Galacto-Oligosaccharide (GOS) Synthesis during Enzymatic Lactose-Free Milk Production: State of the Art and Emerging Opportunities

Abstract

Much attention has recently been paid to β-Galactosidases (β-D-galactoside galactohidrolase; EC 3.2.1.23), commonly known as lactases, due to the lactose intolerance of the human population and the importance of dairy products in the human diet. This enzyme, produced by microorganisms, is being used in the dairy industry for hydrolyzing the lactose found in milk to produce lactose-free milk (LFM). Conventionally, β-galactosidases catalyze the hydrolysis of lactose to produce glucose and galactose in LFM; however, they can also catalyze transgalactosylation reactions that produce a wide range of galactooligosaccharides (GOS), which are functional prebiotic molecules that confer health benefits to human health. In this field, different works aims to identify novel microbial sources of β-galactosidase for removing lactose from milk with the relative GOS production. Lactase extracted from thermophilic microorganisms seems to be more suitable for the transgalactosylation process at relatively high temperatures, as it inhibits microbial contamination. Different immobilization methods, such as adsorption, covalent attachment, chemical aggregation, entrapment and micro-encapsulation, have been used to synthesize lactose-derived oligosaccharides with immobilized β-galactosidases. In this mini-review, particular emphasis has been given to the immobilization techniques and bioreactor configurations developed for GOS synthesis in milk, in order to provide a more detailed overview of the biocatalytic production of milk oligosaccharides at industrial level.

Immobilization of Lactobacillus acidophilus β-galactosidase on chitosan obtained from the shells of the African giant snail, Achatina achatina

“…The chitin was eventually decolorized with 0.1% hypochlorite solution for 48 h and washed to neutrality. The decolorized chitin was deacetylated to chitosan in 40 % sodium hydroxide (10 M NaOH) at 100 °C for six (6) hours. After washing it thoroughly, the chitosan was oven-dried at 60°C for 48 h in an oven box (Gellemp haump, Germany).…”

“…4,5 β-Galactosidase has two crucial applications in the food industry: the hydrolysis of lactose for reducing lactose levels in dairy products, and the transgalactosylation reactions for the synthesis of galactooligosaccharides (GOS). 6,7 Lactose mal-absorption or lactose intolerance is a severe health problem in about 75% of the world population who could be at risk from the consumption of frozen milk products which usually contain large amounts of lactose. 8,9 © 2023 the authors.…”

NMR-Based Metabolomics for a More Holistic and Sustainable Research in Food Quality Assessment: A Narrative Review

“…The main prebiotic agents consist of nondigestible carbohydrates, such as polysaccharides (POS), oligosaccharides (OS), and soluble dietary fibers (mainly inulin) [96]. Prebiotic foods are largely requested on the market; thus, food industries are working on the development of sustainable bioprocesses that can guarantee OS from a waste of different sources [97][98][99]. An important resource of OS comes from lignocellulosic agricultural waste disposals.…”

Characterization of an isolated lactase enzyme produced by Bacillus licheniformis ALSZ2 as a potential pharmaceutical supplement for lactose intolerance

“…These are biomolecules that are required for both the synthesis and breakdown reactions of living organisms (Aggarwal et al, 2021). The enzymes known as β-galactosidases (EC 3.2.1.23), sometimes known as lactases, hydrolyze lactose (the most prevalent milk sugar) into OPEN ACCESS EDITED BY glucose and galactose (Liburdi and Marco, 2022). Although these enzymes are accessible in a range of biological systems, such as plants or microorganisms, they are currently only available commercially from yeasts, molds, and bacteria (Saqib et al, 2017;Martarello et al, 2019).…”