Characteristics, Production Processes and Applications of Casein

Casein, a major protein found in milk, is a vital component that constitutes up to 80% of the total protein content in bovine milk. This protein is typically divided into several types, with the most prevalent being α_S1-, α_S2-, β-, and κ-casein. Casein is well-known for forming micelles, which are essential for the structure and function of dairy products.

Types and Characteristics of Casein

Each type of casein has unique characteristics that contribute to the overall structure and function of casein proteins.

α_S1-Casein

This type of casein is characterized by its high phosphate content, which plays a significant role in stabilizing the casein micelles. α_S1-casein is crucial in maintaining the structural integrity of dairy products and influencing their textural properties.

α_S2-Casein

Another major type of casein, α_S2-casein, contributes to the structural and functional properties of casein micelles. Its presence in the micellar structure influences the stability and solubility of casein in various conditions.

β-Casein

β-casein is known for its regulatory role in the transportation of essential minerals like calcium and phosphorus in the body. It plays a critical function in facilitating the absorption and utilization of these nutrients, especially in processes related to bone health and metabolism.

κ-Casein

κ-casein is involved in the formation of stable micelles through its interactions with calcium and other components. It contributes to the unique properties of casein by influencing the gelation and coagulation processes in dairy products, affecting their texture and consistency.

Caseins from Alfa Chemistry

Catalog	Product Name
ACM9000719-1	Casein from bovine milk (Hammarsten),quality level:300
ACM9000719-10	Casein solution derived from milk
ACM9000719-11	Casein, Carbohydrate and Fatty Acid Free
ACM9000719-12	Casein, dephosphorylated from bovine milk
ACM9000719-13	Casein, high molecular weight phosphoprotein
ACM9000719-2	Casein from bovine milk (Hammarsten),quality level:400
ACM9000719-3	Casein from milk
ACM9000719-4	Casein from milk, BioReagent
ACM9000719-5	Casein from milk, BioReagent, suitable for insect cell culture
ACM9000719-6	Casein from milk, N,N-Dimethylation
ACM9000719-7	Casein from milk, suitable for manufacturing of diagnostic kits and reagents
ACM9000719-8	Casein from milk, suitable for substrate for protein kinase (after dephosphorylation)
ACM9000719-9	Casein from milk, technical grade
ACM9000719-14	α-casein dephosphorylation
ACM9000719-15	α-Casein from milk
ACM9000719-16	β-Casein from milk
ACM9000719-17	κ-Casein from milk

What Are Casein Micelles?

Casein micelles are spherical structures that are formed when casein proteins aggregate in milk. The protein part of casein micelles accounts for about 93% of its dry weight and is composed of four separate gene products (α_S1-, α_S2-, β- and κ- casein) components. The rest of the micelle solid is composed of inorganic materials, collectively known as colloidal calcium phosphate (CCP) or micellar calcium phosphate (MCP).

These micelles are essential for the solubility and stability of casein in milk, as well as for the transport of essential nutrients such as calcium and phosphorus. The size and structure of casein micelles can vary depending on factors such as pH, temperature, and the presence of other proteins or salts in the milk.

Fig 1. Various models of casein micelles. [1]

Production Processes and Applicability of Casein

The production of casein involves several processes that transform milk into a valuable protein ingredient with diverse applications across industries. The primary production processes of casein include:

Acid or Sour Casein Production

In this traditional method, milk is sour-processed by the addition of acid, usually lactic acid. The acidity causes the casein to coagulate, forming curds, which are then washed and dried to yield acid casein. This method is suitable for producing casein with specific functional properties, such as high viscosity and adhesion, and it's commonly used in the paper, textile, and adhesive industries.

Rennet or Sweet Casein Production

This method involves the use of rennet, an enzyme complex, to coagulate the casein in milk. The resulting curds are washed and dried to obtain sweet casein. Sweet casein is commonly used in food applications due to its bland flavor and versatile functional properties, such as emulsification and foaming.

Membrane Filtration

Modern production methods often utilize membrane filtration techniques to isolate casein from milk. Ultrafiltration or microfiltration processes are employed to selectively separate the casein proteins from other components in milk, resulting in a concentrated casein solution that can be further processed into various casein products.

Fractionation and Modification

Advanced processing techniques involve fractionating casein into specific components, such as α-casein and β-casein, to obtain proteins with targeted functionalities. Additionally, casein can undergo various modifications, such as hydrolysis or crosslinking, to tailor its properties for specific applications, such as in the pharmaceutical and food industries.

References

1. De Kruif, Cornelis G., et al. Advances in colloid and interface science, 2012, 171, 36-52.
2. Nayik, Gulzar Ahmad, et al. Cogent Food & Agriculture, 2024, 10(1), 2377686.

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