β -glucan is widely found in various bacteria, fungi and plants such as lentinus edodes, ganoderma lucidum, oat, yeast, etc. Different sources and processing methods of β -glucan have different structures and functional differences. Unlike other β-1,3, β-1,4 and β-1,6 glucans, the β-1,3-1, 6-glucan derived from baker’s yeast has high biological activity due to its β-1, 3-glucan main chain and long β-1, 6-glucan branch chain with complex spatial structure after special processing. Today we continue to introduce the species of β -glucan.
Grain β -glucan
Grain-derived β -glucan was mainly extracted from oat. Oat β -glucan is a kind of non-starch polysaccharide that exists in the endosperm and aleurone cell wall of oat. It is a water-soluble dietary fiber. Its viscosity can hinder the digestion and absorption of starch, protein and other substances, and can regulate blood glucose and lipids, which can reduce the risk of cardiovascular diseases.
Oat β -glucan can also increase the number of lactobacillus in the intestinal tract, regulate the intestinal flora, and can be used as a prebiotic. Its satiety enhancing effect also makes it a weight loss function, which makes it ideal for adding to cereal bars, milkshakes and other meal replacement foods. In addition, oat β -glucan also has certain immune regulation functions and can combine with macrophages of the human immune system to enhance the activity and phagocytosis of macrophages.
Yeast, fungi β -glucan
The yeast cell wall contains β -glucan. Saccharomyces cerevisiae is the preferred source for early extraction of β -glucan due to its safety, wide application, easy availability and low cost. The content of β -glucan in the yeast cell wall was low under the condition of harvesting yeast cells, and only a thin layer was observed by transmission electron microscopy. However, the synthesis of β -glucan could be promoted by adding tannic acid.
When yeast β -glucan enters the body, its helical structure determines that it is not hydrolyzed into monosaccharides such as glucose in the gastrointestinal tract, but binds to specific receptors and eventually passes through the intestinal epithelium into the lymphatic system through endocytosis (or pinocytosis), and from the lymphatic system into the blood system. Yeast β -glucan can specifically bind macrophages to stimulate and activate immune factors, which can better exclude alien cells and prevent the invasion of foreign viruses, and then achieve the effect of immunity. In addition, yeast β -glucan can improve the water retention, stability and emulsification of food, and can partially replace fat used in ice cream, meat products and dairy products. Because yeast β -glucan is insoluble in water, resulting in low bioavailability and poor usability, water solubility can be improved by chemical derivatization, such as acidification, phosphorylation, carboxymethylation, etc. Carboxymethyl β -glucan (sodium), Cm-glucan, is currently the only chemical derivative permitted by cosmetics raw materials regulations.
Fungus-derived β -glucan has similar structures and effects to yeast β -glucan, but studies have shown that fungus-derived β -glucan is not as efficient as yeast β -glucan.
Algae β -glucan
β -glucan from algae and yeast β -glucan share a common 1,3 linkage structure and can also be used as immune modulators. Euglenophyta β -glucan has many unique advantages. Firstly, in terms of content, the content of β(1,3) glucan can reach 30%-70% in the cultured eutrophic algae, while the yeast-derived β(1,3) glucan only accounts for less than 15% of the total yeast cells. Second, the yeast-derived β -glucan binds to the yeast cell wall, making extraction difficult and requiring the use of chemical solvents or enzymes. The extracted β -glucan has two structures, 1,3 and 1,6. However, β -glucan in eutrophic algae only has a linear 1,3 structure and aggregates into particles in eutrophic algae, which can be easily separated and purified to obtain eutrophic algae products with high β(1,3) glucan, which meets consumers’ demands for natural and low-processed raw materials.
Biological fermentation of β -glucan
Currently known β -glucan products produced by industrial fermentation include schizophyllum glucan (schizophyllin), microcarycin, soran gum (selecco) and corderan gum, all of which are released into the medium in the form of extracellular polysaccharides. The first three are soluble, while corderan gum is insoluble in water.
β-1,3/α-1, 3-glucan, which has recently become a new food raw material, is a kind of water-soluble β -glucan which is composed of 7 β-1, 3-D-glucose and 2 α-1, 3-glucose and is composed of 9 D-glucose repeat units.
β-1,3/α-1, 3-glucan was prepared from sucrose by fermentation, alcohol precipitation, filtration, separation, drying and comminution. Compared with traditional β -glucan, β-1,3/α-1, 3-glucan is more water-soluble, colorless, tasteless and stable, and has better processing ability. It is very suitable to be added to all kinds of food and beverage, and it has higher activity and immune enhancement. Practical application shows that it has the functions of moisturizing, delaying aging, increasing skin elasticity, enhancing body immunity, assisting in lowering blood sugar and blood lipids, etc, is a powerful functional raw material.