Development and validation of method for extraction and quantification by HPLC with refractive index to lactose in pasteurized milk

Acquaro Junior, Vinicius Ricardo; Madeira, Tiago Bervelieri; Castilho, Drielle Caroline; Watanabe, Lycio Shinji; Bovolenta, Yuri Renan; Nixdorf, Suzana Lucy

Palavras-chave: Carbohydrates, ethanol, lactose, experimental design, adulteration.

Resumo: Livestock and Food Supply of Brazil), lactose has been chosen as a quality marker to set milk prices and facilitate fraud detection. Since milk is a complex matrix rich in proteins, lipids, carbohydrates, mineral salts and vitamins, it requires proper sample pretreatment. The present work was aimed at developing and validating a methodology for establishing parameters and analytical conditions in order to increase lactose percentage extracted from milk. For this purpose, a central composite statistical design with three independent parameters (centrifugation time, rotation intensity and solvent/sample dilution ratio) was employed. The statistical treatments allowed finding optimum extraction conditions – average recovery rate 105 %, ethanol: milk ratio 4:1 (v/v), and rotation 10,000 rpm for 37 min. The proposed method with appropriate chromatographic resolution between lactulose and lactose, using water as the mobile phase, and only ethanol for sample pretreatment, instead of expensive reagents and toxic solvents, is a distinct and feasible alternative to determine lactose contents of pasteurized milk.

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