Modifizierung von Proteinen durch Reaktion mit Carbonylverbindungen

Schwenke, K. D.; Prahl, L.; Ender, Birgit Elena; Belikow, W. M.; Freimuth, U.; Besrukow, M. G.; Charatjan, S. G.; Wolnowa, A. J.

doi:10.1002/food.19750190925

Cited by 9 publications

(4 citation statements)

References 7 publications

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“…7 shows the maximum of turbidity (minimum of solubility) is shifted to lower values of pH during the reaction with DAS. This fact confirms formerly obtained results with casein in dilute solution [9]. The greatest shift (to pH 3,9 -4,2) was observed for the presence of a high percentage of DAS (0,25) and a reaction in neutral or alcaline solution (pH 7-9).…”

Section: Chemical Analysissupporting

confidence: 93%

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Chemical Modification of Proteins Part 6. Further Studies on Gelation of Casein after Modification by Dialdehyde Starch

Schwenke

Prahl

Titova

et al. 1979

Nahrung

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The physical and chemical changes in casein during the gelation owing to the chemical modification by dialdehyde starch (DAS) in 8-10% solution were studied using electron-microscopy, measuring the mechanical properties (shear deformation), turbidimetric titration, and determination of amino groups.The gelation which proceeds during a storage time of 2 weeks is accomplished by the formation of a supermolecular network structure. Depending on the conditions of modification (pH, percentage of DAS, protein concentration) a more or less dense network is formed. An increase of pH (in the range of pH 6,3-9,7) leads to an increase of gelation speed, which favours the formation of irregular network structures. The denser the network formed the smaller is the shear deformation measured by the device of TOLSTOI. During the storage of the gels the plastic component of compliance decreases to a greater amount than the elastic one. Therefore the relative amount of elastic component increases.During the reaction with DAS the maximum of turbidity of the protein (solubility minimum) shifted to lower pH owing to a blockage of positively charged groups. On the contrary to the changes measured by physical methods, this shift is complete soon after a 1 day storage. Similarly the blockage of amino groups is finished in the most cases this time too.

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Section: Chemical Analysissupporting

confidence: 93%

“…This is also in accordance with the kinetics of the reaction between DAS and charged protein groups P11. The unmodified casein shows two peaks in the turbidimetric titration curve [9]. After modification the more acidic peak occurs in the most cases as a shoulder in the range of pH 3,5 to 4,O.…”

Section: Chemical Analysismentioning

confidence: 99%

Chemical Modification of Proteins Part 6. Further Studies on Gelation of Casein after Modification by Dialdehyde Starch

Schwenke

Prahl

Titova

et al. 1979

Nahrung

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“…DAS was also used to improve the strength of spun protein fibers made from Faba bean proteins and casein (Schmandke and Hartmann 1976). Systematic studies concerning the change in chemical and physico-chemical properties of casein and plant proteins after modification by DAS were performed in our laboratory (Schwenke et al 1975(Schwenke et al , 1976(Schwenke et al , 1977. Owing to crosslinking between the polypeptide chains, casein forms thermoirreversible gels by reaction with DAS.…”

Section: Introductionmentioning

confidence: 99%

Gelation of Casein After Modification by Dialdehyde Starch‐chemical and Physical Aspects2

Schwenke

Prahl

Noack

et al. 1985

Journal of Texture Studies

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The gelation of casein after modification by dialdehyde starch (DAS) was studied by measuring its mechanical and swelling properties, the amount of sol fraction, its melting behaviour, amino acid analysis and polyacrylamide gel electrophoresis. Depending on the concentration of protein and DAS, fusible and infusible gels are formed. The transition from fusible into infusible gels takes place after increasing the amount of DAS, owing to an enhanced blockage of basic amino acid residues and crosslinking of polypeptide chains. The higher the concentration of protein, the lower is the concentration of DAS necessary for gelation. When the DAS concentration is high enough to form a pervading crosslinked network the crosslinking proceeds relatively fast and is nearly completed after one day. The correspondence of the time dependence of chemical andphysical parameters, the irreversible blocking of basic amino acids, especially lysine, the decrease of swelling and nitrogen extractability, the elastic component of creep compliance indicates that during a 7 day storage period the gels are completely crosslinked. Using a corrected Flory relation it was shown that an average of 3.5 crosslinks exist per one polypeptide chain. This number is similar to the number of blocked lysine groups of the same gels (3.6 ‐ 4.5). The melting and creep behaviour of the gels, and especially the effect of sodium do‐decyl sulphate on the creep compliance, point to the formation of a heterogeneous network which includes noncovalently connected mi‐croassociations and covalently connected polypeptide chains as structural elements.

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“…This treatment of the proteins results in desirable changes of the functional properties and in a reduction of the nutritive value (1-7). For a desirable change of the functional properties the reaction of dialdehyde starch with proteins has the same importance; but this treatment also reduces the nutritive value of proteins (8,9).…”

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confidence: 99%