Milk from cows of different β-casein genotypes as a source of β-casomorphin-7

Abstract

The aim of this study was to quantify β-casomorphin-7 in raw, hydrolyzed and processed milk in different stages of the cow lactation. The obtained results lead to the following conclusion: the highest amount of β-casomorphin-7 released from the hydrolyzed and processed milk is related to the β-casein A1 allele, irrespective of a lactation period. Some traces of β-casomorphin-7 in milk from cows with the β-casein A2 variant are probably a result of the acid hydrolysis of β-casein during its digestion with pepsin. It has been shown that processing of raw milk at high temperatures affects, in a slight degree, the differences between β-casomorphins-7 originating from different β-casein genotypes. The obtained results suggest a possibility to provide a new nutritional factor for milk quality based on the content of β-casomorphin-7 liberated in vivo from milk digested by a mixture of the gastrointestinal enzymes.

Keywords::

• β-casein
• β-casomorphin-7
• polymorphism
• biochemical individuality

Declaration of interest: This work has been financially supported by the University of Warmia and Mazury (Project No. 0105-0804), MNiSzW (Project No. N 312034). The first author has been awarded with an EU scholarship within the frames of the European Social Fund. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.