The effect of calcium removal from skim milk by ion exchange on the properties of the ultrafiltration retentate

Qihui Wu; Lydia Ong; George Q Chen; Swati Varshney; Eric Hanssen; Sandra E Kentish; Sally L Gras

doi:10.1016/j.foodres.2023.113305

The effect of calcium removal from skim milk by ion exchange on the properties of the ultrafiltration retentate

Food Res Int. 2023 Nov;173(Pt 1):113305. doi: 10.1016/j.foodres.2023.113305. Epub 2023 Jul 23.

Authors

Qihui Wu¹, Lydia Ong¹, George Q Chen², Swati Varshney³, Eric Hanssen⁴, Sandra E Kentish², Sally L Gras⁵

Affiliations

¹ Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia; The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria 3010, Australia.
² Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia.
³ Mass Spectrometry and Proteomics Facility, The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria 3010, Australia.
⁴ Ian Holmes Imaging Centre and ARC Centre for Cryo Electron Microscopy of Membrane Proteins, The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, 3010, Australia; Department of Biochemistry and Pharmacology, The University of Melbourne, Parkville, Victoria, 3010, Australia.
⁵ Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia; The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria 3010, Australia. Electronic address: sgras@unimelb.edu.au.

PMID: 37803619
DOI: 10.1016/j.foodres.2023.113305

Abstract

New processes are needed to produce concentrated milk feedstocks with tailored calcium content, due to the direct link between calcium concentration and final product texture and functionality. Skim milk treatment with cation exchange resin 1% (w/v) or 2% (w/v) prior to ultrafiltration to a volumetric concentration factor (VCF) of 2.5 or 5 successfully decreased the calcium concentration by 20-30% and produced concentrates with solids content at ∼22-24 g 100 g^-1 at a VCF of 5. Calcium reduction partially solubilized the casein micelles, increasing the concentration of soluble protein and individual caseins, leading to decreased turbidity but increased protein hydration and hydrophobicity. Decalcification (2% (w/v) resin treatment) reduced thermal stability, significantly decreasing the denaturation temperature of α-lactalbumin and β-lactoglobulin in the milk by ∼3 °C and ∼1 °C respectively. Filtration was also altered, reducing permeation flux and the gel concentration and increased filtration time. When combined, calcium reduction and filtration altered functional properties including soluble calcium, soluble protein and sedimentable solids, with increased milk protein hydration also contributing to increased viscosity. This study provides a route to produce calcium-reduced milk concentrates with potential for use in retentate-based dairy products with tailored functionality.

Keywords: Calcium removal; Capillary electrophoresis; Differential scanning calorimetry; Flow curve; Ion exchange; Microstructure; Milk ultrafiltration retentate.

MeSH terms

Animals
Calcium* / analysis
Calcium, Dietary
Caseins
Food Handling
Ion Exchange
Milk / chemistry
Ultrafiltration*

Substances

Calcium
Caseins
Calcium, Dietary