• Investigation of physicochemical and functional properties of gum extracted from Serish root (Eremurus Luteus)

Mahdi salahi

Supervisor: Seyed Mohammad Ali Razavi

In this study, physicochemical properties (chemical compositions, monosaccharides, and uronic acid) and functional properties (intrinsic viscosity, flow behavior, foaming capacity-foam stability, and texture analysis) of Serish root gum (SRG) were measured as a new source of hydrocolloid. The results of chemical compositions showed SRG, on average, consisted of 86 ± 0.35% carbohydrate, 6.22±0.07% protein, 6.13±0.15% moisture, and 4.17±0.06% ash. The main sugars of SRG were glucose (50%) and mannose (45%), indicating the glucomannan structure of SRG. Also, a considerable amount of uronic acid (6.8%) was observed in this gum. The intrinsic viscosity calculated using Huggins and Kramer equations were 6.32 and 6.35 dL/g. The flow behavior of SRG at all concentrations and temperatures was non-Newtonian shear thinning which was well described by the power-law model. The apparent viscosity of SRG at 1% (w/w), 50 s-1, and 25 oC was determined as 250 mPa.s. The foaming capacity and stability of SRG were 85% and 72%, respectively. Hardness, adhesiveness, and consistency of this gum at 3% (w/w) concentration were obtained as 564 (g), 318 (g.s) and 1326 (g.s), respectively.

• Evaluation of physicochemical, rheological and functional properties of nettle seed (Urtica pilulifera) gum

Zahra zamani

Supervisor: Seyed Mohammad Ali Razavi

Hydrocolloids are high-molecular-weight biopolymers, and they are used in food products as gelling and coating factors, texture modifiers, stabilizers, emulsifiers, dietary fiber, and fat replacer. Because of the increasing requests for hydrocolloids, with specific practicality in current societies, introducing new hydrocolloid origins with suitable effects is an essential area of study in the food industry. Within commercial hydrocolloids, those who extracted from seeds are widely applied in food applications primarily due to their proper cost, easy to access, and appropriate performance. Gums are polysaccharide-based hydrocolloids, and they are mostly originated from plants, marine sources, or bacterial excretion. Urtica pilulifera L. is a plant that sorted in the Urticaceae family. Seeds are obtained from the mature fruits of U. pilulifera. When it is put in water, a layer of mucilage occurs on the seeds. Nettle as a medicinal plant and dietary supplement has a long history of the study. The plant is used in cardiovascular problems, stomach pain, rheumatic pain, cough, and liver failure. Chemical composition of this gum consisted of 9.5±0.4% moisture, 15.3±0.76% ash, 10.42±0.12% protein, 63.09±1.69% carbohydrate, 1.02±0.87% fat, and 10.75±0.98 uronic acid. The main sugars that existed in this gum were Galacturonic Acid (24.71±7.44) and rhamnose (13.98±4.9). The existence of glycoside bonds and carboxyl, hydroxyl and, methyl groups in the FT-IR spectra of this gum indicated that nettle seed gum known as a typical polyelectrolyte. Differential scanning calorimetry (DSC) showed the first and second peak of nettle seed gum thermogram at 85.83oC with enthalpy - 222.36J/g and 236.33oC with enthalpy -65.14J/g, respectively. Moreover, the antioxidant activity of the Nettle seed gum at a concentration of 2000 μg/mL was (53.18%). After fitting of semi-dilute and dilute experimental data, Herschel-Bulkley and Higiro2 models were the appropriate model to explain their behaviors, respectively. The intrinsic viscosity of nettle seed gum was in the range of 0.208–0.150dl/g. investigating of viscometric properties of nettle seed gum in the dilute region suggested random coil conformation. Nettle seed gum has hardness, consistency, adhesive Force and viscosity Index in terms of texture. Increasing the concentration increased these parameters. The surface tension results demonstrated that various factors, including protein content and Uronic acid, the affected surface activity of samples. Interfacial tension without adding gum between the water and oil phases 15/15 mN/m was reduced while adding 2% nettle gum to7.08 mN/m. The findings showed that with increasing concentration from 0.25% to 2%w/w, the emulsion capacity and emulsion stability increased, So that the stability of the emulsion at a concentration of 2% was 96.33%; but by enhancing gum concentration, the foaming stability and capacity would be decreased; this might be conducted with the primarily increased viscosity prevents air from entering the system also surface active groups are likely to play a key role in preventing air bubbles from leaking.

3.   Influence of cress seed gum on dilute and concentrated solutions properties of wheat starch in the presence of sucrose

Shokufeh Taziki

Supervisor: Seyed Mohammad Ali Razavi

Advisior: Mahdi irani

 The objective of this study was to investigate the effect of substitution levels of cress seed gum (CSG) (0, 5, 10, 15%) and sucrose (SUC) (0, 5, 10%) on the rheological properties (in the dilute and concentrate regimes), textural characteristics and prediction of retrogradation behavior of wheat starch (WS). The increasing of cress seed gum concentration increased the intrinsic viscosity from 0.271 to 0.326 dl/gr. The molecular conformation of starch moved toward from random coil to rod-like. The substitution of wheat starch with CSG enhanced the specific swollen volume from 0.271 to 0.326 dl/gr and altered the shape factor parameter from spherical to oblate or prolate. In contrast, sucrose with decreasing the solvent quality decreased the intrinsic viscosity to 0.379 dl/gr and the specific swollen volume to 0.150 dl/gr, altered the conformation to more random coil and the shape factor to more compact of sphere. In the mixture systems (especially at high concentration of CSG and low concentration of SUC), the intrinsic viscosity value estimated close to the control and the other parameters had similar results with starch-gum mixture. The time-dependent and time-independent behaviors of all the starch gel samples at selected gum and sucrose substitution levels exhibited a thixotropic and shear thinning behavior with yield stress, respectively. Higher apparent viscosity, consistency coefficient and yield stress values were obtained for the starch-gum gels than the starch-sucrose gels. The mixture gels had a higher apparent viscosity and consistency coefficient and stronger shear thinning behavior than the wheat starch gel. Cress seed gum had a great effect on reducing the hardness (from 140.00 to 55.50 g) and the consistency (from 6.85 to 3.00 mJ) of wheat starch gel during storage for 14 days at 4 ℃. Also, the hardness and the consistency of starch-sucrose gels decreased to 113.50 g and 5.10 mJ, respectively. The mixture gels (especially at high concentration of the gum) had lower hardness (45.50-50 g) and consistency (2.50-2.80 mJ) compared to the wheat starch gel. In addition, the syneresis decreased from 50.58% to 23.41% as a result of gum addition but increased to 57.43% with sucrose addition. The syneresis of the mixture gels (at high concentration of the gum) was estimated in the range of 45.90-46.00%.

4. Optimization of sage seed (Salvia macrosiphon) gum extraction using dry method and investigation of its physicochemical and rheological properties

ahmadreza hosseini

Supervisors: Seyed Mohammad Ali Razavi, Masoud Taghizadeh

In this research, after designing and manufacturing a gum extractor based on friction (dry method) from Salvia macrosiphon seeds, box-behnken design was used to optimize extraction conditions. This method was designed to achieve an economical, inexpensive, fast, eco-friendly (green technology), continuous, easy usage and automated method. The independent variables in this research were rotor speed (750, 825, 900 rpm), angle of friction (0, 10, 20 degree) and friction distance (1.5, 2, 2.5 mm). The effect of these variables on extraction yield, protein content and apparent viscosity (shear rate 46 1/s) was investigated. The results shown quadratic polynominal models adequately explained the data variation and represented the actual relationship between independent variables and responses. The extraction yield and apparent viscosity at the optimum conditions was maximum, while protein content was minimum. In the optimum condition the rotor speed, angle of friction and friction distance were 900 rpm, 6.9 degree, 2.2 mm, respectively. In this condition extraction yield, protein content and apparent viscosity were 10.61%, 7.02% and 112 mPa.s, respectively. Solubility in this condition was 41% and water absorbtion capacity was 13.73 g/g. Also for wet method in the optimum condition respectively was 72% and 18.32 g/g, respectively. Both samples extracted under dry and wet optimum conditions shown a thixostropic behavior. Also the wet method had a higher extent thixotropy. The first-order stress decay model with non-zero equilibrium stress value was able to describe the rheological behavior derived from both extraction methods. Power-law and Herschel-Bulkley models had also been able to describe the pseudoplastic behavior of gum solutions.

5. Functional properties and retrogradation behavior of native wheat starch gel in the presence of sage seed gum and whey protein concentrate

Negar Mirnezhad Anbarani

Supervisors: Seyed Mohammad Ali Razavi, Masoud Taghizadeh

In this study, the effects of sage seed gum (SSG) and whey protein concentrate (WPC) at 5% and 10% substitution levels on the physicochemical properties, rheological behavior, textural attributes and retrogradation kinetics of native wheat starch (NWS) gel were investigated. Weltman and power-law models were found to be the best models in describing the effects of SSG and WPC on the time-dependent and time-independent rheological behavior of NWS gel, respectively. The substitution of NWS with SSG enhanced the swelling of starch granules, viscosity, and pseudoplasticity of NWS gel, while the replacement of NWS with WPC decreased the swelling power and viscosity of NWS gel. SSG had an outstanding effect on reducing the syneresis of NWS gel during storage at 4°C and -18°C, indicating the improvement of cold storage stability of starch gel. From the back-extrusion test, it was found that substitution of NWS with SSG increased hardness, cohesiveness, adhesive force and adhesiveness of starch gel, while these textural attributes were decreased by substitution of NWS with WPC. The effect of SSG on retrogradation behavior of NWS gel was concentration-dependent and it retarded the retrogradation of NWS gel at 5% substitution level. Substitution of NWS with WPC reduced the retrogradation kinetics rate, which was more pronounced at 10% substitution level. However, it was proved that the interactions of SSG and WPC led to a noticeable decrease of retrogradation kinetics rate, indicating the significant retarding effect of these blends on NWS retrogradation rate.

6. Effect of Temperature and Selected Salts and Sugars on Dilute Solution Properties of Two Hairless Canary Seed Varieties

Ali Heydari

Supervisor: Seyed Mohammad Ali Razavi

Advisior: Mahdi irani

This research focused on understanding the molecular behavior of starches from two canary seed varieties (C05041 and CDC Maria), as a new potential source of starch, under different experimental conditions. For this purpose, the influence of temperature (25, 35, 45 and 55°C) sugar type (sucrose and lactose) at different concentrations (0, 5, 10 and 15%) and salt type (NaCl and CaCl2) at different concentrations (5 to 100mM) on some molecular parameters of Canary seed starches (CSSs) were investigated. The results indicated that the intrinsic viscosity ([η]) values of C05041 starch and CDC Maria starch decreased significantly, although the effect of high temperatures were somewhat unnoticeable. By increasing the sugar and salt concentration, at all selected temperatures, intrinsic viscosity of each starch solution significantly decreased in comparison with the value determined for sugar free solution. At all temperatures, the influence of sucrose on the [η] reduction of C05041 starch was more than CDC Maria. Meanwhile, lactose had more pronounced effect on the decreasing intrinsic viscosity of CDC Maria starch at 25°C and 35°C compared with sucrose (P<0.05). But in 55°C, the effect of increasing sucrose concentration on decreasing of [h] of CDC Maria and WS samples were more considerable. The shape factor of starch samples at 25°C were spherical, but increasing temperature from 25°C to 55°C, sugar and salt concentration CSSs took an ellipsoidal shape. Results depicted that the influence of NaCl on the [η] reduction of CDC Maria starch and WS was more than C05041 starch. Berry number and the slope of master curve revealed that CSSs solutions at all temperatures and salts concentrations were in the dilute domain and no molecular entanglements occurred. The importance of these results will be cleared when taking into account the influence of crucial additives generally used in food systems, for instance, different sugars, salts and/or frequent processing parameters such as temperature on rheological and functional properties.

7. Functional properties of mucilage extracted from marshmallow flower (Althaea officinalis)

Fateme Mousavi

Supervisors: Seyed Mohammad Ali Razavi, Arash Koocheki

This study evaluated the effects of different levels of marshmallow flowers (Althaea Officinalis) gum (MFG) (0.25, 0.5, 1.0 and 2.0%), temperature (5, 25, 45 and 60 oC) and pH (5,7, 9 and 11) on the rheological, physical and chemical properties of MFG. The results revealed that MFG was composed of 13.4% (w.b) moisture, 42.86% total carbohydrate, 8.58% protein, 12.11% ash, 12.54% uronic acid respectively. Moreover FT-IR analysis of MFG confirmed the presence of uronic acid as it had absorptions at wavenumber 1400 and 1600 cm−1. Other peaks observed in the FT-IR spectrum of the sample were assigned as 1425 cm−1 (stretching of carboxylate ion, COO-), NH amide (637 cm−1) and O-H stretching vibration (3357 cm−1). DSC thermal profile in powder form showed endothermic event at 85.06 and 239.51 oC . In addition, this antioxidant potential of MFG corresponded with the results of DPPH spectrophotometric assay, so that by increasing the concentration(0 –1.2 mg/mL), increased antiradical activities (11.28- 25.28%). The mucilge solutions exhibited non-Newtoni and anpseudoplastic. An increase in concentration, decreased the flow behavior index, n (0.1889- 0.4866), and increased the consistency coefficient; k (0.2363 – 24.18 Pa.sn). The shear viscosity of the mucilage was temperature dependent and decreased with increasing temperature. An Arrhenius model was also used to describe the effect of temperature. The activation energy (Ea) appeared in the range of 5396.63 - 8480.28 J/mol at as concentration increased from 0.25 to 2%.Among various models for evaluation of the intrinsic viscosity, Tanglertpaibul-Rao model showed a higher performance to determine intrinsic viscosity of Althaea officinalis mucilage at all temperatures (25, 45 and 65℃). By increasing the temperature from 25 to 65℃, the intrinsic viscosity decreased (22.29 dl/g). The surface and interfacial tensions of MFG at various concentrations shows that increasing mucilage concentration slightly reduced the surface and interfacial tensions at air/water and oil/water interfaces. No significant difference was observed in emulsions zeta potential when pH increased from 5 to 9. At pH 7 (-46.6 mV at 0.5w/w), the zeta values of the emulsions slightly decreasing.For prepared emulsions, the mean diameter of droplets slightly decreased from 1.47% to 1.21% as gum concentration increased. The presence of MFG in these emulsions increased the emulsion stability indices, evidently because of the higher viscosity it imparted to the aqueous phase. The emulsions containing MFG were examined to fit the experimental data; of which Herschele–Bulkley model was found to be the best model to describe steady shear flow behavior of these emulsions.