structure as observed by electron scanning microscopy. Bacteria encapsulation yields in the two microcapsules were similar, 37.9% for alginate-CaCO3 and 36.9% for alginate-Ca-EDTA. However, alginate-CaCO3 microcapsule exhibited much higher cell survivals in both simulated gastric juice and bile salts solution (22.2% and 2.6*10−2%, respectively) than alginate-Ca-EDTA (7.1% and 0%, respectively), indicating a more effective protection of L. acidophilus CGMCC1.2686. The protection efficiency was discussed in relation to the mechanical properties of the microcapsules and the calcium sources used. [Copyright &y& Elsevier]

Abstract: It has been suggested that the Traditional Chinese herbal preparation Cordyceps sinensis (CS) may have a beneficial effect in renal disease. We have previously demonstrated bio-activity of naturally occurring CS. To satisfy increasing demand, CS derivatives have been produced by aseptic mycelia cultivation. The aim of this work was to compare and contrast the bio-activity of natural CS and two specific products derived from cultured Cordyceps mycelia, “Jinshuibao Capsule” (Paecilomyces sinensis) and “Corbrin Capsule” (Hirsutella sinensis). In addition using two different cell systems we examined the potential anti-fibrotic potential of these products beyond the kidney. All three preparations antagonised the activity of the pro-fibrotic cytokine TGF-β1 in renal epithelial cells. Activity was seen in the raw water-soluble components, and the hydrophilic and hydrophobic extracts from each preparation suggesting that the bio-activity is not confined to one component of the raw material. In addition to the effects in the renal cell line, similar effects of antagonism of phenotypic activation of pulmonary fibroblasts by TGF-β1 was also seen suggesting an applicability of these observations to solid organ fibrosis beyond the kidney. Mechanistically the data demonstrate antagonism of TGF-β1 activation of Smad signalling and specifically of induction of the hyaladherin TSG-6, which we have previously demonstrated to orchestrate the formation of a hyaluronan, peri-cellular coats driving phenotypic cellular activation. In summary the data support the claim that both naturally occurring and products derived from cultured Cordyceps mycelia have similar bio-activity which may have particular relevance for solid organ fibrosis and associated organ dysfunction. [Copyright &y& Elsevier]

Emulsion-templating techniques have been used to develop structurally anisotropic hydrogels. This paper proposes a method to couple biopolymer assembly behavior with a phase-separated aqueous two-phase system (ATPS) to construct a hierarchical structure on protein-polysaccharide hydrogels. Based on the phase separation of Artemisia sphaerocephala Krasch polysaccharide (ASKP) and whey protein isolate (WPI) fibrils, a bi-continuous hydrogel was fabricated through spontaneous iron-facilitated molecular chelation. The impact of WPI fibrils under ultrasonic treatment for varying durations on gel structurization and physicochemical properties was also exploited. Shorter length of WPI fibrils facilitated stepwise cross-linking gelation during the oxidation of ferrous ions to ferric ions. Specifically, ultrasonic treatment for 6 min and 8 min promoted the accumulation of shorter fibrils, resulting in the formation of a more intensive clockwise-oriented hierarchical network. Compared to the hydrogels with longer linear aggregates without the ultrasonic treatment, the incorporation of the shorter aggregates resulting from ultrasonic treatment for 6 min and 8 min significantly increased the gel's water holding capacity and mechanical properties. Additionally, the fibrils that underwent ultrasonic treatment for 6 min resulted in a more stable three-dimensional network with optimal elastic performance. This study presents a new water-in-water emulsion-templated strategy for structural regulation and stabilization of multiform hydrogel. [Display omitted] • A hierarchical structured hydrogel was created using a phase-separated ATPS. • WPI fibril length effectively impacted the properties of the hierarchical hydrogel. • Shorter fibrils resulted in an oriented network, improving the mechanical properties. [ABSTRACT FROM AUTHOR]

Abstract: The bioavailability of lipids from an emulsion can be controlled and regulated by the property of the stabilizing interfacial layer. Here we evaluate how low-molecular weight surfactants including hexadecyl trimethyl ammonium bromide (CTAB), sodium dodecyl sulfate (SDS), and Tween 80 (T80) influence the interfacial behavior of lipase and bile extract on the surface of lipid droplets stabilized with gum arabic (GA). The lipolysis behavior was influenced by surfactant type and concentration. The results showed that anionic SDS could completely displace GA from droplet surface. Cationic CTAB might either adsorb onto existing GA layers or displace GA, whereas non-ionic T80 could co-adsorb with GA on the interface. When the concentration of surfactants was much higher than the critical micelle concentration (CMC), all the surfactants would form a dense adsorption layer on the droplet interface to prevent lipase from the direct contact with lipids. A considerable amount of surfactant in the aqueous phase may also compete with the bile salt and lipase, thus leading to suppressed digestion of lipids. Ionic surfactants would denature the lipase resulting in reduced enzyme activity, and T80 micelles may interact with the lipase, hindering their adsorption onto the droplet interface as well. These results were confirmed both by the digestion model and interfacial techniques. The results provided guidance for the development of emulsion-based delivery systems for functional lipid foods. [Copyright &y& Elsevier]

Abstract: Fourteen commercial LM-pectin samples were investigated in this study. The degree of esterification (DE) varied from 9.6% to 42.0% and the degree of amidation (DA) from 0% to 25%. Chemical and structural characteristics were examined using atomic absorption (AA), dilute solution capillary viscometry, GPC-MALLS and dynamic light scattering. The intrinsic calcium was in the range of 47–1388ppm, the intrinsic viscosity varied from 2.9 to 4.9 (dL/g) and the weight average molecular weight (M w) from 113 to 290 (kDa). Most of the samples had Huggins constants of ∼0.5. However, for samples having acidic pH, Huggins constant values greater than 1, which can be as an indication of aggregation, were obtained. The high Huggins constant value could be reduced to ∼0.5 by the addition of 3M urea, indicating that the aggregation was stabilised by hydrogen bonding. Shear flow viscosity revealed three types of rheological behaviour. Type A showed pronounced shear thinning behaviour, which was reduced by the addition of hydrogen bonding breaking agent urea. Type B with intrinsic Ca of 1mM and pH ∼4 showed two shear thinning regions, with significantly enhanced shear viscosity upon addition of calcium. Type C showed the least aggregation due to its pH ∼4 and low intrinsic Ca, but could be converted to type B upon addition of Ca. The effect of Ca on the rheological behaviour of types B and C was further confirmed by CaCl2 and Ca-chelating agent (EDTA). Temperature affected the molecular conformation of all types and most significantly type A by eliminating the hydrogen bonding. [Copyright &y& Elsevier]

Abstract: The emulsification performance, stability and competitive adsorption of two natural food emulsifiers, sugar beet pectin (SBP) and hydroxypropyl methylcellulose (HPMC) have been investigated. Both can reduce the surface tension and emulsify oil in water. However, due to their different structure and conformation they operate via different mechanisms. Using 15% middle chain triglycerides (MCTs) oil, the amounts of SBP and HPMC adsorbed in emulsions made with these individually and in mixtures were determined. The interfacial concentration (Γ) for SBP stabilized emulsion was ∼1.25mg/m2 and for HPMC 3.5mg/m2. The higher adsorption of HPMC was due to multilayer adsorption, whereas SBP adsorbed as a monolayer. Competitive adsorption between SBP and HPMC was also investigated. When the HPMC concentration approached that of adsorbed SBP, the effect of HPMC became dominant and at 1.5wt.% controlled the behavior of the mixed emulsions, which were then almost independent of SBP. The minor role of SBP was mainly to decrease the proportion of large droplets in the emulsion. A model to describe the competitive adsorption between SBP and HPMC is proposed. [Copyright &y& Elsevier]

Abstract: The structure and conformation of xanthan in aqueous solution following various processing treatments typically encountered in its application were investigated in this study. Treatments such as heating, autoclaving, high pressure homogenisation and irradiation were subjected to the same sample. Parameters such as weight average molecular weight (M w ), polydispersity index, root mean square radius of gyration, intrinsic viscosity and Huggins constant were used to monitor the effect of these treatments. Additionally, we have quantified the mass recovery of samples examined by gel permeation chromatography and light scattering to properly account for all fractions present in xanthan solutions. Atomic force microscopy (AFM) images together with height measurements confirmed that xanthan conformation is double helical ordered renatured state (pre-heat treated by the manufacturer) in dilute solution conditions and random coil conformation in very dilute solution. The ordered (renatured) conformation is shown to have partially molten double helix, with more flexibility than the perfectly ordered native double helix. Heat treatment for 2h at 85°C reduces the M w of xanthan to half its initial value, and mass recovery measurements indicate that it completely overcomes its associative nature. Thermally treated xanthan solution in the dilute region leads to an order–disorder transition, as determined by contour length per unit mass. Similarly, irradiation of xanthan solution results in an order–disorder transition together with the production of single strand low molecular weight molecules. Autoclaving and high pressure homogenisation treatments cause degradation of xanthan. The results from treated xanthan solutions following high pressure homogenisation and irradiation confirm that xanthan does not reassociate. A revised summary of xanthan conformation in solution together with schematic models following the various treatments are proposed. [Copyright &y& Elsevier]

The Pueraria has been distributed in most countries of the world, but starch isolated from its root is only popular in China, Japan and other East Asian countries. Herein, we summarize the isolation, components, structure, properties, modifications and applications of kudzu starch. The coexistence of isoflavones with starch leads to the unique feature of kudzu starch. Similar to other common starches, kudzu starch molecules are composed of amylose and amylopectin. However, the fine structure of kudzu starch is different from other starches, influencing its transparency, solubility, swelling power, freeze-thaw stability, gelatinization, retrogradation, pasting and rheological properties, and even in vitro digestion. Kudzu starch has been modified by physical, chemical and enzymatical methods to improve its properties and then potentially broaden its applications. Although kudzu starch has been applied in food and non-food fields, its large-scale utility is limited as compared with other commercial starches. This review would provide useful information for the development and applications of kudzu starch. [Display omitted] • We comprehensively review on various aspects of kudzu starch. • Kudzu starch is compared with other common and commercial starches. • The composition, structure and properties of kudzu starch are described. • The modifications and applications of kudzu starch are discussed. [ABSTRACT FROM AUTHOR]

Polymer hydrogels have attracted considerable attention as functional materials. The conventional single network hydrogels (SNs) are mechanically either too soft or brittle to be used as load-bearing substances. Therefore, the interpenetrating network hydrogels (IPNs) with unique physical characteristics paid more and more attention and they have shown great potentials in fabricating a variety of food structures with desired functionalities. This review provided a summary of the latest developments and applications of IPNs in terms of synthesis strategies (heating-cooling, enzymatic, and ionic-induced technique), physical performance (mechanical property, water holding capacity, swelling capacity, and thermal property), formation and strengthening mechanisms, as well as food applications. The major future trends of IPNs in food systems were also discussed. As compared with SNs, IPNs generally exhibited more favorable mechanical performance, water holding capacity and thermal stability. The strengthening mechanisms of IPNs were mainly attributed to the filling of polysaccharides in other biopolymers, the increased density of entangled network, and the possible interactions between individual networks. IPNs with tunable mechanical property could be fabricated, showing great potential for various food applications such as edible films, three-dimensional printing, delivery of bioactive/aroma compounds, as well as fat replacers. • IPNs can be fabricated by heating-cooling, ionic and enzymatic crosslinking. • IPNs exhibit favorable mechanical properties, high WHC and thermal stability. • IPNs provide approving texture and pleasant sensory quality for food. • Strengthening of IPNs is due to "filler effect" and enhanced noncovalent actions. • IPNs show potential application in meat analogues, 3D printing and fat replacers. [ABSTRACT FROM AUTHOR]

High-moisture extrusion (HME) is an appealing strategy for the production of textured vegetable proteins (TVP) with meat-like structures. However, the processing parameters and formulation have a limited influence on the quality characteristics of the final HME-TVP. Therefore, we improved the component design of the cooling die, which is critical to protein texturisation, to yield the desired extruded products. In the present study, a multihole nozzle set was specifically designed to regulate protein texturisation in the cooling die. The fibrous structure, texture, and in vitro digestibility of the nozzle-produced HME-TVP were investigated at different cooling temperatures. The results showed that the integration of a multihole nozzle in the cooling die greatly improved protein texturisation. In contrast to the parabolic fiber distribution of conventionally extruded proteins, the resulting HME-TVP featured a meat-like structure with parallel and straight fibers. Furthermore, nozzle-produced HME-TVP at 40 °C exhibited excellent freeze-thaw stability and rehydration capacity. Significant structural changes in HME-TVP had little impact on protein digestibility unless the cooling die temperature was below 40 °C. These findings provide a valuable technical path to improve the quality of plant-based meat analogue products. [Display omitted] • The multihole nozzle sheet considerably promoted protein texturisation. • Nozzle-formed protein extrudates exhibited a fiber-rich, meat-like structure. • The cooling nozzle set yielded extrudates with improved processing characteristics. [ABSTRACT FROM AUTHOR]

In the present work, the rheological properties of model boli were analysed based on the granular matter physics. Polysaccharide microgels mixed with artificial saliva were prepared as model boli. The storage modulus G ′ of alginate gel beads increased and then decreased with increasing content of artificial saliva. Surface of alginate gel beads prepared by dripping into calcium chloride solution were wiped to remove the moisture to mimic the oral condition of the Sjögren's syndrome. G ′ decreased monotonically with increasing artificial saliva beyond a certain amount of the added saliva, which is similar to the widely observed characteristic of wet granular materials. Although the analysis is limited to a model bolus at a certain stage of oral processing mimicked by instrumentally prepared microgels of uniform size and shape, it revealed some fundamental aspects highlighting the implication of a wet granular matter as a useful concept for further understanding of the bolus rheology. [Display omitted] • Polysaccharide microgels were prepared and mixed with artificial saliva. • Elastic modulus of a microgel was measured using Hertz theory. • Storage modulus of microgels increased and decreased with increasing saliva. • Smaller alginate microgels showed a peak modulus at a lower saliva content. [ABSTRACT FROM AUTHOR]