| Affiliation: | Hannah Research Institute, Ayr, KA6 5HL, UK;BioSS, Hannah Research Institute, Ayr, KA6 5HL, UK;Lund University, Department of Physical Chemistry 1, POB 124, S-221 00, Lund, Sweden;Department of Dairy and Food Science, The Royal Veterinary and Agricultural University, Rolighedsvej 30, DK-1958 Frederiksberg C, Denmark;Department of Mathematics and Physics, The Royal Veterinary and Agricultural University, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark;NIZO Food Research, Postbus 20, 6710 BA, Ede, The Netherlands;INRA Laboratoire de Recherches de Technologie Laitière, 65 rue de Saint Brieuc, 35042 Rennes Cédex, France;Tecnología y Bioquímica de los Alimentos, Facultad de Veterinaria, Miguel Servet 177, 50013 Zaragoza, Spain;University of Edinburgh, Institute of Cell and Molecular Biology, Swann Building, King's Buildings, Edinburgh EH9 3JR, UK;Lab NMR, Istituto di Chimica delle Macromolecole, CNR, Via Ampère 56, 20131 Milano, Italy;Universitàdi Verona, Dipartimento Scientifico e Tecnologico, Via Strada le Grazie, 37134 Verona, Italy;Borculo Domo Ingredients, Needsweg 23, 7271 AB Borculo, PO Box 46, 7270 AA Borculo, The Netherlands;Friesland Coberco Dairy Foods Research Centre Deventer, Harderwijkerstraat 41006, 7418 BA Deventer, PO Box 87, 7400 AB, Deventer, The Netherlands;Armor Protéines S.A.S., Le Pont, Saint Brice-en-Cogles 35460, France;MD Foods Ingredients, DK-6920 Videbæk, Denmark |
| Abstract: | Summary Analytical results are given for whey powders prepared on a commercial or semi-commercial scale by three companies. Altogether, five preparations enriched in β-lactoglobulin, four whey protein isolates and a fraction enriched in α-lactalbumin were analyzed for protein composition, including %β-lactoglobulin, α-lactalbumin, bovine serum albumin, casein (glyco) macropeptide and the main triglycerides. Protein composition was determined by high pressure gel permeation and reversed phase liquid chromatography and by capillary zone electrophoresis. The extent of modification of the native β-lactoglobulin structure was also measured through the degree of lactosylation and the fraction of accessible free sulphydryl groups. One significant finding was that the calculated recovery of protein following quantitation of the chromatogram or electropherogram was seldom above 90% and occasionally below 60% of that loaded onto the column or capillary, raising doubts as to the reliability of the analytical results. Extrapolation by linear regression to 100% recovery allowed estimates to be made of the true β-lactoglobulin composition of the samples. The nine samples could be placed into three distinct groups with estimated true β-lactoglobulin weight % of 70.9 ± 1.1, 62.0 ± 3.4 and 39.5 ± 4.9. Physico-chemical properties of the group of samples are reported elsewhere (Holt et al ., 1999). |
