Limitation of Maillard Reactions in Lactose-Reduced UHT Milk via Enzymatic Conversion of Lactose into Galactooligosaccharides during Production

Abstract

Lactose-hydrolyzed (LH) ultrahigh temperature (UHT) processed milk is more prone to Maillard reactions and formation of advanced glycation end products (AGEs) during processing and storage than conventional (CON) UHT milk because of the presence of free galactose and glucose. Commercially available β-D-galactosidases with transgalactosylating activity can incorporate galactose into galactooligosaccharides (GOSs) and potentially limit Maillard reactions in this lactose-reduced GOScontaining milk. The aim of this study was to examine the extent of Maillard reactions in a lactose-reduced GOS milk compared to LH and CON milk after UHT processing. The GOS milk had significant lower levels of lysine-and arginine-derived AGEs compared to LH milk, while their concentrations were similar to those found in CON milk. The total concentration of measured Arg-derived AGEs was similar to the total concentration of Lys-derived AGEs in the three types of milk, indicating that Arg is an important source of AGEs in milks. Interestingly, the GOS milk generated threefold higher concentrations (up to 330 ± 6 μM) of 3deoxyglucosone (3-DG, a C6 α-dicarbonyl). These results demonstrate that GOS milk could be a potential alternative for LH milk for lactose-intolerant individuals, although further studies are needed to understand the increased formation of 3-DG in GOScontaining milk.

Evaluation of Fructo-, Inulin-, and Galacto-Oligosaccharides on the Maillard Reaction Products in Model Systems with Whey Protein

“…Although we could not obtain an authentic standard of 3-deoxygalactosone, 3-DH observed in almost all models were confirmed to be 3-DG by comparing the retention times with 3-DG-quinoxaline, except for the Gal model. The concentration of 3-DH markedly increased in the GOS model compared with the other models, similar to the previous reports. − , The 3-DH concentration in the GOS model was much higher than in monosaccharide models, which reached a maximum of 1339 μM at 2 weeks, followed by a decrease of up to 513 μM at 8 weeks. In addition, the comparison with the other oligosaccharide models proved that 3-DH was specifically produced in the GOS model.…”

“…The concentration of 3-DH markedly increased in the GOS model compared with the other models, similar to the previous reports. [14][15][16]21 The 3-DH concentration in the GOS model was much higher than in monosaccharide models, which reached a maximum of 1339 μM at 2 weeks, followed by a decrease of up to 513 μM at 8 weeks. In addition, the comparison with the other oligosaccharide models proved that 3-DH was specifically produced in the GOS model.…”

“…Effect of the β-1 → 4 Glycosidic Linkage between Galactoses Contained in GOS on 3-DG Formation. Although previous studies reported that a large amount of 3-DG was generated in GOS-containing model solutions, 15,16 and milk samples, 14 the formation mechanism for 3-DG from GOS has not been demonstrated yet. Zhang et al proposed the mechanism that Gal (1 → 3)-Glc or Gal (1 → 3)-Gal contained in GOS depolymerized to 3-DG via 1,2-enediol.…”

“…The conversion of free galactose into GOS using β-D-galactosidase decreased Lys-derived AGEs [N ε -carboxymethyllysine (CML) and N εcarboxyethyllysine (CEL)] and Arg-derived AGEs (G-H1/H3 and MG-H1/H3) produced in UHT-milk; however, 3-DG production was markedly increased. 14 This phenomena was not observed in samples containing lactose and galactose. The caramelization of GOS, not the Maillard reaction with amines, 15 was probably attributed to a marked increase in 3-DG observed in GOS-containing milk, but it has not been fully elucidated why the amount of 3-DG was markedly increased in a GOS-containing sample.…”

“…α-DCs and AGEs formation in GOS have been studied as dairy-related carbohydrates, whereas those data for FOS and IOS were few. The conversion of free galactose into GOS using β- d -galactosidase decreased Lys-derived AGEs [ N ε -carboxymethyllysine (CML) and N ε -carboxyethyllysine (CEL)] and Arg-derived AGEs (G-H1/H3 and MG-H1/H3) produced in UHT-milk; however, 3-DG production was markedly increased . This phenomena was not observed in samples containing lactose and galactose.…”