Effects of hydrophobized starches on thermoplastic starch foams made from potato starch

Single use food packaging made from expanded polystyrene (EPS) is generally discarded after use and, since it is a difficult material to recycle, generates a large amount of waste. The EPS can be replaced by thermoplastic starch (TPS) foams, which are made from renewable sources and are biodegradable. However, TPS foams are hydrophilic and absorb large amounts of water, which makes it difficult to use. An alternative to this problem is to chemically modify the starch to make it more hydrophobic. Two modifications for potato starch were evaluated: acetylation and esterification with maleic anhydride. Foams with 6.67%, 13.34%, 20% and 26.67% (modified starch weight/ total starch paste mass) of modified starch were prepared. While TPS foams without modified starch absorbed 75 g water /100 g solids, foams with 13% acetylated starch and 20% esterified starch presented lower absorption results (42 g and 45 g water/100 g solids, respectively), which represents an improvement in water resistance.