TY - CHAP
T1 - β-Casein type A1 and A2
AU - Juan, Bibiana
AU - Salama, Ahmed A.K.
AU - Serhan, Suha
AU - Such, Xavier
AU - Caja, Gerardo
AU - Pont, Laura
AU - Benavente, Fernando
AU - Guamis, Buenaventura
AU - Trujillo, Antonio José
N1 - Publisher Copyright:
© 2024 by Elsevier Inc. All rights reserved, including those for text and data mining, AI training, and similar technologies.
PY - 2024/1/1
Y1 - 2024/1/1
N2 - β-Casein (β-CN) is a major protein component of cow milk, and numerous genetic variants have been described, including the most common A1 and A2 types. These two genetic variants differ in terms of the inclusion of either proline in A2 β-CN or histidine in A1 β-CN at position 67 in the peptide chain. Due to the presence of histidine in the A1 variant, digestive enzymes act on it, releasing the bioactive opioid peptide β-casomorphin-7 (BCM-7), while A2 variant releases much less and probably minimal amounts of BCM-7 under normal gut conditions. Nowadays, there exists a controversial debate on the benefits of drinking milk containing A2 β-CN (A2 milk), since recent studies suggest a correlation between the consumption of milk containing A1 β-CN (A1 milk) and gastrointestinal digestive discomfort and the incidence of certain human diseases. For this reason, farmers of different zones of the world are being stimulated to select the A2 genetic variant of β-CN in their dairy cows, reducing the A1 allele frequency. From a physicochemical viewpoint, it has been demonstrated that A2 β-CN has a lower hydrophobicity and forms smaller micelles compared with A1 β-CN, modifying the technofunctional characteristics of milk. Further, recent studies have shown that the selection of a defined β-CN genotype seems to alter other milk proteins genotypes (i.e., κ-CN) and then the physicochemical and functional properties of milk. The aim of this chapter is to examine the influence of A1 and A2 β-CN genotypes on bovine milk production and composition and the impact of these protein variants on the milk technological quality and human health. The current state of the market for dairy products made with A2 milk and the analytical techniques used for their identification will also be reviewed.
AB - β-Casein (β-CN) is a major protein component of cow milk, and numerous genetic variants have been described, including the most common A1 and A2 types. These two genetic variants differ in terms of the inclusion of either proline in A2 β-CN or histidine in A1 β-CN at position 67 in the peptide chain. Due to the presence of histidine in the A1 variant, digestive enzymes act on it, releasing the bioactive opioid peptide β-casomorphin-7 (BCM-7), while A2 variant releases much less and probably minimal amounts of BCM-7 under normal gut conditions. Nowadays, there exists a controversial debate on the benefits of drinking milk containing A2 β-CN (A2 milk), since recent studies suggest a correlation between the consumption of milk containing A1 β-CN (A1 milk) and gastrointestinal digestive discomfort and the incidence of certain human diseases. For this reason, farmers of different zones of the world are being stimulated to select the A2 genetic variant of β-CN in their dairy cows, reducing the A1 allele frequency. From a physicochemical viewpoint, it has been demonstrated that A2 β-CN has a lower hydrophobicity and forms smaller micelles compared with A1 β-CN, modifying the technofunctional characteristics of milk. Further, recent studies have shown that the selection of a defined β-CN genotype seems to alter other milk proteins genotypes (i.e., κ-CN) and then the physicochemical and functional properties of milk. The aim of this chapter is to examine the influence of A1 and A2 β-CN genotypes on bovine milk production and composition and the impact of these protein variants on the milk technological quality and human health. The current state of the market for dairy products made with A2 milk and the analytical techniques used for their identification will also be reviewed.
KW - A1 and A2 genetic variants
KW - A2 milk
KW - A2 milk market
KW - analytical methods
KW - human health
KW - milk composition
KW - technofunctional properties
KW - β-Casein
KW - β-casomorphin-7
UR - http://www.scopus.com/inward/record.url?scp=85202866601&partnerID=8YFLogxK
UR - https://www.mendeley.com/catalogue/414711ec-792b-3b02-ab9d-9c272694a080/
UR - https://portalrecerca.uab.cat/en/publications/86d54e4f-fc6c-4858-b491-26a2c334a548
U2 - 10.1016/b978-0-443-15836-0.00010-x
DO - 10.1016/b978-0-443-15836-0.00010-x
M3 - Chapter
AN - SCOPUS:85202866601
SN - 9780443158360
SP - 99
EP - 121
BT - Casein: Structural Properties, Uses, Health Benefits and Nutraceutical Applications
PB - Elsevier
ER -