Neste estudo, a cromatografia por exclusão de tamanho (SEC) com detecção online ultravioleta (UV), espectrometria de absorção atômica em forno de grafite (GF AAS) e a espectrometria de massa por tempo de voo com dessorção/ionização de matriz assistida por laser (MALDI-TOF-MS) foram usadas para estudar a associação de selênio com macromoléculas e compostos presentes no soro de leite de búfala e bovino. Os perfis de SEC-UV obtidos para as amostras de soro de leite de búfala e soro de leite bovino indicaram a presença de espécies de alta e baixa massa molecular. A combinação das informações obtidas com SEC-UV, GF AAS e MALDI-TOF-MS para as frações < 10 kDa confirmou a associação de selênio com espécies de baixa massa molecular.In this study, size exclusion chromatography (SEC) coupled with an online ultraviolet detection (UV) and graphite furnace atomic absorption spectrometry (GF AAS) and matrix-assisted laser desorption ionisation time-of-flight mass spectrometry (MALDI-TOF-MS) were used to study the association of selenium with macromolecules and compounds present in buffalo and cow's milk whey. SEC-UV profiles obtained from buffalo and cow's milk whey samples indicate the presence of high molecular weight (HMW) and low molecular weight (LMW) species in both samples studied. The combined information obtained with SEC-UV, GF AAS and MALDI-TOF-MS for fractions < 10 kDa confirmed the association of selenium with LMW species.
Keywords: buffalo and cow's milk whey, SEC offline GF AAS, SEC online UV, MALDI-TOF-MS
IntroductionBuffalo (Bubalus bubalis) milk is a food highly nutritious and beneficial to the human health due to the biological value of its constituents. It has pronounced differences when compared to cow's milk, due to the presence of greater percentages of constituents such as fat, protein, lactose, total solids and some minerals. 1 Buffalo milk is used in northern Brazil for making different dairy products, including butter, various cheeses and yogurt. 2 However, studies concerning the chemical composition of buffalo milk are limited compared with cow's milk ones.Milk proteins are classified according to their structural and physicochemical properties, and consist of the following: casein, whey proteins, fat globule membrane proteins, enzymes and growth factors. However, from a nutritional and industrial perspective, casein and whey proteins are more widely applicable and have significant economic value. The total protein concentration and ratio of casein and whey protein fractions vary considerably in milk from different species. a-lactalbumin, bovine serum albumin, immunoglobulin, lactoferrin and lysozyme are whey proteins that provide health benefits. b-lactoglobulin, which is not found in human milk, 3 is the most abundant protein in cow's milk whey and is associated with allergies, particularly in children.The elemental composition of food plays important biological roles. However, the bioavailability and toxicity of these elements strongly depend on the chemical form in which they occur in biologica...