A Review of the Methods for Modification of Hydrophilic Properties of Starch Based Biopolymers as a Biod egradable Food Packaging Material

Today, an important part of the materials used in the food packaging industry is oil derivatives. This has caused much environmental pollution in the world. One of the proposed solutions to tackle this problem is the use of edible and biodegradable films as a good alternative to nondegradable polymers. Starch is being studied for its ability to form film, availability, renewability and low cost as a bio-polymer, but disadvantages such as high hydrophilic properties and poor mechanical properties limit the industrial use of this highly valued material. The presence of hydroxyl groups in the starch chains creates a hydrogen bond between the polysaccharide and water. Also, there is a lot of free space in the starch chains, so that molecules of water can easily pass through this space. Today, many researches has been done to reduce hydrophilic properties of starch using genetically modification, enzymatic, chemical (esterification, acetylation, phosphorylation) the use of nanoparticles in the polymer matrix, starch composition with lipids, and other biopolymers. Most of the methods are based on inhibition of starch hydroxyl groups in various ways. One of the methods for inhibiting the starch hydrophilic groups is the esterification of starch chains with hydrophobic agents, the formation of emulsions by fatty acids, and the filling of pores in the polysaccharide network by nanoparticles.