Search results for "beta-Lactoglobulin"
showing 10 items of 27 documents
Interactions entre la beta-lactoglobuline et les arômes : impact au niveau moléculaire
2008
Interactions between β-lactoglobulin (BLG) and aroma compounds were investigated by complementary techniques for a better knowledge of binding mechanisms between proteins and aroma compounds at a molecular scale. Two binding sites have been defined for the monomeric BLG, one internal site within the central calyx, and one external site between the calyx and the α helix. In a first step, a relation between the ligand structure and its binding behaviour was established from the study of impact of a wide range of aroma compounds on the structure of native BLG. We evidenced at least two binding behaviours as a function of the chemical class, the hydrophobicity, or the structure of the ligands. …
Polymorphisms of beta-lactoglobulin promoter region in three Sicilian goat breeds
2012
Several beta-lactoglobulin (BLG) polymorphisms have been described within the proximal promoter region and coding region of the caprine gene, although no genetic variants affecting the protein amino acid composition and/or expression level have been characterized so far. Binding sites for several transcription factors (TFs) are present in the BLG promoter region. The aims of this work were to sequence the full-length promoter region of three Sicilian goat breeds in order to identify polymorphisms, analyze the identified haplotypes, search for differences between breeds for the presence of polymorphisms in this gene region, search for putative TFs binding sites, and check if polymorphisms la…
Understanding the release and metabolism of aroma compounds using micro-volume saliva samples by ex vivo approaches
2018
International audience; This study investigated the behaviour of key aroma compounds in the presence of human saliva (200 mu L) from different individuals (n = 3) submitted or not to centrifugation (whole vs clarified saliva). HS-GC results showed that human saliva strongly decreased the release of carbonyl compounds (aldehydes and ketones). This effect was dependent on i) the structure of the aroma compounds and ii) the saliva composition. Whole saliva exerted a higher effect than clarified saliva on aroma compounds. Moreover, this effect was individual-dependent and related to the total protein content and the total antioxidant capacity of saliva. HS-SPME and LLE-GC/MS analyses revealed t…
Influence of the composition and the structure of different media on the release of aroma compounds
2004
International audience; The release of 2-nonanone and hexenol (hex-4-en-3-ol) was studied in model media with different structures and compositions: water, a gel of $\beta$-lactoglobulin, gelified or non-gelified emulsions (5.0% Miglyol, 6.9% $\beta$-lactoglobulin; the gelation was realized by heating) and milk. The aroma compounds were analyzed by gas chromatography. A strong influence of the nature of the volatile compound on its behavior towards the food matrix was observed: in the case of 2-nonanone, a hydrophobic compound (log P = 2.9) with a relatively high vapor-water partition coefficient (Kmol = 33.6), the release was greatly influenced by the composition and the structure of the m…
Relationship between beta lactoglobulin and subclinical mastitis in Valle del Belice sheep breed
2010
The objective of the following research was to determine the effect of LGB genotypes on subclinical mastitis in Valle del Belice dairy sheep. Ewes were classified as affected or not by subclinical mastitis within a lactation based on i) a positive culture in one of the test-days and ii) more than 750,000 somatic cells. Generalized linear mixed models were fitted to assess the significance of LGB genotypes on MTB and MTC. The LGB genotypes significantly affected MTB (p=0.0387), and showed a tendency on MTC (p=0.1104). Least square means showed that in the analysis for MTB, individuals with genotypes BB and AB had a higher frequency of subclinical mastitis. Moreover, the least square differen…
Determination of cow’s milk in non-bovine and mixed cheeses by capillary electrophoresis of whey proteins in acidic isoelectric buffers
2000
An improved method for the determination of cow's milk in non-bovine cheese is reported: electrophoresis of whey proteins in acidic, isoelectric buffers. Two background electrolytes (BGEs) have been tested: (i) 50 mM iminodiacetic acid (pH=isoelectric point=2.30 at 25 degrees C), 0.5% hydroxyethylcellulose, 0.1% Tween 20 and 6 M urea (apparent pH 3.1), E=300 V/cm, for the separation of alpha-lactalbumins (alpha-LAs); (ii) a BGE with the same composition, but supplemented with 10% Tween 20, E=450 V/cm, for the fractionation of beta-lactoglobulins (beta-LGs). Surfactants have a discriminating effect on the retention behaviour of the bovine alpha-LA and beta-LG proteins, owing to the different…
Interactions between aroma compounds and beta-lactoglobulin in the heat-induced molten globule state
2010
; he present study aims to elucidate the binding of small hydrophobic ligands onto the molten globule state of β-lactoglobulin (BLG). The conversion of the native BLG into a molten globule state was induced by heat treatment at acidic pH. The molten globule state was evidenced by far and near-UV circular dichroism spectra. β-Ionone and guaiacol exhibited a higher binding ability to BLG in the heat-induced molten globule state compared to unheated BLG, as assessed by protein surface hydrophobicity measurements, using 6-propionyl-2-(dimethylamino)naphthalene (PRODAN) fluorescent probe. The binding sites of the two aroma compounds were determined by 2D nuclear magnetic resonance (NMR) spectro…
The foaming properties of camel and bovine whey: The impact of pH and heat treatment
2018
International audience; he effect of heat treatment (70 degrees C or 90 degrees C for 30 min) on the foaming and interfacial properties of acid and sweet whey obtained from bovine and camel fresh milk was examined. The maximum foamability and foam stability were observed for acid whey when compared to sweet whey for both milks, with higher values for the camel whey. This behavior for acid whey was explained by the proximity of the pI of whey protein (4.9-5.2), where proteins were found to carry the lowest negative charge as confirmed by the zeta potential measurements. Interfacial properties of acid camel whey and acid bovine whey were preserved at air water interface even after a heat trea…
Peroxydation des lipides émulsionnés et transfert d'ions fer à l'interface huile / eau stabilisée par des protéines de lait : influence des résidus p…
2010
Iron incorporated into food systems induces oxidation and precipitation. The consequences are a reduced bioavailability and a modification of other food flavor. The iron chelates such as Fe-bisglycinate and Fe-EDTA represent a possibility to avoid side effects, since the iron is protected. The inertety of Fe bisglycinate and NaFe EDTA for lipid peroxidation has been verified in oil-in-water emulsion models stabilized by sodium caseinate or by β lactoglobulin through the following studies: i/ increase of primary and secondary products of oxidation, ii/ change of the properties of the oil/water interface (tension and interfacial rheology), iii/ the stability of the chelate iron (Fe-bisglycina…
Use of Catalyst in a 3D-QSAR study of the interactions between flavour compounds and beta-lactoglobulin
2003
International audience