title: Time resolved fluorescence of cow and goat milk powder.
abstract: Milk powder is an international dairy commodity. Goat and cow milk powders are significant sources of nutrients and the investigation of the authenticity and classification of milk powder is particularly important. The use of time-resolved fluorescence techniques to distinguish chemical composition and structure modifications could assist develop a portable and non-destructive methodology to perform milk powder classification and determine composition. This study goal is to differentiate milk powder samples from cows and goats using fluorescence lifetimes. The samples were excited at 315nm and the fluorescence intensity decay registered at 468nm. We observed fluorescence lifetimes of 1.5±0.3, 6.4±0.4 and 18.7±2.5ns for goat milk powder; and 1.7±0.3, 6.9±0.2 and 29.9±1.6ns for cow's milk powder. We discriminate goat and cow powder milk by analysis of variance using Fisher's method. In addition, we employed quadratic discriminant analysis to differentiate the milk samples with accuracy of 100%. Our results suggest that time-resolved fluorescence can provide a new method to the analysis of powder milk and its composition.
authors.affiliation: Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Juiz de Fora, Rua José Lourenço Kelmer, s/n São Pedro, 36036-900 Juiz de Fora, MG, Brazil. Electronic address: mpbrandao@gmail.com.
authors.forename: Mariana P
authors.initials: MP
authors.lastname: Brandao
authors.affiliation: Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Juiz de Fora, Rua José Lourenço Kelmer, s/n São Pedro, 36036-900 Juiz de Fora, MG, Brazil.
authors.forename: Virgílio
authors.initials: V
authors.lastname: de Carvalho Dos Anjos
authors.affiliation: Departamento de Física, Instituto de Ciências Exatas, Universidade Federal de Juiz de Fora, Rua José Lourenço Kelmer, s/n São Pedro, 36036-900 Juiz de Fora, MG, Brazil.
authors.forename: Maria José V
authors.initials: MJV
authors.lastname: Bell
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002417:Cattle; D006041:Goats; D008892:Milk / Q000737:chemistry*; D011208:Powders; D025341:Principal Component Analysis; D013050:Spectrometry, Fluorescence; D013997:Time Factors
chemical_list: D011208:Powders
keywords: Goat; Lifetimes; Milk powder; Spectroscopy; Time-resolved fluorescence