Properties of agar-based CO2 absorption film containing Na2CO3 as active compound

• Na2CO3 incorporated agar-based films were fabricated for absorbing CO2 and water vapor.
• Their use is desired as inner insert inside food packages due to apparent properties.
• CO2 and water vapor absorptions went parallel in relative dependence on extra additive.

A CO2–H2O absorption smart film was prepared from solutions containing agar (2% of water) as matrix and water vapor absorbent, glycerol (30% of agar) as plasticizer, Na2CO3 (300% of agar) as CO2 absorbent and/or additive (50% of agar) as CO2 absorption rate regulator. The objectives of this work were to develop an active insert film based on agar and Na2CO3 with controlled CO2 absorption rate and water absorption capacity. For this purpose, ingredients of lecithin, vitamin E powder and polysorbate were examined as extra additive to control the CO2 absorption. Apparent, mechanical and both CO2 and water vapor absorption properties were investigated. The inclusion of additives in matrix resulted in film's lower transparency, higher tensile strength and lower elongation at break. Adding lecithin, vitamin E powder or polysorbate into matrix did not change both CO2 and water vapor absorption capacities of agar-based films incorporated with Na2CO3. However, the rates of CO2 and water vapor absorptions went parallel in their relative dependence on the additive, both being reduced when incorporated with the lipophilic lecithin.