Presence Of Beta-lactoglobulin Research Articles

Beta-Lactoglobulin Sensor Based on ISFET with CеO2 Gate Dielectric

In this article sensor with improved measurement technique for the detection of milk allergens was developed. β-lactoglobulin (BLG) protein was used as the biomarker for cow milk detection. The structure of the sensor with nanocrystalline cerium oxide is proposed with an advanced measurement method, which consists of using a micro-flow system to provide a constant volume of the substance to be tested for the dynamic analysis of the beta-lactoglobulin protein, the major milk allergen. The influence of illumination on the experiment and the degree of cleaning of the sensor surface between each measurement are analyzed. Because the existing ELISA method is too long (1.5 hours), and the proposed method allows to identify the presence of beta-lactoglobulin in a few minutes. U gs = µA

Stability of vitamin B12 with the protection of whey proteins and their effects on the gut microbiome.

Cobalamin degrades in the presence of light and heat, which causes spectral changes and loss of coenzyme activity. In the presence of beta-lactoglobulin or alpha-lactalbumin, the thermal- and photostabilities of adenosylcobalamin (ADCBL) and cyanocobalamin (CNCBL) are increased by 10-30%. Similarly, the stabilities of ADCBL and CNCBL are increased in the presence of whey proteins by 19.7% and 2.2%, respectively, when tested in gastric juice for 2 h. Due to the limited absorption of cobalamin during digestion, excess cobalamin can enter the colon and modulate the gut microbiome. In a colonic model in vitro, supplementation with cobalamin and whey enhanced the proportions of Firmicutes and Bacteroidetes spp. and reduced those of Proteobacteria spp., which includes pathogens such as Escherichia and Shigella spp., and Pseudomonas spp. Thus, while complex formation could improve the stability and bioavailability of cobalamin, these complexes might also mediate gut microecology to influence human nutrition and health.

ALERGIA AO LEITE DE VACA: MECANISMO, DIAGNÓSTICO E PERSPECIVAS BIOTECNOLÓGICAS

A frequência dos portadores de alergia ao leite de vaca tem-se tornado alarmante. Relatórios epidemiológicos recentes demonstraram que um dos motivos mais preocupantes para ocorrência desse tipo de alergia é a presença da beta-lactoglobulina no leite. Os agravos a saúde incluem hipersensibilização do sistema imunológico, problemas gastrointestinais, cutâneos, respiratórios, e quando mais graves, surgem os eventos anafiláticos. No presente trabalho estudamos a alergenicidade ao leite de vaca frente aos mecanismos envolvidos na sensibilização dos sistema imunológico, diagnósticos e perspectivas biotecnológicas, através da análise de 52 artigos associados a essa problematização. Os resultados da análise baseados na alergenicidade ao leite de vaca revelaram a existência de uma diversidade de sintomas inespecíficos que corroboram no retardamento do diagnóstico. Além disso, foi possível perceber que a maioria dos protocolos de diagnósticos baseam-se estritamente na restrição do leite e seus derivados. Apesar das dificuldades enfrentadas no diagnóstico correto e tratamento eficaz, muitos estudos seguem em desenvolvimento utilizando tecnologias visando a correção da hipersensibilização do sistema imunológico provocada pelos alergénos do leite, edição/interferência da transcrição gênica e, consequentemente, alterando a tradução. Nesse sentido, tais processos poderão contribuir para redução e/ou eliminação da alergenicidade ao leite de vaca no cotidiano dos portadores dessa condição.

Factors Affecting Foamed Emulsions Prepared with an Extract from Quillaja saponaria Molina: Oil Droplet Size, pH and Presence of Beta-Lactoglobulin

Oil is well-known to act as antifoam and to destabilize foam lamellae by bridging between two adjacent foam bubbles. It was hypothesized that an optimal oil droplet size exists with respect to the stability of a foamed emulsions, where the oil droplets are sufficiently small to postpone bridging and the amount of free surfactant is sufficient to stabilize the oil/water-interface and the air/water-interface. Emulsions with 0.3% Quillaja saponin and a median oil drop-let size between 0.2 and 2.0 μm were prepared under varying homogenization conditions and characterized in a dynamic foam analyzer. Results confirmed the above mentioned hypothesis. Stability of the foamed emulsions considerably increased with increasing pH, which was attributed to electrostatic repulsion between oil droplets and the effect on the balance between disjoining pressure and capillary pressure. In a binary system containing proteins and saponins, stability of foamed emulsions can be further increased when emulsifiers are added sequentially. When the emulsion is stabilized by β-LG and QS is added after emulsification stability of the foamed emulsion is distinctly higher compared to systems, where QS and β-LG are added prior to emulsification. Future studies should deepen our understanding of these complex dispersed systems by investigating the molecular interactions including other proteins and additional food constituents.

Disruption of Viscoelastic β-Lactoglobulin Surface Layers at the Air−Water Interface by Nonionic Polymeric Surfactants

Nonequilibrium interfacial layers formed by competitive adsorption of beta-lactoglobulin and the nonionic triblock copolymer PEO99-PPO65-PEO99 (F127) to the air-water interface were investigated in order to explain the influence of polymeric surfactants on protein film surface rheology and foam stability. Surface dilatational and shear rheological methods, surface tension measurements, dynamic thin-film measurements, diffusion measurements (from fluorescence recovery after photo bleaching), and determinations of foam stability were used as methods. The high surface viscoelasticity, both the shear and dilatational, of the protein films was significantly reduced by coadsorption of polymeric surfactant. The drainage rate of single thin films, in the presence of beta-lactoglobulin, increased with the amount of added F127, but equilibrium F127 films were found to be thicker than beta-lactoglobulin films, even at low concentration of the polymeric surfactant. It is concluded that the effect of the nonionic triblock copolymer on the interfacial rheology of beta-lactoglobulin layers is similar to that of low molecular weight surfactants. They differ however in that F127 increases the thickness of thin liquid films. In addition, the significant destabilizing effect of low molecular weight surfactants on protein foams is not found in the investigated system. This is explained as due to long-range steric forces starting to stabilize the foam films at low concentrations of F127.

κ -Carrageenan—Protein Interactions: Effect of Proteins on Polysaccharide Gelling and Textural Properties

Gelation and melting processes of kappa-carrageenan (κ-C) in the presence of beta-lactoglobulin (β-lg), native and denatured soy protein (NSP and DSP) isolates were investigated by dynamic rheological techniques, apparent viscosity measurements and DSC. In the presence of proteins, large increases in gelation temperatures and storage moduli of the mixed gels compared to single κ-C gel were observed. Differences between the proteins in the first steps of the gelation process were revealed by apparent viscosity measurements. Although little changes in melting temperatures were observed in the presence of proteins by dynamic rheology, the DSC analysis showed a large increase in these temperatures. Synergistic effects were also observed on textural properties and water absorption of the gels. The addition of proteins increased gel hardness, cohesiveness, gumminess, springiness and reduced syneresis. These results might be due to excluded volume effects that increased the effective concentration of the hydrocolloid and electrostatic interactions between both biopolymers in solution. The different behaviours observed with the three proteins would be related to their water absorption capacity, molecular size, flexibility and superficial charge under the experimental conditions described.

Transfer of aroma compounds through the lipidic-aqueous interface in a complex system.

The transfer kinetics of aroma compounds from the aqueous phase to the lipidic phase (miglyol) and from miglyol to the aqueous phase have been studied in the presence or absence of a protein, beta-lactoglobulin, and at different pH values. In the presence of beta-lactoglobulin, the transfer at the interface from the aqueous to the lipidic phase decreases, with a greater effect of the presence of the protein at pH 3 than at pH 6. This barrier effect of the protein plays a role in the transfer of the aroma compounds between the different phases of the matrix.

Interleukin-10-secreting Peyer's patch cells are responsible for active suppression in low-dose oral tolerance.

We demonstrate the induction of antigen-specific interleukin-10 (IL-10)-secreting cells in murine Peyer's patches (PPs) after low-dose beta-lactoglobulin (BLG) feeding. In addition, we show that PP cells can inhibit the T-cell proliferative response in vitro as well as T-cell-mediated inflammation in vivo. The active suppression mediated by these regulatory cells was seen only within a narrow range of antigen dosage (feeding), with the most prominent effect at 5 x 1 mg BLG. On either side of this range, T-helper 1-like cytokine responses were observed when PP cells were stimulated with antigen in vitro. This result correlated with reduced production of regulatory cytokines as well as reduced activity of bystander suppression. We found that changes in IL-10 production correlated inversely with changes in interferon-gamma production. Inhibitory effects mediated by CD4(+) PP cells were partially neutralized by antibodies to IL-10 and transforming growth factor-beta. Interestingly, the generation of such regulatory cells after low-dose BLG feeding exhibited organ dependence. Among spleen, lymph node and PP cells derived from orally tolerized mice, PP cells were the most effective in promoting bystander suppression in the presence of BLG, indicating the significance of PPs as an inductive site for antigen-specific regulatory cells upon induction of low-dose oral tolerance. Moreover, PP cells from mice fed 5 x 1 mg BLG were shown to suppress a BLG-specific delayed-type hypersensitivity response induced in footpads, suggesting that IL-10-secreting PP cells regulate systemic inflammation.

Evaluation of the presence of bovine proteins in human milk as a possible cause of allergic symptoms in breast-fed children.

It is generally believed that the elimination of certain foods from the diet of mothers during the lactation period produces a significant improvement in breast-fed children who develop allergic symptoms. Several studies have shown the presence of food proteins in human milk; on the other hand, no study has been able to correlate unequivocally the presence of these allergens in human milk with newborn sensitization. The aim of this study was to evaluate the presence of bovine proteins in breast milk. Milk samples were separated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). To detect bovine proteins in human milk, immunoblotting was performed by using monoclonal antibodies (MA) specific for beta-lactoglobulin and bovine caseins. The results of this study do not confirm the presence of bovine proteins in breast milk suggested by other authors and shows unequivocally that the conflicting results reported in the literature about the presence of betalactoglobulin in human milk are due to cross-reactivity between bovine milk proteins and human proteins. Components other than bovine betalactoglobulin or caseins could be involved in the induction of allergic symptoms in exclusively breast-fed children.

Consumption of cow milk and egg by lactating women and the presence of beta-lactoglobulin and ovalbumin in breast milk

beta-Lactoglobulin and ovalbumin in mature human milk in healthy lactating Japanese women (n = 24) were determined by using an enzyme-linked immunosorbent assay. Subjects consumed > or = +200 mL cow milk/d for 1 wk before the sampling day and exactly 200 mL cow milk on the morning of the sampling day. beta-Lactoglobulin was detected (> 0.1 microgram/L) in breast milk in 15 of the 24 subjects (62.5%), with a maximum concentration of 16.5 micrograms/L. Ovalbumin was detected in only two subjects (8.3%) after the subjects followed their usual diet. beta-Lactoglobulin concentrations were low in the subjects whose cow milk consumption during the entire lactating period was low, even though all subjects consumed the same amount of cow milk before sampling. This result suggests that beta-lactoglobulin concentrations in breast milk are related to long-term consumption of cow milk. Amounts of food antigens in breast milk may be controlled by modifying the daily maternal diet.

Reduction of ferrylmyoglobin by beta-lactoglobulin.

Reduction of iron (IV) in ferrylmyoglobin in the presence of beta-lactoglobulin in aqueous solution is the result of two parallel reactions: (i) a so-called autoreduction, and (ii) reduction by beta-lactoglobulin in a second-order-reaction resulting in bityrosine formation in beta- lactoglobulin. In the pH-region investigated (5.4-7.4), the rate of reduction increased for both reactions with decreasing pH. The second order-reaction had for non-denatured beta-lactoglobulin the activation parameters: delta H* = 45 kJ.mol-1 and delta S not equal to = -93 J.mol-1.K-1 at pH = 7.0 and ionic strength 0.16 (NaCl). Reduction of ferrylmyoglobin by beta-lactoglobulin denatured by heat (86 degrees C for 3 min) or by hydrostatic pressure (300 MPa for 15 min) resulted in formation of higher molecular weight species as detected by size-exclusion chromatography and by SDS-PAGE. No molecular weight changes were observed for reduction of ferrylmyoglobin by native beta-lactoglobulin. Detection of bityrosine in the native beta-lactoglobulin fraction after oxidation with ferrylmyoglobin indicated intra-molecular bityrosine formation. In heat-denatured beta-lactoglobulin bityrosine formation could be of intra-molecular and/or of inter-molecular origin, the latter being confirmed by size-exclusion chromatography.

Proliferation of the MAC-T bovine mammary epithelial cell line in the presence of mammary secretion whey proteins

Development of the MAC-T bovine mammary epithelial cell line by stable transfection with simian virus-40 large T-antigen should greatly assist study of possible intrinsic (local) and extrinsic (systemic) factors regulating bovine mammary epithelial cell development, differentiation, and function. This study evaluated the influence of mammary secretion whey proteins alpha-lactalbumin (ALA), beta-lactoglobulin (BLG), lactoferrin (LF), transferrin (TF) and serum albumin (SA) on MAC-T cell proliferation in the absence and presence of 10% fetal bovine serum (FBS). Concentration of whey proteins in culture ranged from 0 to 625 μg/ml. MAC-T cell proliferation in the absence of FBS was significantly lower than in presence of 10% FBS. Alpha-lactalbumin and LF significantly decreased MAC-T proliferation in both the absence and presence of 10% FBS. Transferrin significantly increased MAC-T cell proliferation only in the absence of FBS. There were no significant differences in MAC-T cell proliferation cultured in the presence of BLG or SA. These experiments illustrate the potential usefulness of MAC-T cells for the study of factors involved in mammary cell proliferation. Results identified ALA, LF and TF as possible intrinsic factors associated with regulation of mammary epithelial cell proliferation.