Moisture sorption isotherm modelling of cassava starch edible films incorporated with glycerol and kaffir lime for food packaging

The moisture sorption isotherm (MSI) of the cassava starch edible film with added of glycerol as a plasticizer and kaffir lime oil as essential oil was studied. The MSI were determined gravimetrically over a relative humidity of 6.1 – 97% at room temperature 25°C. The film then was weighed and calculated to obtain the equilibrium moisture content (EMC) value. The graph between EMC and water activity (aw) was plotted. The models of moisture sorption isotherm GAB, BET, Olswin, Helsey, Peleg and Langmuir were applied to describe the moisture sorption behaviour by varying the composition of kaffir lime oil from 0 mL, 0.20 mL, 0.4 mL, 0.6 mL, 0.8 mL and 1.0 mL. The MSI modelling shows that Peleg model is the best fitted model to describe the moisture sorption behaviour for this starch film with the regression coefficient (R2) values are 0.9811, 0.9895, 0.9885, 0.9927, 0.9983 and 0.9969 respectively. This research also proves that the addition of kaffir lime essential oil could reduce the equilibrium moisture content toward the film.