Recent Advances in the Production, Analysis, and Application of Galacto-Oligosaccharides

Galacto-oligosaccharides (GOS) are the prebiotic constituents with various functional qualities that promote the optimal proliferation of gut microbiota and are consequently beneficial to human health. GOS are not absorbed by humans and animals, but they play numerous health-related positive roles in the human body. Currently, their production has occupied much attention due to the increasing demand for functional foods. It could be produced by enzymatic and chemical approaches. Many microbial enzymes have been utilized for GOS production but the main source of these enzymes is lactose. Moreover, characterization of GOS structures is also a necessary and critical effort for understanding their mechanism of action. Hence, this review is written to understand the extensive but related features for the synthesis of GOS which includes: the enzymatic production of GOS through various enzymes and the types of enzymes such as free, immobilized, recombinant, crude, and purified enzymes that are involved in their synthesis, the techniques used in the purification of GOS, the analysis and quantification of GOS through various practices, and the functional properties of GOS are also discussed in this review. It also aims to combine new findings with current information in order to improve understanding of GOS formation and other factors related to its functionality.