Production of foam trays based on starch for using food packaging and service

The subject of the research is to produce foam trays having good mechanic strength and water resistant from starch by crosslink with glyoxal or phosphor oxychloride and adding some additives. Natural corn starch cross linked by using two different cross linking agents (glyoxal, phosphor oxichloride) in different concentrations. As a result of pre-researches, it was found that it cannot be produced foam trays by starch cross linked with phosphor oxchloride. Corn starch was reacted with glyoxal at different ratios (0.127, 0.381, 0.641, 1.270 g/kg starch) and after reaction, unreacted glyoxal amount in the suspension was determined. Different amount of glyoxal (0.126, 0.269, 0.271, 0.468 g/kg, respectively) was cross-linked with starch depending on added amount of glyoxal. Gelatinization temperature of starch decreased while peak viscosity and end viscosity values of starch increased proportionally to the degree of cross-linkage. Both the visual observation and micrograph view of the trays produced from natural starch show that native cornstarch trays had a surface with a lot of small holes and occasionally cracks. No cracks and holes were seen on the surface of trays made from cross-linked starches. It was found that the density of the trays produced from starch cross-linked with 0.126 g/kg and 0.269 g/kg glyoxal (G1 and G2) was 61% less than native starch trays. The water absorption capacity of the native starch trays was found as 95.5% however that of trays made from G1 decreased to 44.7%. The amount of glyoxal migrated from trays (produced from G1) to food like material was determined. It was found that 0.175 mg/dm2 glyoxal migrated from the trays in an hour. This value is nearly 10 times less than the glyoxal limit that can migrate from papers contacting with food was established by German Federal Institute for Risk Assessment (BfR). The result of all the analysis showed that the trays produced from G1 had superior properties than the other trays. Further developing of properties of the trays, trays were prepared by adding corn fiber, kaolin and beeswax at different amounts. The result of visual inspection and analysis, it was found that 10% corn fiber, kaolin or beeswax addition to the tray formulation decreased water absorption capacity and increased physical properties of the trays. Also trays were produced by adding two or three combinations of corn fiber (%10), kaolin (10%) and beeswax (10%) and their properties were investigated. It was found that the water absorption capacities of the trays produced by adding kaolin + beeswax, fiber + beeswax and fiber + kaolin + beeswax combinations were 13%, 14% and 9%, respectively. Furthermore, all the mechanical properties of these trays were superior to the trays produced from only G1.As a result of this study, it was concluded that the best trays that can be used in food packaging and service could be produced by adding corn fiber + beeswax, kaolin + beeswax or kaolin+ fiber+ beeswax combination to the G1.