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H Neukom

Publications and source records attributed to H Neukom.

11 recordsLinked to original sources

Gravimetric method for the determination of insoluble and soluble dietary fibres.

The present paper describes a simple method for the determination of the insoluble and soluble dietary fibres in food. In a first step, starch and proteins are removed by enzyme treatment. The insoluble dietary fibres are determined gravimetrically after centrifugation and washing of the residue with water, ethanol, acetone and diethyl ether. The water-soluble dietary fibres are recovered from the supernatant liquid of the centrifugation by dialysis, freeze-drying, and subsequent weighing. The method has been used for the determination of dietary fibres in by-products from the industry.

Dietary Fiber↗

Formation of dityrosine cross-links in proteins by oxidation of tyrosine residues.

1. Enzymic oxidation of proteins with peroxidase and hydrogenperoxide at a basic pH value leads to an oxidative phenolic coupling of adjacent tyrosine residues forming cross-linked proteins. 2. Dityrosine (3,3'-bityrosine) was identified as the cross-link in oxidised proteins by thin-layer chromatography, amino acid analysis and fluorescence measurements. 3. Gel filtration experiments with oxidised insulin showed that the cross-linkage is predominantly intermolecular. 4. In tetranitromethane treated proteins, dityrosine could be identified after hydrolysis.

Amino Acids↗