Food additives has been widely used and with increasing demand in foods and beverages products with longer shelf life and low fat or sugar,for example the ready to eat products.
On the other hand,people pay more and more attention to their health care and there is a trend to reduce the use of many food additives, to replace chemically food additive with natural original food additives.
The term“natural gums”is refer to a group of naturally occurring polysaccharides which have been widely used in foods & beverages as gelling agent,thickener,stabilizer.etc.
Most of the gums for example,Gellan Gum,used by the food industry are extracts from plants and seaweeds,and in recent decades bacterial fermentation has been utilized as a source of new group of polysaccharides, the fermentation production is easily controllable and produce products of reproducible physical and chemical properties.
The advantages of natural gums:
-Natural gums are biodegradable polymers as they are produced by living organisms.
-Natural gums are biocompatible and non-toxic.
-Natural gums are readily available as a local source or through cultivation.
-Natural gums production is ecofriendly.
-Many of the gums are obtained from an edible source, hence they are easily acceptable.
Gellan gum is a bacterial exopolysaccharide, prepared commercially by aerobic submerged fermentation with Sphingomonas paucimobilis (previously called Pseudomonas elodea).
Gellan gum is a linear polysaccharide consisting of about 50,000 residues. It is composed of a repeating tetrasaccharide of D-glucose, D-glucuronic acid and L-rhamnose in the molar ratio 2:1:1.
In high acyl gellan gum O(2) glyceryl and O(6) acetyl substituents are present on the glucose unit adjacent to glucuronic acid.
Because of its unique physico-chemical properties,gellan gum could be used in a wide variety of food applications, especially as a texturizer and gelling agent.The high acyl gellan gum forms soft, elastic, non-transparent and flexible gels, whereas the low acyl gellan gum forms non-elastic, brittle, hard gels.
Gellan gum may also be used in film preparations and encapsulation techniques, not only in food industry but potentially also in pharmaceuticals. An important role of a packaging film is to reduce exchange of water between the product and the environment. Diffusivity and solubility of water molecules in the film material influence water transmission through the film and characterize its water sorption properties.
The presence of water in food is generally determined in terms of water activity. Water activity is a parameter that indicates how available water is for participation in physical and chemical reactions and microbiological growth.
