Aspects of the chemistry of milk protein films formed on stainless steel
type: CreativeWork
description: The literature on the properties of stainless steel surfaces, the physico-chemical properties of milk and the surface chemistry of proteins was reviewed to gain an insight into the formation, of protein-mineral films (“milkstone”) on the contact surfaces of dairy milk lines. Protein adsorption processes were considered fundamental to the formation of such deposits. Standard methods of protein separation and purification were employed to obtain purified αₛ₁, β, and K-casein. Radiochemical methods provided a convenient means of studying protein adsorption on to low surface area systems. Of the various methods for labelling proteins, radioiodination by a slightly modified version of Hunter and Greenwood Chloramine T method proved to be the most satisfactory. By this method, stable labelled milk proteins of high specific activity containing not more than one iodine atom per protein molecule and having properties that could not be distinguished from those of unlabelled proteins were prepared. In the course of the work several further aspects of the iodination reaction and the reactions of iodine species with milk components were investigated. Iodination efficiencies were found to be sensitive to the storage time of the radioactive iodine stock solutions (supplied free of reducing agent at pH 8-11). The drop in iodination efficiency was correlated with an increase in the concentration of oxidised iodine species in the radioactive stock solutions. Studies of the iodination of whole milk showed that with the exception of K-casein, the tyrosyl residues of all proteins in milk were iodinated with approximately the same iodination efficiency. The iodination efficiencies of K-casein tyrosyls were significantly lower. A theoretical examination of the effect of the hydrophobicity of the molecular environment on tyrosyl iodination efficiency, indicated the likelihood that the affect observed was due to the incorporation of the K-casein in inaccessible regions of the micelle rather…
abstract: The literature on the properties of stainless steel surfaces, the physico-chemical properties of milk and the surface chemistry of proteins was reviewed to gain an insight into the formation, of protein-mineral films (“milkstone”) on the contact surfaces of dairy milk lines. Protein adsorption processes were considered fundamental to the formation of such deposits. Standard methods of protein separation and purification were employed to obtain purified αₛ₁, β, and K-casein. Radiochemical methods provided a convenient means of studying protein adsorption on to low surface area systems. Of the various methods for labelling proteins, radioiodination by a slightly modified version of Hunter and Greenwood Chloramine T method proved to be the most satisfactory. By this method, stable labelled milk proteins of high specific activity containing not more than one iodine atom per protein molecule and having properties that could not be distinguished from those of unlabelled proteins were prepared. In the course of the work several further aspects of the iodination reaction and the reactions of iodine species with milk components were investigated. Iodination efficiencies were found to be sensitive to the storage time of the radioactive iodine stock solutions (supplied free of reducing agent at pH 8-11). The drop in iodination efficiency was correlated with an increase in the concentration of oxidised iodine species in the radioactive stock solutions. Studies of the iodination of whole milk showed that with the exception of K-casein, the tyrosyl residues of all proteins in milk were iodinated with approximately the same iodination efficiency. The iodination efficiencies of K-casein tyrosyls were significantly lower. A theoretical examination of the effect of the hydrophobicity of the molecular environment on tyrosyl iodination efficiency, indicated the likelihood that the affect observed was due to the incorporation of the K-casein in inaccessible regions of the micelle rather…
author: Nisbet, Trevor John
license: https://researchcommons.waikato.ac.nz/bitstreams/8167fed5-2dc2-40f7-b2d9-8c384b93391c/download
date published: 1979
date modified: 2026-07-24T05:57:15Z
provider: University Waikato
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: The University of Waikato