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Water Sorption Isotherm of Pea Starch Edible Films and Prediction Models
Bahareh Saberi1, Quan V Vuong2, Suwimol Chockchaisawasdee3
1School of Environmental and Life Sciences, University of Newcastle, Ourimbah NSW 2258, Australia. bahareh.saberi@uon.edu.au.
Foods (Basel, Switzerland)
|February 24, 2017
Summary
Glycerol-plasticized pea starch films absorb more moisture at higher relative humidities and lower temperatures. The Lewicki model best describes this moisture sorption behavior, crucial for film stability.
Area of Science:
- Food Science and Technology
- Materials Science
- Physical Chemistry
Background:
- Pea starch films are biodegradable materials with potential applications in packaging.
- Plasticizers like glycerol are used to improve film flexibility and processability.
- Understanding moisture sorption is critical for predicting film stability and performance.
Purpose of the Study:
- To investigate the moisture sorption isotherms of pea starch films plasticized with glycerol.
- To determine the effect of temperature and relative humidity on moisture adsorption.
- To identify the best-fit model for describing the sorption data.
Main Methods:
- Gravimetric method used to measure equilibrium moisture content at various temperatures (5-40°C) and relative humidities (11-96% RH).
- Experimental data fitted to multiple sorption models (Oswin, Henderson, BET, Flory-Huggins, Iglesias-Chirife, GAB, Ferro-Fontan, Lewicki, Peleg).
- Net isosteric heat of sorption analyzed.
Main Results:
- Equilibrium moisture content increased significantly above 0.6 water activity.
- Glycerol-plasticized films showed higher moisture adsorption across all conditions.
- Lower temperatures enhanced equilibrium moisture content and monolayer water.
- The Lewicki model provided the best fit for the experimental data (11-98% RH).
- Glycerol addition increased the net isosteric heat of moisture sorption.
Conclusions:
- Glycerol content significantly influences the moisture sorption behavior of pea starch films.
- The Lewicki model accurately predicts moisture sorption for these films.
- Findings are vital for assessing film stability and functionality in diverse environmental conditions.
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