Moisture Sorption Isotherm Modeling Approach and Effect of Packaging Material on Quality Changes in Extruded Product Stored Under Controlled Conditions

The aim of this study was to investigate the moisture sorption isotherms and the effect of storage on the quality of extruded snacks packed in low-density polythene and aluminium-laminated polythene at ambient (51 ± 1%, Relative humidity and 30 ± 1 °C, temperature) storage conditions. Moisture sorption isotherms were determined at temperature range 25–45 °C and relative humidity from 11 to 84% using the standard gravimetric static method. The experimental data were analyzed using five model equations such as GAB, Oswin, Smith, Caurie, and Halsey. The sorption isotherms for extruded product exhibited sigmoid curve of type II behavior and were found to be decreased with increasing temperature. The GAB, Oswin, Smith, and Caurie models were found to be the most suitable for describing the sorption curves. Storage stability in terms of quality parameters such as moisture content, lateral expansion, bulk density, hardness, color and sensory characteristics was assessed in both pouches. The extruded snack packed in low-density polythene pouches showed greater changes to quality parameters in comparison to aluminium-laminated pouches during storage. Therefore, it was suggested that aluminium-laminated pouches can store extruded product for a longer time period than low-density polythene pouches.