Beta-Glucan as a Soluble Dietary Fiber Source: Origins, Biosynthesis, Extraction, Purification, Structural Characteristics, Bioavailability, Biofunctional Attributes, Industrial Utilization, and Global Trade

Abstract

This paper explores the multifaceted nature of β-glucan, a notable dietary fiber (DF) with extensive applications. Beginning with an in-depth examination of its intricate polysaccharide structure, the discussion extends to diverse sources like oats, barley, mushrooms, and yeast, emphasizing their unique compositions. The absorption and metabolism of β-glucan in the human body are scrutinized, emphasizing its potential health benefits. Extraction and purification processes for high-quality β-glucan in food, pharmaceuticals, and cosmetics are outlined. The paper underscores β-glucan's biofunctional roles in immune modulation, cholesterol regulation, and gastrointestinal health, supported by clinical studies. The review discusses global trade dynamics by tracing its evolution from a niche ingredient to a global commodity. In summary, it offers a comprehensive scientific perspective on β-glucan, serving as a valuable resource for researchers, professionals, and industries exploring its potential in the dietary fiber landscape.

Keywords: bioavailability; biofunctionalities; cereals; fungus; industrial applications; microbes; β-glucan.

Figure 1

Schematic presentation of the β-glucan biosynthetic pathway in cereals. CO₂: carbon dioxide, D-Glucose-6-P: D-Glucose-6-Phosphate, α-D-Glucose-1-P: α-D-Glucose-1-Phosphate, UDP-Glucose: uridine diphosphate, SBE: starch branching enzyme, GBSS-1: granule bound starch synthase-1, Cslf6: Cellulose synthase-like family 6, DP: degree of polymerization. Red arrows indicate the site of action of the lichenase enzyme.

Figure 2

Model representing the β-glucan biosynthetic pathway in yeast. UMP: uridine monophosphate, UDP: uridine diphosphate, Glc-6-P: Glucose-6-Phosphate, Glc-1-P: Glucose-1-Phosphate, BGS: β-glucan synthase, ATP: adenosine triphosphate, ADP: adenosine diphosphate, GTP: guanosine triphosphate, GDP: guanosine diphosphate, Pi: inorganic phosphate, Rho 1: Ras like GTP binding protein.

Figure 3

Extraction and purification of β-Glucan, along with the factors influencing their extraction and purification. Abbreviations: EtOH: ethanol, HClO₄: perchloric acid, Vol.: volume, NaOH: sodium hydroxide, HCl: hydrochloric acid, C₂H₃NaO₂: sodium acetate, dd H₂O: double distilled water, Ppt.: precipitates, Sup.: supernatant.

Figure 4

Schematic model representing structure and branching degree of β-glucan from different sources.

Figure 5

Immunomodulatory and proapoptotic effects of β-Glucan. β-glucan binds to the receptors such as dectin-1, CR-3, and TLRs present in immune cells like macrophages, dendritic cells, neutrophils, and natural killer cells to induce the production of cytokines and co-stimulatory molecules, including IL-12, IL-6, IL-1, TNF-α, B7.1, and B7.1 which results in the activation of Th and Tc cells. TH cells and Tc cells, along with natural killer cells, release perforin and granzyme, resulting in the apoptosis of cells. Also, β-glucan in the tumor cells binds to the FAS receptor, promotes Bax/Bak, and inhibits Bcl2, leading to the activation of caspases and, consequently, apoptosis of tumor cells. Abbreviations: TLRs: Toll-like receptors, CR3: compliment receptor 3, IL: interleukin, TNF-α: tumor necrosis factor-α, TH: T helper cells, TC: T cytotoxic cells, Bcl2: B-cell lymphoma, Bax: Bcl associated X-protein, Bak: Bcl-2 antagonistic/killer, CytC: Cytochrome C, FAS: TNF Family death receptor, FADD: FAS associated protein and death domain.

Figure 6

Multifaceted applications of β-glucan in different industries.