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Bhesh Bhandari - One of the best experts on this subject based on the ideXlab platform.

  • change in molecular structure and dynamics of Protein in Milk Protein Concentrate powder upon ageing by solid state carbon nmr
    Food Hydrocolloids, 2015
    Co-Authors: Enamul Haque, Hilton C. Deeth, Michael J. Gidley, Bhesh Bhandari, Andrew K. Whittaker
    Abstract:

    Abstract Instability of Proteins in dry form causes solubility loss of Milk Protein Concentrate (MPC) powder upon ageing. High resolution solid state NMR techniques were used to investigate the changes in molecular structure and dynamics of Proteins in MPC with varying moisture content (5.5–16.5% w/w) and storage period. The results indicate a slight higher rigidity of molecular domains of Protein molecules of non-aged MPC compared to that of the long aged (at 25 °C) MPC. It could be suggested from this observation that long-term storage at high relative humidity (RH) may reduce rigidity of the molecular domains due to interaction with water rather than short-term storage at high RH. This may indicate increased molecular mobility of backbone and side chains of Protein molecules due to plasticization during ageing which could facilitate Protein–Protein interaction and Protein denaturation.

  • kinetics of enthalpy relaxation of Milk Protein Concentrate powder upon ageing and its effect on solubility
    Food Chemistry, 2012
    Co-Authors: Enamul Haque, Hilton C. Deeth, Michael J. Gidley, Andrew K. Whittaker, Kiki Fibrianto, Bhesh Bhandari
    Abstract:

    Abstract Kinetics of enthalpy relaxation of Milk Protein Concentrate (MPC) powder upon short-term (up to 67 h) storage at 25 °C and aw 0.85, and long-term (up to 48 days) storage at 25 °C and a range of aw values (0–0.85) were studied by differential scanning calorimetry (DSC). The short-term study showed a rapid recovery of enthalpy for the first 48 h, followed by a slower steady increase with time. The non-exponential β parameter was calculated using the Kohlrausch–Williams–Watts function and found to be 0.39. Long-term storage showed that enthalpy relaxation depends on both storage period and water activity. The enthalpy value was much less for lower moisture content (mc) (aw ⩽ 0.23, mc ⩽ 5.5%) than for higher mc (aw ⩾ 0.45, mc ⩾ 8%) samples for a particular storage period. The results suggest that the presence of more water molecules, in close proximity to the Protein surface facilitates kinetic unfreezing and subsequent motion of molecular segments of Protein molecules towards thermodynamic equilibrium. Although de-ageing of stored samples did not reverse storage-induced solubility losses, the timescale of enthalpy relaxation was similar to that of solubility loss. It is suggested that enthalpy relaxation within stored samples allows structural rearrangements that are responsible for subsequent solubility decreases.

  • A proteomic approach to detect lactosylation and other chemical changes in stored Milk Protein Concentrate.
    Food Chemistry, 2011
    Co-Authors: Hilton C. Deeth, Bhesh Bhandari, Paul F. Alewood, John W. Holland
    Abstract:

    Milk Proteins undergo chemical changes such as lactosylation, deamidation and Protein cross-linking during processing and storage of Milk products. A proteomic technique combining two-dimensional gel electrophoresis and mass spectrometry was used to investigate chemical modifications to Proteins, in Milk Protein Concentrate (MPC80), during storage. Lactosylation, deamidation and Protein cross-linking were observed on 2-DE gels. They were storage temperature-, humidity- and time-dependent. Lactosylated whey Proteins were well separated on 2-DE in vertical stacks of spots. The masses of the spots varied by multiples of 324, indicating the attachment of lactose to lysine residues in the Proteins. The trypsin-digested spots of α-lactalbumin were analysed by MALDI–TOF mass spectrometry, which indicated multiple lactosylation sites. The lactose adducts on gels were quantified by image analysis, allowing development of adducts over time to be monitored. The results show that proteomics can be used for the detection and quantification of chemical modifications to Proteins in stored MPC80.

  • ageing induced solubility loss in Milk Protein Concentrate powder effect of Protein conformational modifications and interactions with water
    Journal of the Science of Food and Agriculture, 2011
    Co-Authors: Enamul Haque, Hilton C. Deeth, Michael J. Gidley, Bhesh Bhandari, Andrew K. Whittaker
    Abstract:

    BACKGROUND: Protein conformational modifications and water-Protein interactions are two major factors believed to induce instability of Protein and eventually affect the solubility of Milk Protein Concentrate (MPC) powder. To test these hypotheses, MPC was stored at different water activities (a(w) 0.0-0.85) and temperatures (25 and 45 degrees C) for up to 12 weeks. Samples were examined periodically to determine solubility, change in Protein conformation by Fourier transform infrared (FTIR) spectroscopy and water status (interaction of water with the Protein molecule/surface) by measuring the transverse relaxation time (T-2) with proton nuclear magnetic resonance (H-1 NMR).

  • Ageing‐induced solubility loss in Milk Protein Concentrate powder: effect of Protein conformational modifications and interactions with water
    Journal of the Science of Food and Agriculture, 2011
    Co-Authors: Enamul Haque, Hilton C. Deeth, Michael J. Gidley, Bhesh Bhandari, Andrew K. Whittaker
    Abstract:

    BACKGROUND: Protein conformational modifications and water-Protein interactions are two major factors believed to induce instability of Protein and eventually affect the solubility of Milk Protein Concentrate (MPC) powder. To test these hypotheses, MPC was stored at different water activities (a(w) 0.0-0.85) and temperatures (25 and 45 degrees C) for up to 12 weeks. Samples were examined periodically to determine solubility, change in Protein conformation by Fourier transform infrared (FTIR) spectroscopy and water status (interaction of water with the Protein molecule/surface) by measuring the transverse relaxation time (T-2) with proton nuclear magnetic resonance (H-1 NMR).

Andrew K. Whittaker - One of the best experts on this subject based on the ideXlab platform.

  • change in molecular structure and dynamics of Protein in Milk Protein Concentrate powder upon ageing by solid state carbon nmr
    Food Hydrocolloids, 2015
    Co-Authors: Enamul Haque, Hilton C. Deeth, Michael J. Gidley, Bhesh Bhandari, Andrew K. Whittaker
    Abstract:

    Abstract Instability of Proteins in dry form causes solubility loss of Milk Protein Concentrate (MPC) powder upon ageing. High resolution solid state NMR techniques were used to investigate the changes in molecular structure and dynamics of Proteins in MPC with varying moisture content (5.5–16.5% w/w) and storage period. The results indicate a slight higher rigidity of molecular domains of Protein molecules of non-aged MPC compared to that of the long aged (at 25 °C) MPC. It could be suggested from this observation that long-term storage at high relative humidity (RH) may reduce rigidity of the molecular domains due to interaction with water rather than short-term storage at high RH. This may indicate increased molecular mobility of backbone and side chains of Protein molecules due to plasticization during ageing which could facilitate Protein–Protein interaction and Protein denaturation.

  • kinetics of enthalpy relaxation of Milk Protein Concentrate powder upon ageing and its effect on solubility
    Food Chemistry, 2012
    Co-Authors: Enamul Haque, Hilton C. Deeth, Michael J. Gidley, Andrew K. Whittaker, Kiki Fibrianto, Bhesh Bhandari
    Abstract:

    Abstract Kinetics of enthalpy relaxation of Milk Protein Concentrate (MPC) powder upon short-term (up to 67 h) storage at 25 °C and aw 0.85, and long-term (up to 48 days) storage at 25 °C and a range of aw values (0–0.85) were studied by differential scanning calorimetry (DSC). The short-term study showed a rapid recovery of enthalpy for the first 48 h, followed by a slower steady increase with time. The non-exponential β parameter was calculated using the Kohlrausch–Williams–Watts function and found to be 0.39. Long-term storage showed that enthalpy relaxation depends on both storage period and water activity. The enthalpy value was much less for lower moisture content (mc) (aw ⩽ 0.23, mc ⩽ 5.5%) than for higher mc (aw ⩾ 0.45, mc ⩾ 8%) samples for a particular storage period. The results suggest that the presence of more water molecules, in close proximity to the Protein surface facilitates kinetic unfreezing and subsequent motion of molecular segments of Protein molecules towards thermodynamic equilibrium. Although de-ageing of stored samples did not reverse storage-induced solubility losses, the timescale of enthalpy relaxation was similar to that of solubility loss. It is suggested that enthalpy relaxation within stored samples allows structural rearrangements that are responsible for subsequent solubility decreases.

  • ageing induced solubility loss in Milk Protein Concentrate powder effect of Protein conformational modifications and interactions with water
    Journal of the Science of Food and Agriculture, 2011
    Co-Authors: Enamul Haque, Hilton C. Deeth, Michael J. Gidley, Bhesh Bhandari, Andrew K. Whittaker
    Abstract:

    BACKGROUND: Protein conformational modifications and water-Protein interactions are two major factors believed to induce instability of Protein and eventually affect the solubility of Milk Protein Concentrate (MPC) powder. To test these hypotheses, MPC was stored at different water activities (a(w) 0.0-0.85) and temperatures (25 and 45 degrees C) for up to 12 weeks. Samples were examined periodically to determine solubility, change in Protein conformation by Fourier transform infrared (FTIR) spectroscopy and water status (interaction of water with the Protein molecule/surface) by measuring the transverse relaxation time (T-2) with proton nuclear magnetic resonance (H-1 NMR).

  • Ageing‐induced solubility loss in Milk Protein Concentrate powder: effect of Protein conformational modifications and interactions with water
    Journal of the Science of Food and Agriculture, 2011
    Co-Authors: Enamul Haque, Hilton C. Deeth, Michael J. Gidley, Bhesh Bhandari, Andrew K. Whittaker
    Abstract:

    BACKGROUND: Protein conformational modifications and water-Protein interactions are two major factors believed to induce instability of Protein and eventually affect the solubility of Milk Protein Concentrate (MPC) powder. To test these hypotheses, MPC was stored at different water activities (a(w) 0.0-0.85) and temperatures (25 and 45 degrees C) for up to 12 weeks. Samples were examined periodically to determine solubility, change in Protein conformation by Fourier transform infrared (FTIR) spectroscopy and water status (interaction of water with the Protein molecule/surface) by measuring the transverse relaxation time (T-2) with proton nuclear magnetic resonance (H-1 NMR).

  • investigation of the microstructure of Milk Protein Concentrate powders during rehydration alterations during storage
    Journal of Dairy Science, 2010
    Co-Authors: Arnaud Mimouni, Hilton C. Deeth, Michael J. Gidley, Andrew K. Whittaker, Bhesh Bhandari
    Abstract:

    The aim of this work was to use scanning electron microscopy to investigate the microstructure of rehydrated Milk Protein Concentrate powder (MPC) particles. A sample preparation method for scanning electron microscopy analysis of rehydrated MPC particles is described and used to characterize the time course of dissolution and the effects of prior storage on the dissolution process. The results show that a combination of different types of interactions (e.g., bridges, direct contact) between casein micelles results in a porous, gel-like structure that restrains the dispersion of individual micelles into the surrounding liquid phase without preventing water penetration and solubilization of nonmicellar components. During storage of the powder, increased interactions occur between and within micelles, leading to compaction of micelles and the formation of a monolayer skin of casein micelles packed close together, the combination of which are proposed to be responsible for the slow dissolution of stored MPC powders.

Hilton C. Deeth - One of the best experts on this subject based on the ideXlab platform.

  • change in molecular structure and dynamics of Protein in Milk Protein Concentrate powder upon ageing by solid state carbon nmr
    Food Hydrocolloids, 2015
    Co-Authors: Enamul Haque, Hilton C. Deeth, Michael J. Gidley, Bhesh Bhandari, Andrew K. Whittaker
    Abstract:

    Abstract Instability of Proteins in dry form causes solubility loss of Milk Protein Concentrate (MPC) powder upon ageing. High resolution solid state NMR techniques were used to investigate the changes in molecular structure and dynamics of Proteins in MPC with varying moisture content (5.5–16.5% w/w) and storage period. The results indicate a slight higher rigidity of molecular domains of Protein molecules of non-aged MPC compared to that of the long aged (at 25 °C) MPC. It could be suggested from this observation that long-term storage at high relative humidity (RH) may reduce rigidity of the molecular domains due to interaction with water rather than short-term storage at high RH. This may indicate increased molecular mobility of backbone and side chains of Protein molecules due to plasticization during ageing which could facilitate Protein–Protein interaction and Protein denaturation.

  • kinetics of enthalpy relaxation of Milk Protein Concentrate powder upon ageing and its effect on solubility
    Food Chemistry, 2012
    Co-Authors: Enamul Haque, Hilton C. Deeth, Michael J. Gidley, Andrew K. Whittaker, Kiki Fibrianto, Bhesh Bhandari
    Abstract:

    Abstract Kinetics of enthalpy relaxation of Milk Protein Concentrate (MPC) powder upon short-term (up to 67 h) storage at 25 °C and aw 0.85, and long-term (up to 48 days) storage at 25 °C and a range of aw values (0–0.85) were studied by differential scanning calorimetry (DSC). The short-term study showed a rapid recovery of enthalpy for the first 48 h, followed by a slower steady increase with time. The non-exponential β parameter was calculated using the Kohlrausch–Williams–Watts function and found to be 0.39. Long-term storage showed that enthalpy relaxation depends on both storage period and water activity. The enthalpy value was much less for lower moisture content (mc) (aw ⩽ 0.23, mc ⩽ 5.5%) than for higher mc (aw ⩾ 0.45, mc ⩾ 8%) samples for a particular storage period. The results suggest that the presence of more water molecules, in close proximity to the Protein surface facilitates kinetic unfreezing and subsequent motion of molecular segments of Protein molecules towards thermodynamic equilibrium. Although de-ageing of stored samples did not reverse storage-induced solubility losses, the timescale of enthalpy relaxation was similar to that of solubility loss. It is suggested that enthalpy relaxation within stored samples allows structural rearrangements that are responsible for subsequent solubility decreases.

  • A proteomic approach to detect lactosylation and other chemical changes in stored Milk Protein Concentrate.
    Food Chemistry, 2011
    Co-Authors: Hilton C. Deeth, Bhesh Bhandari, Paul F. Alewood, John W. Holland
    Abstract:

    Milk Proteins undergo chemical changes such as lactosylation, deamidation and Protein cross-linking during processing and storage of Milk products. A proteomic technique combining two-dimensional gel electrophoresis and mass spectrometry was used to investigate chemical modifications to Proteins, in Milk Protein Concentrate (MPC80), during storage. Lactosylation, deamidation and Protein cross-linking were observed on 2-DE gels. They were storage temperature-, humidity- and time-dependent. Lactosylated whey Proteins were well separated on 2-DE in vertical stacks of spots. The masses of the spots varied by multiples of 324, indicating the attachment of lactose to lysine residues in the Proteins. The trypsin-digested spots of α-lactalbumin were analysed by MALDI–TOF mass spectrometry, which indicated multiple lactosylation sites. The lactose adducts on gels were quantified by image analysis, allowing development of adducts over time to be monitored. The results show that proteomics can be used for the detection and quantification of chemical modifications to Proteins in stored MPC80.

  • ageing induced solubility loss in Milk Protein Concentrate powder effect of Protein conformational modifications and interactions with water
    Journal of the Science of Food and Agriculture, 2011
    Co-Authors: Enamul Haque, Hilton C. Deeth, Michael J. Gidley, Bhesh Bhandari, Andrew K. Whittaker
    Abstract:

    BACKGROUND: Protein conformational modifications and water-Protein interactions are two major factors believed to induce instability of Protein and eventually affect the solubility of Milk Protein Concentrate (MPC) powder. To test these hypotheses, MPC was stored at different water activities (a(w) 0.0-0.85) and temperatures (25 and 45 degrees C) for up to 12 weeks. Samples were examined periodically to determine solubility, change in Protein conformation by Fourier transform infrared (FTIR) spectroscopy and water status (interaction of water with the Protein molecule/surface) by measuring the transverse relaxation time (T-2) with proton nuclear magnetic resonance (H-1 NMR).

  • Ageing‐induced solubility loss in Milk Protein Concentrate powder: effect of Protein conformational modifications and interactions with water
    Journal of the Science of Food and Agriculture, 2011
    Co-Authors: Enamul Haque, Hilton C. Deeth, Michael J. Gidley, Bhesh Bhandari, Andrew K. Whittaker
    Abstract:

    BACKGROUND: Protein conformational modifications and water-Protein interactions are two major factors believed to induce instability of Protein and eventually affect the solubility of Milk Protein Concentrate (MPC) powder. To test these hypotheses, MPC was stored at different water activities (a(w) 0.0-0.85) and temperatures (25 and 45 degrees C) for up to 12 weeks. Samples were examined periodically to determine solubility, change in Protein conformation by Fourier transform infrared (FTIR) spectroscopy and water status (interaction of water with the Protein molecule/surface) by measuring the transverse relaxation time (T-2) with proton nuclear magnetic resonance (H-1 NMR).

Y. C. Liang - One of the best experts on this subject based on the ideXlab platform.

  • effect of sugar type and concentration on the heat coagulation of oil in water emulsions stabilized by Milk Protein Concentrate
    Food Hydrocolloids, 2014
    Co-Authors: Lara Matiamerino, Graeme Gillies, Y. C. Liang, Aiqian Ye, H A Patel, Matt Golding
    Abstract:

    The influence of various sugars, on the heat stability of a Milk-Protein-Concentrate (MPC)-stabilized emulsion (10% w/w Protein, 10% w/w oil) was studied. Regardless of concentration, the addition of sugars during emulsification slightly increased the droplet diameter except the addition of 20–30% w/w maltodextrin significantly (p < 0.05) decreased the droplet diameter and was attributed to the larger change in disperse/continuous phase viscosity ratio. Generally, the addition of sugar reduced the heat coagulation time (HCT) determined at 140 °C. The increased concentration of glucose, maltose, sucrose, trehalose shifted the pH at heat stability maximum towards more acidic values whereas the increased concentration of maltodextrin shifted the pH at heat stability maximum towards more alkaline values. The extent of destabilization also varied between sugars, with trehalose being particularly effective in retaining the original heat stability of the MPC-stabilized emulsions. Reducing sugars (glucose, maltose, maltodextrin) decreased the heat stability maximum more significantly than non-reducing sugars (sucrose and trehalose). Particle size, microstructure, and rheological measurements showed good correlations with the heat stability. Several factors, including free calcium ion level, volume fraction of the continuous phase Protein and solvent quality, will also affect the heat stability of MPC-stabilized emulsions with added sugars.

  • Effect of sugar type and concentration on the heat coagulation of oil-in-water emulsions stabilized by Milk-Protein-Concentrate
    Food Hydrocolloids, 2014
    Co-Authors: Y. C. Liang, Graeme Gillies, Aiqian Ye, Lara Matia-merino, H A Patel, Matt Golding
    Abstract:

    The influence of various sugars, on the heat stability of a Milk-Protein-Concentrate (MPC)-stabilized emulsion (10% w/w Protein, 10% w/w oil) was studied. Regardless of concentration, the addition of sugars during emulsification slightly increased the droplet diameter except the addition of 20–30% w/w maltodextrin significantly (p 

Renata Golin Bueno Costa - One of the best experts on this subject based on the ideXlab platform.