"Curdling" of soymilk in coffee: a study of the phase behaviour of soymilk coffee mixtures

Mairi Brown, Francesca Laitano, Calum Williams, Bruce Gibson, Mark Haw, Jan Sefcik, Karen Johnston

Research output: Contribution to journalArticle

Abstract

Soymilk is often observed to “curdle” (become inhomogeneous) and then sediment in coffee, which makes it an undesirable product for consumers. This work investigates the phase behaviour (curdling) of an organic, unsweetened, long-life soymilk in instant coffee solutions for a range of coffee and soymilk concentrations, temperature and pH. The temperature vs soymilk concentration phase diagram exhibits a coexistence curve, separating a two-phase region at high temperature from a single-phase region at low temperature. The phase transformation is reversible and it is possible to recover a single phase mixture from the “curdled” mixture either by cooling the mixture or by increasing the soymilk concentration. Image analysis was used to investigate the time evolution of the phase separation and sedimentation processes. Fourier transformation of the images resulted in peaks corresponding to the growing length scale of the phase separation. The rate of growth of peak intensity over time shows a power law dependence on temperature characteristic of spinodal decomposition. However, the observed separation kinetics are not entirely straightforward to explain with common phase separation models.
LanguageEnglish
Pages462-467
Number of pages6
JournalFood Hydrocolloids
Volume95
Early online date20 Apr 2019
DOIs
Publication statusPublished - 1 Oct 2019

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coffee
Coffee
Phase behavior
Phase separation
Fourier transformation
image analysis
Temperature
phase transformations
temperature
sediments
Spinodal decomposition
phase diagrams
cooling
decomposition
Sedimentation
Image analysis
kinetics
Phase diagrams
curves
products

Keywords

  • food engineering
  • soymilk
  • curdling
  • soymilk stability

Cite this

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title = "{"}Curdling{"} of soymilk in coffee: a study of the phase behaviour of soymilk coffee mixtures",
abstract = "Soymilk is often observed to “curdle” (become inhomogeneous) and then sediment in coffee, which makes it an undesirable product for consumers. This work investigates the phase behaviour (curdling) of an organic, unsweetened, long-life soymilk in instant coffee solutions for a range of coffee and soymilk concentrations, temperature and pH. The temperature vs soymilk concentration phase diagram exhibits a coexistence curve, separating a two-phase region at high temperature from a single-phase region at low temperature. The phase transformation is reversible and it is possible to recover a single phase mixture from the “curdled” mixture either by cooling the mixture or by increasing the soymilk concentration. Image analysis was used to investigate the time evolution of the phase separation and sedimentation processes. Fourier transformation of the images resulted in peaks corresponding to the growing length scale of the phase separation. The rate of growth of peak intensity over time shows a power law dependence on temperature characteristic of spinodal decomposition. However, the observed separation kinetics are not entirely straightforward to explain with common phase separation models.",
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"Curdling" of soymilk in coffee : a study of the phase behaviour of soymilk coffee mixtures. / Brown, Mairi; Laitano, Francesca; Williams, Calum; Gibson, Bruce; Haw, Mark; Sefcik, Jan; Johnston, Karen.

In: Food Hydrocolloids, Vol. 95, 01.10.2019, p. 462-467.

Research output: Contribution to journalArticle

TY - JOUR

T1 - "Curdling" of soymilk in coffee

T2 - Food Hydrocolloids

AU - Brown, Mairi

AU - Laitano, Francesca

AU - Williams, Calum

AU - Gibson, Bruce

AU - Haw, Mark

AU - Sefcik, Jan

AU - Johnston, Karen

PY - 2019/10/1

Y1 - 2019/10/1

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AB - Soymilk is often observed to “curdle” (become inhomogeneous) and then sediment in coffee, which makes it an undesirable product for consumers. This work investigates the phase behaviour (curdling) of an organic, unsweetened, long-life soymilk in instant coffee solutions for a range of coffee and soymilk concentrations, temperature and pH. The temperature vs soymilk concentration phase diagram exhibits a coexistence curve, separating a two-phase region at high temperature from a single-phase region at low temperature. The phase transformation is reversible and it is possible to recover a single phase mixture from the “curdled” mixture either by cooling the mixture or by increasing the soymilk concentration. Image analysis was used to investigate the time evolution of the phase separation and sedimentation processes. Fourier transformation of the images resulted in peaks corresponding to the growing length scale of the phase separation. The rate of growth of peak intensity over time shows a power law dependence on temperature characteristic of spinodal decomposition. However, the observed separation kinetics are not entirely straightforward to explain with common phase separation models.

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