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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., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

The food industry is investigating new technological applications of lactobionic acid (LBA). In the current work, the effect of lactobionic acid on the acidification of dairy gels (pH 5.5 and 6.2), rheological properties using a double compression test, sodium mobility using (23)Na NMR technique and aroma release using headspace GC-FID were studied. Our results showed that it is possible to use LBA as an alternative to glucono-δ-lactone (GDL) for the production of dairy gels with a controlled pH value. Small differences in the rheological properties and in the amount of aroma volatile organic compounds that were released in the vapour phase, but no significant difference in the sodium ion mobility were obtained. The gels produced with LBA were less firm and released less volatile aroma compounds than the gels produced with GDL. The gels at pH 6.2 were firmer than those at pH 5.5 and had a more organised structure around the sodium ions., (Copyright © 2016 Elsevier Ltd. All rights reserved.)