With the use of Fourier Transform Infrared (FTIR) analysis applied to methylcellulose (MC) films, the hydrogen bonding formation between MC-MC molecules and between MC and a series of different-molecularweight PEGs was studied. The spectra of the films were interpreted in terms of the symmetry distortion of hydroxyl stretch at 3466.5 cm Ϫ1 , which is the measure of hydrogen bonding interactions in the polymer matrix. The symmetry distortion was determined to be affected by the MC concentration, indicating the presence of intra-and intermolecular hydrogen bonding between MC molecules. Neither ethanol nor its concentration influenced the symmetry distortion. A competition for hydrogen bonding via hydroxyl groups between MC-MC and MC-PEG occurred when PEG was incorporated into the polymer matrix.

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Desorption isotherms of unblanched and blanched red peppers were experimentally obtained at 30C. The desorption data were exploited to estimate equilibrium moisture contents of the peppers at drying temperatures other than 30C by using a semi‐empirical method. Red pepper samples were dried in a tunnel‐type drier with an air velocity of 2 m/s at 50C, 60C, 70C, and 80C. The blanched samples dried faster than the unblanched ones. The drying behavior of unblanched and blanched samples was characterized by falling rate period, and constant and falling rate drying periods, respectively. The interphase mass and heat transfer coefficients of the blanched sample during the constant rate period were not affected by temperature and estimated to be 1.94*10−3 kg mol/s. m2 and 57.3 W/m2. K, respectively. Effective moisture diffusivity was estimated between 6.83*10−10−17.4*10−10 m2/s for the unblanched sample and 11.4*10−10−31.0*10−10 m2/s for the blanched sample within the given temperature range. Effect of temperature on the diffusivity was described by an Arrhenius‐type equation with an activation energy of 28.4 kJ/mol for the unblanched pepper and 33.3 kJ/mol for the blanched pepper.

Water vapour permeability (WVP) and mechanical properties were assessed in edible films prepared from methylcellulose (MC) and MC-whey protein isolate (WPI) or MC-whey protein concentrate (WPC). Glycerol (Gly) was used as the plasticizer. Two MC-WP films were formulated. For Group I films, the mass ratio of WP : Gly was constant, whereas for Group II films the mass ratio of polymer (MC + WP) : Gly was constant. The WVP of MC-Gly film decreased with increasing MC concentration, while the tensile strength (TS) and percent elongation (E) increased. The WVP of Group I and Group II films decreased erratically and TS increased when the MC concentration was increased. Group I films had higher TS values than Group II films at the same MC : WP ratios. E of both groups increased with increasing MC concentration (p < 0.05), excluding the films with the highest MC : WP ratio tested (0.8) in Group I films. Group I films had lower E values than Group II films at the same MC : WP ratios. MC effectively governed WVP, TS and E of the WP films. Generally, MC-WP films of this work showed lower WVP than that of MC-and WP-based edible films in the literature. This can potentially make MC-WP films a suitable film material for moisture-sensitive food products.