title: Some instrumental methods applied in food chemistry to characterise lactulose and lactobionic acid.
abstract: Lactose is obtained as a by-product from whey. It is a source of several derivatives, including lactulose and lactobionic acid. These two compounds were analysed by using the following techniques: thermogravimetry/derivative thermogravimetry (TG/DTG), differential scanning calorimetry coupled with optical microscope (DSC-thermomicroscopy), infrared spectroscopy (FTIR) and X-ray diffractometry (XRD). The DSC technique coupled with microscopy made it possible to observe that the lactobionic acid showed several thermal events upon decomposition, which occurred at temperatures higher than 50°C. The lactulose began to decompose above 180°C. The DSC curve was used to calculate the purity of the lactulose (according to Van't Hoff equation), which was 98% and the melting point peak occurred at 171°C. The lactulose showed crystalline behaviour that was different to that of the lactobionic acid, which was attributed to its high hygroscopicity. Purity of lactobionic acid was not calculated because the decomposition occurred in consecutive stages.
authors.affiliation: Federal University of Paraná - UFPR, R. Francisco H. dos Santos s/n, 81531-980 Curitiba, PR, Brazil.
authors.forename: Radla Zabian Bassetto
authors.initials: RZ
authors.lastname: Bisinella
authors.affiliation: Federal University of Paraná - UFPR, R. Francisco H. dos Santos s/n, 81531-980 Curitiba, PR, Brazil.
authors.forename: Jéssica Caroline Bigaski
authors.initials: JC
authors.lastname: Ribeiro
authors.affiliation: State University of Ponta Grossa - UEPG, Av. Carlos Cavalcanti, 4748, 84030-900 Ponta Grossa, PR, Brazil.
authors.forename: Cristina Soltovski
authors.initials: CS
authors.lastname: de Oliveira
authors.affiliation: Federal University of Grande Dourados, Rod. Dourados-Itahum, Km 12, 79804-970, C.P. 364 Dourados, MS, Brazil.
authors.forename: Tiago André Denck
authors.initials: TA
authors.lastname: Colman
authors.affiliation: State University of Ponta Grossa - UEPG, Av. Carlos Cavalcanti, 4748, 84030-900 Ponta Grossa, PR, Brazil. Electronic address: egons@uepg.br.
authors.forename: Egon
authors.initials: E
authors.lastname: Schnitzler
authors.affiliation: Federal University of Paraná - UFPR, R. Francisco H. dos Santos s/n, 81531-980 Curitiba, PR, Brazil.
authors.forename: Maria Lúcia
authors.initials: ML
authors.lastname: Masson
mesh_terms: D002152:Calorimetry, Differential Scanning; D004187:Disaccharides / Q000032:analysis*; D007792:Lactulose / Q000032:analysis*; D013055:Spectrophotometry, Infrared; D017550:Spectroscopy, Fourier Transform Infrared; D013818:Thermogravimetry; D014961:X-Ray Diffraction
chemical_list: D004187:Disaccharides; D007792:Lactulose; C005608:lactobionic acid
keywords: FTIR; Kinetic studies; Lactobionic acid; Lactulose; Thermal analysis; X-ray