thermal properties

This study aimed to investigate the effect of chemical modification with adipic acid/acetic anhydride mixture (1:30) on the physicochemical and functional properties of amaranth starch and also to determine the optimal conditions for amaranth starch chemical modification with the mentioned mixture. Amaranth starch was isolated and then modified under nine different treatments designed by the Taguchi method using three main chemical modification factors, including the mixture of adipic acid /acetic anhydride concentration (4%, 6%, and 8%), reaction time (60, 90 and 120 min) and suspension pH (8, 8.5 and 9). Swelling power, solubility, color, paste clarity, thermal properties, freeze-thaw stability, and apparent viscosity of starch samples were investigated. Modification optimal conditions were determined using Taguchi analysis and the related percentage deviation (RPD) method. The result obtained from this study showed that the chemical modification significantly changed the physicochemical and functional properties of amaranth starch. Adipic acid/ acetic anhydride mixture improved the swelling power, solubility, viscosity, and paste clarity of modified starch than native. Modified starch powders showed more lightness, less yellowness, and redness in color. Chemical modification reduced gelatinization temperatures, gelatinization enthalpy, and freeze-thaw stability. However, since other food components such as sugars, salt, hydrocolloids, etc., influence the freeze-thaw stability of starch, the possibility of modified amaranth starch utilization as a stabilizer, thickener, or fat replacer in food products with the mentioned mixture needs additional research is required to be conducted. The optimum modification conditions were a concentration of 6%, a reaction time of 120 minutes, and a pH of 9.

The objective of this research was to investigate the feasibility of edible film made from salep in which the hydrophobicity of film was modified by using stearic acid as a lipid agent. In addition its mechanical, thermal, permeability and color changes of film were analyzed. For this purpose, edible composite films were prepared from salep, stearic acid, and tween 80 in emulsion form using an ultra turax apparatus. The water vapor permeability (WVP) of the emulsified films was reduced by fatty acid addition. Also the permeability to oxygen of the emulsified films was lower than that of a salep film without fatty acid, but the difference was not significant in higher concentration of stearic acid. Scanning electron microscopy (SEM) was also used in order to analyze films microstructure. Finally, differential scanning calorimetry showed that the glass transition temperature (Tg) of the salep film was 12 °C and was considerably affected by stearic acid concentration.

In this study, low soluble and mechanical-tension resistant nanocomposite films were developed by adding different concentrations (5, 10 and 15% dw) of nanoclay type Cloisite Na (CNa) to the soy flour polysaccharide. In order to investigate the physico-mechanical, structural and thermal properties of the developed nanocomposite, it has been synthetized by soluble molding method. When the nanoclaywas added to the biopolymer film, water solubility decreased, although the aforementioned trend was more significant when the concentration of the nanoclaywas raised. The film transparency was significantly declined when the nanoclay was added. By adding the nanoparticle, the film strength increased and this was increased when the nanoparticle concentration increased. Elongation at break decreased when the nanoparticle concentration was increased. The XRD results indicate that pure film specimen is amorphous whereas the biopolymer structure is becoming order and crystallinity increased when the nanoparticle was increased. These results revealed the peaks shifting to the lower degrees, increasing the interspace between nanoclaylayers and intercalation. From morphological point of view, a homogenous texture caused by adding nanoparticle to the polymer matrix was investigated using SEM. This study aimed to be successful for using the soy polysaccharide film as well as nanoparticle in order to introduce a new film in which used for nanocomposite synthetize.

In this study, emulsified nanocomposite films based on carboxymethyl cellulose (CMC) - titanium dioxide (TiO2) (rutile phase) were made by casting method. In order to investigate the resulting films characteristics, different tests including X-ray diffraction (XRD) analysis, water vapor permeability (WVP), Atomic force microscopy (AFM), UV-VIS transmittance spectra and differential scanning calorimetry (DSC)were performed. TiO2 nanoparticles, as a filler, were added to the CMC –oleic acid emulsion at different concentrations (0.5, 1, 2% w/w) after homogenization by an ultrasonic device. Study of nanocomposite structure by XRD test showed that nanofiller have been homogeneously dispersed in the biopolymer matrix .The WVPsof the films were reduced significantly from 7.15×10 -8 g/m.h.Pa in the control sampleto 6.09×10 -8 g/m.h.Pa in the films containing2% nanoparticle. Topography images obtained from AFM showed that addition of TiO2nanoparticles increased the roughness of CMC based films. The ultraviolet and visible radiation transmittance values in the nanocomposite containing 2% TiO2 nanoparticles were 15.13% and 30.58%, respectively, i.e., 85% of UV radiation and 70% of VIS radiation were absorbed or scattered. DSC test showed that, the glass transition temperature increased from 86.65 ˚C in the control film to 81.4 ˚C in the film containing 2% nanoparticle.

Barley is an ancient and important cereal grain crop in iran. Complete knowledge of properties of barley grains such as physical¡ mechanical and thermal properties has a decisive importance for the realization of many technological processes¡ especially for monitoring of their qualities and health harmlessness during their production and storage. The aim of this study was to measuring of Physical¡ Mechanical and Thermal Properties of two varieties of persian barely grain¡ Nosrat and Kavir. For this purpose¡ effect of moisture content at four levels of 7.3¡ 12.1¡ 16.8¡ and 21.6% d.b. for Nosrat variety¡ and four levels of 6.7¡ 11.6¡ 15.4¡ and 21.2% d.b. for Kavir variety¡ on some physical properties of barley grain was studied. Effects of moisture content¡ grain orientation¡ and variety on mechanical properties namely¡ rupture force Strain energy density were determined. In addition¡ thermal properties of barley grain varieties such as specific heat¡ thermal conductivity¡ and thermal diffusivity at initial moisture contents of the grains and temperature of 25°C¡ were measured.The results showed that¡ with increasing moisture content¡ length¡ width¡ thickness¡ arithmetic mean diameter¡ geometric mean diameter¡ sphericity¡ surface area¡ thousand grains mass¡ angle of repose¡ and static coefficient of friction on various surfaces¡ for both varieties increased. Bulk density and true density of the two varieties increased as moisture content increased. The effect of moisture content on porosity of the two varieties of barley grain was not significant. With increasing moisture content¡ the rupture force for both varieties decreased¡ while the rupture energy of the varieties increased. In addition¡ rupture force and Strain energy density for both varieties under horizontal orientation was higher than vertical orientation The average value of the rupture force for Nosrat variety was obtained as 104.28 N¡ varying from 53.11 to 172.39 N¡ while the value for Kavir variety was 71.76 N¡ varying from 40.88 to 111.72 N. The mean value of the rupture energy for Nosrat variety was calculated as 54.38 mJ¡ ranging from 29.10 to 78.24 mJ¡ while the value for Kavir variety was 60.65 mJ¡ in the range of 40.33 to 77.43 mJ. There is not any significant difference between the two varieties in the case of thermal properties.