Synthesis of Galacto-oligosaccharides in Milk by Using Bifidobacterium bifidum β-galactosidases (Saphera 2600L and Nola Fit 5500) Immobilized on Chitosan Beads

Abstract

The lactose intolerance—as a limiting factor for dairy milk consumption—has a high prevalence worldwide. Dairy milk and milk-derived products are major sources of multiple inorganic compounds and nutrients and thus are considered to be functional foods. β-galactosidases are able to hydrolyze lactose and are therefore widely applied for the production of lactose-free products. In addition, they are capable of the synthesis of galacto-oligosaccharides (GOSs); thus, the dairy industry has a special interest in applying them for the enrichment of dairy products with prebiotic GOSs. In this work, we studied two commercially available β-galactosidase products: Saphera 2600L and Nola Fit 5500. Both enzyme solutions contain a recombinant β-galactosidase of Bifidobacterium bifidum and have already been authorized for food industrial application, but the information about their hydrolytic and/or synthetic activities is only limited. After immobilization on chitosan beads, the enzymes were used for lactose hydrolysis and simultaneous synthesis of GOSs, by performing the reactions in pasteurized milk (skim milk). Both immobilized β-galactosidase exhibited elevated lactose hydrolysis (vmax increased from ~ 1 to ~ 4 mM/min) and GOS synthesis as compared to the free enzymes. The enzyme-coated beads were efficiently re-used at least 15 cycles; the residual lactose concentration was < 2 mg/ml after each cycle. After treatment, GOSs were present in ≤ 9% of the total sugar content, indicating that the prepared low-lactose milks were enriched in prebiotic GOSs. The application of immobilized Saphera 2600L and Nola Fit 5500 β-galactosidases may be implemented for the large-scale production of GOS-enriched low-lactose milk. Graphical Abstract

Reutilization of the Most Stable Coimmobilized Enzyme Using Glutaraldehyde Chemistry to Produce a New Combi-biocatalyst When the Coimmobilized Enzyme with a Lower Stability Is Inactivated

“…As model enzymes, we have used Eversa Transform 2.0 (EVR), a very stable lipase that is commercially available, which has been prepared by genetic modification of the lipase from Thermomyces lanuginosus − and the β-galactosidase from Aspergillus oryzae as an enzyme showing a lower stability. − Although the enzymes have been chosen just as a model system, we can envisage some joint applications of both enzymes. One likely application may be the simultaneous modification of the fats and lactose of milk to produce free-lactose milk (or lactose enriched in prebiotic galactosides) − that could also bear flavors produced by the lipase action, decrease the triglyceride concentration, − or be protected by the presence of some free fatty acids with antimicrobial agent activity. − Other application may be the production of galactosyl-diglycerides using lipase to produce specific diglycerides from the corresponding triglyceride (e.g., 1,2 diacetin) and the β-galactosidase from A. oryzae as the catalyst to produce the O-link ,− between galactose and diglyceride via kinetically controlled synthesis. − In this instance, the high concentration inside the particle of the diglyceride may be critical to have good reaction yields, and the immediate modification can prevent the fact that the acyl migration results in 1,3 diacetin …”

The Brønsted-Lewis acid sites in Metal-organic framework nanozymes for cooperatively enhancing the hydrolysis of lactose

“…Milk and dairy products are consumed in huge quantities with lactose as the main carbohydrate in milk (Bodnár, et al, 2023;Fassio, et al, 2018). Lactose digestion requires lactase.…”