HPLC and NMR Study of the Reduction of Sweet Whey Permeate
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Sweet whey permeate was hydrogenated under high pressure and temperature with Raney Ni as a catalyst. Different reaction conditions, such as reaction time, amount of catalyst, and initial hydrogen pressure and temperature, were studied. The reaction mixtures were analyzed by HPLC and NMR. The major whey component, lactose (4-O-β-d-galactopyranosyl-d-glucose), was converted under these conditions to lactitol (4-O-β-d-galactopyranosyl-d-glucitol) to different degrees. Hydrolysis of lactose to galactose and glucose and further reduction was also observed over a wide temperature range, whereas isomerization of lactose to lactulose (4-O-β-d-galactopyranosyl-d-fructose) and subsequent reduction only occurred above 110 °C. With reaction time of 4 h, an initial hydrogen pressure of 1500 psi, 40.5 g of Raney Ni, and a temperature = 120 °C, sweet whey permeate (42%, 340 g) gives lactitol (85.2 %), lactulitol (1.7%), and sorbitol and dulcitol (0.8%) together with unreacted fat, protein, and salts (12.3%). Keywords: Sweet whey permeate; lactose; lactitol; isomerization; hydrolysis; lactulose; glucose; galactose; sorbitol; dulcitol; lactulitol; catalytic hydrogenation; HPLC; NMRKeywords:
Lactulose
SUMMARY The kinetics of the epimerization of lactose to lactulose were determined for two ‘model milk’ solutions, one containing lactose and the other lactose and lysine. The lysine was added to lactose to determine whether amino groups of proteins act as base catalysts promoting the production of free lactulose. The presence of lysine actually reduced the rate of production of free lactulose, presumably by the formation of amino-sugar complexes. The rate of production of free lactulose over the range of processing conditions was shown to be first order for both systems. Thermal effects on lactose were shown to be complex. The epimerization of lactose to lactulose was reversible and both sugars were thermally decomposed to their monosaccharides. The difference in the rate of production of free lactulose between the lactose, and the lactose and lysine solutions was also observed in processed milk and its ultrafiltrate (protein free).
Lactulose
Epimer
Monosaccharide
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Lactulose
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Lactulose
Reaction conditions
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The standard 3 h breath hydrogen (3hBH 2 ) test distinguishes lactose maldigesters from lactose digesters. However, multiple factors impact on BH 2 and care is needed to exclude a priori variables. When these factors are controlled, a negative BH 2 test implies lactase persistent status or lactase nonpersistent status with colonic adaptation. A case of a Sicilian man who tested negative (lactase persistent status confirmed) on an initial 50 g lactose challenge is described. It was observed that he consumed 28.1 g lactose/day before testing. He subsequently underwent five additional challenge tests in the course of the next 10 months. In four tests the dose intake of lactose was varied upon instruction, and in the fifth test a 30 g lactulose challenge was carried out. It was demonstrated that on radically decreasing lactose intake, a full lactase nonpersistent status was unmasked. Output of 3hBH 2 varied inversely with daily lactose intake. Finally, at a time when he was readapted to lactose, there was no discernible adaptation to lactulose challenge. It was concluded that 'occult' colonically adapted subjects may contribute to negative BH 2 tests. There is a relationship between variation in lactose intake and the results of BH 2 testing. Finally, there was no cross-adaptation to lactulose challenge when lactose was used as the adapting sugar.
Lactulose
Lactase
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Lactulose
Disaccharide
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Intestinal mucosal damage causes impaired digestive capacity and increased mucosal permeability. Quantification of damage can be used to improve treatment options. Currently, the Lactose Digestion Index (LDI) and the Sugar Absorption Test (SAT) are used for evaluation. The investigation studied whether both tests could be combined to provide a useful multifunctional test and whether measurements in blood (LDI) could be replaced by measurements in urine.The LDI (25 g 13C-lactose, 0.5 g 2H-glucose), the SAT (5 g lactulose, 1 g L-rhamnose) and the LDI/SAT combination test were performed in seven lactose-digesting and eight lactose-maldigesting adults. Plasma glucose 13C-enrichment was determined by gas-chromatography/combustion/isotope ratio mass-spectrometry (GC/C/IRMS), 2H enrichment determined by gas-chromatography/mass-spectrometry (GC/MS) and urinary sugars by gas-chromatography (GC).The results of the separate LDI test were not different from those of the LDI/SAT in the lactose-digester group (0.82 +/- 0.06 vs. 0.81 +/- 0.09), nor in the lactose-maldigester group (0.36 +/- 0.12 vs. 0.35 +/- 0.06). A significant correlation was found between the 10-h urinary-lactose/lactulose ratio and the LDI (R2 = 0.71, P < 0.01). There were no differences in the lactulose/L-rhamnose ratio between lactose-digesters and lactose-maldigesters using both the SAT and LDI/SAT tests.The LDI/SAT test is a reliable method of measuring digestion and permeability simultaneously. The 10-h period urinary lactose/lactulose excretion ratio following lactose consumption reflects lactose digestive capacity.
Lactulose
Rhamnose
Digestion
Intestinal Permeability
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Lactulose
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In this research hydrolysis and transgalactosylation reactions in lactulose synthesis from lactose and fructose by commercial s-galactosidase from Klyveromyces lactis were studied. At first stage, lactose and lactulose conversion to the hydrolysis products was investigated. Morethan 90% of lactose and 75% of lactulose were consumed with addition of 100 ml of enzyme solution (3000 U/ml) tothe 100 g of 5% (w/w) sugar solutions in 40°C and pH6.7 after 1 and 3 hr respectively. Then transgalactosylation reaction for synthesis of lactulose in the presence of lactose as galactosyl donor and fructose as an acceptor was studied and the effect of some parameters such as reaction time, acceptor concentration, temperature, enzyme amount on maximal produced lactulose concentration was investigated. Maximum lactulose concentration of 1.22% was achieved by adding of 400 ml of enzyme solution (3000 U/ml) to the 100 g of sugars solution, containing 10% (w/w) lactose and 30% (w/w) fructose, in 40°C and pH 6.7 after 120 minutes.
Lactulose
Kluyveromyces lactis
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