Effects of salep gum at concentrations of 0.5%, 1%, 3%, and 5% (w/w flour basis) and the Persian gum at concentrations of 0.5%, 1%, and 3% (w/w flour basis) and combination of the two gums at concentrations of 0.5% + 0.5%, 0.75% + 0.25%, and 0.25% + 0.75% on rheological properties of the wheat flour dough and quality of Taftoon bread were studied with regard to retardation of staling. Rheological (farinograph and extensograph) characteristics, staling, and organoleptic evaluations were performed on the dough and the resulting Taftoon bread. Statistical results showed that the salep gum at 5% and Persian gum at 3% (w/w flour basis) had a significant effect on the dough properties. Salep and Persian gums when each separately added increased and decreased dough water absorption, respectively. Both hydrocolloids increased the dough resistance to extension and decreased its extensibility. Persian gum shows dual nature in water absorption and some other baking properties. Textural studies revealed that addition of 5% salep gum (w/w flour basis) reduced the bread crumb firmness and delayed the staling process of the Taftoon bread. X-ray diffraction study also confirmed this result.

A B S T R A C TBackground and Objectives: Preparation and evaluation of nanocomposite films have become prevalent in recent years. Depending on the purpose of using the film, and considering the effects and interaction effects of nanomaterial and other modifiers on the film properties, the amounts of nanomaterials and modifiers should be optimized. The effects of montmorillonite (MMT), glycerol (GL), and their interaction effects on the properties of polyvinyl alcohol-montmorillonite (PVA-MMT) films were evaluated in this research. Materials and Methods:PVA-MMT films were produced based on a full factorial experiment in a completely randomized design (CRD) with 16 treatments and three replicates. There were two factors with four levels: MMT (0, 5, 12, and 20% weight per weight of polymer W/WP), and GL (0, 10, 30, and 50% W/WP). The films were characterized by mechanical properties, opacity, water vapor permeability (WVP), and color.Results: MMT increased tensile strength (TS), b*, yellowness index (YI), and opacity of the films. MMT, however, reduced elongation (E%) and WVP of the films. The effect of GL on the films was quite opposite the MMT. In addition, the interaction effects of MMT-GL on WVP, YI, and b* were significant (p<0.01). MMT contents could reduce WVP just in the presence of GL in the films, while GL contents could increase WVP at all MMT concentrations. Furthermore, MMT contents could increase YI of the films at all GL concentrations, while GL could increase YI just at 20% MMT content. Strong affinities of MMT, and GL with PVA were proved by FTIR. Conclusions:Considering the target of utilizing PVA-MMT films, appropriate concentrations of MMT, GL, and their proper combination should be selected.

Methylcellulose-montmorillonite films were prepared via solvent casting method. The effects of different ultrasound times (0,15,30, 45, 60, and 75 min) on the properties of methylcellulose-montmorillonite films were evaluated. Fourier transform infrared and X-ray diffraction were applied to investigate and prove the effects of ultrasound time. The films were characterized by mechanical properties, opacity, water vapor permeability, yellowness index, and color. Ultrasound time significantly affected the characteristics of the films, except for elongation. Maximum tensile strength, opacity, YI, and b* as well as minimum L* and water vapor permeability were related to 60 min. The results from X-ray diffraction and Fourier transform infrared verified the effects of sonication time on the films properties, especially for 60 min. The Fourier transform infrared spectrum related to 60 min had more new and sharper peaks. The maximum compactness and strength of methylcellulose-montmorillonite films and the highest X-ray diffraction peak were also attributed to 60 min. Using ultrasound radiation for the production of such films is strongly recommended. To obtain the best quality and reach the required properties, considering the aim of the films, optimization of sonication time is mandatory.