Milk protein analysis

Abstract

Summary -After a short description of bovine milk proteins, the various methods of current or potential use for detecting and determining them in dairy products are reviewed. This includes, first, the determination of total protein from nitrogen analysis, dye-binding capacity, infra-red spectrometry and amino acid analysis. The methods that allow determination of sorne milk protein fractions of interest (whole casein, whey proteins,~-Iactoglobulin) are then given. They include the Aschaffenburg-Rowland procedure, dye-binding and infra-red methodologies. A description of the various methods (electrophoresis, column chromatography, immunochemical or enzymatic tests), that can be used for detecting and individually quantitating the various caseins and whey proteins is presented. Finally, sorne applications of various analytical procedures to the analysis of different classes of dairy products are given.

Calculation of Nitrogen‐to‐Protein Conversion Factors: A Review with a Focus on Soy Protein

“…They point out the difficulty in obtaining accurate or “true” NPCF and acknowledge that researchers rely on amino acid composition to derive these factors but argue that these methods do not account for the molecular weight of the prosthetic groups (glycosylated, phosphorylated). Marriotti et al () and Ribadeau‐Dumas and Grappin, acknowledge that including the weight of prosthetic groups raises the NPCF value but they question whether it overrepresents the delivery of amino acids per se. It should be noted that the inclusion of prosthetic group weights in the NPCF calculation is only conducted by dairy protein analysts.…”

“…In the case of soybeans, the overall number of proteins contributing to total protein (Schmutz et al, ) is significantly higher than that of milk protein (Farrell Jr. et al, ); therefore, it is unlikely that using primary sequences for NPCF calculations would be practical. Also, Ribadeau‐Dumas and Grappin, noted “that experimental determination of the Kjeldahl factor on (pure) protein fractions leads to substantial discrepancies from the theoretical values obtained from amino acid sequences.”…”

Proliferation and immunoglobulin production of hybridoma cells cultured on mastitic whey

“…Total protein (TP), soluble protein (SP) and tCN contents were calculated according to the method of Ribadeau-Dumas and Grappin [29]. The pH 4.6 insoluble peptides or IP (including g-CN) part of tCN was determined with fast protein liquid chromatography (FPLC) with a Mono Q HR 5/5 anion exchange column (Pharmacia, Uppsala, Sweden) according to the method adapted by Le Roux et al [16].…”

Changes in the composition of plasma very low density lipoprotein during pregnancy and lactation in genetic lines of pigs

“…X Present address: Centro de Ciencias Experimentales y Tecnicas, Universidad San Pablo-CEU, 28668-Madrid, Spain. of the neonatal carcass is fat, compared with about 160 g/kg in humans (Pettigrew, 1981;Gurr, 1988)) but receives milk with a high fat content compared with many other terrestrial mammals (70 to 90 g/kg compared with about 40 g/kg in human milk) (Ribadeau-Dumas, 1983;Gurr, 1988). X Present address: Centro de Ciencias Experimentales y Tecnicas, Universidad San Pablo-CEU, 28668-Madrid, Spain. of the neonatal carcass is fat, compared with about 160 g/kg in humans (Pettigrew, 1981;Gurr, 1988)) but receives milk with a high fat content compared with many other terrestrial mammals (70 to 90 g/kg compared with about 40 g/kg in human milk) (Ribadeau-Dumas, 1983;Gurr, 1988).…”