Lactulose, monosaccharides and undenatured serum protein contents in commercial UHT creams and their usefulness for thermal treatment assessment

Fifteen UHT cream samples with different fat levels (ranging from 10% to 35%) were analysed for free carbohydrates (lactose, lactulose, glucose, galactose and myoinositol) and undenaturated whey proteins using gas chromatography and high-performance liquid chromatography, respectively. Lactulose concentrations ranged from 7 to 177 mg per 100 ml, α-lactalbumin from 5.1 to 61.6 mg per 100 ml and β-lactoglobulin from 1.0 to 64.0 mg per 100 ml. These values were similar to those reported for UHT milks. The ratio β-lactoglobulin/lactulose was found to be significantly higher than that reported for UHT milk.