Reaction Kinetics of the Denaturation of Whey Proteins in Milk

Dannenberg, F.; Keßler, H. G.

doi:10.1111/j.1365-2621.1988.tb10223.x

Cited by 392 publications

(388 citation statements)

References 19 publications

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“…Preheating milk above 70−75°C causes denaturation of the whey proteins, with the order of denaturation being: immunoglobulins > serum albumin > β-lactoglobulin A > β-lactoglobulin B > α-lactalbumin [7,17]. The extent of denaturation of the whey proteins is dependent on both the temperature and the time of heat treatment, but the kinetics of denaturation of the whey proteins are quite complex, with the reaction characteristics showing marked changes above 80−100°C.…”

Section: Protein Interactions During the Manufacture Of Smpmentioning

confidence: 99%

Controlling milk protein interactions to enhance the reconstitution properties of whole milk powders – A minireview

Singh

2009

Dairy Sci. Technol.

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-Spray-dried milk powders are widely used in recombined milk products and processed foods. The interactions of the specific components in milk, i.e. casein micelles, whey proteins and fat globules, dictate how milk will behave during processing and the functional properties of the powder in different applications. The manufacture of milk powders involves heat treatments, evaporation, homogenisation and spray drying. The major effect of heat treatment is the denaturation of whey proteins and their association with casein micelles. During evaporation, the casein micelle size increases due mainly to the aggregation of some of the micelles and increased association of the whey proteins with the micelles. During whole milk powder manufacture, there are also considerable changes in the size of fat globules and the protein composition of the milk fat globule membrane (MFGM). This modified composition and the consequent reactivity of the MFGM play a major role in determining the functionality of whole milk powders, in particular its reconstitution properties. milk powder / interaction / processing / functionality / solubilityRésumé -Contrôle des interactions des protéines laitières pour favoriser l'aptitude à la reconstitution des poudres de lait entier. Les poudres de lait séché par atomisation sont largement utilisées dans les produits laitiers recombinés et les aliments transformés. Les interactions des composants spécifiques du lait, comme les micelles de caséines, les protéines sériques et les globules gras, conditionnent le comportement du lait au cours du traitement et les propriétés fonctionnelles de la poudre dans différentes applications. La fabrication de poudres de lait implique traitements thermiques, évaporation, homogénéisation et séchage par atomisation. L'effet principal *Corresponding author (通讯作者): H.Singh@massey.ac.nz Dairy Sci. Technol. 90 (2010) 123-136

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Section: Protein Interactions During the Manufacture Of Smpmentioning

confidence: 99%

Controlling milk protein interactions to enhance the reconstitution properties of whole milk powders – A minireview

Singh

2009

Dairy Sci. Technol.

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“…According to Dannenberg & Kessler (1988), a substance, in this case water, can have only negative entropy if the degrees of freedom of the movement of translation or rotation are lost. Gibbs free energy is an amount that can be considered as a measurement of work performed by the system in the process of adsorption or desorption (Kaleemullah & Kailappan, 2007).…”

Section: Modelsmentioning

confidence: 99%

Mathematical modeling and determination of thermodynamic properties of jabuticaba peel during the drying process

Costa

Corrêa

Bustos-Vanegas

et al. 2016

Rev. bras. eng. agríc. ambient.

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A B S T R A C TJabuticaba is a fruit native of Brazil and, besides containing many nutritional qualities, it also has a good field for use in products such as flour for cakes and biscuits, juice, liqueur, jelly and others. This study aimed to model the drying kinetics and determine the thermodynamic properties of jabuticaba peel at different drying air temperatures. Ripe fruits of jabuticaba (Myrciaria jaboticaba) were collected and pulped manually. Drying was carried out in a forced-air circulation oven with a flow of 5.6 m s -1 at temperatures of 40, 50, 60 and 70 °C. Six mathematical models commonly used to represent the drying process of agricultural products were fitted to the experimental data. The Arrhenius model was used to represent the drying constant as a function of temperature. The Midilli model showed the best fit to the experimental data of drying. The drying constant increased with the increment in drying temperature and promoted an activation energy of 37.29 kJ mol -1 . Enthalpy and Gibbs free energy decreased with the increase in drying temperature, while entropy decreased and was negative.Modelagem matemática e propriedades termodinâmicas da casca da jabuticaba durante o processo de secagem R E S U M OA jabuticaba é um fruto nativo do Brasil e além de conter muitas qualidades nutricionais também possui bom campo para a utilização em subprodutos como farinhas para bolos e biscoitos, suco, licor, geleia e outros. Objetivou-se modelar a cinética de secagem e determinar as propriedades termodinâmicas de casca de jabuticaba em diferentes temperaturas do ar de secagem. Foram utilizadas jabuticabas maduras, colhidas e separadas da polpa manualmente, da espécie Myrciaria jaboticaba. A secagem foi realizada em estufa de circulação forçada de ar com velocidade de 5,6 m s -1 nas temperaturas de 40; 50; 60 e 70 °C. Seis modelos matemáticos usualmente utilizados para a representação do processo de secagem de produtos agrícolas foram ajustados aos dados experimentais. A relação do tipo Arrhenius foi utilizada para representar a constante de secagem em função da temperatura. O modelo de Midilli foi o que melhor se ajustou aos dados experimentais da secagem. A constante de secagem aumentou com o incremento da temperatura de secagem e proporcionou energia de ativação de 37,29 kJ mol -1 . A entalpia e a energia livre de Gibbs diminuíram com o aumento da temperatura de secagem; já a entropia diminuiu e foi negativa.

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“…There is a vast and somewhat confusing literature on the different chemical and physical properties of BLG, such as chemical reactivity of the free cysteine at position 121, thermal denaturation, Dannenberg & Kessler, 1988;Anema & McKenna, 1996;Hill et al, 1996!, and induces more readily the coagulation of milk at 140 8C~Rose, 1962; Feagan et al, 1972;McLean et al, 1987;van den Berg et al, 1992;Robitaille, 1995;Hill et al, 1996!-all undesirable properties for various heat treatments involved in standard milk processing~Hill et al, 1996!. Variant C is noticeably more stable than variant B to both thermal~Manderson et al, 1995thermal~Manderson et al, , 1998Hill et al, 1996!…”

Section: Functional Consequences Of Sequence Differences Of Blga and mentioning

confidence: 99%

Functional implications of structural differences between variants A and B of bovine β‐lactoglobulin

Qin

Bewley

Creamer³

et al. 1999

Protein Science

135

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The structure of the trigonal crystal form of bovine b-lactoglobulin variant B at pH 7.1 has been determined by X-ray diffraction methods at a resolution of 2.22 Å and refined to values for R and R free of 0.239 and 0.286, respectively. By comparison with the structure of the trigonal crystal form of bovine b-lactoglobulin variant A at pH 7.1, which was determined previously @Qin BY et al., 1998, Biochemistry 37:14014-14023#, the structural consequences of the sequence differences D64G and V118A of variants A and B, respectively, have been investigated. Only minor differences in the core calyx structure occur. In the vicinity of the mutation site D64G on loop CD~residues 61-67!, there are small changes in main-chain conformation, whereas the substitution V118A on b-strand H is unaccompanied by changes in the surrounding structure, thereby creating a void volume and weakened hydrophobic interactions with a consequent loss of thermal stability relative to variant A. A conformational difference is found for the loop EF, implicated in the pH-dependent conformational change known as the Tanford transition, but it is not clear whether this reflects differences intrinsic to the variants in solution or differences in crystallization.Keywords: bovine b-lactoglobulin; crystal structure; genetic variants; hydrophobic stabilization Bovine b-lactoglobulin~BLG!, the major whey protein of cow's milk at a concentration of 0.3 g0100 mL~Bell & McKenzie, 1964!, was first isolated by Palmer~1934!. Mature bovine b-lactoglobulin has 162 residues, and is a member of the lipocalin protein superfamily~Flower, 1994, 1996!. Members of this family have a distinctive eight-stranded b-barrel structure, the central cavity of which binds a variety of hydrophobic molecules~Banaszak et al., 1994!. In the case of BLG, the primary site for fatty-acid binding has recently been established crystallographically to be inside this cavity~Qin et al., 1998b; Wu et al., 1999!. The structure of BLG is now reliably known following two independent redeterminations of the structure in the triclinic~lattice X!~Brownlow et al., 1997! and orthorhombic~lattice Y! forms~Bewley et al., 1997!. The latter structure has led to our redetermination of the structure in the trigonal~lattice Z! form~Qin et al., 1998a!. In lattice Z, in contrast to lattices X and Y, the entire molecule is well defined from electron density maps.Three variants of BLG, labeled as A, B, and C, commonly occur in cow's milk. Variants A and B~BLGA and BLGB! differ at two sites: Asp64 in A is changed to Gly in B, and Val118 in A is changed to Ala in B. Variants B and C differ at one site: Gln59 in B is changed to His in C. Thus, the isoelectric points for variants A, B, and C differ slightly: pI ϭ 5.26, 5.34, and 5.33, respectively, in 0.1 M KCl at room temperature~McKenzie, 1971!. Of technological significance, bovine BLG variants have different effects on the industrial processing of milk and on the characteristics of milk products~Hill et al., 1996!. Thermal stability is in the order B ...

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Reaction Kinetics of the Denaturation of Whey Proteins in Milk

Cited by 392 publications

References 19 publications

Controlling milk protein interactions to enhance the reconstitution properties of whole milk powders – A minireview

Controlling milk protein interactions to enhance the reconstitution properties of whole milk powders – A minireview

Mathematical modeling and determination of thermodynamic properties of jabuticaba peel during the drying process

Functional implications of structural differences between variants A and B of bovine β‐lactoglobulin

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