Heat-induced Ovalbumin Research Articles

Rheological and physicochemical properties of heat-induced ovalbumin gels in presence of sodium carboxymethyl cellulose.

In this study, the effect of sodium carboxymethylcellulose (CMC-Na) on the rheological and physicochemical properties of heat-induced ovalbumin (OVA) gels was evaluated. The OVA/CMC-Na composite gels were prepared by heat-induced (85 °C, pH 7.0) a mixture of CMC-Na (0, 0.2, 0.4, 0.8 and 1%) and OVA. The results revealed that the addition of CMC-Na dramatically reduced the springiness and hardness of the composite gels, while slightly enhancing the intermolecular hydrogen bonding interactions, which facilitated the improvement of the softness of the gels. It can be observed by SEM that the added CMC-Na was stacked on the surface of the OVA, resulting in visible "linear bumps". All gel samples exhibited shear-thinning behavior. The apparent viscosity of the composite gels increased with the addition of CMC-Na, and the OVA gel with 1% CMC-Na showed the highest apparent viscosity and the lowest storage modulus (G'). Additionally, low field nuclear magnetic resonance (LF-NMR) measurements indicated that the increasing CMC-Na boosted the water mobility of the composite gel. This study offers a novel approach to the development of ovalbumin-based soft gel foods, especially for certain populations with swallowing difficulties.

Development and characterization of high internal phase pickering emulsions stabilized by heat-induced electrostatic complexes particles: Growth nucleation mechanism and interface architecture

In this work, the heat-induced ovalbumin (OVA)-pectin (PE) electrostatic complex particles (HIECP) prepared by different heating sequences (type I particles (I): Heat-treated ovalbumin/pectin complexes at pH 4; type II particles (II): Complexes between pre-heated ovalbumin and pectin at pH 4) and biopolymer ratios were used as stabilizers to form high internal phase Pickering emulsions (HIPPEs). The results showed that I had a more compact structure, higher net surface charge, and smaller particle size than II, due to the different growth nucleation mechanism. II-stabilized HIPPEs exhibited a smaller oil droplet size, stronger gel structure, and better stability than I-stabilized HIPPEs, owing to their suitable wettability, rigid “core–shell” structure, and robust and dense interface architecture. Moreover, the stability and gel-like structure of HIECP-stabilized HIPPEs improved with increasing PE content due to steric barrier and thickening effects. Our findings provide a new perspective for understanding heat-induced biopolymer particles as effective Pickering stabilizers.

Physicochemical properties and digestibility of thermally induced ovalbumin–oil emulsion gels: Effect of interfacial film type and oil droplets size

To investigate the effect of oil droplets surface film type and droplets size on the physicochemical properties and digestibility of thermally induced ovalbumin–oil emulsion gels, Tween 80 and ovalbumin were selected as individual emulsifiers for the emulsification of sunflower oil at different homogenization speeds (6000, 8000, and 10000 rpm), and the formed emulsions were mixed with ovalbumin matrix solution and then heated to form heat-induced ovalbumin emulsion gels (OEG). The OEG with ovalbumin as emulsifier had higher hardness, water holding capacity (WHC), and surface hydrophobicity, and lower digestibility, spin−spin relaxation time ( T 2 ) and free sulfhydryl content than those of the OEG with Tween 80 as the emulsifier ( p < 0.05). As the oil droplets size decreased, the hardness increased, WHC increased, the amide A band shifted to lower wavenumbers, digestibility decreased, T 2 decreased, free sulfhydryl content decreased, and surface hydrophobicity increased for both OEG ( p < 0.05). These results collectively indicated that the physicochemical properties of the OEG are influenced by the property of the oil interfacial film and the size of the oil droplets. The oil droplets surrounded by the interfacial protein film improved the performance of the OEG greatly, and the proteins within its OEG formed a dense gel network structure through hydrophobic aggregation, disulfide bond crosslinking, and hydrogen bonding. The oil droplets with smaller sizes favored the enhancement in the physicochemical properties of the OEG. Changes in the size of oil droplets and the type of film wrapped around them regulated the digestibility of the OEG. • The OEG-O with the small size of oil droplets had the highest hardness. • Small oil droplets filled better in the gel network to improve the hardness of OEG. • IPF-encapsulated oil droplets as active filler to increase the hardness of OEG. • Effect of filler on hardness depends on the heat stability of its interfacial layer. • Changes in oil droplet size and interfacial layer type regulated OEG digestibility.

加熱誘導卵白アルブミンゲルの形成に及ぼす乳&lt;i&gt;α&lt;/i&gt;-カゼインおよびカプリン酸ナトリウム添加の影響

加熱誘導卵白アルブミンゲルの形成に及ぼす乳&lt;i&gt;α&lt;/i&gt;-カゼインおよびカプリン酸ナトリウム添加の影響

Study on the dissolution of heat-induced ovalbumin gel in alkaline solutions relevant to the removal of fouling deposits

Heat-induced whey protein concentrate gels (HIWPCG) have previously been used to simulate milk fouling and cleaning processes. The related research has generated considerable knowledge, which is of practical interest. In the current study, heat-induced ovalbumin gels (HIOVAG) have been employed to investigate the dissolution process (related to chemical cleaning process). Both HIOVAG and HIWPCG are sensitive to NaOH solution, which is a common cleaning fluid in food industry. In contrast to the HIWPCG behavior, HIOVAG dissolution presents no optimal NaOH concentration where the rate of dissolution is highest. The dissolution temperature was found to positively influence the dissolution process of HIOVAG, i.e. the dissolution rate increased with increasing dissolution temperature. In addition, ovalbumin (OVA) concentration in HIOVAG was found to be another important factor influencing the dissolution process. However, the stirring speed (convection) and heating time had no effect in the range tested, indicating that the process was internally limited.

Appraisal of casein’s inhibitory effects on aggregation accompanying carbonic anhydrase refolding and heat-induced ovalbumin fibrillogenesis

It is well accepted that whole casein and its purified major components, due to their chaperone-like activity, are able to suppress the thermal and chemical aggregation of several substrate proteins. In this study, we set out to determine whether whole and β-casein are able to prevent (or attenuate) aggregation accompanying refolding of chemically denatured carbonic anhydrase or to recover lost biological activity after its denaturation. Additionally, we showed attenuated heat-induced fibrillar aggregation of egg white ovalbumin in the presence of these commonly occurring unfolded proteins, as molecular chaperones. Also, the extent, rate and order of aggregation, in the presence and absence of aggregation suppressors, were compared. Although β-casein did not prevent aggregation as strong as whole casein, both chaperones were efficient not only in suppressing the aggregation extent of denatured carbonic anhydrase, but also in delaying elongation process of amyloid fibril formation with no effect on nucleation phase.

Role of Amyloid Type Cross β-Structure in the Formation of Soluble Aggregate and Gel in Heat-Induced Ovalbumin

The heat-induced denaturation curve of ovalbumin followed by the ellipticity at 222 nm in circular dichroism spectra was consistent with that monitored by fluorescence with thioflavin T, which is an indication of amyloid fibril formation, while other proteins such as lysozyme and ovotransferrin did not fluoresce with thioflavin T during heat denaturation. The amount of soluble aggregate formed during heat denaturation was proportional to the increase in fluorescence with thioflavin T. The binding of soluble aggregates with thioflavin T was greatly suppressed in heat-denatured ovalbumin in the presence of thioflavin T. The similar inhibition effect of thioflavin T on the gel formation of heat-induced ovalbumin was observed. These results suggest that the amyloidogenic intermolecular beta-structure is involved in the formation of soluble aggregate and gel of heat-induced ovalbumin.

Laser Light Scattering Study on the Heat-Induced Ovalbumin Aggregates Related to Its Gelling Property

A Multiangle laser photometer and a dynamic light scattering spectrophotometer were used to characterize the aggregation behavior and gel network structure of elastic and less elastic gels of ovalbumin. Ovalbumin formed opaque and less elastic gels in 50 mM phosphate buffer (pH 7.0). However, succinylated ovalbumin formed transparent and elastic gels. Heat-induced ovalbumin protein formed high molecular weight and polydisperse aggregates. Succinylation of the protein contributed to formation of lower molecular weight polymers with a narrow molecular size distribution during subsequent heat gelation. The root mean square and hydrodynamic radii of the protein polymers indicated that the elastic gel consisted of a more extended protein polymer network compared to that of the less elastic gel. The aggregation behavior of denatured ovalbumin appeared to play a crucial role in the subsequent gelling process of the proteins.

Melting of heat-induced ovalbumin gel by pressure

The effects of pressure on heat-induced gels of ovalbumin were examined. A heat-induced gel containing 7% ovalbumin and 10 mmol/dm 3 Na-phosphate buffer, pH 7.0, melted completely with pressure at 600 MPa for 20 min at 20°C. The melted sample gelled again after the pressure ceased. Most of the heat-induced gels of ovalbumin prepared under various conditions (different protein concentrations, ionic strengths, pHs and heating methods) melted partly with pressure at 600 MPa for 20 min at 20°C, and gelled again at atmospheric pressure. However, a heat-induced gel of glycinin and cold-set gels of gelatin or agarose did not melt with pressure at 400–700 MPa for 20 min at 20°C. The pressure denaturation of ovalbumin and the renaturation of heat-denatured ovalbumin caused by pressure were also examined. The pressure denaturation of ovalbumin was partly reversible and heat-denatured ovalbumin renatured somewhat with treatment at 600 MPa for 20 min at pH 7.0 and low ionic strength.

Melting of the Ovalbumin Gels by Heating: Reversibility between Gel and Sol.

Heat-induced ovalbumin gels prepared under given conditions were melted with a second heating to below 90°C. The sample melted was gelled again on cooling. This gel-sol transition, which was detected both by eye and by the change in the dynamic viscoelastic parameters G' and G, was reversible. Differential scanning calorimetry showed that the endothermic heat flow that accompanied the gel-sol transition was much lower than that accompanied the denaturation of ovalbumin. With the repetition of the gel-sol transition, intermolecular disulfide bridges were formed, detected by sodium dodecyl sulfate-polyacrylamide electrophoresis done without a reducing agent.

Estimation of the molecular weight distribution of heat-induced ovalbumin aggregates by the low-angle laser light scattering technique combined with high-performance gel chromatography

Fractionnement par chromatographie en gel et analyse de la distribution des poids moleculaires des differentes fractions obtenues pour differents traitements thermiques