A model for predicting salt equilibria in milk and mineral-enriched milks

Mekmene, Omar; Graët, Y. Le; Gaucheron, Frédéric

doi:10.1016/j.foodchem.2009.02.039

Cited by 72 publications

(66 citation statements)

References 32 publications

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“…Although no significant differences in Ca content were found in this particular study, this data is generally consistent with what has been previously reported concerning the effect of mineral addition on the Ca system in milk (Dalgleish and Parker, 1980, Dickson and Perkins, 1971, Horne, 1998. According to the previously established work, as well as work which attempts to model ionic calcium as a function of ionic strength (Mekmene et al, 2009), as ionic strength of the milk solution increases, a larger percentage of total calcium will be found in the ionic phase. Ionic-phase minerals are then able to be removed by the UF/DF processes, which should lead to an overall lower level of Ca in the final UF/DF product.…”

Section: Mineral Content Of Skim Milk Uf and Df Products On Wet Basissupporting

confidence: 93%

“…Milk contains roughly 130 mg/L Mg, and of that amount roughly 33 % is found in the colloidal phase (Fox, 1989); yet, this association may shift as minerals are added to the milk system and overall ionic strength of the milk system increases (Walstra et al, 2006). The observation that treatment level 1 had a significantly larger increase in Mg between UF and DF than treatment level 4 is generally consistent with previous observations relating an increase in ionic strength to increased solubility of milk salts (Mekmene et al, 2009). At α = 0.01, there is a statistically significant difference in the difference in K content due to process (p < 0.001).…”

Section: Mineral Content Of Skim Milk Uf and Df Products On Wet Basissupporting

confidence: 91%

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Effect of sodium chloride addition during diafiltration on the solubility of milk protein concentrate

Gualco¹

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There is considerable interest among food manufacturers to incorporate protein into food products in both developed and developing countries. Dairy proteins are excellent choices for many different applications, as they are known to have several nutritional and functional benefits. Membrane filtration techniques are often utilized as the preferred method of fractionation, due to the high throughput and continuous nature of the process. One such product produced from membrane filtration of skim milk is called milk protein concentrate. This product is valued for its high protein content, but it has historically exhibited poor solubility when reconstituted into water, which severely restricts the food applications for which it is suitable. There is some existing evidence that milk protein concentrates which contain elevated levels of sodium exhibit higher solubility upon reconstitution into water. The main objective of this thesis project was to demonstrate the effect of sodium chloride, added to diafiltration water utilized during the manufacturing process, on the solubility of milk protein concentrate.It was observed that the addition of sodium chloride into diafiltration water at levels of 50 mM, 100 mM, and 150 mM had a beneficial effect on the solubility of milk protein concentrate across a variety of reconstitution conditions. For example, when milk protein concentrate was mixed for 1 h on a stage mixer at 23 °C ± 1 °C, a significant increase (p < 0.001) in mean solubility was observed when at least 50 mM NaCl had been incorporated into DF water. The incorporation of 50 mM NaCl into DF water v significantly increased (p < 0.001) the mean solubility of milk protein concentrate from 59.81 % to between 64.34 % and 71.78 %. The addition of 100 mM NaCl significantly increased (p < 0.001) the solubility to between 88.80 % and 96.24 %, and the addition of 150 mM NaCl significantly increased (p = 0.005) the solubility to between 92.79 % and 100 %.Minerals analysis of dry powders revealed a significant increase (p < 0.001) in levels of sodium. The addition of 50 mM NaCl into DF water was associated with a significant increase (p < 0.001) in powder Na content to between 2.48 mg/g and 7.44 mg/g. The addition of 100 mM NaCl into DF water was associated with a significant increase (p = 0.002) in powder Na content to between 5.80 mg /g and 10.75 mg/g, and the addition of 150 mM NaCl into DF water was associated with a significant increase (p = 0.001) in powder Na content to between 9.57 mg/g and 14.53 mg/g. A significant difference (p < 0.001) in magnesium level was also detected. Differences in calcium content were not found to be statistically significant (p = 0.016) at α = 0.01.Preliminary observations of milk protein concentrate upon reconstitution were made using a confocal laser scanning microscopy method. This method showed evidence of possible differences in powder particle rehydration and affinity for lipid association between powder particles manufactured at different treatment levels. As the level of NaCl incorp...

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Section: Mineral Content Of Skim Milk Uf and Df Products On Wet Basissupporting

confidence: 93%

Section: Mineral Content Of Skim Milk Uf and Df Products On Wet Basissupporting

confidence: 91%

Effect of sodium chloride addition during diafiltration on the solubility of milk protein concentrate

Gualco¹

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“…A commercially available program uses a more empirical approach without explicitly allowing for the protein equilibria (Mekmene et al, 2009(Mekmene et al, , 2010. The principal environmental factors affecting these equilibria are temperature, pressure, pH, and ionic strength, and these can produce effects that are reversible, slow to reverse, or effectively irreversible.…”

Section: Environmental Effects On the Partition Of Milk Saltsmentioning

confidence: 99%

Invited review: Caseins and the casein micelle: Their biological functions, structures, and behavior in foods

Holt

Carver

Ecroyd

et al. 2013

Journal of Dairy Science

394

240

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A typical casein micelle contains thousands of casein molecules, most of which form thermodynamically stable complexes with nanoclusters of amorphous calcium phosphate. Like many other unfolded proteins, caseins have an actual or potential tendency to assemble into toxic amyloid fibrils, particularly at the high concentrations found in milk. Fibrils do not form in milk because an alternative aggregation pathway is followed that results in formation of the casein micelle. As a result of forming micelles, nutritious milk can be secreted and stored without causing either pathological calcification or amyloidosis of the mother's mammary tissue. The ability to sequester nanoclusters of amorphous calcium phosphate in a stable complex is not unique to caseins. It has been demonstrated using a number of noncasein secreted phosphoproteins and may be of general physiological importance in preventing calcification of other biofluids and soft tissues. Thus, competent noncasein phosphoproteins have similar patterns of phosphorylation and the same type of flexible, unfolded conformation as caseins. The ability to suppress amyloid fibril formation by forming an alternative amorphous aggregate is also not unique to caseins and underlies the action of molecular chaperones such as the small heat-shock proteins. The open structure of the protein matrix of casein micelles is fragile and easily perturbed by changes in its environment. Perturbations can cause the polypeptide chains to segregate into regions of greater and lesser density. As a result, the reliable determination of the native structure of casein micelles continues to be extremely challenging. The biological functions of caseins, such as their chaperone activity, are determined by their composition and flexible conformation and by how the casein polypeptide chains interact with each other. These same properties determine how caseins behave in the manufacture of many dairy products and how they can be used as functional ingredients in other foods. aBStraCtA typical casein micelle contains thousands of casein molecules, most of which form thermodynamically stable complexes with nanoclusters of amorphous calcium phosphate. Like many other unfolded proteins, caseins have an actual or potential tendency to assemble into toxic amyloid fibrils, particularly at the high concentrations found in milk. Fibrils do not form in milk because an alternative aggregation pathway is followed that results in formation of the casein micelle. As a result of forming micelles, nutritious milk can be secreted and stored without causing either pathological calcification or amyloidosis of the mother's mammary tissue. The ability to sequester nanoclusters of amorphous calcium phosphate in a stable complex is not unique to caseins. It has been demonstrated using a number of noncasein secreted phosphoproteins and may be of general physiological importance in preventing calcification of other biofluids and soft tissues. Thus, competent noncasein phosphoproteins have similar patterns of phosp...

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“…Ca is present in the casein micelle as two components: CCP and Ca directly bound to phosphoserine residues [24]. Due to different association constants of Ca for organic phosphate (P o ) and P i and to the low solubility of Ca inorganic phosphate salts, Ca in milk is present 1/3 in the soluble phase of milk, 1/6 bound to the phosphoserines and 1/2 in CCP [29]. According to Le Graët and Brulé [24], acidification to pH 5.2 as performed in [27] solubilises mainly CCP, probably as did Ca chelatants, but Odagiri and Nickerson [30] reported that EDTA could make both forms of micellar Ca diffusible, while with citrate addition only CCP becomes diffusible.…”

Section: Introductionmentioning

confidence: 99%

“…According to Le Graët and Brulé [24], acidification to pH 5.2 as performed in [27] solubilises mainly CCP, probably as did Ca chelatants, but Odagiri and Nickerson [30] reported that EDTA could make both forms of micellar Ca diffusible, while with citrate addition only CCP becomes diffusible. For example, calculations according to Mekmene et al [29] show that addition of trisodium citrate at 10 and 20 mmol·L −1 lead to a reduction in Ca as CCP of 50% and 98%, respectively, but also to a reduction in phosphoserine-bound Ca of 5% and 11%. Citrate is less efficient in Ca solubilisation than EDTA, due to weaker chelating properties [29,39].…”

Section: Introductionmentioning

confidence: 99%

Acid gelation of colloidal calcium phosphate-depleted preheated milk

Famelart

Gauvin

Pâquet

et al. 2009

Dairy Sci. Technol.

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-This study aimed at understanding the role of colloidal calcium phosphate (CCP) in acid gelation of milk. Milks were depleted in Calcium (Ca) by dialysis against milk permeate containing a cation-exchange resin. Dialysed milks were then heated (90°C-10 min) and acidgelled at 42°C with a yoghurt culture. Minerals, total and soluble protein contents, pH and optical density were measured in unheated and heated dialysed milk, together with diameters and ζ-potentials of particles. Dialysis of milk led to a dissociation of 45% total Ca and 30% total phosphorus, to an increase in sodium content and pH of milk, to lower turbidity and ξ-potential, but did not change the casein particle size. Soluble Ca and casein-bound Ca were removed from milk, CCP being removed increasingly, while Ca removed from the phosphoserine residues increased very little during the dialysis experiments. Maximal dissociation of α s1 -and α s2 -casein was 20%, while that of β-and κ-casein was 35-40% of total at the end of dialysis, and it increased after heating, especially for κ-casein. The pH value at which the milk sample begins to gel increased for low mineral depletion rates but decreased for higher depletion levels. This was due to the increase in the pH value of milk and in the κ-casein dissociation. The elastic modulus decreased in samples at the lowest depletion and then levelled off, which suggested that the phosphoserine-bound Ca played a critical role in the formation of acid gels.colloidal calcium phosphate / CCP / acid milk gel / dialysis Article published by EDP SciencesRésumé -Gélification acide de lait déplétés en phosphate de calcium et chauffés. Cette étude a pour objectif de comprendre le rôle du phosphate de calcium colloïdal (CCP) dans la gélification acide du lait. Dans ce but, les micelles de caséines ont été déplétées en CCP par dialyse de lait contre un perméat de lait contenant une résine échangeuse de cations. Les laits dialysés étaient ensuite chauffés (90°C-10 min) et gélifiés à 42°C par acidification avec une culture bactérienne de yaourt. Les minéraux, les protéines totales et solubles, le pH et la blancheur ont été mesurés dans les laits dialysés chauffés et non chauffés, ainsi que le diamètre et le potentiel ζ des particules. La dialyse a entraîné une solubilisation maximale de 45 % du calcium total et de 30 % du phosphore total, une augmentation des teneurs en sodium et du pH, une densité optique réduite des laits et de plus faibles potentiels ζ, mais n'a pas eu d'effet sur la taille des particules. Le Ca soluble et le Ca lié à la caséine diminuaient dans le lait, le CCP diminuant régulièrement, tandis que le Ca lié aux phosphosérines diminuait peu, au fil de la dialyse. La dissociation de la caséine s′élevait à 20 % (caséines α s1 et α s2 ) et 35-40 % (caséines β et κ) dans le lait en fin de dialyse et augmentait après le traitement thermique, particulièrement pour la caséine κ. Le pH de gélification augmentait pour de faibles déplétions minérales et diminuait pour des plus fortes déplétions. Ceci s′ex...

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A model for predicting salt equilibria in milk and mineral-enriched milks

Cited by 72 publications

References 32 publications

Effect of sodium chloride addition during diafiltration on the solubility of milk protein concentrate

Effect of sodium chloride addition during diafiltration on the solubility of milk protein concentrate

Invited review: Caseins and the casein micelle: Their biological functions, structures, and behavior in foods

Acid gelation of colloidal calcium phosphate-depleted preheated milk

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