Physical stability of caseinate - stabilized emulsions during heating

J.M.M. Cruijsen

    Research output: Thesisexternal PhD, WU

    Abstract

    <br/>The physical stability of caseinate stabilized emulsions was studied during heating (80- 120°C). Coagulation, coalescence and phase separation of the caseinate emulsions was studied using objective heat stability tests. The physical changes were characterized by light microscopy, particle size measurements and by determination of the solubility of coagula in various reagents. Additional information about physico-chemical changes in caseinate dispersions was obtained by determination of association of salts with caseinates, association of caseins with emulsion droplets, <sup><font size="-2">1</font></SUP>H-NMR, <sup><font size="-2">31</font></SUP>P-NMR and SDS- Page.<p>The susceptibility towards heat coagulation of caseinate emulsions was mainly determined by volume fraction of oil, decrease of pH during heating and initial Ca <sup><font size="-2">2+</font></SUP>- activity. The heat coagulation time could be related to association of calcium and magnesium and caseinate and to association of caseinate and emulsion droplets. Association of calcium and magnesium and caseinate in these conditions would diminish electrostatic repulsion between caseinate molecules, which would lead to aggregation of the caseinate. It was shown that the formation of chemical cross-links is not rate determining in heat coagulation.<p>During heating of caseinate emulsions containing malto-dextrins or a lactose/sucrose mixture, phase droplets were formed. The appearance of these phase droplets was accompanied by multi-layer formation of caseinate on the oil-droplets and a decreased stability to heating, often resulting in a highly viscous mass. Phase separation could be prevented in several ways; by using phosphates as stabilizing salt, by using maltodextrins or glucose syrups with relatively high DE values or by using soya lecithin. The effect of lecithin was only found when lecithin was added prior to homogenization. It appeared that the association of caseinate in solution or with the emulsion droplet was modified and thereby prevented phase separation.<p>Although soya lecithin proved to be a very effective stabilizer, coalescence of the emulsion droplets could be observed when the concentration exceeded a certain value or when the phosphatidylcholine fraction of soya lecithin was used. The lecithins affected the coalescence behaviour, presumably by lowering the interfacial tension and lowering the caseinate surface load, and possibly by changing the structure of the caseinate layer on the emulsion droplets.
    Original languageEnglish
    QualificationDoctor of Philosophy
    Awarding Institution
    Supervisors/Advisors
    • Walstra, P., Promotor
    • van Boekel, Tiny, Promotor
    Award date6 May 1996
    Place of PublicationDelft
    Publisher
    Print ISBNs9789056510305
    Publication statusPublished - 1996

    Fingerprint

    Emulsions
    Lecithins
    Heating
    Coagulation
    Association reactions
    Coalescence
    Phase separation
    Magnesium
    Oils
    Dextrins
    Salts
    Nuclear magnetic resonance
    Calcium
    Lactose
    Caseins
    Phosphatidylcholines
    Dispersions
    Optical microscopy
    Surface tension
    Sucrose

    Keywords

    • casein
    • dispersion
    • liquids
    • emulsions
    • milk
    • heating

    Cite this

    Cruijsen, J.M.M.. / Physical stability of caseinate - stabilized emulsions during heating. Delft : Eburon, 1996. 126 p.
    @phdthesis{0196009c1e3443f8b47b8429bfb9bd57,
    title = "Physical stability of caseinate - stabilized emulsions during heating",
    abstract = "The physical stability of caseinate stabilized emulsions was studied during heating (80- 120°C). Coagulation, coalescence and phase separation of the caseinate emulsions was studied using objective heat stability tests. The physical changes were characterized by light microscopy, particle size measurements and by determination of the solubility of coagula in various reagents. Additional information about physico-chemical changes in caseinate dispersions was obtained by determination of association of salts with caseinates, association of caseins with emulsion droplets, 1H-NMR, 31P-NMR and SDS- Page.The susceptibility towards heat coagulation of caseinate emulsions was mainly determined by volume fraction of oil, decrease of pH during heating and initial Ca 2+- activity. The heat coagulation time could be related to association of calcium and magnesium and caseinate and to association of caseinate and emulsion droplets. Association of calcium and magnesium and caseinate in these conditions would diminish electrostatic repulsion between caseinate molecules, which would lead to aggregation of the caseinate. It was shown that the formation of chemical cross-links is not rate determining in heat coagulation.During heating of caseinate emulsions containing malto-dextrins or a lactose/sucrose mixture, phase droplets were formed. The appearance of these phase droplets was accompanied by multi-layer formation of caseinate on the oil-droplets and a decreased stability to heating, often resulting in a highly viscous mass. Phase separation could be prevented in several ways; by using phosphates as stabilizing salt, by using maltodextrins or glucose syrups with relatively high DE values or by using soya lecithin. The effect of lecithin was only found when lecithin was added prior to homogenization. It appeared that the association of caseinate in solution or with the emulsion droplet was modified and thereby prevented phase separation.Although soya lecithin proved to be a very effective stabilizer, coalescence of the emulsion droplets could be observed when the concentration exceeded a certain value or when the phosphatidylcholine fraction of soya lecithin was used. The lecithins affected the coalescence behaviour, presumably by lowering the interfacial tension and lowering the caseinate surface load, and possibly by changing the structure of the caseinate layer on the emulsion droplets.",
    keywords = "case{\"i}ne, dispersie, vloeistoffen (liquids), emulsies, melk, verwarming, casein, dispersion, liquids, emulsions, milk, heating",
    author = "J.M.M. Cruijsen",
    note = "WU thesis 2078 Proefschrift Wageningen",
    year = "1996",
    language = "English",
    isbn = "9789056510305",
    publisher = "Eburon",

    }

    Cruijsen, JMM 1996, 'Physical stability of caseinate - stabilized emulsions during heating', Doctor of Philosophy, Delft.

    Physical stability of caseinate - stabilized emulsions during heating. / Cruijsen, J.M.M.

    Delft : Eburon, 1996. 126 p.

    Research output: Thesisexternal PhD, WU

    TY - THES

    T1 - Physical stability of caseinate - stabilized emulsions during heating

    AU - Cruijsen, J.M.M.

    N1 - WU thesis 2078 Proefschrift Wageningen

    PY - 1996

    Y1 - 1996

    N2 - The physical stability of caseinate stabilized emulsions was studied during heating (80- 120°C). Coagulation, coalescence and phase separation of the caseinate emulsions was studied using objective heat stability tests. The physical changes were characterized by light microscopy, particle size measurements and by determination of the solubility of coagula in various reagents. Additional information about physico-chemical changes in caseinate dispersions was obtained by determination of association of salts with caseinates, association of caseins with emulsion droplets, 1H-NMR, 31P-NMR and SDS- Page.The susceptibility towards heat coagulation of caseinate emulsions was mainly determined by volume fraction of oil, decrease of pH during heating and initial Ca 2+- activity. The heat coagulation time could be related to association of calcium and magnesium and caseinate and to association of caseinate and emulsion droplets. Association of calcium and magnesium and caseinate in these conditions would diminish electrostatic repulsion between caseinate molecules, which would lead to aggregation of the caseinate. It was shown that the formation of chemical cross-links is not rate determining in heat coagulation.During heating of caseinate emulsions containing malto-dextrins or a lactose/sucrose mixture, phase droplets were formed. The appearance of these phase droplets was accompanied by multi-layer formation of caseinate on the oil-droplets and a decreased stability to heating, often resulting in a highly viscous mass. Phase separation could be prevented in several ways; by using phosphates as stabilizing salt, by using maltodextrins or glucose syrups with relatively high DE values or by using soya lecithin. The effect of lecithin was only found when lecithin was added prior to homogenization. It appeared that the association of caseinate in solution or with the emulsion droplet was modified and thereby prevented phase separation.Although soya lecithin proved to be a very effective stabilizer, coalescence of the emulsion droplets could be observed when the concentration exceeded a certain value or when the phosphatidylcholine fraction of soya lecithin was used. The lecithins affected the coalescence behaviour, presumably by lowering the interfacial tension and lowering the caseinate surface load, and possibly by changing the structure of the caseinate layer on the emulsion droplets.

    AB - The physical stability of caseinate stabilized emulsions was studied during heating (80- 120°C). Coagulation, coalescence and phase separation of the caseinate emulsions was studied using objective heat stability tests. The physical changes were characterized by light microscopy, particle size measurements and by determination of the solubility of coagula in various reagents. Additional information about physico-chemical changes in caseinate dispersions was obtained by determination of association of salts with caseinates, association of caseins with emulsion droplets, 1H-NMR, 31P-NMR and SDS- Page.The susceptibility towards heat coagulation of caseinate emulsions was mainly determined by volume fraction of oil, decrease of pH during heating and initial Ca 2+- activity. The heat coagulation time could be related to association of calcium and magnesium and caseinate and to association of caseinate and emulsion droplets. Association of calcium and magnesium and caseinate in these conditions would diminish electrostatic repulsion between caseinate molecules, which would lead to aggregation of the caseinate. It was shown that the formation of chemical cross-links is not rate determining in heat coagulation.During heating of caseinate emulsions containing malto-dextrins or a lactose/sucrose mixture, phase droplets were formed. The appearance of these phase droplets was accompanied by multi-layer formation of caseinate on the oil-droplets and a decreased stability to heating, often resulting in a highly viscous mass. Phase separation could be prevented in several ways; by using phosphates as stabilizing salt, by using maltodextrins or glucose syrups with relatively high DE values or by using soya lecithin. The effect of lecithin was only found when lecithin was added prior to homogenization. It appeared that the association of caseinate in solution or with the emulsion droplet was modified and thereby prevented phase separation.Although soya lecithin proved to be a very effective stabilizer, coalescence of the emulsion droplets could be observed when the concentration exceeded a certain value or when the phosphatidylcholine fraction of soya lecithin was used. The lecithins affected the coalescence behaviour, presumably by lowering the interfacial tension and lowering the caseinate surface load, and possibly by changing the structure of the caseinate layer on the emulsion droplets.

    KW - caseïne

    KW - dispersie

    KW - vloeistoffen (liquids)

    KW - emulsies

    KW - melk

    KW - verwarming

    KW - casein

    KW - dispersion

    KW - liquids

    KW - emulsions

    KW - milk

    KW - heating

    M3 - external PhD, WU

    SN - 9789056510305

    PB - Eburon

    CY - Delft

    ER -