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Isopropanol was used to sequentially precipitate sugar beet pectin (SBP) and generate six fractions that varied in galacturonic acid, protein, ferulic acid and other physic–chemical characteristics. Protein was high in Fractions 1 and 2 at 209 and 154 μg/mg alcohol insoluble solids (AIS), respectively. Fractions 3, 4, and 5 had lower protein values of 77–106 μg/mg AIS; the protein content was 87 μg/mg AIS in unfractionated control. Ferulic acid content in Fraction 1 was 93 μg/mg AIS and at least three times higher than measured in other fractions. The degree of esterification in Fraction 1 was 11% and ranged from 46 to 74% in later precipitating fractions. The relative fluorescence with an external probe for hydrophobicity ranged from 159 to 254 in F1, F2 and F3 compared to negligible values in later fractions. The ζ-potential ranged from −25 to −33 mV and was not different between fractions or control. Molecular weight analysis indicated highly heterogenous pectin (Mw/Mn greater than 2.5) with MW values of 398,630, 543,900, and 442,330 g/mol for F1, F4 and control, respectively. FTIR analysis confirmed that F1 and F2 were richer in protein. SBP that precipitated at the lowest isopropanol addition had the greatest protein, ferulic acid content, particle size, relative fluorescence intensity and lowest uronic acid content and degree of esterification. The type and/or nature of protein in F1 and F4 is likely different. Isopropanol fractionation resulted in SBP fractions with unique physico–chemical properties. [ABSTRACT FROM AUTHOR]

The objective of this study was to determine the water distribution in maize starch (MS) and pea protein isolate (PPI) composite gels and understand how the separate contributions of MS and PPI affect the mechanical properties of composite gels with varying MS/PPI ratios. A series of MS gels with increasing PPI contents and a series of PPI gels with increasing MS contents were prepared. The water distribution was evaluated with a novel image analysis method using confocal laser scanning microscopy (CLSM). This method was used to quantify the volume fraction of each phase, from which the water distribution between the starch phase and the protein phase within the gels was estimated. Depending on the MS/PPI ratios, either a dispersed or a bicontinuous gel was formed. The estimated stiffness of each phase was used to estimate the gel stiffness using models for either dispersed or bicontinuous structures. These predictions were shown to be in good agreement with experimental data obtained from compression tests. The determination of the properties of each phase separately allowed us to determine which phase dominated the properties of the composite gel. In filled gels, the MS network dominated the gel properties, unless the stiffness of PPI fillers was remarkably higher than that of the MS network. In bicontinuous gels, the stiffness of the composite gels was determined by the network with the highest stiffness. Dispersing pea protein aggregates (PPA) with different size into MS gels resulted in minor differences in mechanical properties compared to PPI-MS gel. These results show that this new analysis method can be used to predict water distribution within gels, and how this leads to changes in the stiffness, hardness and brittleness of the gels. [Display omitted] • Water distribution can be estimated with a CLSM imaging analysis method. • Uneven water distribution was observed in all studied starch-protein gels. • Stiffness estimated based on theoretical models was in good agreement with experimental data. • In composite gels, the stiffer component dominates the gel properties. [ABSTRACT FROM AUTHOR]

The upsurging global population, along with the increasing cost of traditional sources of food proteins, provides an opportunity to directly utilize plant-derived proteins in human diets. Recently, the utilization of agro-industrial-generated raw byproducts has attracted the attention of modern food industries toward the production of sustainable, nutritious, and biofriendly products. Plant-derived proteins are among the promising materials being investigated. In particular, cottonseed protein, an important byproduct generated during the processing of cottonseed, is abundant in basic amino acids linked with several bioactivities. The suitability of using cottonseed protein products in terms of functional attributes and nutritional value in food systems will ultimately determine the magnitude of their application in the food industry. Techniques used for the most effective extraction of cottonseed protein with an esculent gossypol concentration have been comprehensively discussed. The bioactivities of enzymatically obtained cottonseed protein hydrolysates can be employed for fabricating bioactive packaging materials. Cottonseed proteins exhibit a plethora of bioactivities, such as antioxidant, antimicrobial, immunomodulatory, and angiotensin-converting enzyme inhibitory activities. Their superior functional food properties and relatively lower cost than other plant proteins make them suitable candidates for various food and nonfood applications. In this review, recent developments regarding the extraction, hydrolysate preparation, bioactivities, and industrial applications of cottonseed protein are thoroughly discussed. [Display omitted] • First review considering extraction of cotton seed protein and preparation of its hydrolysates. • Bifunctionalities associated with bioactive peptides from cottonseed are discussed. • Bioactive peptides exhibit antioxidant, antimicrobial and immunomodulatory activities. • Cottonseed protein have multifaceted food and non-food industrial applications. [ABSTRACT FROM AUTHOR]

The destabilization of water-in-oil (W/O) emulsions greatly restricts their application. Converting the inner water droplets into soft solid-like gelled particles is an appealing strategy to improve the stability of W/O emulsions. In the present communication, we propose a novel method for preparing stable W/O emulsions containing gelled water droplets. In this method, the 3% (w/v) casein dispersions containing 0.9% (w/v) glucono-δ-lactone (GDL) and soybean oil with 2% or 6% lipophilic emulsifier polyglycerol polyricinoleate (PGPR) were homogenized to form W/O emulsions. Three hours later, the GDL-induced gelation of caseins in the inner aqueous phase occurred; thus, the W/O emulsions containing gelled water droplets were formed. The stability of the emulsions was characterized by Turbiscan analysis, particle size changes and visual inspection of phase separation. It was found that the W/O emulsions containing GDL-induced casein gels in the inner aqueous phase showed higher resistance to destabilization than the non-gelled W/O emulsions. In addition, the stability of the emulsions formulated by the gelled aqueous phase and 2% PGPR was even higher than emulsions with 6% PGPR in the absence of the gelled aqueous phase. These findings suggested that this method is an effective strategy for improving the long-term stability of W/O emulsions. [ABSTRACT FROM AUTHOR]

Protein plays an important role in the emulsifying properties of sugar beet pectin (SBP). The present work was carried out to investigate the role of protein content and the combination mode between proteins and pectins on the emulsifying properties of SBP. It was found that protein contents and structural differences of SBPs affected the stability of emulsion. As the protein content increased from 0.5 to 3.0%, droplet size of emulsion stabilized by SBP decreased sharply. It turned to be stable when the protein content increased to a high level (from 3.0 to 6.0%). Thermal gravimetric analysis confirmed the structural differences among SBP samples. In order to study the functionality of protein/pectin combination mode to emulsifying properties, modification of SBP was conducted by depleting a portion of proteins, and electrostaticly or covalently binding BSA to the de-proteinized SBP. Results showed that Maillard induced conjugates exhibited the best emulsifying stability, as compared with original SBP, de-proteinized SBP and the electrostatic bonding complex. These results suggested that both protein content and the combination mode between protein and pectin could affect the emulsifying properties of SBP. [ABSTRACT FROM AUTHOR]

The study involved the investigation of the antioxidant and antihypertensive properties of the phenolic–protein complexes obtained from isolated protein fractions from Nigella damascena and Nigella arvensis . Protein fractions from flours made from the seeds of Nigella species were isolated and included albumin, globulin, glutelin-1, glutelin-2 and prolamin. Albumin and glutelin-1 fractions were the predominant proteins in the two Nigella species studied in terms of protein content and percent protein yield. Free phenolics were extracted from the isolated protein fractions by methanol treatment at either 25 °C or 60 °C followed by acid and base hydrolysis to obtain bound phenolics. The free and bound phenolic composition was assessed by RP-HPLC. The highest phenolic content was observed in the free phenolic extract at 25 °C (FP-25 °C) in glutelin-2 of both Nigella species. The free and bound phenolics of the protein fractions were tested for angiotensin converting enzyme (ACE) inhibitory and antioxidant activities. The greatest ACE inhibitory activities were seen for the free and bound phenolic extracts obtained from glutelin-2 and globulin fractions of both Nigella species. The highest antioxidant activities were observed in the extracted phenolics from glutelin-1 and globulin from N. damascena and albumin from N. arvensis . Only a weak correlation was seen between the phenolic content of the isolated protein fractions and the ACE inhibitory and antioxidant activities. The present study indicates that phenolic–protein complexes in the Nigella species have significant antioxidant and ACE inhibitory properties although the bioactivities of the protein fractions are not closely related to their total phenolic content. [ABSTRACT FROM AUTHOR]

Structuring wheat gluten proteins into gels with tunable mechanical properties would provide more versatility for the production of plant protein-rich food products. Gluten, a strongly elastic protein material insoluble in water, is hardly processable. We use a novel fractionation procedure allowing the isolation from gluten of a water/ethanol soluble protein blend, enriched in glutenin polymers at an unprecedented high ratio (50%). We investigate here the viscoelasticity of suspensions of the protein blend in a water/ethanol (50/50 v/v) solvent, and show that, over a wide range of concentrations, they undergo a spontaneous gelation driven by hydrogen bonding. We successfully rationalize our data using percolation models and relate the viscoelasticity of the gels to their fractal dimension measured by scattering techniques. The gluten gels display self-healing properties and their elastic plateaus cover several decades, from 0.01 to 10,000 Pa. In particular very soft gels as compared to standard hydrated gluten can be produced. [ABSTRACT FROM AUTHOR]

This study investigated the relationship between the ionic binding of sodium and salty perception in protein matrices. Protein type (i.e. gelatin, milk protein and soy protein), protein concentration and pH were varied to obtain matrices with distinct compositions and rheological properties. 23 Na NMR spectroscopy was used to determine the ratio of sodium ions bound to proteins and the mobility of sodium ions. The results showed that protein type, concentration and pH affected the rheological properties of the protein matrices, the ionic binding of sodium ions and taste intensity. As the protein concentration increased, the mobility of sodium ions decreased and the ratio of bound sodium ions increased. Gelatin matrices displayed the greatest mobility of total sodium ions and the smallest amount of bound sodium. Soy protein had a larger amount of bound sodium than milk protein. Lowering the pH of milk protein matrices tended to decrease the ratio of bound sodium and increase sodium mobility. We suggest that sodium ionic binding is related to the presence of negatively charged groups in proteins. Although changes in matrix composition modified sodium ionic interactions, taste perception was mainly affected by the rheological properties of the protein matrices. As the values of fracture stress or viscosity increased, firmness intensity increased and saltiness intensity decreased. The observed effects of texture on taste could be explained by cross-modal texture-taste interactions and by differences in the oral breakdown behavior of protein matrices. [ABSTRACT FROM AUTHOR]

Soybean oleosome-associated protein (SOP) plays a vital role in stabilizing soy oleosomes owing to its unique amphipathic topological structure. Inspired by the structure of natural oleosomes, in the current study, SOP-decorated liposomes (SOP-Lips) were proposed as a vehicle for improving phospholipid bilayer membrane stability. The micro morphology, size, encapsulation efficiency, and retention rate of SOP-Lips were characterized, the interactions between SOP and the phospholipid bilayer and their effects on the protein and lipid bilayer structures were evaluated. When the liposomes/SOP mass ratio was 1: 0.2 and 1: 0.4, the SOP-Lips exhibited spherical morphology and favorable dispersibility. The quartz crystal microbalance with dissipation monitoring (QCM-D) result suggested that most of SOP bound to liposomes in a tightly integrated way. Spectroscopy analysis indicated that the aromatic amino acids in the protein were exposed to a more hydrophobic microenvironment due to the interactions between the SOP and liposomes. There was an increase in α-helix and decrease in β-sheet and random curl contents in SOP upon exposure to liposomes. The decoration of SOP to liposomes could decrease membrane fluidity and enhance lateral packing of the phospholipid fatty acyl chain. The SOP coating increased the pH, ionic strength and temperature stability of luteolin liposomes (LUT-Lips). In the simulated digestion, SOP-decorated luteolin liposomes (SOP-LUT-Lips) showed a delayed release effect compared with LUT-Lips, suggesting that the inclusion of SOP resulted in a more digestion-resistant structure. This work provides a viable strategy for using SOP-Lips as a delivery system for nutraceuticals in functional food, dietary supplements and pharmaceuticals. [Display omitted] • Soybean oleosome-associated protein (SOP) decorated liposomes were constructed. • SOP interacted with liposomes through hydrogen bonding and hydrophobic interaction. • SOP decreased phospholipid membrane fluidity and enhanced the bilayer orderness. • Inclusion of SOP increased the load efficiency of luteolin in liposomes. • SOP modified liposomes exhibited sustained luteolin release profile. [ABSTRACT FROM AUTHOR]

The electrostatic interactions between cationized gelatin (CG) and gum arabic (GA) have been investigated through turbidity measurements and dynamic light scattering. Gelatin was modified with ethylenediamine (EA) to introduce additional primary amino groups to enhance polycationic nature needed for complexation with polyanionic gum arabic. This study aims to gain an insight into the interactions of gelatin with GA after modification with EA. The interaction between these polyelectrolytes (GA and CG) has been studied by varying different parameters. Nanosized CG/GA complex was formed by the simple mixing of CG (0.1%, w/v) and GA (0.1%, w/v) with mixing ratio 1:1 (v/v). The effect of pH on the CG/GA complex nanoparticles (1:1, v/v) was examined by measuring changes in turbidity, hydrodynamic size and zeta potential. By varying the mixing ratio of the corresponding polymers, different types of CG/GA complex (clear and turbid) could be prepared. This study provides information regarding the effect of pH, ionic strength and biopolymer mixing ratio on the formation of polyelectrolyte complexes of cationized gelatin and gum arabic. [ABSTRACT FROM AUTHOR]

Whey protein isolate – WPI/cellulose fibers were obtained combining formation of cellulose fibers with acid induced gelation of whey protein in the simultaneous process. The mechanical properties of the cellulose fibers were improved by adding whey protein. Regenerated cellulose fibrils exhibited a dense structure with voids of several micrometers pore size. The blend fibers were smoother than cellulose fibers with smaller void spaces and attached protein filaments. On the surface of the regenerated cellulose fibers, formation of hierarchical flowerlike micro/nanostructures was observed. The XRD pattern indicated that the flowerlike microstructure was composed of ammonium copper(II) sulfate hexahydrate. Regenerated cellulose alone and in the mixtures with WPI crystallized partly in the cellulose II monoclinic system. For cellulose/WPI blend reduction in –C–OH groups was observed, which was probably caused by interactions of cellulose with the protein molecules. The obtained blended cellulose/WPI fibers can have tremendous potential use in medicine, tissue engineering and as a material for active ingredients release. [ABSTRACT FROM AUTHOR]

The natural consistency of processed tomato products arises from cell wall particles and the interactions between them. In this study, ion exchange resins were used to investigate these interactions. Two types of resins were used, a hydrogen form cation exchange resin and an anion resin in the hydroxide form. Serum phase of tomato suspensions were treated with either a cationic or an anionic resin to exchange various ionic compounds with hydrogen and hydroxide ion respectively. The treated serum was then reconstituted to the tomato pulp and the suspension was re-suspended with shear. The linear storage modulus varied with the different types of resin treatment. Samples treated with the anion exchange resin resulted in a higher modulus than the untreated tomato puree and the puree treated with the cation resin. Effect of the resins was dependent on the concentration of resin used. The anion treated sample resulted in a network formation which was quite sensitive to pH and was attributed to long range electrostatic interactions caused by protein–pectin interactions. Using Infrared spectroscopy the conformational changes in the protein structure as a result of resin treatment was detected by analyzing the amide-I and amide-II regions. [ABSTRACT FROM AUTHOR]

Beta-carotene (BC) was encapsulated by sodium caseinate (SC), whey protein isolate (WPI), and soybean protein isolate (SPI) by the homogenization-evaporation method forming nanoparticles of 78, 90 and 370 nm diameter. Indices of the chemical antioxidant assays, the reducing power, DPPH radical scavenging activity, and the hydroxyl radical scavenging activity (OH ) were improved by nanoencapsulation, compared to free BC. Caco-2 cells were treated with dichlorofluorescin diacetate (DCFH-DA) to determine the cellular antioxidant activity (CAA) of BC. CAA of SC, WPI, and SPI nanoparticles was higher (60%) compared to BC alone (45%). FTIR-ATR showed the presence of BC in the nanoparticle preparations. XRD and DSC analyses suggested that BC is amorphous in the nanoparticles. BC encapsulated by WPI had the most advantageous release properties. Release was low with pepsin but high with trypsin suggesting that WPI might be the best protein delivery vehicle to deliver BC to the intestine. [ABSTRACT FROM AUTHOR]

The objectives of this work were to 1) determine the role of pH in forming thermally stable whey protein isolate (WPI) soluble aggregates (SA), 2) evaluate the functionality of SA formed under a range of conditions, and 3) evaluate SA stability in a model beverage. Whey protein isolate SA were formed using two sources of WPI at pH 6.5 or 7.5, and thermal stability was tested in the presence of 30–60 mM NaCl or 15–30 mM CaCl 2 . Soluble aggregates from the two sources of WPI exhibited physicochemical and functional differences over the range of conditions investigated. Soluble aggregates formed at pH 7.5, 7% w/w protein, by heating statically at 90 °C for 10 min exhibited lower turbidity and viscosity, and higher solubility when thermally treated in solutions containing salt for both types of WPI, and were more sensitive to CaCl 2 . Soluble aggregates and a model beverage containing the SA were prepared at pilot scale and evaluated for shelf stability. Soluble aggregates were formed under continuous flow at pH 6.5, 7% w/w WPI, added at 5% w/w to the beverage, and thermally processed. Over nine weeks of storage at 22.5 °C, the beverage with SA had lower turbidity, aggregate size, and viscosity; and the aggregates had a more negative zeta potential. Results indicate that SA can be used to improve thermal and storage stability in beverages containing salts, and that solution and heating conditions can be optimized for improved thermal stability. [ABSTRACT FROM AUTHOR]

Introduction There is great interest in converting gluten, a by-product from wheat starch isolation, into a value added functional food ingredient. Earlier, gliadin nanoparticles were produced using liquid antisolvent precipitation, but they did not prove to be very stable in conditions relevant to food products. Materials and methods Gliadin nanoparticles were produced by antisolvent precipitation: a gliadin in ethanol solution was titrated into water. After production, the nanoparticles (0.5 w/v% protein) were coated with different polysaccharides: octenyl succinic anhydride (OSA) starch; low methoxyl pectin (LMP); or, high methoxyl pectin (HMP). Results and discussion At all concentrations used (0.001 – 0.20 w/v%), OSA-starch led to particle flocculation and precipitation, whereas both LMP and HMP were able to coat the particles without inducing flocculation at certain levels (0.10 w/v%). The mean particle size of pectin-coated particles was about double that of uncoated ones, and the charge reversed from positive (uncoated) to negative (coated) under mildly acidic conditions. The pectin coating was shown to improve the stability of the gliadin nanoparticles to environmental stresses, such as pH, ionic strength, and thermal treatment. Conclusions Coating gliadin nanoparticles with pectin may therefore be a useful means of forming stable functional ingredients for use in the food industry, e.g., as texture modifiers, lightening agents, or delivery systems. [ABSTRACT FROM AUTHOR]

The objective of this work was to study delivery systems of water-soluble bioactive compounds using solid/oil/water emulsions to minimize the release during storage and gastric digestion. Spray-dried glutamine solid particles were suspended in milk fat that was emulsified by whey protein isolate or sodium caseinate at neutral pH as primary emulsions, followed by deposition of pectin at pH 3.0 to obtain secondary emulsions. Zeta-potential results verified the preparation of secondary emulsions. Secondary emulsions showed a higher efficiency of encapsulating glutamine and retaining glutamine during storage. For emulsions reconstituted from spray dried secondary emulsions, <20% release of glutamine was observed at pH 2.0–7.0 after 2-week refrigerated storage. The secondary emulsions retained glutamine during the 2-h simulated gastric digestion better than primary emulsions and showed gradual release to >90% after the subsequent 4-h simulated intestinal digestion. Therefore, the solid/oil/water secondary emulsions can be used as delivery systems of water-soluble bioactive compounds. [ABSTRACT FROM AUTHOR]

Response surface methodology (RSM) was employed to optimize the process conditions for production of protein-enriched animal feed from cassava peel by a locally isolated white rot fungus Panus tigrinus . Face-Centered Central Composite Design (FCCCD) with three variables (pH, inoculum size and moisture content) was used to determine the effect of these operational parameters on the protein increase of cassava peel as animal feed under solid-state fermentation. A significant quadratic model was obtained for protein increase using this design. Results of the statistical analysis showed that a significant ( P < 0.05) linear effect was obtained for moisture content, while only the interaction effect between moisture content and inoculum size was significant ( P < 0.01). The optimum process combination was found to be 75% (v/w) of moisture content, a pH of 5.3 and 7% (v/w) inoculum size. A maximum increase of protein (55.16%) was obtained during 15-day of solid-state fermentation. [ABSTRACT FROM AUTHOR]

Abstract: This study was conducted to evaluate the influence of cellulose whiskers (CW) from cotton linter and sonication on physical properties of glycerol-plasticized tilapia gelatin films produced by casting technique. The tensile strength and elastic modulus of the films have been improved by the addition of CW, while elongation tended to be impaired by CW loading. The barrier to water vapor has also been improved by the whiskers, and the film transparency has been unaffected. The sonication improved modulus, elongation, and transparency of the films, probably by enhancing CW dispersion on the nanocomposite films, and maybe by inducing some conformational changes on the gelatin matrix. FTIR spectroscopy study on films revealed some gelatin conformational changes induced by cellulose whiskers. [Copyright &y& Elsevier]

ε-polylysine (EPL) is an antimicrobial peptide. Despite the utilization of EPL as a natural preservative worldwide, it will be deactivated owing to phase separation when it encounters some macroions. Interestingly, previous studies demonstrated the approach to preserve its antimicrobial efficacy by forming another delicate structure, the "soluble" complexes, but their interaction mechanism and structure remain unclear. This work elucidated the hierarchically structural complexation of EPL with three representative proteins β-casein, β-lactoglobulin and bovine serum albumin. It was found that these hierarchical structures separated into compact mesophase dispersions and porous precipitations, and range from nanometers to microns length scales. The driving forces for the association between EPL and protein have been mainly considered as electrostatic and subsequently hydrophobic attractions. Our results illustrated how the differences in topology (spatial structure, charge anisotropy, and hydrophobicity) among various proteins determined the specifically hierarchical structures of EPL-protein complexation. Unfolded protein with the concentrated negative charge and hydrophobicity patches inclined to form aggregation readily, whereas the folded protein with a relative disperses geometry could create the structural forces to form partial steady-state complexes. This work provides a general structural evolution of EPL-protein complexation and paved the way for its future application in food science and biotechnology. [Display omitted] • The hierarchically structural complexation of EPL with proteins was investigated. • These structures are comprised of both compact dispersions and porous precipitates. • The protein topology determines the specifically hierarchical structures. • The unfolded protein with both polar and apolar domains inclines to aggregate. • The folded protein with a disperses geometry forms steady-state complexes readily. [ABSTRACT FROM AUTHOR]

One of the current trends prominent in the food and pharmaceutical industries is the use of colloidal structures to stabilize emulsions. Complexes formed by bio-compounds, such as protein (ptn), polysaccharides (poly), and phenolic compounds (phe) have the potential to offer physical stability, besides other functional properties to emulsions, such as preservation against oxidation and thermal stability. This review focuses on recent insights regarding the contribution of ptn-poly, ptn-phe and ptn-poly-phe complexes on liquid interfaces designing innovative colloidal arrangements. Topics on the formation of non-covalent or covalent binary and ternary complexes, processes involved in the modification of molecules or complexes formation, and the different strategies of colloidal structures at the water-oil interface are addressed. Herein the information may contribute to the rational design of novel complexes with specific physicochemical and functional attributes, as well as encourage further research on this topic. [Display omitted] • Biopolymers and phenolic compounds were used to form complex. • Binary and ternary complexes can be applied to produce stable emulsions. • Complex type influences interfacial properties. • Complexation between biopolymers is affected by process conditions. [ABSTRACT FROM AUTHOR]

Abstract: Composition of soybean proteins is briefly described. Gels and gelling processes of soybean proteins and other functionalities such as colloidal properties and emulsifying properties are described. The effects of temperature, pH, ionic strength, processing conditions such as high pressure, ultrasonic treatment, utilisation of enzyme, chemical modification are also described since they have been found useful to improve the processing and final product. [Copyright &y& Elsevier]

Abstract: The emulsifying properties and emulsion stability of medium chain triglyceride (MCT) oil in water emulsions stabilized by plant proteins (potato, soy, and pea) as well as those extracted from milk (sodium caseinate and whey) have been investigated at two different pH values (7 and 10). The effect of protein type, concentration, pH and temperature has been studied using droplet size distribution, interfacial tension, and interfacial elasticity measurements. The interfacial tension is measured as a function of concentration ranging from 0.01% to 2.5% using the pendant drop method. The interfacial elasticity is also measured using the oscillating drop technique. The stability of the resulted emulsions is assessed using a stress test whereby the emulsions are placed at 60 or 40 °C for 24 h by measuring the droplet size distribution before and after the stress test. The interfacial tension decreases with increase of the pH and increase of the protein concentration pH value. A higher elasticity at the oil/water interface is obtained at pH = 10 when compared to that at pH = 7 for both Na-caseinate and pea proteins. Fine and stable emulsions are obtained at pH = 10, showing good correlation between interfacial tension and emulsion formation as well as between interfacial elasticity and emulsion stability for milk and plant proteins. [Copyright &y& Elsevier]

Abstract: It was studied the effect of the bile salts on protein interfacial films at oil–water interfaces under simulated duodenal conditions (37 °C, pH 7.0 and 39 mM K2HPO4, 150 mM NaCl and 30 mM CaCl2) in order to develop an interfacial film which could resist the interfacial displacement by the bile salts in the duodenum to control the lipids digestion process, as it could retard the next action of lipase and colipase. The proteins studied were β-lactoglobulin, soy proteins and egg white proteins as well as non-ionic low molecular weight surfactants (Tween 20). The interfacial characterization was done by using a pendant drop tensiometer by analyzing the competitive and sequential adsorption of these components at the oil–water interface. The results demonstrated that soy protein film was particularly more resistant to bile salts displacement. [Copyright &y& Elsevier]

Abstract: This study aimed characterization of bioactive, functional and edible film making properties of isolated proteins from untreated (HPI), hot extracted (HPI-H), acetone washed (HPI-AW), and acetone washed and hot extracted (HPC-AW-H) hazelnut meals. The most bioactive protein extract was HPC-AW-H, followed by HPI-AW, HPI-H and HPI, based on antioxidant activity (TEAC and ORAC: 158–461 mmol Trolox/kg), iron chelation (60.7–126.7 mmol EDTA/kg), angiotensin-converting enzyme inhibition (IC50: 0.57–1.0 mg/mL) and antiproliferative activity on colon cancer cells (IC50: 3.0–4.6 mg/ml). Protein contents of HPI, HPI-H and HPI-AW (93.3–94.5%) were higher than that of HPC-AW-H (86.0%), but HPC-AW-H showed the best pH-solubility profile. The extracts showed good oil absorption (7.4–9.4 g/g) and foaming, but limited water holding and gelling capacities, and emulsion stability. The protein extracts gave transparent, yellowish to brownish and reddish colored and water soluble edible films. The HPI gave the lightest colored films with acceptable mechanical properties (elongation up to 144% and tensile strength up to 4.9 MPa). 1-D and 2-D electrophoresis clearly showed the molecular and isoelectric profiles of hazelnut proteins. The overall results of this study showed that the bioactive, solubility and gelation properties of hazelnut proteins could be improved by simple processes like acetone washing and/or heat treatment. The hazelnut proteins are valuable as multipurpose food ingredients. [Copyright &y& Elsevier]

Abstract: Stable suspensions of spherical protein particles (microgels) can be formed by heating beta-lactoglobulin solutions in the presence of calcium ions. The conditions for the calcium induced microgel formation were studied at different pH between 5.8 and 7.5 and different protein concentrations between 5 and 100 g/L after heating at 85 °C for 15 h. The results showed that a critical molar ratio of calcium to proteins (R) is needed to form microgels independent of the protein concentration. R decreases with decreasing pH. The microgels have a hydrodynamic radius ranging from 100 to 300 nm and their internal protein concentration ranges from 0.2 to 0.45 g/mL. The amount of calcium bound to the proteins was determined and the results suggest that the crucial parameter for microgel formation is the net charge density of the native proteins. The microgel suspensions are stable in a narrow range of R but the microgels aggregate at higher calcium concentrations. [Copyright &y& Elsevier]

Abstract: Aqueous mixtures of small aggregates of the globular whey protein (β-lactoglobulin) and the anionic polysaccharide (κ-carrageenan) were studied at neutral pH. The effect of the temperature on the phase separation was investigated by measuring the turbidity during cooling and heating. Gelation of κ-carrageenan was induced by adding small quantities of KCl. It is shown that gelation partially reverts phase separation. The dependence of phase separation on the elastic modulus was quantified. Phase separation could be rendered irreversible by ageing in the presence of calcium ions. [Copyright &y& Elsevier]

Abstract: Class II hydrophobin (HFBII) is a highly surface active molecule and in the context of aeration can be considered to be an air structuring protein conferring exceptional stability to foams for periods far in excess of that obtained with any other commonly used protein. This is of interest to the food industry, since producing shelf stable foams in food formulations is very difficult. Although HFBII has proven to be very promising in terms of foam stability when used alone, it is still unknown whether HFBII will be able to maintain its functionality when other surface active agents are present, such as in real food systems. The surface rheology: surface shear viscosity (η s) and surface dilatational elasticity (ε), for HFBII and β-casein mixes at various ratios is described in this paper and how this relates to bubble stability. The addition of β-casein up to a certain ratio seems to increase η s significantly, whilst ε is less affected. This is accompanied by improved stability of air bubbles to coalescence and allows the formation of very small air bubbles that remain extremely stable to disproportionation. Overall, there is the suggestion of some kind of synergy between the two proteins. The exact nature of this interaction is unknown. Measurements of the ζ-potential of the proteins suggest that electrostatic interactions are probably not important at the pH investigated (pH 7). Confocal microscopy of individual bubbles over prolonged periods of time, stabilized by HFBII and a fluorescently labeled β-casein, suggests that the enhanced stability is due to highly unusual and complicated interfacial packing phenomena plus local bubble curvature effects that require further investigation. [Copyright &y& Elsevier]

To address the limitations of existing konjac glucomannan (KGM)-based films, KGM films activated by zein–pectin nanoparticle-stabilized oregano essential oil Pickering emulsions (ZPEOs) were prepared. Results showed that the hydrophilicity/hydrophobicity of KGM films can be tuned through adjusting the ZPEO concentration. ZPEO addition altered the hydrogen bonding, electrostatic interactions and hydrophobic effects among film components. The ZPEO-KGM composites behaved as high-performance films with good uniformity, compatibility, along with antioxidant, antibacterial and fruit preservation properties. Increasing ZPEO content in ZPEO-KGM films increased the elongation at break, DPPH free radical scavenging and antibacterial effect and decreased water vapor permeability. The ZPEO-KGM films with ZPEO-to-KGM ratios of 50 : 50 and 60 : 40 had the highest tensile strength (30.98 MPa) and water contact angle (93.56°), respectively. The essential oil in the ZPEO-KGM film can be slowly released for 21 days or even longer. This research demonstrates the plasticizing effect of ZPEO and potential of ZPEO-KGM films for food preservation/packaging. [Display omitted] • Oregano essential oil (OEO) was stabilized by zein-pectin nanoparticles (ZPNPs). • Konjac glucomannan (KGM) films were activated by ZPNP-OEO Pickering emulsion (ZPEO). • KGM-ZPEO films showed superior mechanical and water barrier properties. • KGM-ZPEO films exhibited antioxidant, antibacterial and fresh-keeping effects. • Adding ZPEO to KGM films led to high-performance films for fruit preservation. [ABSTRACT FROM AUTHOR]

The development of nutrient and bioactive delivery vehicles has become a burgeoning field with the worldwide growing demand for healthy foods and supplements. Food-grade protein particles have attracted significant attention for their great potentials in fabricating nutrient delivery vehicles. This review aims to summarize a wide range of food-grade protein particles used for the fabrication of nutrient delivery systems, with a particular focus on analyzing the digestion behaviors and nutrient release mechanisms using digestion models. The review of the current literature reveals that a variety of modification techniques exist to promote the formation of protein particles with desirable structures and physicochemical properties (particle size, surface charge, hydrophobicity, and interfacial wettability). Furthermore, nano/microparticles, hydrogels and Pickering emulsions have emerged as three main delivery vehicles based on food protein particles, and many studies have demonstrated their excellent ability to encapsulate and protect nutrients from degradation during storage and/or under exposure to light and heat. The digestion profile of these delivery systems and the release properties of nutrients are related to the composition, interfacial structure, and enzymatic responsiveness of the delivery system as well as the bulk environment. However, significant gap of knowledge still exists in the current understanding of these delivery systems at the biological interface. Future studies should focus on elucidating the digestion, the release of the encapsulated nutrients, and the intestinal absorption/transport using advanced simulated conditions and in in vivo models. [Display omitted] • Protein based nano/microparticles, hydrogels and Pickering emulsions are discussed. • The digestion profile and nutrient release mechanism are related to the wall materials. • Protein complexation with polysaccharide and cross-linking agent is used to control nutrient release. • Future studies should focus on elucidating the nutrient release in in vivo models. [ABSTRACT FROM AUTHOR]

Abstract: In oil-in-water (O/W) emulsions, the droplets covered by native proteins are more prone to oxidation than droplets covered by surfactants. We attempted in this work to improve the barrier properties of protein-stabilized interfacial layers by controlled modifications of their composition and structure. Native bovine β-lactoglobulin (BLG) or β-casein (BCN), partially aggregated BLG and mixtures of the proteins with dilauroyl phosphatidylcholine (DLPC) were used to prepare emulsions and reconstituted Langmuir–Blodgett films. Lipid oxidation in the emulsions, as evaluated from oxygen uptake and formation of conjugated dienes, propanal and hexanal was roughly unmodified with aggregated BLG and DLPC–BLG mixtures and even favored with DLPC–BCN mixtures. The reconstituted phospholipid/protein interfacial layers presented interfacial heterogeneity evidenced by atomic force microscopy (AFM). This indicates that the structural homogeneity of the interface could be a key factor in controlling lipid oxidation. [Copyright &y& Elsevier]

Abstract: The influence of the κ-carrageenan concentration and pH on the properties of oil-in-water multilayered emulsions was studied. Multilayered emulsions were prepared by the mixture of a primary emulsion stabilized by 0.5% (w/v) sodium caseinate (Na-CN) with κ-carrageenan solutions with different concentrations (0.05–1% w/v). The emulsions were evaluated at pH 7 and 3.5. At pH 7, there was little adsorption of κ-carrageenan onto the droplet surface and a depletion flocculation was observed when the polysaccharide concentration exceeded 0.5% (w/v). At pH 3.5, a mixed κ-carrageenan–Na-CN second layer was formed around the protein-covered droplets and the emulsions showed bridging flocculation at lower polysaccharide concentrations (0.05–0.25% w/v). Stable emulsions could be formed with the highest κ-carrageenan concentration (1% w/v) at both pH values (7.0 and 3.5). Thus, stable emulsions were successfully produced using protein–polysaccharide interfacial complexes, and the oil droplet diameter, zeta potential and rheological properties of these emulsions were not affected by changes in the pH. [Copyright &y& Elsevier]

Abstract: The microstructure of oil droplets of bi-layer emulsions was studied as a function of pH (i.e. 7, 5, and 3) using scanning electron microscopy. The bi-layer emulsions consisted of a primary emulsion: 5 wt% soybean oil (SBO) in a 1% protein (nonfat dry milk) aqueous solution. The secondary layer was ι-carrageenan, high- (HMp), low (LMp)-methoxyl pectin, or gelatin. The secondary emulsions consisted of 2.5% SBO, 0.5% protein, and 0.2% polysaccharide or protein. Gelatin secondary emulsions were stable at pH 7 with defined droplets and became unstable at pH 5 and 3. The destabilization mechanisms for these emulsions at pH 5 and 3 were different as observed with the SEM: at pH 5 there is complete aggregation of protein due to their proximity to the isoelectric point; and at pH 3 the droplets are perfectly separated, suggesting that at this pH, when the net charge is positive, the destabilization is mainly due to depletion flocculation. HMp secondary emulsions shift from being stable (individual droplets) at pH 3 to being unstable at pH 7 where an extensive webbing is observed between the droplets at this pH value. The ι-carrageenan secondary emulsions are stable at each pH and the individual droplet microstructure is minimally altered as the pH changes. LMp secondary emulsions shift from being stable at pH 7 with individual droplets observed in the SEM micrographs to being unstable at pH 3 where extensive webbing is observed in the SEM micrographs. [Copyright &y& Elsevier]

Abstract: Gelling profiles and interaction between basil seed gum (BSG) and β-lactoglobulin (BLG) were characterized using dynamic rheology and scanning electron microscopy. Sequence of experimental sweeps of time–temperature, frequency, and strain were applied for BSG, BLG and BLG–BSG mixtures in the ratio of 10:1, 5:1, 2:1 & 1:2. Rheological behavior of BLG was found to be different from that of BSG and gelling point was raised during the heating period. By increasing BSG concentration, storage and loss moduli were increased and gel point was determined at about 80 °C, which was dependent of concentration and occurred during cooling period. Upon heating–cooling period (temperature sweep) of BLG–BSG mixture from 20 °C to 90 °C and coming back to original temperature, mixed gels presented a biphasic profile: the first phase, characterized by a sharp increase in the storage modulus in which gelation of BLG happened and the second phase exhibiting an increase in the storage modulus, corresponded to the build-up of a BSG network. Strain sweep results obtained for mixed gels at the end of the temperature sweep tests supported the biphasic hypothesis. The SEM results showed that BLG has a globular structure in comparison with BSG which has fibril and globular structure and the mean diameter of its globular structure was higher than that of BLG. Increasing the ratio of BSG to BLG resulted in a finer microstructure, which could retain higher water to form gel. In addition, microstructural study showed that BLG–BSG mixed is a bicontinuous network in which BSG dispersed in BLG continuous phase. [Copyright &y& Elsevier]

Abstract: Soybean soluble polysaccharide (SSPS), extracted from the by-product obtained during isolation of soybean protein, is an anionic polysaccharide that stabilizes milk proteins under acidic conditions. We developed a high-molecular-mass complex of SSPS cross-linked via phosphate (SSPS-HC; absolute molecular weight = 2850 kg/mol, radius of gyration = 106 nm), and found that it has different protein stabilization properties when compared with the original SSPS (absolute molecular weight = 550 kg/mol, radius of gyration = 36 nm). The objective of this work was not only to study the rheological properties of SSPS-HC, but also clarify its protein-stabilizing properties in comparison with SSPS; if molecular mass or negative charge affected protein dispersion. Irrespective of high-molecular-mass, SSPS-HC possessed similar rheological properties to SSPS such as low viscosity in aqueous solution. The absolute negative charges of SSPS-HC measured by a zeta potential analyzer at pH range of 2.0–7.0 were higher than those of SSPS. Acidified milk drinks prepared with 8.4% non-fat milk solids and 0.4% SSPS-HC or SSPS showed low viscosity and small protein particle size, and did not aggregate for 14 days. The thickness of the hydrated layer, which was formed on the surface of protein particles by SSPS molecules measured after hemicellulase treatment with DLS (dynamic light scattering), was estimated to be about 89 nm for SSPS-HC and 33 nm for SSPS. These numerical values were in good relation to the molecular diameter of SSPS-HC and SSPS in aqueous solution measured by DLS and AFM image, and suggested that protein particles were dispersed and the hydrated monolayer made on the surface of protein particles by SSPS-HC or SSPS molecules prevented aggregation. However, stabilizing pH ranges were different with stability of SSPS-HC at pH range of 4.0–4.8 and stability for SSPS at pH range of 3.6–4.2. In addition to the difference in the molecular mass and absolute negative charge, the phosphate groups of SSPS-HC were possibly influenced on the protein-dispersing property approximately at isoelectric point of milk protein; SSPS-HC prevent aggregation of casein by accelerating solubility of calcium phosphate under acidic conditions as is already reported in the starches phosphorylated. [Copyright &y& Elsevier]

Abstract: Hydrophobins, small, amphipathic proteins found only in filamentous fungi, have the ability to form elastic layers at air/water or oil/water interfaces. To identify potentially useful hydrophobins for technological applications, a bioinformatics approach has been employed. The methodology used is not only useful for the identification of hydrophobins but, can be used for the identification of other structurally similar proteins that have little amino-acid homology. The Aspergillus comparative database initially revealed 25 officially annotated hydrophobins from a keyword search. A detailed manual annotation using Blast searches and multiple alignments showed common errors in assigning descriptions centred upon difficulties in recognising the relatively small conserved motif of four pairs of cysteines. Searches across the databases gave two protein sequences from the Central Aspergillus Data Repository (CADRE) and two from Uniprot which did not match to any found on the Aspergillus comparative database. A total of 74 putative hydrophobin sequences were found across the different databases. The number per species ranges from six for Aspergillus oryzae to ten for Aspergillus clavatus, Aspergillus fischeri, Aspergillus terreus, Aspergillus nidulans and Aspergillus niger. Possible examples of proteins which appear to be an intermediate form between Class I and II were found. It is thought that this intermediate form may be of most use for food applications as hopefully it will have amenable solubility and assembly kinetics to be used in standard food production operations. The applications of computer aided bioinformatics for the selection and development of hydrophobins for model production systems are discussed. [Copyright &y& Elsevier]

Abstract: The aim of the present study was to describe the fundamental physical characteristics of spray-dried carrier matrices based on sodium caseinate and casein hydrolyzate and microcapsules as well as their impact on the stability of a microencapsulated functional ingredient. Spray-dried carrier matrix was characterized by different physical methods (helium pycnometry, nitrogen displacement for surface area analysis, X-ray photoelectron spectroscopy, positron annihilation lifetime spectroscopy). Surface viscoelasticity of protein-stabilized oil–water interfaces was analyzed using dynamic pendant drop tensiometry. Fish oil was microencapsulated and microencapsulation efficiency as well as oxidative stability over time was monitored. Surface accumulation of proteins at the air–water interface led to a modified surface composition of spray-dried carrier matrix particles for microencapsulation. However, interfacial elasticity was markedly altered when using hydrolyzed casein as emulsifier, which is related to a decrease in microencapsulation efficiency. Lipid oxidation during storage of the microencapsulated oil increased with the protein content in the formulation. Excess protein led to an increase in free volume elements and is suspected to negatively affect oxygen diffusion. [Copyright &y& Elsevier]

Abstract: Almost all published studies of heat-induced β-lactoglobulin self-assembly into amyloid-like fibrils at low pH and low ionic strength have involved heating at 80 °C, and the effect of heating temperature on self-assembly has received little attention. Here we heated β-lactoglobulin at pH 2 and 75 °C, 80 °C, 90 °C, 100 °C, 110 °C or 120 °C and investigated the kinetics of self-assembly (using Thioflavin T fluorescence), the morphology of fibrils, and the rheological properties of fibril dispersions. Self-assembly occurred at all temperatures tested. Thioflavin T fluorescence increased sigmoidally at all temperatures, however it decreased sharply with >3.3 h heating at 110 °C and with >5 h heating at 120 °C. The sharp decreases were attributed partly to local gelation, but destruction of fibrils may have occurred at 120 °C. Thioflavin T fluorescence results indicated that maximal rates of fibril formation increased with increasing temperature, especially above 100 °C, but fibril yield (maximum Thioflavin T fluorescence) was not affected by temperature. At 100 °C and 110 °C, fibrils were slightly shorter than at 80 °C, but otherwise they looked very similar. Fibrils made by heating at 120 °C for 1 h were also similar, but heating at 120 °C for 8 h gave predominantly short fibrils, apparently the products of larger fibrils fragmenting. Heating at 100 °C gave consistently higher viscosity than at 80 °C, and heating for >2 h at 120 °C decreased viscosity, which may have been linked with fibril fragmentation seen in micrographs. [Copyright &y& Elsevier]

Abstract: Although many different methods for microencapsulation are known only some of them had been applied at industrial scale, due to complexity, lack of mechanical strength of the resulting capsules, and the costs related to their production. One of such methods is the electrostatic layer-by-layer (LbL) adsorption, which produce shells from oppositely charged polymers. The thickness of those shells can be tuned with nanometric precision, but to build enough strength for practical applications requires the adsorption of an impractical number of layers. We present here a method to produce strong microcapsules combining the assembly of a protein/pectin shell via electrostatic LbL adsorption with the adsorption of bigger charged colloidal particles. Those colloidal particles do not need any pretreatment to modify their wettability, as would be the case for a standard colloidosome route. In this way strong encapsulates with porous walls are obtained, which can be used as easy to load scaffolds. The pores in the walls can be closed through subsequent adsorption of more layers of protein and pectin. Since the assembly scheme occurs at pH 3.5 we expect the produced microcapsules to act as an effective delivery system in food products, protecting their contents from the acidity of the stomach and dissolving later at the small intestine. The proteins and pectins used as basic building blocks are food-grade and inexpensive. [Copyright &y& Elsevier]

Abstract: This article provides a summary of an example of how relationships between molecular scale properties and macroscopic properties are formulated, in this case with a focus on fibril microstructures and according system elasticity. Entropy plays a dominant role on all length scales. The elasticity is reviewed in terms of the micro-mechanical properties of the fibrils over a wide range of concentrations. The elasticity is concluded to be of an entropic nature. The micro-mechanical fibril property is the persistence length. For fibrils based on globular proteins the response to temperature change and flow has been reported to be either reversible or non-reversible, dependent on the age of the fibril. The reversibility is argued to be related to the fact that the fibril consists of peptides originating from hydrolysis of the globular proteins, and that the initial step of fibrillar peptide assembly is entropic of nature. The longer term irreversibility is speculated to be caused by a secondary assembly step being a collective transition into inter-beta-sheets. [Copyright &y& Elsevier]

Abstract: The stability of oil-in-water, water-in-water and multiple emulsions containing sodium caseinate (Na-CN) and/or locust bean gum (LBG) at pH 5.5 was investigated with different compositions using a visual analysis (creaming and/or phase separation), optical microscopy and rheological measurements. Oil-in-water emulsions (O/W) were produced by high pressure homogenization, which promoted the formation of very small droplets (∼0.4μm) and hindered the destabilization process. In the second step of this study, a visual phase diagram was constructed in order to identify the concentrations of sodium caseinate (Na-CN) and locust bean gum (LBG) that led to phase separation at pH 5.5. A mixed solution composed of 3% (w/v) Na-CN and 0.3% (w/v) LBG was chosen to produce the water-in-water and multiple emulsions. After centrifugation, the solution was separated into an upper phase rich in polysaccharide (PS) and a bottom phase rich in protein (PR), which were mixed in different proportions (1:3, 1:1, 3:1), forming the water-in-water (W/W) emulsions. The stability, microstructure and rheological properties of the W/W emulsions depended strongly on the composition of the biopolymers. An increase in the polysaccharide concentration in the W/W emulsions led to the production of more viscous and stable systems. Multiple emulsions with different characteristics were prepared and also depended on the biopolymer composition. The system with the highest polysaccharide content was the only one that showed an O/W/W structure, while the others presented the microstructure of an O/W-W/W emulsion. [Copyright &y& Elsevier]

Abstract: Food protein functionality has classically been viewed from the perspective of how single molecules or protein ingredients function in solutions and form simple colloidal structures. Based on this approach, tests on protein solutions are used to produce values for solubility, thermal stability, gelation, emulsifying, foaming, fat binding and water binding to name a few. While this approach is beneficial in understanding the properties of specific proteins and ingredients, it is somewhat restricted in predicting performance in real foods where the complexities of ingredients and processing operations have a significant affect on the colloidal structures and therefore overall properties of the final food product. In addition, focusing on proteins as just biopolymers used to create food structures ignores the biological functions of proteins in the diet. These can be beneficial, as in providing amino acids for protein synthesis or bioactive peptides, or these can be detrimental, as in causing a food allergic response. This review will focus on integrating the colloidal/polymer and biological aspects of protein functionality. This will be done using foams and gels to illustrate colloidal/polymer aspects and bioactive peptides and allergenicity to demonstrate biological function. [Copyright &y& Elsevier]

Abstract: Protein–polysaccharide interactions find many applications in food engineering and new food formulations. This review article describes recent research on the effect of protein–polysaccharide interactions on the properties of air–water and oil–water interfaces, as affected by their behaviour in the bulk phase. The interfacial behaviour of protein–polysaccharide mixtures exhibiting associative (i.e., net attractive) interactions as well as their performance in food emulsions and foams has been the subject of several reviews in the last decade. Much less attention has been paid to the interfacial behaviour of protein–polysaccharide mixtures exhibiting unfavourable interactions. Thus we are concerned here with the interfacial behaviour of both kinds of mixtures. [Copyright &y& Elsevier]

Abstract: Both gelatin and poly(vinyl alcohol) (PVA) can be cross linked with glutaraldehyde (GLU). In the case of gelatin, the GLU reacts with each ε-NH2 functional group of adjacent lysine residues, while for PVA, the GLU reacts with two adjacent hydroxyl groups, forming acetal bridges. Thus it can be considered possible to cross link adjacent macromolecules of gelatin and PVA using GLU. In this context, the aims of this work were the development of biodegradable films based on blends of gelatin and poly(vinyl alcohol) cross linked with GLU, and the characterization of some of their main physical and functional properties. All the films were produced from film-forming solutions (FFS) containing 2 g macromolecules (PVA + gelatin)/100 g FFS, 25 g glycerol/100 g macromolecules, and 4 g GLU (25% solution)/100 g FFS. The FFS were prepared with two concentrations of PVA (20 or 50 g PVA/100 g macromolecules) and two reaction temperatures: 90 or 55 °C, applied for 30 min. The films were obtained after drying (30 °C/24 h) and conditioning at 25 °C and 58% of relative humidity for 7 days, and were then characterized. The results for the color parameters, mechanical properties, phase transitions and infrared spectra showed that some chemical modifications occurred, principally for the gelatin. However, in general, all the characteristics of the films were either typical of films based on blends of these macromolecules without cross linking, or slightly higher. A greater improvement in the properties of this material was probably not observed due to the crystallinity of the PVA, which has a melting point above 90 °C. The presence of microcrystals in the polymer chain probably reduced macromolecular mobility, hindering the reaction. Thus more research is necessary to produce biodegradable films with improved properties. [Copyright &y& Elsevier]

Abstract: A new technique for the purification of pectins using protein (sodium caseinate) was developed and that could replace the process of ethanol which is currently used in industries. Commercial pectins were used as a model to verify the feasibility of the process and to define some important parameters. The results indicated that this purification technique is based primarily on the electrostatic interactions between these two polymers. The electrostatic interactions were strongly dependent on pH and salt concentration. The maximum pectin precipitation was obtained at pH 3.5. At this pH, the pectin acquires a negative charge while the protein is positively charged, promoting thus their attractions. Furthermore, the dissociation of the pectin–caseinates complex and the precipitation of caseinate at pH 4.6 were observed in the presence of salt. This method is very specific, suggesting that it could be used to purify some electrically charged polysaccharides. [Copyright &y& Elsevier]

Abstract: Gelation of sodium κ-carrageenan (KC) in the presence of sodium caseinate (SC) was investigated by oscillating shear rheology. The effect of adding NaCl and KCl was investigated. Temperature ramps showed that SC had no influence on the critical gelation temperature, but increased the melting temperature when that of the pure gels was less than about 30 °C. The presence of SC also increased the gel strength of weak KC gels. Light scattering and confocal laser scanning microscopy showed that the proteins associated with the KC network. The rheology of the gels indicated that the mixed gels contained bonds involving both SC and KC in addition to pure KC bonds. At relatively high SC content the former type of bonds dominated. [Copyright &y& Elsevier]

Abstract: Mixtures of the polysaccharide κ-carrageenan (KC) and caseinate proteins (SC) from milk were investigated at pH 7 in aqueous solution using confocal scanning laser microscopy and light scattering. Phase separation was observed at higher concentrations and the phase diagram was established. In the mixtures SC was observed to form large aggregates mediated by a relatively small amount of KC. At small KC concentrations the aggregates were initially relatively small and could be characterized by light scattering. At higher KC concentrations or on longer storage at 20°C, dense clusters with a radius of a few microns were formed that slowly precipitated. The fraction of precipitated protein increased linearly with increasing KC concentration, but was independent of the protein concentration. It increased with decreasing pH from about 20% at pH 8 to 100% at pH 5. [Copyright &y& Elsevier]

Abstract: The microstructural and large deformation rheological properties of model food gels were studied by performing notch propagation tensile testing on the gels using a tensile stage and observing changes in the microstructure of the gels during tensile testing using confocal laser scanning microscopy (CLSM). Heat-set whey protein (WP) gels containing either added sodium caseinate (NaCN) or sunflower oil droplets emulsified with WP or NaCN as the emulsifier protein were prepared in 0 or 50mM NaCl. The WP gel structure strengthened in the presence of added NaCl and NaCN. The rheological properties of WP gels containing sunflower oil droplets emulsified with WP or NaCN were influenced by the NaCl concentration, oil concentration and extent of oil droplet aggregation in the gel or by the type of emulsifier protein used. During tensile testing, the notch length in all gels increased above a certain critical stress, leading to fracture of the gels through the notch. Also, the microstructural changes in the oil phase of emulsion filled gels subjected to tensile testing were influenced by the structural properties of the WP gel matrix and the proximity of the oil droplet to the fracture path. [ABSTRACT FROM AUTHOR]