Changes in proteins, physical stability and structure in directly heated UHT milk during storage at different temperatures

Bozena Malmgren; Ylva Ardö; Maud Langton; Annika Altskär; Maria G.E.G. Bremer; Petr Dejmek; Marie Paulsson

doi:10.1016/j.idairyj.2017.03.002

Changes in proteins, physical stability and structure in directly heated UHT milk during storage at different temperatures

Bozena Malmgren^*, Ylva Ardö, Maud Langton, Annika Altskär, Maria G.E.G. Bremer, Petr Dejmek, Marie Paulsson

^*Corresponding author for this work

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Abstract

Changes occurring in directly heated UHT milk were studied during storage at 5, 22, 30 and 40 °C. Industrially produced UHT milk samples were analysed for changes in enzymatic activity, protein modification, destabilisation of casein micelles and relocation of milk proteins in relation to sedimentation and gel formation. Sedimentation occurred at all temperatures, and the protein composition of the sediments reflected the composition of its liquid phase; however, there was no α-lactalbumin, β-lactoglobulin or κ-casein present in sediments. Tendrils composed of β-lactoglobulin and κ-casein were seen on casein micelles after UHT treatment and grew in length prior to gelation. High degrees of lactosylation of proteins and peptides were clearly correlated with the absence of gelation and long tendrils. Gelled samples showed complete hydrolysis of intact β-casein, and limited lactosylation of β-lactoglobulin and κ-casein.

Original language	English
Pages (from-to)	60-75
Journal	International Dairy Journal
Volume	71
DOIs	https://doi.org/10.1016/j.idairyj.2017.03.002
Publication status	Published - Aug 2017

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10.1016/j.idairyj.2017.03.002

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title = "Changes in proteins, physical stability and structure in directly heated UHT milk during storage at different temperatures",

abstract = "Changes occurring in directly heated UHT milk were studied during storage at 5, 22, 30 and 40 °C. Industrially produced UHT milk samples were analysed for changes in enzymatic activity, protein modification, destabilisation of casein micelles and relocation of milk proteins in relation to sedimentation and gel formation. Sedimentation occurred at all temperatures, and the protein composition of the sediments reflected the composition of its liquid phase; however, there was no α-lactalbumin, β-lactoglobulin or κ-casein present in sediments. Tendrils composed of β-lactoglobulin and κ-casein were seen on casein micelles after UHT treatment and grew in length prior to gelation. High degrees of lactosylation of proteins and peptides were clearly correlated with the absence of gelation and long tendrils. Gelled samples showed complete hydrolysis of intact β-casein, and limited lactosylation of β-lactoglobulin and κ-casein.",

author = "Bozena Malmgren and Ylva Ard{\"o} and Maud Langton and Annika Altsk{\"a}r and Bremer, {Maria G.E.G.} and Petr Dejmek and Marie Paulsson",

year = "2017",

month = aug,

doi = "10.1016/j.idairyj.2017.03.002",

language = "English",

volume = "71",

pages = "60--75",

journal = "International Dairy Journal",

issn = "0958-6946",

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TY - JOUR

T1 - Changes in proteins, physical stability and structure in directly heated UHT milk during storage at different temperatures

AU - Malmgren, Bozena

AU - Ardö, Ylva

AU - Langton, Maud

AU - Altskär, Annika

AU - Bremer, Maria G.E.G.

AU - Dejmek, Petr

AU - Paulsson, Marie

PY - 2017/8

Y1 - 2017/8

N2 - Changes occurring in directly heated UHT milk were studied during storage at 5, 22, 30 and 40 °C. Industrially produced UHT milk samples were analysed for changes in enzymatic activity, protein modification, destabilisation of casein micelles and relocation of milk proteins in relation to sedimentation and gel formation. Sedimentation occurred at all temperatures, and the protein composition of the sediments reflected the composition of its liquid phase; however, there was no α-lactalbumin, β-lactoglobulin or κ-casein present in sediments. Tendrils composed of β-lactoglobulin and κ-casein were seen on casein micelles after UHT treatment and grew in length prior to gelation. High degrees of lactosylation of proteins and peptides were clearly correlated with the absence of gelation and long tendrils. Gelled samples showed complete hydrolysis of intact β-casein, and limited lactosylation of β-lactoglobulin and κ-casein.

AB - Changes occurring in directly heated UHT milk were studied during storage at 5, 22, 30 and 40 °C. Industrially produced UHT milk samples were analysed for changes in enzymatic activity, protein modification, destabilisation of casein micelles and relocation of milk proteins in relation to sedimentation and gel formation. Sedimentation occurred at all temperatures, and the protein composition of the sediments reflected the composition of its liquid phase; however, there was no α-lactalbumin, β-lactoglobulin or κ-casein present in sediments. Tendrils composed of β-lactoglobulin and κ-casein were seen on casein micelles after UHT treatment and grew in length prior to gelation. High degrees of lactosylation of proteins and peptides were clearly correlated with the absence of gelation and long tendrils. Gelled samples showed complete hydrolysis of intact β-casein, and limited lactosylation of β-lactoglobulin and κ-casein.

U2 - 10.1016/j.idairyj.2017.03.002

DO - 10.1016/j.idairyj.2017.03.002

M3 - Article

AN - SCOPUS:85016613718

SN - 0958-6946

VL - 71

SP - 60

EP - 75

JO - International Dairy Journal

JF - International Dairy Journal

ER -

Changes in proteins, physical stability and structure in directly heated UHT milk during storage at different temperatures

Abstract

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