Complexation of bovine β-lactoglobulin with malvidin-3-O-glucoside and its effect on the stability of grape skin anthocyanin extracts

A Novel method for Thermodynamic Study on the Binding of Milk Carrier protein of BLG-A with Cr+3 Thermodynamics of the interaction between Cr3+ with β-lactoglobulin type A (BLG-A) was investigated at pH 7.0 and 37°C by isothermal titration calorimetry. A new method to follow the effect of Cr3+ on the stability of BLG-A was introduced. The new solvation model was used to reproduce the enthalpies of BLG-A+ Cr3+ interactions over the whole range of Cr3+ concentrations. The solvation parameters recovered from the new equation are attributed to the structural change of BLG-A and its biological activity. The results obtained indicate that there is a set of two identical binding sites for Cr3+ ions with positive cooperativity. The association equilibrium constants are 14.39 and 0.49 mM-1 for the first and second binding site, respectively. The enthalpy of binding for one mole of Cr+3 ion to one mole of the binding site on BLG-A (ΔH=104.60 kJ mol-1) is obtained.

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β-Lactoglobulin Adsorption Layers at the Water/Air Surface: 4. Impact on the Stability of Foam Films and Foams

Minerals ◽

10.3390/min10070636 ◽

2020 ◽

Vol 10 (7) ◽

pp. 636

Author(s):

Georgi G. Gochev ◽

Vamseekrishna Ulaganathan ◽

Inga Retzlaff ◽

Cécile Gehin-Delval ◽

Deniz Z. Gunes ◽

...

Keyword(s):

Foam Stability ◽

Building Blocks ◽

Disjoining Pressure ◽

Foaming Properties ◽

Film Rupture ◽

Foam Films ◽

The Stability ◽

The Impact ◽

Adsorption Layers ◽

Β Lactoglobulin

The complexity and high sensitivity of proteins to environmental factors give rise to a multitude of variables, which affect the stabilization mechanisms in protein foams. Interfacial and foaming properties of proteins have been widely studied, but the reported unique effect of pH, which can be of great interest to applications, has been investigated to a lesser extent. In this paper, we focus on the impact of pH on the stability of black foam films and corresponding foams obtained from solutions of a model globular protein—the whey β-lactoglobulin (BLG). Foam stability was analyzed utilizing three characteristic parameters (deviation time, transition time and half-lifetime) for monitoring the foam decay, while foam film stability was measured in terms of the critical disjoining pressure of film rupture. We attempt to explain correlations between the macroscopic properties of a foam system and those of its major building blocks (foam films and interfaces), and thus, to identify structure-property relationships in foam. Good correlations were found between the stabilities of black foam films and foams, while relations to the properties of adsorption layers appeared to be intricate. That is because pH-dependent interfacial properties of proteins usually exhibit an extremum around the isoelectric point (pI), but the stability of BLG foam films increases with increasing pH (3–7), which is well reflected in the foam stability. We discuss the possible reasons behind these intriguingly different behaviors on the basis of pH-induced changes in the molecular properties of BLG, which seem to be determining the mechanism of film rupture at the critical disjoining pressure.

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Effect of pH on the copigmentation of anthocyanins from Cabernet Sauvignon grape extracts with organic acids

Scientia Agricola ◽

10.1590/s0103-90162010000100006 ◽

2010 ◽

Vol 67 (1) ◽

pp. 41-46 ◽

Cited By ~ 32

Author(s):

Cony Gauche ◽

Elisa da Silva Malagoli ◽

Marilde Terezinha Bordignon Luiz

Keyword(s):

Organic Acids ◽

Life Time ◽

Vitis Vinifera L ◽

Cabernet Sauvignon ◽

Skin Extract ◽

Grape Skin ◽

Anthocyanin Stability ◽

The Stability ◽

Ferulic Acids

Anthocyanins show low-stability when exposed to different food processing conditions. Copigmentation is one of the main reactions contributing to the in vivo color responsible to the stability of anthocyanins. In the aim of holding the red color, copigmentation effect of organic acids (caffeic, ferulic, gallic and tannic acids) combined with anthocyanins in crude Cabernet Sauvignon (Vitis vinifera L.) grape skin extract at pH values (1.0, 2.0, 3.0, 3.3, 3.5, 3.7, 4.0, 4.5) was evaluated in this research. The maximum copigmentation effect, revealed by the hyperchromic and bathochromic shifts in anthocyanin maximum absorbance wavelength, was obtained at pH 3.3 with every acid used. Anthocyanin stability was followed by measuring the loss of color, thus it was possible to determine the protecting effects of these copigments. Tannic acid was the best copigment in our model system, giving half-life time of 2,585 h. We are suggesting the formation of pyranoanthocyanins by the reactions of anthocyanins with caffeic and ferulic acid, these substances could be avoiding the observation of the copigmentation effect. Addition of organic acids could improve the anthocyanin stability; though, more studies are needed to justify the lack of copigmenting effect observed with the caffeic and ferulic acids.

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Effect of the Air−Water Interface on the Stability of β-Lactoglobulin

The Journal of Physical Chemistry B ◽

10.1021/jp074777r ◽

2007 ◽

Vol 111 (48) ◽

pp. 13527-13537 ◽

Cited By ~ 40

Author(s):

Adam W. Perriman ◽

Mark J. Henderson ◽

Stephen A. Holt ◽

John W. White

Keyword(s):

Water Interface ◽

Air Water Interface ◽

The Stability ◽

Β Lactoglobulin

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Validation of the RIDASCREEN®FAST Milk Kit

Journal of AOAC International ◽

10.5740/jaoacint.15-0290 ◽

2016 ◽

Vol 99 (2) ◽

pp. 495-503 ◽

Cited By ~ 3

Author(s):

Thomas Weiss ◽

Markus Lacorn ◽

Jonathan Flannery ◽

M Joseph Benzinger ◽

Patrick Bird ◽

...

Keyword(s):

Milk Protein ◽

Incubation Temperature ◽

Sandwich Elisa ◽

Milk Proteins ◽

Cross Reactivity ◽

Significant Loss ◽

Extraction Temperature ◽

Independent Laboratory ◽

The Stability ◽

Β Lactoglobulin

Abstract The RIDASCREEN®FAST Milk test is a sandwich ELISA for the rapid quantification of milk proteins in various foods. The specific antibodies target casein and β-lactoglobulin. Samples are extracted and can then be analyzed in less than 40 min. The calibration curve covers a range from 2.5 to 67.5 mg/kg milk protein. The assay was validated with cookies, infant formula, chocolate dessert, ice cream, and sausages. All negative samples were found well below the LOQ of 2.5 mg/kg. Recoveries of the spiked samples were mostly in the range of 80–120%. The LOD of the ELISA was found below 1 mg/kg. The analysis of 39 different substances of interest revealed that no cross-reactivity above the LOQ occurred. Ruggedness testing proved that variations in incubation temperature, reagent volume, incubation time, extraction temperature, and extraction time had no significant influence. The stability at 4–8°C of three independent lots was investigated and found to exceed 18 months. Very good lot-to-lot consistency and no significant loss of the analytical capacity over the shelf life were observed. Incurred cookies and chocolate dessert samples were prepared and analyzed by an independent laboratory; mean recoveries of 94.4 and 102.2% and mean SDs of 10.9 and 6.3%, respectively, were found. For the 0 mg/kg level for both materials, all samples tested returned values of <2.5 mg/kg. Therefore, the analytical performance claims of the manufacturer were confirmed.

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