The decrease in the IgG-binding capacity of intensively dry heated whey proteins is associated with intense Maillard reaction, structural changes of the proteins and formation of RAGE-ligands

Milk proteins were subjected to treatment with various levels of benzoyl peroxide, with and without heating at 60 C for 2 h. Heating had a pronounced effect on whey proteins, but polyacrylamide gel electrophoresis revealed changes in proteins not attributable to heat alone. The effect on proteins was reflected in an increased tendency for the benzoyl peroxide-heat treated cheeses to expel moisture during leakage tests. Use of 17.8 ppm benzoyl peroxide resulted in a markedly whiter cheese than that made using 5.9 ppm and reflectance studies indicated this to be true even when no heat treatment accompanied the benzoyl peroxide. Use of benzoyl peroxide in the bleaching process did not decrease mold development in ripening loaves nor was acid production by lactic cultures diminished. In addition, proteolysis of milk proteins by rennet was not reduced by the presence of benzoyl peroxide.

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Contribution of Chemical Modifications and Conformational Epitopes to IgE Binding by Ara h 3

Foods ◽

10.3390/foods7110189 ◽

2018 ◽

Vol 7 (11) ◽

pp. 189 ◽

Cited By ~ 3

Author(s):

Scott Dyer ◽

Jacqueline Nesbit ◽

Beatriz Cabanillas ◽

Hsiaopo Cheng ◽

Barry Hurlburt ◽

...

Keyword(s):

Heat Treatment ◽

Secondary Structure ◽

Disulfide Bonds ◽

Structural Changes ◽

Polyacrylamide Gel Electrophoresis ◽

Sodium Dodecyl ◽

Cd Spectroscopy ◽

Chemical Modifications ◽

Ige Binding ◽

Ara H 3

Roasting is known to change the allergenic properties of peanuts. To study these observations at a molecular level, the relationship of IgE binding to the structure of Ara h 3 from raw and roasted peanuts was assessed. Ara h 3 (A3) was purified from raw (R), light roast (LR) and dark roast (DR) peanuts, the purity was assessed using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and the secondary structures were compared with circular dichroism (CD) spectroscopy. In order to understand the contribution of structure to IgE binding, the R A3 was partially denatured (PD) by heat treatment (65 °C for 2 h), subjected to CD spectroscopy and IgE spot blot analysis with sera from peanut- allergic individuals. While we observed that the secondary structure of purified A3 from R and LR peanut in solution was affected by the reduction of disulfide bonds and heat treatment when purified from the peanut following the roasting process, only small alterations were seen in the secondary structure. The purified LR A3 bound higher levels of IgE than the RA3. CD spectroscopy of PD A3 revealed a reduction in the percentage of alpha helices, and serum IgE binding. Therefore, while A3 purified from roasted peanuts did not show significant changes in secondary structure, it showed higher IgE binding than R A3. Therefore, the higher IgE binding to LR A3 was more likely to be due to chemical modifications than structural changes. However, a decrease in the IgE binding was seen if R A3 was deliberately unfolded, indicating that the structure played an important role in IgE binding to A3.

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Dielectric-barrier discharge (DBD) plasma treatment reduces IgG binding capacity of β-lactoglobulin by inducing structural changes

Food Chemistry ◽

10.1016/j.foodchem.2021.129821 ◽

2021 ◽

Vol 358 ◽

pp. 129821

Author(s):

Zhi-Wei Liu ◽

Lian-Jie Liu ◽

Ying-Xue Zhou ◽

Yi-Cheng Tan ◽

Jun-Hu Cheng ◽

...

Keyword(s):

Plasma Treatment ◽

Dielectric Barrier Discharge ◽

Structural Changes ◽

Barrier Discharge ◽

Binding Capacity ◽

Dbd Plasma ◽

Dielectric Barrier ◽

Igg Binding ◽

Β Lactoglobulin

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Limited Lactosylation of Beta-Lactoglobulin from Cow’s Milk Exerts Strong Influence on Antigenicity and Degranulation of Mast Cells

Nutrients ◽

10.3390/nu13062041 ◽

2021 ◽

Vol 13 (6) ◽

pp. 2041

Author(s):

Gerlof P. Bosman ◽

Sergio Oliveira ◽

Peter J. Simons ◽

Javier Sastre Torano ◽

Govert W. Somsen ◽

...

Keyword(s):

Mast Cells ◽

Elevated Temperatures ◽

Binding Capacity ◽

Milk Proteins ◽

Primary Objective ◽

Molar Ratio ◽

Cow’S Milk ◽

Cow's Milk ◽

Igg Binding ◽

Beta Lactoglobulin

Background: beta-lactoglobulin (BLG) is one of the major cow’s milk proteins and the most abundant allergen in whey. Heating is a common technologic treatment applied during milk transformational processes. Maillardation of BLG in the presence of reducing sugars and elevated temperatures may influence its antigenicity and allergenicity. Primary objective: to analyze and identify lactosylation sites by capillary electrophoresis mass spectrometry (CE-MS). Secondary objective: to assess the effect of lactosylated BLG on antigenicity and degranulation of mast cells. Methods: BLG was lactosylated at pH 7, a water activity (aw) of 0.43, and a temperature of 65 °C using a molar ratio BLG:lactose of 1:1 by incubating for 0, 3, 8, 16 or 24 h. For the determination of the effect on antibody-binding capacity of lactosylated BLG, an ELISA was performed. For the assessment of degranulation of the cell-line RBL-hεIa-2B12 transfected with the human α-chain, Fcε receptor type 1 (FcεRI) was used. Results: BLG showed saturated lactosylation between 8 and 16 incubation hours in our experimental setup. Initial stage lactosylation sites L1 (N-terminus)—K47, K60, K75, K77, K91, K138 and K141—have been identified using CE-MS. Lactosylated BLG showed a significant reduction of both the IgG binding (p = 0.0001) as well as degranulation of anti-BLG IgE-sensitized RBL-hεIa-2B12 cells (p < 0.0001). Conclusions and clinical relevance: this study shows that lactosylation of BLG decreases both the antigenicity and degranulation of mast cells and can therefore be a promising approach for reducing allergenicity of cow’s milk allergens provided that the process is well-controlled.

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Binding of zinc to bovine and human milk proteins

Journal of Dairy Research ◽

10.1017/s0022029900026455 ◽

1989 ◽

Vol 56 (2) ◽

pp. 235-248 ◽

Cited By ~ 32

Author(s):

Harjinder Singh ◽

Albert Flynn ◽

Patrick F. Fox

Keyword(s):

Ionic Strength ◽

Binding Sites ◽

Binding Capacity ◽

Equilibrium Dialysis ◽

Whey Proteins ◽

Milk Proteins ◽

Association Constants ◽

Zn Concentration ◽

Β Lactoglobulin ◽

Scatchard Plots

SummaryZn binding by whole bovine and human casein and by purified bovine caseins and whey proteins was investigated by equilibrium dialysis. Bovine αs1 casein had the greatest Zn-binding capacity (˜ 11 atoms Zn/mol). Protein aggregation was observed as Zn concentration was increased and- the protein precipitated at a free Zn concentration of 1·7 mM. Zn binding increased with increasing pH in the range 5·4–7·0 and decreased with increasing ionic strength. Competition between Zn and Ca was observed for binding to αs1-casein indicating common binding sites for these two metals. Bovine β-casein bound up to 8 atoms Zn/ mol and precipitated at a free Zn concentration of ˜ 2·5 mM, while K-casein bound 1–2 atoms Zn/mol. Whole bovine and human casein bound 5–8 atoms Zn/mol and precipitated at a free Zn concentration of ˜ 2·0 mM. Scatchard plots for Zn binding to caseins showed upward convexity, possibly due to Zn-induced association of caseins. Apparent average association constants (K¯app) for all caseins were similar (log K¯app 3·0–3·2). Enzymic dephosphorylation of αs1- or whole bovine casein markedly reduced, but did not eliminate, Zn binding. Thus, phosphoserine residues appeared to be the primary Zn-binding sites in caseins. With the exception of bovine serum albumin. which bound over 8 atoms Zn/mol, the bovine whey proteins, β-lactoglobulin, α-lactalbumin and lactotransferrin, had little capacity for Zn binding.

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Effect of milk proteins aggregation using Transglutaminase and Maillard reaction on Ca2+ milk gel

Kurdistan Journal of Applied Research ◽

10.24017/science.2018.1.13 ◽

2018 ◽

Vol 3 (1) ◽

pp. 63-67

Author(s):

Hassan Mahdi Alfayadh ◽

Mohammed Latif Hamk ◽

Kocher Jamal Ibrahim ◽

Jasim Mohammed Al-Saadi

Keyword(s):

Maillard Reaction ◽

Whey Proteins ◽

Milk Proteins ◽

Gel Strength ◽

Water Holding Capacity ◽

Gel Properties ◽

Water Holding

Effect of transglutaminase, Maillard reaction induced crosslinking and the combination of transglutaminase and Maillard reaction induced crosslinking between whey proteins and caseins in milk on calcium milk gel properties were investigated. Treatment of milk with transglutaminase, Maillard reaction, and transglutaminase + Maillard reaction cause to the appearance of new high MW protein bands. Water holding capacity, gel strength and sensory scores of gel samples increased and spontaneous whey separation decreased in calcium-induced milk gel made from transglutaminase and combination of transglutaminase and Maillard reaction treated milk compare with calcium-induced milk gel made from untreated milk alone.

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Reduction in the antigenicity of whey proteins by heat treatment: a possible strategy for producing a hypoallergenic infant milk formula

British Journal Of Nutrition ◽

10.1079/bjn19840006 ◽

1984 ◽

Vol 51 (1) ◽

pp. 29-36 ◽

Cited By ~ 32

Author(s):

L. M. J. Heppell ◽

A. J. Cant ◽

P. J. Kilshaw

Keyword(s):

Heat Treatment ◽

Whey Protein ◽

Antibody Production ◽

Guinea Pigs ◽

Whey Proteins ◽

Milk Proteins ◽

Heat Denaturation ◽

Milk Formula ◽

Milk Whey ◽

Β Lactoglobulin

1. Residual antigenic protein in heat-denatured cow's milk whey and in two commercial infant milk formulas was determined using enzyme-linked immunosorbent assays specific for β-lactoglobulin, α-lactalbumin, bovine serum albumin, bovine IgG1 and α-casein. This immunochemical assessment of antigenicity was related to the capacity of the preparations to sensitize immunologically when fed to guinea-pigs for 2 weeks. Antibody production was measured and the susceptibility of the animals to systemic anaphylaxis was assessed by injecting them intravenously with heated or unheated milk proteins.2. Whey protein that had been heated at 100° or 115° for 30 min was extensively denatured and, in contrast to pasteurized whey, failed to sensitize guinea-pigs for anaphylaxis. Antibody production was undetected or very low. The proteins in SMA powder and SMA Gold Cap liquid concentrate were less denatured and animals given these formulas prepared according to the maker's instructions produced relatively high levels of antibodies to β-lactoglobulin and α-casein and a majority developed anaphylaxis when injected intravenously with these products.3. As well as failing to sensitize, whey that had received severe heat treatment did not, in most cases, elicit anaphylaxis when injected into animals that had been sensitized with unheated milk.4. Discrimination between antibodies of the IgG1 and IgG2 subclasses specific for β-lactoglobulin showed that IgG1, the principal anaphylactic antibody in guinea-pigs, was preferentially depressed in animals drinking heat-denatured milk preparations.5. The results suggest that heat denaturation of whey protein may be a logical and simple strategy for producing a hypoallergenic baby milk. Nevertheless, the value of experiments in guinea-pigs for predicting results in man is uncertain and the proposal awaits assessment in clinical trials.

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Physical methods of research and monitoring

Industrial laboratory Diagnostics of materials ◽

10.26896/1028-6861-2019-85-1-i-35-44 ◽

2019 ◽

Vol 85 (1(I)) ◽

pp. 35-44

Author(s):

S. G. Sandomirski

Keyword(s):

Heat Treatment ◽

Coercive Force ◽

Remanent Magnetization ◽

Structural Changes ◽

Mechanical Load ◽

Magnetic Hysteresis ◽

Steel Structures ◽

Magnetic Characteristics ◽

Magnetic Parameters ◽

Saturation Intensity

The main magnetic parameters sensitive to the structure of steels are the parameters of their saturation loop of magnetic hysteresis: the coercive force Hcs and remanent magnetization Mrs. The saturation magnetization or saturation intensity Mr is most sensitive to the phase composition of steels. The variety of steel grades and modes of technological treatment (e.g., heat treatment, mechanical load) determined the use of magnetic structurescopy and magnetic characteristics — the coercive force Hc, remanent magnetization Mr , and specific hysteresis losses Wh on the subloops of the magnetic hysteresis of steels — as control parameters in diagnostics of the stressed and structural states of steel structures and pipelines. It has been shown that changes in Hc, Mr , and Wh are more sensitive to structural stresses and structures of steels than the parameters of the saturation hysteresis loop of magnetic hysteresis (Hcs, Mrs, and Mrs). The formulas for calculating Hc, Mr and Wh are presented to be used for estimation of changes in the parameters upon heat treatment of steels. Features of the structural sensitivity of the subloop characteristics and expediency of their use for magnetic structural and phase analyzes are determined. Thus, the range of changes in Ìr attributed to the structural changes in steels upon gradual Hm decrease is many times wider compared to the range of possible changes in Mrs under the same conditions. Conditions (relations between the magnetic parameters) and recommendations regarding the choice of the field strength Hm are given which provide the justified use of Hc, Mr and Wh parameters in magnetic structurescopy

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