M.N. Nasriyanti, Noor Aziah, A.A. and R. Ahmad
Abstract
Mung bean protein isolate was prepared from mung bean (Vigna radiata) flour by extraction with 1N NaOH and precipitated at pH 4 with 1N HCl. Glycerol 3% (w/v) was added to the mung bean protein isolate 5% (w/v) solution to form a transparent edible film. The films were then adjusted to pH 8, 10 and 12 with 2N NaOH and dried at 60 °C for 12 h. The water vapour permeability of the films was evaluated using the ASTM Method E96-80, the tensile tests of the films were evaluated using the ASTM Method D882-80a, with some modifications. The water vapour permeability of protein (5%) films at three different pH did not differ significantly (p <0.05). The protein film at pH 8 has a higher moisture sorption isotherm than those made at pH 10 and 12 as a function of aw. The elastic modulus differed significantly (p <0.05) between the protein films at aw 0.22. The tensile strength of protein film at pH 8 was significantly lower (p <0.05) than those of protein films at pH 10 and 12 at aw 0.22–0.84. Protein film at pH 12 was significantly higher (p <0.05) on elongation percentage than at pH 8 and 10 at aw 0.22–0.84.
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