ISBN 9783843904728

978-3-8439-0472-8, Reihe Lebensmitteltechnologie

Antonie E. Post
Fractionation of bovine casein and enrichment of functional casein peptides

146 Seiten, Dissertation Universität Hohenheim Stuttgart-Hohenheim (2011), Softcover, A5

Zusammenfassung / Abstract

For the application of techno- and bio-functional peptides in food formula, these peptides have to be available as individual peptides or fractions, which contain only a small number of peptides and have a similar functionality. By combining a highly pure protein precursor, a specifically cleaving enzyme, and an advanced separation technology, individual peptides or fractions with a small number of peptides may be achieved. The objective of this work was to produce pure β-casein, to generate functional peptides by means of enzymatic hydrolysis, and to enrich these functional target peptides. Therefore, the isolation of β-casein by means of selective precipitation was optimised on a laboratory scale in order to maximise the β-casein purity and yield. A screening was done to determine the purity and yield of β-casein fractions isolated from commercial caseinate in comparison to micellar casein. The influence of pH and temperature on the solubility of αS- and β-casein was investigated to understand the differences in β-casein yield depending on the casein raw material. β-casein isolation from micellar casein by means of selective precipitation was then transferred to a large technical scale and the micellar casein and produced β-casein were subjected to tryptic hydrolysis. The major functional peptides of the casein hydrolysates were identified using reversed-phase high-performance liquid chromatography and electrospray ionisation mass spectrometry. Target peptides were selected by means of data base search and enriched using two-stage ultrafiltration from the β-casein tryptic hydrolysate in comparison to micellar casein tryptic hydrolysate. Generating functional peptides as presented in this study can be continued by using αS- and κ-casein as precursors for functional peptides, by choosing other selectively cleaving enzymes or by adjusting the degree of hydrolysis. In addition, the separation of functional peptides from casein hydrolysates may be improved by emerging technologies such as electro membrane filtration, where an electrical field is superimposed upon pressure-driven cross-flow membrane filtration. With this approach, innovative peptide products may be available for the food industry.