Structure and surface properties of the serum heat-induced protein aggregates isolated from heated skim milk

Jean, Karine; Renan, Marie; Famelart, Marie-Hélène; Guyomarc’H, Fanny

doi:10.1016/j.idairyj.2005.04.001

Cited by 85 publications

(98 citation statements)

References 34 publications

(54 reference statements)

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“…A band representing the largest casein, α S2 , is present on SDS-PAGE in some of the samples, notably 1.1 and 1.4, and in 2.1 and 2.4. The qualitative compositional analyses of the soluble aggregate fractions are generally in line with previous reports [17,18,22,32]. These studies consider that the primary constituents of the aggregates are β-lactoglobulin, α-lactalbumin and κ-casein.…”

Section: Soluble Aggregate Compositionsupporting

confidence: 88%

“…Unfortunately many different techniques have been used to separate the micellar and serum phases. Centrifugation is the most common but many different conditions have been used, ranging from 175 000× g/60 min to 19 200× g/240 min [2,4,11,17,18,22,29,32,33,[35][36][37]41]. Other researchers have rejected the use of centrifugation on the basis of being too harsh and likely to cause micellar disintegration and have used treatment with rennet to precipitate the micelle fraction instead [38].…”

Section: Resultsmentioning

confidence: 99%

“…Previous studies have shown that the aggregates are chiefly comprised of the major whey proteins β-lactoglobulin and α-lactalbumin but may also contain some caseins [18,22]. Their formation is therefore likely to be linked not only to the process through which the whey proteins interact with each other, but also to the availability of caseins which are largely organized into micelles.…”

Section: Introductionmentioning

confidence: 99%

“…More recent investigations have included works by Newstead et al [26] and Darling [15]. There has also been a growing interest in the formation and structure of milk protein aggregates in heated milks [17,18,22,32,33,38,39]. These investigations have generally been directed towards understanding the importance of these aggregates on the formation of acid induced gels and although Corredig and Dalgleish [11] hinted that variation in the composition of heat induced soluble aggregates may be related to the effects of preheating, their influence on heat stability has not yet been described.…”

Section: Introductionmentioning

confidence: 99%

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Role of protein aggregation in heat-induced heat stability during milk powder manufacture

Williams

D'ath

Zisu

2008

Dairy Sci. Technol.

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-Although the inherent heat stability and the processes leading to the heat-induced coagulation of milk and reconstituted milk powders have been studied extensively, the processes that lead to heat-induced heat stability are less well established. An investigation has been undertaken into the effects of standardization with milk permeate or lactose and the heat-stabilization of milk powders. Standardized and unstandardized milk powders were produced in spring and autumn to determine seasonal effects on their heat stability. Other standardized powders were produced using a range of preheat treatments (85 • C/1800 s, 120 • C/120 s, and 140 • C/5 s) to evaluate the effects of preheat treatment and standardization on the heat stability of milk powders. Micelle size and the soluble aggregates formed during the preheat treatment were characterized by a combination of size-exclusion chromatography and SDS-PAGE. The heat stability of the powders was evaluated in a bench-scale model of retorted recombined evaporated milk manufacture. As has been generally accepted, the heat stability may be mediated by the way in which the milk responds to the preheat treatment given during milk powder manufacture. However, we have found that causing the denaturation of the whey proteins in itself, as is indicated by analytical measures such as the whey protein nitrogen index (WPNI) is not sufficient to impart heat stability. Our work suggests that milks with good heat stability are achieved by heating to give a low WPNI and a balance of moderately sized soluble aggregates and a decrease in the proportion of smaller micelles. The formation of these aggregates is influenced by the heating regime applied and varies at different times of year.heat stability / milk protein aggregation / micellar integrity Résumé -Rôle de l'agrégation des protéines dans la stabilité thermique thermo-induite au cours de la fabrication de poudre de lait. Bien que la stabilité thermique inhérente et les processus conduisant à la coagulation thermo-induite du lait et des poudres de lait reconstituées aient été largement étudiés, les processus qui conduisent à la stabilité thermique thermo-induite sont moins bien établis. Une étude a été entreprise concernant les effets de la standardisation avec du perméat de lait ou du lactose et la stabilisation thermique des poudres de lait. Des poudres de lait, standardisé et non standardisé, ont été produites au printemps et en automne pour déterminer l'effet saison sur leur stabilité thermique. D'autres poudres standardisées ont été produites en appliquant différents prétraitements thermiques (85 • C/1800 s, 120 • C/120 s et 140 • C/5 s) pour évaluer les effets du pré-traitement et de la standardisation sur la stabilité thermique des poudres de lait. La taille des micelles et les agrégats solubles formés au cours du prétraitement thermique ont été caractérisés en combinant chromatographie d'exclusion de taille et électrophorèse SDS-PAGE. La stabilité thermique des poudres était évaluée à l'aide d'un modèle simulant...

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Section: Soluble Aggregate Compositionsupporting

confidence: 88%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Role of protein aggregation in heat-induced heat stability during milk powder manufacture

Williams

D'ath

Zisu

2008

Dairy Sci. Technol.

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“…The protein composition of the initial milk samples and of their serum and colloidal phases separated by ultracentrifugation were determined by RP-HPLC as described in [16]. Briefly, the samples were diluted 5 times with denaturing buffer (7 mol·L -1 urea, 20 mmol·L -1 Bis-Tris Propane, pH 7.5, + 5 µL·mL -1 of fresh β-mercaptoethanol) then incubated for 1 h at 37 °C.…”

Section: Quantification Of Heat-induced Protein Transfers By Reversepmentioning

confidence: 99%

Effect of heat treatment at alkaline pH on the rennet coagulation properties of skim milk

Ménard

Camier

Guyomarc’H

2005

Lait

Self Cite

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-Reconstituted skim milk was heated at 90 °C for 30 s at pH values ranging from 6.6 to 8.1, stored overnight at 5 °C then renneted at pH values ranging from 6.2 to 6.6. The heat-induced disimprovement of the rennet coagulation properties of the milk (longer rennet coagulation time and lower gel firmness) were partially reduced as heat-treatment pH increased, except at pH 6.6. These properties were related to the increased heat-induced dissociation of micellar κ-casein and subsequent formation of serum, rather than micelle-bound, heat-induced whey protein/κ-casein aggregates. It was postulated that such distribution of the denatured whey protein and κ-casein slightly reduced the detrimental effects of heating on the enzymatic coagulation, as well as helped earlier destabilisation of the micelles. These results are discussed with respect to the amplitude of the effect of the heat-treatment pH, as well as the side effects of alkalinisation and heat treatment on casein dissociation.whey protein / heat treatment / rennet coagulation / pHRésumé -Effets d'un traitement thermique à pH alcalin sur l'aptitude du lait écrémé à la coagulation présure. Du lait écrémé reconstitué est traité thermiquement à 90 °C pendant 30 s à des pH variant de 6,6 à 8,1, stocké à 5 °C pendant une nuit puis emprésuré à des pH variant de 6,2 à 6,6. La perte d'aptitude à la coagulation présure des laits chauffés (temps de coagulation plus long et moindre fermeté) a été réduite pour des pH de traitement thermique croissants, sauf à pH 6,6. Ces propriétés ont été mises en relation avec un taux de dissociation accru de la caséine κ quand le pH de traitement thermique augmente, et donc une proportion accrue d'agrégats thermo-induits de protéines sériques dénaturées et de caséine κ dans la phase soluble du lait. Il est postulé que cette distribution en protéines réduit légèrement les effets rédhibitoires du traitement thermique sur la coagulation enzymatique, et accélère la déstabilisation des micelles de caséines. Ces résultats sont discutés relativement à l'amplitude de l'effet du pH de traitement thermique ainsi qu'à la dissociation alcaline ou thermo-induite des autres caséines.protéine sérique / traitement thermique / coagulation présure / pH

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Dry Milk Products

Singh

2015

Dairy Processing and Quality Assurance

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Structure and surface properties of the serum heat-induced protein aggregates isolated from heated skim milk

Cited by 85 publications

References 34 publications

Role of protein aggregation in heat-induced heat stability during milk powder manufacture

Role of protein aggregation in heat-induced heat stability during milk powder manufacture

Effect of heat treatment at alkaline pH on the rennet coagulation properties of skim milk

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