Investigating the effect of powder manufacturing and reconstitution on casein micelles using asymmetric flow field-flow fractionation (AF4) and transmission electron microscopy

Lie-Piang, Anouk; Leeman, Mats; Castro, Alejandra; Börjesson, Erik; Nilsson, Lars

doi:10.1016/j.foodres.2020.109939

Cited by 10 publications

(9 citation statements)

References 27 publications

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“…β-casein is known to self-assemble in solution and the components eluted in this elution time interval may be components that are at the onset of that phenomenon ( Cragnell et al., 2017 ; de Kruif et al., 2012 ). This peak seems to be wider in the reconstituted milk sample, which could point to the association of FITC-β-casein to the aggregated protein population present at the corresponding elution time in this sample ( Lie-Piang et al., 2021 ). Finally, in the elution time-range where the casein micelles are eluted ( Lie-Piang et al., 2021 ), there is also a significant FL response for both the fresh and reconstituted milk samples in which FITC-β-casein was added.…”

Section: Resultsmentioning

confidence: 95%

“…This peak seems to be wider in the reconstituted milk sample, which could point to the association of FITC-β-casein to the aggregated protein population present at the corresponding elution time in this sample ( Lie-Piang et al., 2021 ). Finally, in the elution time-range where the casein micelles are eluted ( Lie-Piang et al., 2021 ), there is also a significant FL response for both the fresh and reconstituted milk samples in which FITC-β-casein was added. Given that the FL elution profile in the range 12–40 min match very well that of casein micelles, and no particles of this size eluted in the pure reference FITC-β-casein, it seems reasonable that the added FITC-β-casein associates with the casein micelles and that the MALS and UV detector are measuring this phenomenon.…”

Section: Resultsmentioning

confidence: 95%

“…An earlier study on the macromolecular and colloidal components of reconstituted milk showed that the response of the UV and MALS detectors for the casein micelle population were not increasing proportionally with the RI response after AF4 fractionation ( Lie-Piang et al., 2021 ). Therefore, it was hypothesized that the phenomenon observed could be related to the migration of β-casein between the serum and micellar phase.…”

Section: Resultsmentioning

confidence: 99%

“…The size and structure of casein micelles were characterized with transmission electron microscopy (TEM) according to the method of Martin et al., (2007) and Lie-Piang et al. (2021) .…”

Section: Methodsmentioning

confidence: 99%

“…Asymmetrical Flow Field-Flow Fractionation (AF4) ( Wahlund et al., 2012 ; Wahlund and Giddings, 1987 ) in combination with various detectors has proven to provide detailed information about the properties of individual components in polydisperse food-related solutions and dispersions ( Nilsson, 2013 ). This method has been applied earlier to macromolecular and colloidal components in fresh milk ( Glantz et al., 2010 ; Guyomarc’h et al., 2010 ; Silva et al., 2013 ) and reconstituted skim milk ( Lie-Piang et al., 2021 ). For reconstituted milk, the authors concluded that the casein micelle population contained larger components than the casein micelle population in fresh milk.…”

Section: Introductionmentioning

confidence: 99%

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Revisiting the dynamics of proteins during milk powder hydration using asymmetric flow field-flow fractionation (AF4)

Lie-Piang

Leeman

Castro

et al. 2021

Current Research in Food Science

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The dynamics of β-casein and casein micelles in the reconstitution of skim milk were revisited in this study. β-casein migrates into casein micelles upon an increase in temperatures due to an increase in the hydrophobic effect and lower calcium-phosphate cluster solubility. This process can be reversed upon cooling. These phenomena are well known in fresh milk and are not yet clearly established for reconstituted milk powder. As milk powder is commonly used as a functional ingredient in food products, it is of interest to investigate the migration of casein micelle β-casein to and from the serum phase in reconstituted milk. This study aimed to use asymmetrical flow field flow fractionation (AF4) in combination with various detectors to revisit the dynamics of β-casein when reconstituting skim milk at different temperatures. Fluorescence-labelled β-casein was added to fresh and reconstituted skim milk and rapid transport of β-casein into the outer shell of the casein micelles could be observed already after 5 min of reconstitution at 50 °C. This process stabilized after approximately 5 h, which indicates that an equilibrium of β-casein between the serum and the micellar phase was reached. Similar results were found for fresh milk. The apparent density of the casein micelles in the skim milk samples was also found to increase during reconstitution at 50 °C. During cold reconstitution of milk powders, the migration of β-casein to the serum was not observed. The results suggest that β-casein was already present in the serum phase upon reconstitution at 6 °C. When a sample was reconstituted for 180 min at 50 °C, the migration of β-casein back into the serum was observed upon cooling the same sample to 6 °C. The size of casein micelles in reconstituted milk at 6 °C was larger compared to reconstitution at 50 °C. With AF4 and the multi-detector approach, the change in concentration and size of casein micelles can be readily investigated and the migration of β-casein can be tracked simultaneously. Therefore, the method is a valuable tool for studies of the properties and changes in various milk samples.

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Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 95%

Section: Resultsmentioning

confidence: 99%

“…The size and structure of casein micelles were characterized with transmission electron microscopy (TEM) according to the method of Martin et al., (2007) and Lie-Piang et al. (2021) .…”

Section: Methodsmentioning

confidence: 99%