Phenolic composition and antioxidant activity of aqueous infusions from Capparis spinosa L. and Crithmum maritimum L. before and after submission to a two-step in vitro digestion model.

This study investigated the phenolic composition and antioxidant activities of aqueous infusions from wild-grown caper (Capparis spinosa L.) and sea fennel (Crithmum maritimum L.) from the Dalmatia region (Croatia) before and after their submission to an in vitro digestion process. HPLC/UV-vis-DAD/ESI-MS analysis of the caper infusion identified rutin, kaempferol 3-O-rutinoside, and isorhamnetin 3-O-rutinoside as dominant flavonoids in the matrix together with a series of cinnamoylquinic acid derivatives, whereas in the sea fennel aqueous infusion chlorogenic acid (5-caffeoylquinic acid), its isomers, and higher derivatives were identified as almost the sole class of phenolics. Both infusions exhibited good and dose-dependent antioxidant activity before in vitro digestion by the DPPH method, the ß-carotene bleaching method, and copper-induced oxidation of human LDL. The amount of total phenolics (Folin-Ciocalteu assay) strongly decreased in digested samples (from 3.0 and 2.2% in caper and sea fennel infusions, respectively, to <1.0%), as did their antioxidant activity as measured by the three aforesaid methods. The results showed that the majority of phenolic compounds detected in both infusions are not stable under applied simulated gastrointestinal conditions and that the stability of these secondary metabolites strongly depends on the nature of the corresponding matrix.

Separation of a glycosylated and non-glycosylated fraction of caseinomacropeptide using different anion-exchange stationary phases.

Caseinomacropeptide (CMP), a heterogeneous group of peptides regarding the degree of glycosylation and phosphorylation, has so far not been effectively fractionated into its two major fractions: the glycosylated gCMP and the non-glycosylated aCMP. Therefore, an anion-exchange chromatography (AEC) process for the fractionation of CMP in those two fractions was developed and optimized. Furthermore, the method was applied to compare membrane adsorption chromatography (MAC) devices with classical bead-based column chromatography. It was shown that MAC devices can separate gCMP from aCMP, however, at a lower level of binding capacity and chromatographic resolution compared to classical chromatography. On the other hand, a fractionation is achieved at a four times faster separation speed.

Gram scale separation of casein proteins from whole casein on a Source 30Q anion-exchange resin column utilizing fast protein liquid chromatography (FPLC).

Casein is used as an additive in binders or paints and as such exhibits unique properties which might be based on the properties of certain subproteins in the complex whole casein mixture. Therefore, the separation of whole casein (CN) from cow milk was performed on a gram scale in order to yield sufficient amounts of the protein subfractions alpha-, beta-, and kappa-casein for further testing utilizing fast protein liquid chromatography (FPLC) and preceding enrichment in the case of kappa-casein. Construction chemical grade casein, which differs in quality from dairy grade casein, was used for separation because of our interest in the proteins responsible for plastification of cementitious systems such as mortar. The solubilized proteins were separated chromatographically via ion exchange chromatography (IEX) and the subsequently desalted protein fractions were tested for purity by isoelectric focusing (IEF).

Efficient analysis of egg yolk proteins and their thermal sensitivity using sodium dodecyl sulfate polyacrylamide gel electrophoresis under reducing and nonreducing conditions.

The multiple functional properties of egg yolk are mostly influenced by its complex protein composition. The high lipid content of egg yolk as well as the low solubility of delipidated egg yolk lipoproteins make analysis by conventional chromatographic or electrophoretic techniques a difficult task. This work describes a method to profile egg yolk proteins after delipidation with acetone using sodium dodecyl sulfate polyacrylamide gel electrophoresis on precast 8-18% T polyacrylamide gradient gels. Twenty bands were obtained for the whole egg yolk profile with molecular weights ranging between 5 and 221 kDa. The bands were identified based on their molecular weight and by comparison with isolated egg yolk subfractions. The dissociation behavior under reducing and nonreducing conditions provided additionally helpful information for identification and characterization of the yolk proteins. The method presented is very well suited for assaying the thermal sensitivity of whole yolk and its components and thus for the characterization of heat treatment processes.