This study aimed to evaluate the potential of Brea gum (BG) in the microencapsulation of corn oil in comparison with gum arabic (GA) and evaluate the effect of adding inulin at the matrix ...formulation. Different concentration of BG and inulin were used to emulsify pure corn oil using a homogenizer followed by an ultrasonic treatment. Then, emulsions were spray dried in laboratory scale equipment to obtain the microcapsules. Overall, powders presented spherical shape with surface concavities, no apparent cracks and high polydispersity. However, some powders containing inulin showed particles that seem to have fused together reflecting a coating effect of inulin. Moisture content of BG powders were low but increased with inulin addition, while water activities (˂0.4) were not affected by inulin. The color analysis showed that BG powders presented lower luminosity and higher red and yellow parameters than GA powder, and adding inulin decreased the lightness, redness and yellowness resulting in powders with more pale color. Encapsulation efficiency increased with BG concentration, reaching 76.12% with 20% of BG. Further efficiency improvement was achieved in presence of inulin, reaching the highest value (91.72) with 20% BG/20% inulin formulation, which was higher than the efficiency achieved with GA (88.66%). It was concluded that the combination of BG and inulin could be used as an alternative wall material for microencapsulation of hydrophobic compounds in replacement of GA.
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•Brea gum and inulin were used for corn oil encapsulation by spray drying.•Powders presented good quality: low moisture content and aw, no crack or fissures.•Encapsulation efficiency increased with gum concentration.•Inulin addition improved encapsulation efficiency up to 91.72%.
In the present work, ovalbumin (OVA) solutions (10 g/L, 50 mM NaCl, pH 7.5) were heat-treated at 75, 80 and 85°C (namely, OVA-75, OVA-80 and OVA-85, respectively), from 0 to 25 min. OVA nanoparticles ...(OVAn) around 100 nm were obtained. For 3 min of heat treatment, OVAn sizes increased with temperature, but for a heating time longer than 10 min, OVA-75 showed the highest size values. OVAn surface hydrophobicity increased 6-8 folds in comparison with native OVA and wavelength blue shifts of 25-30 nm in maximum fluorescence intensity were registered. These results suggest that buried hydrophobic residues were exposed to the aqueous medium. Binding experiments with linoleic acid (LA) as polyunsaturated fatty acid (PUFA) model were carried out. Firstly, binding ability of OVAn was determined from LA titration curves of intrinsic fluorescence measurements. OVA-85 at 5 min presented the highest binding ability and it was used for further binding properties studies (turbidity, particle size distribution--PSD--analysis and ζ-potential measurements). Turbidity measurement and PSD analysis showed that OVAn-LA nanocomplexes were formed, avoiding LA supramolecular self-assembly formation. The union of LA to OVAn surface confers them significant lower ζ-potential and larger size. Hence, fluorescence and ζ-potential results showed that LA would bind to OVAn by mean of hydrophobic interactions. Information derived from this work could be important to potentially use OVAn as PUFA vehiculization with applications in several industrial sectors (food, pharmaceutical, cosmetics, etc.).
It is well known that protein/polysaccharide conjugates obtained by Maillard reaction (MR) have good emulsifying properties. However, there is little information about the use of these conjugates in ...gel systems. Structural characteristics and rheological properties of conjugates obtained by MR of whey protein isolate (WPI) and dextrans (DX) of various molecular weight (MW: 6, 40 and 70 kDa) were studied. Conjugation was confirmed by electrophoresis; browning intensity was measured by absorbance at 420 nm; and conformational changes were studied by fluorescence emission of tryptophan (Trp) (λex = 280 nm). Rheological properties were determined by oscillatory rheometry with temperature ramp (25–90 °C). After each measure, a mechanical spectrum (at 25 °C) was obtained. The electrophoresis indicated the presence of WPI/DX conjugates in all systems. Browning intensity increased with decreasing MW of DX. Fluorescence emission of WPI incubated increased, but decreased in WPI/DX incubated systems. The gelation time (obtained by G′–G″ crossover) and G′ value at 25 °C increased in conjugate systems compared with WPI alone. Stability of gel structures were shown by frequency sweeps.
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•WPI/DX conjugates could be obtained successfully for all DX molecular weights.•Late-stage compounds of Maillard reaction were produced as observed by absorbance measurements.•Fluorescence determined that DX attachment produced structural changes in WPI/DX conjugates.•Maillard reaction (MR) significantly modified rheological behaviour of WPI/DX systems.•Molecular weight of dextran has an effect on rheological properties, influencing more in mixed systems.
Brea gum (BG) is an exudate gum obtained from the Cercidium praecox tree. It is an acidic polysaccharide, made up of 75 g/100 g of hydrolysable sugars, such as L-arabinose, D-xylose, D-glucuronic ...acid and 4-O-methyl-D-glucuronate. The purpose of this study was to investigate the role of BG as a structural agent in the formulation of emulsion based films. Beeswax (BW) and glycerol (Gly) were added as moisture barrier and plasticizer, respectively. Mechanical and optical properties, microstructure and water vapour permeability were studied. The concentration of BW and Gly was ranged from 0 to 40 g/100 g in a dry basis with respect to BG. We found that, regardless the BW concentration, films with 0 g/100 g Gly were too brittle and they could not be handled. In contrast, films with 40 g/100 g Gly were too tacky and gummy, consequently they could not be unpeeled. Only those films with 20 g/100 g Gly (and 0, 20 and 40 g/100 g of BW) were assayed. Increasing BW concentration resulted in better vapour permeability, to the detriment of its mechanical properties; meanwhile it had no influence in colour parameters. BG may be considered to be a structural support for emulsion based films, being 20 g/100 g of Gly the satisfactory amount of plasticizer.
•The potential of Brea gum as structural agent of emulsion based films was studied.•Beeswax (BW) were added as moisture barrier and glycerol (Gly) as plasticizer.•Films with 0 g/100 g Gly were too brittle, and films with 40 g/100 g Gly were too tacky.•20% Gly resulted in an optimum concentration regardless the amount of BW.•Brea gum may be considered as a structural support for emulsion based films.
The effect of Maillard reaction on the mechanical properties of whey protein isolate (WPI) heat-induced gels was evaluated. WPI and dextran (15–25 kDa) conjugates were obtained by controlled dry ...heating during storage at 60 °C and 63% relative humidity for 2, 5 and 9 days. Changes in browning intensity and content of free amino groups were used to estimate the Maillard reaction. A decrease in free amino groups of WPI was observed when increasing polysaccharide concentration and reaction time. An increase in both a* and b* CIE Lab colour parameters indicated the development of a reddish-brown colour, typical of the Maillard reaction. Uniaxial compression and stress relaxation tests were performed to measure the mechanical properties of mixed and conjugate gels. Maillard reaction significantly modified the mechanical properties of WPI/DX gels, and even prevented fracture when conjugate gels were subjected to 80% deformation in uniaxial compression test.
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► Whey protein isolate (WPI)/Dextran (DX) conjugates were obtained by Maillard reaction. ► Decrease in free amino groups and development of colour indicated the reaction progress. ► Maillard reaction (MR) significantly modified the mechanical properties of WPI/DX gels. ► MR even prevented fracture when conjugate gels were subjected to 80% deformation.
•Linoleic acid bound to ovalbumin nanoparticles through a physical adsorption process.•Adsorption equilibrium was reached within 1h.•The adsorption process was spontaneous, endothermic and ...entropically-driven.
Stoichiometric, kinetic and thermodynamic aspects of complex formation between heat-induced aggregates of ovalbumin (ovalbumin nanoparticles, OVAn) and linoleic acid (LA) were evaluated. Extrinsic fluorescence data were fitted to modified Scatchard model yielding the following results: n: 49±2 LA molecules bound per OVA monomer unit and Ka: 9.80±2.53×105M. Kinetic and thermodynamic properties were analyzed by turbidity measurements at different LA/OVA monomer molar ratios (21.5–172) and temperatures (20–40°C). An adsorption approach was used and a pseudo-second-order kinetics was found for LA-OVAn complex formation. This adsorption process took place within 1h. Thermodynamic parameters indicated that LA adsorption on OVAn was a spontaneous, endothermic and entropically-driven process, highlighting the hydrophobic nature of the LA and OVAn interaction. Finally, Atomic Force Microscopy imaging revealed that both OVAn and LA-OVAn complexes have a roughly rounded form with size lower than 100nm.
The emulsifying properties of Brea gum (BG), the exudate from Cercidium praecox, were studied in comparison to gum Arabic (GA). Droplet size distributions, rheological properties and stability of ...corn oil emulsion stabilized with BG and GA solutions were analyzed. The results showed that an increase in BG concentration led to a decrease in Z-average diameter and to an increase in emulsion apparent viscosity and stability. All emulsion flow curves presented shear-thinning behavior at low shear rates and Newtonian plateau at high shear rates. The mechanical spectra showed droplets tending to arrange as a network in the emulsions which was related to the high stability. BG emulsion presented higher viscosity and stability than GA emulsion at the same concentration suggesting that BG could replace GA in some industrial applications.
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•Brea gum emulsifying properties were analyzed in comparison with gum arabic.•Increase in gum concentration decrease emulsion droplet sizes and increase stability.•Emulsions presented shear-thinning tending to Newtonian plateau at high shear rates.•Droplets tending to arrange as a network and high viscosities contributed to stability.•Brea gum emulsion presented higher viscosity and stability than gum arabic one.
In this work we have studied the interactions between a commercial whey protein concentrate (WPC) and two anionic polysaccharides (sodium alginate, SA, and λ
-carrageenan, λ-C) in the aqueous phase. ...The concentration of WPC at 1.0% and the pH 7.0 of the aqueous phase were maintained constant, while polysaccharides (PS) were evaluated within a 0.0–1.0% concentration range. Interactions between WPC and PS in the aqueous phase were analysed by fluorescence spectroscopy, absorption spectroscopy in the presence of methylene blue (MB), and confocal laser scanning microscopy. The results from these methodologies revealed differences in the molecular dynamics of mixed systems. The nature of the interactions between WPC and PS depended on the PS type, its relative concentration in the aqueous phase and also on the two WPC fractions. Whey protein concentrate/sodium alginate (WPC/SA) mixed systems were distinguished by a tendency to protein aggregation in the aqueous phase and their segregation into separated microdomains. On the other hand, WPC/λ-carrageenan (WPC/λ-C) mixed systems showed a high degree of attractive interactions over the whole range of concentrations. The ultrastructure revealed the existence of hybrid macromolecular entities (biopolymer network). Interaction of WPC and polysaccharide in the aqueous phase has an effect on the adsorption of mixed systems at the air–water interface and on their foaming characteristics.
Protein/polysaccharide conjugates have been widely studied because of their good emulsifying properties and their potential use as food ingredients. However, there is little information about the use ...of these conjugates in gel systems. Rheological properties of conjugates of whey protein isolate (WPI) and dextran (DX) of 15 kDa obtained by Maillard reaction (RM) at different incubation times (2, 5 and 9 days) were studied. Conjugation was confirmed by electrophoresis, conformational changes were studied by DSC and rheological properties were determined by means of an oscillatory rheometer with a temperature ramp ranging from 25 to 90 °C. After each rheological measure, a mechanical spectrum from 0.01 to 10 Hz was also obtained. Electrophoresis indicated the presence of WPI/DX conjugates for all incubation days, though their molecular weight could not be determined. Both, time and temperature of gelation (G′–G″ crossover), increased in WPI/DX conjugate systems compared with WPI without DX (same time of incubation). However, these parameters decreased in WPI/DX mixed system. G′ values at 25 °C decreased in WPI/DX conjugates and increased in WPI/DX mixed system with respect to WPI alone. Frequency sweeps showed that all gels were stable.
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•Whey Protein Isolate (WPI)/Dextran (DX) conjugates were obtained by Maillard reaction.•Structural changes, studied by DSC, were much more marked in WPI/DX conjugates.•Maillard reaction (MR) significantly modified rheological behaviour of WPI/DX systems.•Gelation of conjugates was delayed and the resulting gel was weaker than mixed system.
► Alternative processes to obtain amaranth protein concentrates were studied. ► Electrophoresis, HPLC, amino acid determination of protein fractions were carried out. ► Alternative processes resulted ...in higher protein concentration and low protein yield. ► Ultrafiltration protein concentrate presented high phenylalanine and lysine content.
The aim of this study was to compare protein yield, protein concentration and physicochemical characteristics of Amaranth mantegazzianus protein concentrates (APC) obtained at pilot-scale by a conventional process (CP) (alkaline extraction and isoelectric precipitation) and two alternative processes (AP): (1) acid pre-treatment process combined with isoelectric precipitation and (2) acid pre-treatment process combined with ultrafiltration. Although AP resulted in higher protein concentration, protein yield was lower than in CP. SDS–PAGE and size-exclusion chromatography showed high molecular weight fractions only for isoelectric precipitation concentrates (obtained by CP and AP). The amino acids concentration, especially phenylalanine, isoleucine and methionine, increased in all protein concentrates respect to the amaranth flour. Particularly, the product obtained by ultrafiltration was rich in phenylalanine and lysine, and presented no limiting amino acid with respect to the recommendation of the Food and Agriculture Organization of the United Nations (FAO).
In conclusion, process (2) improved protein concentration and nutritional quality (balanced amino acid composition) of A. mantegazzianus protein concentrates respect to CP and process (1), suggesting that the ultrafiltration process is a viable alternative to conventional process and a promising method for obtaining protein concentrates.
