RESEARCH ARTICLE


Relation Between αS1-Casein Content and Coagulation Properties of Milk from Swedish Dairy Goats



Monika Johansson*, 1, Madeleine Högberg2, Anders Andrén1
1 Department of Food Science, Uppsala BioCenter, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden
2 Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden


© 2015 Johansson et al.;

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: https://creativecommons.org/licenses/by/4.0/legalcode. This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Department of Food Science, Uppsala BioCenter, Swedish University of Agricultural Sciences, SE-750 07, Uppsala, Sweden; Tel: +4618672041; Fax: +4618672995; E-mail: monika.johansson@slu.se


Abstract

High frequency of Swedish Landrace goats are the carriers of a mutation, where the affected goats are not able to produce α-casein (α-CN) in the milk. As a consequence the lack of this protein is connected to lower cheese yield. The aim of this study was thus to determine the relationship between the α-CN content and coagulation properties of milk from Swedish Landrace goats. Milk samples from 62 dairy goats from two herds were analysed. As many as 44% goats showed low or no production of αS1-CN. Only 24% of the investigated goats showed high production of this protein. The coagulation properties of milk from the dairy goats were clearly influenced by the concentration of αS1-CN. The milk from low level αS1-CN animals resulted in 15% longer coagulation time and 60% weaker gels compared to the gel firmness of the high expressing group. The coagulation time was strongly associated with the pH of the milk (p<0.001), where the milk with low αS1-CN content had higher pH. Further, goat milk with low levels of αS1-CN was shown to have significantly lower total protein (p<0.05) compared to milk from high expressing αS1-CN goats.

Keywords: αS1-casein, capillary zone electrophoreses, coagulation time, gel firmness, rheology, Swedish Landrace goats.