Characteristics and specific applications of microbial polysaccharides
1.1 Xanthan gum
1.1.1 Structural characteristics
Among microbial polysaccharides, xanthan gum is widely used. The production of polysaccharides is closely related to wild Xanthomonas. This polysaccharide is an acidic extracellular heteropolysaccharide, and its molecular composition is mainly D-glucose and acetic acid. The primary structure is based on D-glucose as the main chain, and the side chain end of the molecule is mainly pyruvic acid. The content of pyruvic acid affects the properties of the polysaccharide. Xanthan gum has a unique structure, good viscosity enhancement synergy and high viscosity at low concentrations. Its good dispersion characteristics make microbial polysaccharides widely used in the food processing industry.
1.1.2 Specific applications
As one of the food additives, xanthan gum can be used to make cakes, improve the cake structure, make the cake gaps uniform, more elastic, and extend the shelf life of the cake; in cream and dairy products, the application of xanthan gum can make the dairy product structure more solid, the aroma better, and the taste more delicate; if xanthan gum is used in beverages, it will make the beverage refreshing, if used in fruit juice, it can make the liquid clearer, and if used in beer making, it can make the bubble effect better. Xanthan gum is more widely used in other foods, such as jelly and preserved fruits.
1.2 Gellan Gum
1.2.1 Gellan Gum Properties
This polysaccharide is fermented by Pseudomonas elodea. Carbohydrates need to be added during fermentation. It is mainly anionic linear and has a double helix structure. The basic component unit is four sugar molecules. When the amount of gellan gum is low, it can form a transparent gel. This polysaccharide can make the gel contain a lot of juice, with good release, melt in the mouth, and good stability. During storage, the internal structure will not change with time and temperature.
1.2.2 Specific Applications
Gellan gum has excellent gelling properties and can replace agar. It is usually used in beverages, pastries and dairy products, and as a gelling agent in the production of jams and jellies.
1.3 Pullulan
1.3.1 Structural characteristics
This polysaccharide is also called pullulan. It is mainly derived from the spore-forming fungus. It is a polyglucose. It is connected to maltotriose through repeated connections and then to a high molecular weight polysaccharide. This polysaccharide is colorless and tasteless, has good acid resistance and heat resistance, good adhesion, and gas barrier properties. This polysaccharide can be used as one of the pharmaceutical raw materials in the pharmaceutical field.
1.3.2 Specific applications
Most of this polysaccharide is used to make food packaging materials. It has good gas barrier properties and can effectively prevent food from oxidation and deterioration. It is more widely used in food products such as meat products and instant noodles. The use of this polysaccharide to make packaging materials can effectively extend the shelf life of food. It can be used as a food improver. By adding pullulan, meat food can be made more elastic. When used in seasonings, the seasoning will be more stable.
Characteristics and specific applications of lactic acid bacteria polysaccharides
2.1 Structural characteristics
Lactic acid bacteria polysaccharides are specifically divided into two categories. The first type is homopolysaccharides composed of one monosaccharide, and the other type is heteropolysaccharides composed of two or more monosaccharides. Generally speaking, the branching quality of homopolysaccharides is higher than that of heteropolysaccharides, but the complexity of heteropolysaccharides is higher than that of homopolysaccharides.
This polysaccharide originates from plants, microorganisms and algae. There are many ways to extract lactic acid bacteria polysaccharides. The simplest method is to observe the state of bacterial colonies on agar plates, but the yield of polysaccharides extracted by this method is low. The most commonly used extraction method today is organic solution precipitation. Lactic acid bacteria polysaccharides have good antioxidant activity and anti-biofilm activity. They are used in the pharmaceutical industry and have good immune activity, which can inhibit the production of cancer cells.
2.2 Specific applications
In the application of food processing industry, it is mainly used in the dairy industry. Lactic acid bacteria are often used for milk acidification and probiotic fermentation. Among them, heteropolysaccharides act on yogurt fermentation, which can make the taste more delicious.
In the fermentation of soy milk, fat is reduced and the viscosity of the taste is increased to better meet people's taste. There are pros and cons. The application of lactic acid bacteria polysaccharides in the wine industry is not ideal. During the fermentation process, adhesion problems will occur, the rheological properties of the liquor may be affected, and it is easy to spoil. Therefore, this polysaccharide is rarely used in the wine industry.
Characteristics and specific applications of animal polysaccharides
3.1 Chitin
3.1.1 Structure of chitin
Chitin is a natural polysaccharide. Its content in nature is second only to cellulose and it is the second most abundant polysaccharide on earth. Chitin is mainly extracted from the shells of crustaceans and is composed of acetylglucosamine. The application and extraction of chitin must be completed through decalcification and protein. The resulting substance is called chitosan, which has antibacterial effects and is mainly used as a preservative in food processing management.
3.1.2 Specific applications
This polysaccharide has good film-forming properties. The food packaging film produced with it can effectively regulate the air in the packaging bag, prevent the evaporation of food moisture, and extend the shelf life of fruits and vegetables. Through the research and processing of chitin and chitosan, a substance called lauric acid is produced. This substance can be used as a food preservative film and can be eaten.
3.2 Characteristics and applications of chondroitin sulfate
3.2.1 Structural characteristics
This polysaccharide is extracted from cartilage tissue and contains D-glucuronic acid of varying lengths. Under acidic conditions, this polysaccharide can be hydrolyzed to produce substances such as aminohexose. Chondroitin sulfate can also be divided into different types according to its chemical structure. Chondroitin sulfate C is mainly found in marine animals.
3.2.2 Specific applications
Chondroitin sulfate has rich biological functions and is widely used in medicines to treat diseases such as arthritis. In the field of food processing, this substance can be used in food additives to emulsify food, maintain food humidity, and remove odors from food.
3.3 Hyaluronic acid
3.3.1 Structural characteristics
It is an acidic mucopolysaccharide, specifically composed of D-glucuronic acid and N-acetylglucosamine. This substance can lubricate joints, regulate water and electrolytes, and accelerate wound healing. This substance is the best moisturizing substance in the world so far and is a very useful cosmetic raw material.
3.3.2 Specific Applications
This substance is mostly used in the processing and production of health foods. It can be digested and absorbed through oral administration, effectively increasing endogenous substances and having a lasting effect on the skin, making the skin elastic, smooth and shiny. This product has been launched in different countries and regions.