Moisture sorption isotherm and isosteric heat of sorption of edible films made from blends of starch, amylose and methyl cellulose
2012
Chowdhury, T. | Das, M.
Effect of incorporation of amylose, and methylcellulose in glycerol-water as well as glycerol-polyethylene glycol-water plasticized starch films on their moisture sorption characteristic was determined at 25, 35, and 45oC using isopiestic vapor transfer technique. Among the three models like GAB, modified Oswin and Peleg for sorption, modified Oswin was found to be the best describing the behavior. Within the temperature range studied, methylcellulose reduced the moisture content of starch film for both the plasticizer systems. For amylose incorporation, reduction in equilibrium moisture content occurred at all the temperatures for glycerol-water plasticizer, whereas for glycerol-polyethylene glycol-water such effect was evident at 25ºC only. Addition of amylose and methylcellulose, respectively, increased and decreased the net isosteric heat of moisture sorption of control starch film; for all the films developed, exponential function fitted the net heat of sorption values at various moisture contents
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