Cargando…

Effect of Temperature, Added Calcium and pH on the Equilibrium of Caseins between Micellar State and Milk Serum

Micellar casein and casein monomers in milk serum are in a dynamic equilibrium. At temperature below 15–20 °C a considerable amount of casein monomers, β-casein in particular, is released from the casein micelle into the aqueous serum phase. This study investigates the effects of added calcium and r...

Descripción completa

Detalles Bibliográficos
Autores principales: Schiffer, Simon, Scheidler, Eva, Kiefer, Tim, Kulozik, Ulrich
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2021
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8069005/
https://www.ncbi.nlm.nih.gov/pubmed/33920136
http://dx.doi.org/10.3390/foods10040822
_version_ 1783683135754469376
author Schiffer, Simon
Scheidler, Eva
Kiefer, Tim
Kulozik, Ulrich
author_facet Schiffer, Simon
Scheidler, Eva
Kiefer, Tim
Kulozik, Ulrich
author_sort Schiffer, Simon
collection PubMed
description Micellar casein and casein monomers in milk serum are in a dynamic equilibrium. At temperature below 15–20 °C a considerable amount of casein monomers, β-casein in particular, is released from the casein micelle into the aqueous serum phase. This study investigates the effects of added calcium and related variations of pH on this peculiar equilibrium in order to minimize the amount of caseins in the serum and to better understand the casein permeation during microfiltration. The pH was varied in the range of 6.3 to 7.3 and the content of calcium was increased up to 7.5 mM by adding CaCl(2). Upon equilibration, the milk was separated by ultracentrifugation and the amounts of protein in the supernatant were analyzed. It was shown that the addition of low amounts of calcium shifts the equilibrium towards the micellar casein phase and can, thus, lower the serum casein content induced at low temperatures. Relative to that, the adjustment of pH separately from the CaCl(2) addition had a minor effect on casein concentration and composition in the serum.
format Online
Article
Text
id pubmed-8069005
institution National Center for Biotechnology Information
language English
publishDate 2021
publisher MDPI
record_format MEDLINE/PubMed
spelling pubmed-80690052021-04-26 Effect of Temperature, Added Calcium and pH on the Equilibrium of Caseins between Micellar State and Milk Serum Schiffer, Simon Scheidler, Eva Kiefer, Tim Kulozik, Ulrich Foods Article Micellar casein and casein monomers in milk serum are in a dynamic equilibrium. At temperature below 15–20 °C a considerable amount of casein monomers, β-casein in particular, is released from the casein micelle into the aqueous serum phase. This study investigates the effects of added calcium and related variations of pH on this peculiar equilibrium in order to minimize the amount of caseins in the serum and to better understand the casein permeation during microfiltration. The pH was varied in the range of 6.3 to 7.3 and the content of calcium was increased up to 7.5 mM by adding CaCl(2). Upon equilibration, the milk was separated by ultracentrifugation and the amounts of protein in the supernatant were analyzed. It was shown that the addition of low amounts of calcium shifts the equilibrium towards the micellar casein phase and can, thus, lower the serum casein content induced at low temperatures. Relative to that, the adjustment of pH separately from the CaCl(2) addition had a minor effect on casein concentration and composition in the serum. MDPI 2021-04-10 /pmc/articles/PMC8069005/ /pubmed/33920136 http://dx.doi.org/10.3390/foods10040822 Text en © 2021 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Schiffer, Simon
Scheidler, Eva
Kiefer, Tim
Kulozik, Ulrich
Effect of Temperature, Added Calcium and pH on the Equilibrium of Caseins between Micellar State and Milk Serum
title Effect of Temperature, Added Calcium and pH on the Equilibrium of Caseins between Micellar State and Milk Serum
title_full Effect of Temperature, Added Calcium and pH on the Equilibrium of Caseins between Micellar State and Milk Serum
title_fullStr Effect of Temperature, Added Calcium and pH on the Equilibrium of Caseins between Micellar State and Milk Serum
title_full_unstemmed Effect of Temperature, Added Calcium and pH on the Equilibrium of Caseins between Micellar State and Milk Serum
title_short Effect of Temperature, Added Calcium and pH on the Equilibrium of Caseins between Micellar State and Milk Serum
title_sort effect of temperature, added calcium and ph on the equilibrium of caseins between micellar state and milk serum
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8069005/
https://www.ncbi.nlm.nih.gov/pubmed/33920136
http://dx.doi.org/10.3390/foods10040822
work_keys_str_mv AT schiffersimon effectoftemperatureaddedcalciumandphontheequilibriumofcaseinsbetweenmicellarstateandmilkserum
AT scheidlereva effectoftemperatureaddedcalciumandphontheequilibriumofcaseinsbetweenmicellarstateandmilkserum
AT kiefertim effectoftemperatureaddedcalciumandphontheequilibriumofcaseinsbetweenmicellarstateandmilkserum
AT kulozikulrich effectoftemperatureaddedcalciumandphontheequilibriumofcaseinsbetweenmicellarstateandmilkserum