Rennet coagulation of casein micelles and heated casein micelles: action of Ca2+ and pH

Pires, Miryam S.; Orellana, Gabriela A.; Gatti, Carlos A.

doi:10.1016/s0268-005x(99)00004-1

Cited by 18 publications

(12 citation statements)

References 19 publications

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“…This positive effect of Ca 2+ at lower concentrations has been attributed to the action of Ca 2+ on the second step of coagulation caused by the neutralization of casein micelles' negative residues (phosphoserine and carboxylic groups) by Ca 2+ and calcium-phosphate complexes [29]. The lower level of activity at higher concentrations of Ca 2+ results from a progressive saturation of negative residues of the micelles with increasing concentration of Ca 2+ in the medium [30]. Fig.…”

Section: Effect Of the Concentration Of Caclmentioning

confidence: 95%

Purification and properties of a milk-clotting enzyme produced by Bacillus amyloliquefaciens D4

Ren

Guo

et al. 2010

Korean J. Chem. Eng.

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The milk-clotting enzyme from Bacillus amyloliquefaciens D4 was purified to 17.2-fold with 20% recovery by precipitation in ammonium sulfate and ion-exchange chromatography. The molecular mass of the enzyme was 58.2 kDa as determined by SDS-PAGE, and it was proved to be a metalloprotease by EDTA inhibition. The enzyme was active in the pH range 5.5-7.0 and was inactivated completely by heating at 55 o C for 20 min. The highest level of enzyme activity was obtained at 65 o C, pH 5.5, in the presence of 25 mM CaCl 2 . The milk-clotting activity was inhibited only slightly by Na + and K + and significantly by Cu 2+ , Zn 2+ and Sn 2+ . The K m value of this enzyme was 0.471 mg/mL. The high level of milk-clotting activity coupled with a low level of thermal stability suggested that the milk-clotting enzyme from B. amyloliquefaciens D4 should be considered as a potential substitute for calf rennet.

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Section: Effect Of the Concentration Of Caclmentioning

confidence: 95%

Purification and properties of a milk-clotting enzyme produced by Bacillus amyloliquefaciens D4

Ren

Guo

et al. 2010

Korean J. Chem. Eng.

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“…Heat stability at the acidic side of the HCT/pH profile is generally recognised as an acidic coagulation [42]. As the pH of micellar casein or milk is lowered the increased protonation of protein groups decreases the net negative charge of the casein micelle [43] and the amount of Ca 2+ ions increases due to the solubilisation of colloidal calcium phosphate [9,35]. However, casein micelle stability at acidic pH is attributed to steric stabilisation by κ-casein [5].…”

Section: Effect Of Tgase On the Propertiesmentioning

confidence: 99%

Influence of transglutaminase treatment on properties of micellar casein and products made therefrom

Mounsey

O’Kennedy

Kelly

2005

Lait

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-This work investigated the effect of transglutaminase on (1) micellar casein (phosphocasein) suspensions at pH 6.7; (2) gel formation at pH 4.6; and (3) viscosity of the subsequently produced sodium caseinates. Micellar casein (25 g protein·kg -1 in simulated milk ultrafiltrate, pH 6.7) was incubated with and without 1% microbial transglutaminase (Tgase) at 40°C for 5-60 min, prior to thermal inactivation (78°C × 30 min). The particle size of micellar casein incubated with Tgase (mean between treatments of 213 nm) was not markedly different from the control micellar casein (195 nm), indicating very little inter-micellar cross-linking. Heat stability was markedly improved at pH > 6.8 following incubation with Tgase. When Tgase was not inactivated prior to acidification gels were markedly stronger. The maximum in casein hydration (pH 5.2-5.5) and tan δ (pH 5.0) were eliminated by the action of Tgase indicating a loss of casein mobility. In the absence of Tgase, a sodium caseinate suspension had a low apparent viscosity of 7.6 mPa·s (100 s -1 ) with Newtonian behaviour, low turbidity (A 600nm = 0.28 and an ethanol stability of 530 mL·L -1 ). Sodium caseinate could not be produced where the Tgase was active during the acidification step. Sodium caseinate made from micellar casein treated with Tgase (5 min) showed increased viscosity (64.6 mPa·s at 100 s -1 ), turbidity (A 600nm = 1.37) and ethanol stability (621 mL·L -1 ). With the exertion of proper control, Tgase can improve some of the functional properties of micellar casein or its sodium caseinate derivative.high viscosity / sodium caseinate / transglutaminase / milk protein Résumé -Influence de la transglutaminase sur les propriétés de la caséine micellaire et de ses produits dérivés. L'effet de la transglutaminase sur (1) des suspensions de caséine micellaire (phosphocaséine) à pH 6,7; (2) la formation de gel à pH 4,6; et (3) la viscosité du caséinate de sodium obtenu par la suite, était étudié. La caséine micellaire (25 g protéine·kg -1 dans un ultrafiltrat de lait simulé, pH 6,7) était incubée en présence ou non de 1 % de transglutaminase (Tgase) d'origine microbienne à 40 °C pendant 5-60 min, avant inactivation thermique (78 °C × 30 min). La taille des particules de caséine micellaire incubée avec la Tgase (moyenne de 213 nm entre traitements) n'était pas considérablement différente de celle du contrôle de caséine micellaire (195 nm), indiquant de très faibles liaisons inter-micellaires. La stabilité thermique était considérablement améliorée à pH > 6,8 après incubation avec la Tgase. Quand la Tgase n'était pas inactivée avant acidification, les gels étaient considérablement plus forts. Les maxima d'hydratation de la caséine (pH 5,2-5,5) et tan δ (pH 5,0) étaient éliminés par l'action de la Tgase indiquant une perte de mobilité de la caséine. En absence de Tgase, une suspension de sodium de caséinate avait une faible viscosité apparente de 7,6 mPa·s (100 s -1 ) avec un comportement Newtonien, une faible turbité (A 600nm = 0,28) et une stabilité à...

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“…Due to the inherent low ionic strength conditions prevailing in phosphocasein dispersions, stability to flocculation at processing temperatures (60-80°C) is limited [15]. Phosphocasein exhibits physico-chemical and micellar behaviour similar to milk in terms of particle size, rennet gelation [20] and acid gelation [5]. Little is available in the literature on the corresponding properties of casein re-micellised from acid casein.…”

Section: Introductionmentioning

confidence: 99%

Comparison of re-micellised casein prepared from acid casein with micellar casein prepared by membrane filtration

Mounsey

Kelly

2005

Lait

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-Re-micellised casein was prepared by adding various calcium and phosphate salts to acid casein followed by heating and dispersing in distilled water or simulated milk ultrafiltrate (SMUF). The rheological properties, solubility, particle size, ethanol stability and heat stability of the re-micellised acid casein were examined in water or SMUF and compared with micellar casein prepared by membrane filtration. Acid and rennet gelation behaviour of both micellar casein types was different in water than in SMUF. Re-micellised casein had poorer acid gelation properties than phosphocasein but formed stronger rennet gels. Re-micellised casein exhibited increased heat stability at pH ≤ 6.6 under both low and higher ionic strength conditions compared with phosphocasein. Ethanol stability was greater in SMUF than in water. Differences between re-micellised casein and phosphocasein were attributed to the inherent increased ionic strength of re-micellised casein dispersions. It was shown that insoluble acid casein could be successfully re-micellised while retaining good functionality.re-micellisation / acid casein / phosphocasein / ionic strength Résumé -Comparaison de micelles de caséine reconstituées préparées à partir de caséine acide avec des micelles de caséine obtenues par filtration sur membrane. Des micelles de caséine reconstituées étaient préparées par addition de différents sels de calcium et de phosphate à de la caséine acide, suivie d'un traitement thermique et d'une dispersion dans de l'eau distillée ou dans un ultrafiltrat de lait simulé (SMUF). Les propriétés rhéologiques, la solubilité, la taille de particules ainsi que la stabilité thermique et à l'éthanol, étaient étudiées dans de l'eau ou dans le SMUF et comparées avec celles de micelles de caséine obtenues par filtration sur membrane. Les propriétés de coagulation par acidification et par action de la présure différaient dans l'eau ou dans le SMUF. Les micelles de caséine reconstituées avaient de plus faibles propriétés de gélification acide que la phosphocaséine mais formaient des gels présure plus forts. Elles montraient une stabilité thermique accrue à pH ≤ 6,6 pour des conditions de force ionique basse et plus élevée, comparée à celle de la phosphocaséine. La stabilité à l'éthanol était plus élevée dans le SMUF que dans l'eau. Les diffé-rences entre les micelles de caséine reconstituées et la phosphocaséine ont été attribuées à l'augmentation inhérente de la force ionique dans les dispersions de micelles de caséine reconstituées. Ces résultats montrent que des caséines acides insolubles pourraient être remises sous forme de micelles tout en retenant une bonne fonctionnalité.re-micellisation / caséine acide / phosphocaséine / force ionique * Corresponding author: pkelly@moorepark.teagasc.ieArticle published by EDP Sciences and available at http://www.edpsciences.org/lait or http://dx

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Rennet coagulation of casein micelles and heated casein micelles: action of Ca2+ and pH

Cited by 18 publications

References 19 publications

Purification and properties of a milk-clotting enzyme produced by Bacillus amyloliquefaciens D4

Purification and properties of a milk-clotting enzyme produced by Bacillus amyloliquefaciens D4

Influence of transglutaminase treatment on properties of micellar casein and products made therefrom

Comparison of re-micellised casein prepared from acid casein with micellar casein prepared by membrane filtration

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