Lactose: Crystallization, hydrolysis and value-added derivatives

Gänzle, Michael G.; Haase, G.; Jelen, P.

doi:10.1016/j.idairyj.2008.03.003

Cited by 259 publications

(194 citation statements)

References 92 publications

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“…For fluorescence and optical absorption measurements, 2-bilayer (PEI/PVS) 2 LbL films were used as a cushion to reduce the influence of substrate morphology on film growth, 26 while the amperometric measurements were made with a 1-bilayer cushion of (PEI/PVS) 1 . LbL films were assembled by dipping the substrate in PEI and β-Gal solutions, both for 3 min, interspersing the immersion in sodium acetate buffer during 30 s for washing.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…All the films were assembled at room temperature. For Fourier transform infrared (FTIR) and SFG spectroscopic measurements, a 2-bilayer cushion of (PEI/PVS) 2 was deposited onto the CaF 2 windows, on top of which one bilayer of (PEI/β-Gal) 1 was added, leaving the β-Gal exposed in the outermost layer.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…In the experiments with the enzyme powder, 0.5% of β-Gal was dispersed in pellets in a KBr matrix. For the measurements on films, (PEI/PVS) 3 and (PEI/PVS) 2 +(PEI/β-Gal) 1 LbL films were grown onto CaF 2 windows and then dried in a weak flow of N 2 . All measurements were carried out in the transmission mode with a resolution of 6 cm −1 .…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…The SFG spectroscopy measurements were performed on the upper face of a CaF 2 plate at a film−air interface, on which LbL films were grown with the enzyme immobilized. The film architectures investigated were (PEI/PVS) 3 and (PEI/PVS) 2 +(PEI/β-Gal) 1 , which were exposed to buffer or lactose solutions and then dried in a low flux of N 2 before the experiments. The setup consists of two laser beams, one in the visible range (ω vis ) and another, tunable in the infrared (ω IR ), both overlapping spatially and temporally at the interface giving rise to a sum-frequency signal ω SFG = ω vis + ω IR .…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…1 It is hydrolyzed by lactase in the digestive system to the monosaccharides glucose and galactose. For humans suffering from lactose intolerance for the lack of lactase, the commercially available β-galactosidase may be used to hydrolyze lactose to be absorbed by the body.…”

Section: ■ Introductionmentioning

confidence: 99%

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Amperometric Detection of Lactose Using β-Galactosidase Immobilized in Layer-by-Layer Films

Campos

Moraes

Volpati

et al. 2014

ACS Appl. Mater. Interfaces

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A direct, low-cost method to determine the concentration of lactose is an important goal with possible impact in various types of industry. In this study, a biosensor is reported that exploits the specific interaction between lactose and the enzyme β-galactosidase (β-Gal) normally employed to process lactose into glucose and galactose for lactose-intolerant people. The biosensor was made with β-Gal immobilized in layer-by-layer (LbL) films with the polyelectrolyte poly(ethylene imine) (PEI) and poly(vinyl sufonate) (PVS) on an indium tin oxide (ITO) electrode modified with a layer of Prussian Blue (PB). With an ITO/PB/(PEI/PVS) 1 (PEI/β-Gal) 30 architecture, lactose could be determined with an amperometric method with sensitivity of 0.31 μA mmol −1 cm −2 and detection limit of 1.13 mmol L −1, which is sufficient for detecting lactose in milk and for clinical exams. Detection occurred via a cascade reaction involving glucose oxidase titrated as electrolytic solution in the electrochemical cell, while PB allowed for operation at 0.0 V versus saturated calomel electrode, thus avoiding effects from interfering species. Sum-frequency generation spectroscopy data for the interface between the LbL film and a buffer containing lactose indicated that β-Gal lost order, which is the first demonstration of structural effects induced by the molecular recognition interaction with lactose.

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Section: ■ Experimental Sectionmentioning

confidence: 99%

Section: ■ Experimental Sectionmentioning

confidence: 99%