ISBN 978-3-8439-5502-7

978-3-8439-5502-7, Reihe Lebensmitteltechnologie

Thomas Schubert
Technical extraction of beta- , alphaS- and kappa-casein from bovine milk

161 Seiten, Dissertation Universität Hohenheim Stuttgart-Hohenheim (2024), Softcover, A5

Zusammenfassung / Abstract

Caseins and their individual fractions find wide use in the food application due to their techno-functional characteristics. Ensuring a consistent supply of these raw materials requires a process to isolate casein fractions efficiently. Substantial advancements were made in obtaining food-grade β-casein. For an economically sustainable production, the yield of β-casein needs to be increased, while also making effective use of the αS-casein and κ-casein fractions.

The hypothesis posits that, it is possible to obtain individual fractions from micellar casein by exploiting properties, such as hydrophobicity, pH- ,calcium- , and temperature sensitivity, using a combination of different separation methods.

A technical-scale process was devised, involving the use of selective precipitation and separation via decanter centrifuge, which offers several advantages: (i) a high operational capacity on a continuous basis, (ii) adaptability to operational parameters, and (iii) an active transport system for the solid phase to prevent blockages. Achieving high yields for the precipitated fractions was typically favored by using low to moderate feed rates, medium to high centrifugal force, low to moderate differential speeds, and a high pond depth. This resulted in yields up to 97.5 % for separation steps involving high total solid feeds and up to 47.3 % for those involving low total solid feeds, yielding a highly purified combined αS+β-casein fraction (> 95 %) and significantly enriched κ-casein (55.3 %). A filtration process was designed to generate a β-casein-reduced micellar casein. This approach resulted in a β-casein-reduced micellar concentrate, while preserving a native and highly pure β-casein fraction (> 90 %). Through further process optimization the reduction of β-casein in the micellar casein concentrate was increased, allowing for the isolation of a κ-casein fraction with a purity of 70 % through selective precipitation, and separation via decanter centrifuge.