title: Application of a dye-binding method for the determination of available lysine in skim milk powders.
abstract: A dye-binding method using Acid Orange 12 was investigated regarding its suitability for the quantification of available lysine, as a means of monitoring the Maillard reaction in skim milk powders. The method was evaluated by analyzing a wide range of milk powders produced by three different drying methods and stored under various conditions. A pilot-scale freeze-dryer, spray-dryer and drum-dryer were used to produce skim milk powders and the samples were stored at two temperatures (20 °C and 30 °C) and two relative humidities (33% and 52%) under strictly controlled conditions. Moreover to validate the method, two protein isolates; bovine serum albumin and casein were investigated for their available lysine content. The results demonstrate the suitability of this method for measuring the available lysine in skim milk powders with good precision and high reproducibility. The relative standard deviations obtained from the 125 freeze-dried powders were 1.8%, and those from the 100 drum-dried samples were all 1.9%. The highest variation was found for the spray-dried powders, which showed relative standard deviations between 0.9% and 6.7%.
authors.affiliation: Department of Food Technology, Engineering and Nutrition, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden. Electronic address: Kataneh.aalaei@food.lth.se.
authors.forename: Kataneh
authors.initials: K
authors.lastname: Aalaei
authors.affiliation: Department of Food Technology, Engineering and Nutrition, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden.
authors.forename: Marilyn
authors.initials: M
authors.lastname: Rayner
authors.affiliation: Food for Health Science Centre, Lund University, Medicon Village, SE-223 81 Lund, Sweden.
authors.forename: Eden
authors.initials: E
authors.lastname: Tareke
authors.affiliation: Department of Food Technology, Engineering and Nutrition, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden.
authors.forename: Ingegerd
authors.initials: I
authors.lastname: Sjöholm
mesh_terms: D000818:Animals; D061353:Food Storage / Q000379:methods*; D008239:Lysine / Q000032:analysis / Q000737:chemistry*; D015416:Maillard Reaction; D008892:Milk / Q000737:chemistry*; D011208:Powders / Q000032:analysis
chemical_list: D011208:Powders; D008239:Lysine
keywords: Available lysine; Drying; Dye binding methods; Skim milk powders; Storage stability