Association of caseins with β-lactoglobulin influenced by temperature and calcium ions: A multi-parameter analysis

• Published in: Food hydrocolloids Vol. 137; p. 108373
• Main Authors: Mohammad-Beigi, Hossein, Wijaya, Wahyu, Madsen, Mikkel, Hayashi, Yuya, Li, Ruifen, Maria Rovers, Tijs Albert, Jæger, Tanja Christine, Buell, Alexander K., Hougaard, Anni Bygvrå, Kirkensgaard, Jacob J.K., Westh, Peter, Ipsen, Richard, Svensson, Birte
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2023
• Subjects: Aggregation propensity; Caseins; Chaperone; Colloidal stability; Milk; β-lactoglobulin; Colloidal stability; Caseins; Chaperone; Aggregation propensity; β-lactoglobulin; Milk
• ISSN: 0268-005X; 1873-7137
• DOI: 10.1016/j.foodhyd.2022.108373

Aggregation of the major whey protein in bovine milk, β-lactoglobulin (β-Lg) is strongly influenced by association with caseins (CNs). Here, by using combined differential scanning fluorimetry and dynamic light scattering, the conformational stability and aggregation propensity of β-Lg and three types of CNs (α, β and ĸCNs) as well as their mixture have been systematically evaluated at different temperatures and Ca2+ concentrations in a multi-parametric approach. While β-Lg was affected significantly through denaturation and resulting aggregation by heat treatment with little dependency on Ca2+, αCN and βCN were influenced considerably by Ca2+. Through modifying the aggregation of β-Lg, CNs showed a different chaperone-like activity among the three types which were markedly dependent on the temperature and Ca2+ concentration. The presence of CNs resulted in smaller mixed aggregates compared to pure β-Lg aggregates, mainly through interaction of CNs with unfolded β-Lg and also by influencing the process of β-Lg unfolding. This was further confirmed by small angle X-ray scattering and isothermal titration calorimetry indicating that Ca2+ enhanced the interaction between β-Lg and CNs. Our experimental approach sheds light on molecular understanding of CN- β-Lg interactions and provides insight into how micro-structural assembly of milk proteins can be modulated to enable different functionalities in milk-based products. [Display omitted] •Ca2+ and heating enhanced the aggregation of caseins and β-lactoglobulin.•Caseins showed chaperone-like activity against β-lactoglobulin aggregation.•Caseins reduced the aggregation of unfolded β-lactoglobulin in the absence of Ca2+.•Caseins reduced the size of β-lactoglobulin aggregates in the presence of Ca2+.•Caseins and unfolded β-lactoglobulin form stable aggregates.