Comparative study of the influence of chitosan as coating of thermoplastic starch foam from potato, cassava and corn starch

The expanded polystyrene (EPS) is used in a variety of food packaging, mainly in packages whose characteristics is the single use. These packages are usually discarded soon and generate large amounts of waste. Thermoplastic starch (TPS) foams can replace the EPS in these cases, because it comes from renewable and biodegradable sources. However, TPS packaging has great affinity for water and it affects its use. One way to solve this problem is to cover the TPS foam with a more hydrophobic material, hindering the contact of water with starch. In this work, chitosan was used as coating, since it is also a biodegradable material and more hydrophobic than starch. Three sources of starch (potato, cassava and corn) were analyzed conjointly to produce TPS foams. The foams were made from starch, glycerol and water in the weight proportion of 62/5/33. Results showed that TPS foams made from corn starch are denser and have greater modulus compared to other foams. The chitosan coating decreased water absorption and increased the tensile strength in TPS foams.