title: Assessment of heat treatment of dairy products by MALDI-TOF-MS.
abstract: The formation of the Amadori product from lactose (protein lactosylation) is a major parameter to evaluate the quality of processed milk. Here, MALDI-TOF-MS was used for the relative quantification of lactose-adducts in heated milk. Milk was heated at a temperature of 70, 80, and 100 degrees C between 0 and 300 min, diluted, and subjected directly to MALDI-TOF-MS. The lactosylation rate of alpha-lactalbumin increased with increasing reaction temperature and time. The results correlated well with established markers for heat treatment of milk (concentration of total soluble protein, soluble alpha-lactalbumin and beta-lactoglobulin at pH 4.6, and fluorescence of advanced Maillard products and soluble tryptophan index; r=0.969-0.997). The method was also applied to examine commercially available dairy products. In severely heated products, protein pre-purification by immobilized metal affinity chromatography improved spectra quality. Relative quantification of protein lactosylation by MALDI-TOF-MS proved to be a very fast and reliable method to monitor early Maillard reaction during milk processing.
authors.affiliation: Department of Chemistry and Pharmacy, Emil-Fischer-Center, University of Erlangen-Nuremberg, Germany.
authors.forename: Jasmin
authors.initials: J
authors.lastname: Meltretter
authors.forename: Inès
authors.initials: I
authors.lastname: Birlouez-Aragon
authors.forename: Cord-Michael
authors.initials: CM
authors.lastname: Becker
authors.forename: Monika
authors.initials: M
authors.lastname: Pischetsrieder
mesh_terms: D053000:Analytic Sample Preparation Methods; D000818:Animals; D002846:Chromatography, Affinity; D003611:Dairy Products / Q000032:analysis*; D005511:Food Handling / Q000379:methods*; D006031:Glycosylation; D006358:Hot Temperature; D006801:Humans; D007223:Infant; D041943:Infant Formula / Q000737:chemistry; D007782:Lactoglobulins / Q000737:chemistry; D007785:Lactose / Q000737:chemistry; D015416:Maillard Reaction; D008832:Microchemistry / Q000379:methods; D008892:Milk / Q000737:chemistry; D008894:Milk Proteins / Q000032:analysis / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D007782:Lactoglobulins; D008894:Milk Proteins; D007785:Lactose