Research Institute of Food Science and Technology RIFST


Research Institute of Food Science and Technology RIFST


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Rafe A.,Research Institute of Food Science and Technology RIFST | Razavi S.M.A.,Ferdowsi University of Mashhad
Food Hydrocolloids | Year: 2017

The scaling behavior and fractal analysis of basil seed gum (BSG) cross-linked with sodium trimetaphosphate (STMP) have been investigated by rheological small amplitude oscillatory shear measurements. Storage modulus and critical strain (γo) of the gels exhibited power law relationships with BSG concentration. Based on the power-law exponent values, the fractal dimension (df) of gels was estimated using scaling models, revealed the weak-link regime of BSG. The df values lied well within the range of fractal dimension values (1.5–2.8) reported for protein gels. However, they slightly differed from df for diffusion-limited and reaction limited cluster-cluster aggregation processes. Stress sweep test was shown that STMP addition to BSG made a stronger gel than that of BSG lacking STMP. Mechanical spectrum of gels was also revealed that adding STMP can improve the elasticity of gels. BSG had a tan δ of >0.1, indicating paste-like weak gel, while tan δ of BSG-STMP has approached to 0.1 exhibited the character of a cross-linked network near to “true gel”. BSG-STMP was also recognized as a thermo-reversible physical gel, which gelation and thermal properties did not affect by STMP. Therefore, the scaling behavior can be applied for hydrocolloids gels to extract structural information through rheological measurements. Moreover, the rheological characteristics of BSG-STMP showed it can be used as a proper hydrogel in food and pharmaceutical applications. © 2016 Elsevier Ltd

Shahbazi M.,Research Institute of Food Science and Technology RIFST | Rajabzadeh G.,Research Institute of Food Science and Technology RIFST | Ahmadi S.J.,Nuclear Science and Technology Research Institute, Iran
Carbohydrate Polymers | Year: 2017

Different electron beam doses (10, 20, 30 and 40 kGy) were tested with the purpose of investigating their influences on chitosan/clay (cloisite 20A) nanocomposite film to improve its functional performance by providing a crosslinked matrix. Water resistance, water contact angle and water barrier property of nanocomposite film were increased up to 30 kGy, and then drastically decreased at the level of 40 kGy. Characteristic diffraction peak of chitosan shifted to low angle with an increase in the interlayer spacing of the nanoclay after 30 kGy irradiation, indicating a superlative intercalation. Crystallinity degree of chitosan/clay nanocomposite was increased in the amorphous region as the irradiation dose increased up to 30 kGy. However, irradiation at level of 40 kGy was converted the crystalline region of nanocomposite film to the amorphous state with losing the chitosan crystallinity. Irradiation increased the film tensile strength due to crosslinking of chitosan chains, with more pronounced effect at 30 kGy and decreased it by chain degradation at 40 kGy. A glass transition temperature was detected in DSC thermogram of chitosan/clay film, and it shifted to higher temperatures as the irradiation dose increased. Moreover, cold-crystallization exothermic peak of the chitosan/clay film moved to the lower temperature after irradiation, suggesting a faster crystallization rate. FE-SEM showed that the chitosan chains were more intercalated between the nanoclay platelets with increasing the irradiation dose. A progressive decrease in the roughness parameters of 20 and 30 kGy irradiated nanocomposite films revealed by atomic force microscopy, whereas irradiation at 40 kGy increased roughness values. © 2016 Elsevier Ltd

Emadzadeh B.,Research Institute of Food Science and Technology RIFST | Emadzadeh B.,Ferdowsi University of Mashhad | Razavi S.M.A.,Ferdowsi University of Mashhad | Schleining G.,University of Natural Resources and Life Sciences, Vienna
International Journal of Food Properties | Year: 2013

The small and large deformation properties of different low-calorie pistachio butter formulas were studied in order to develop a background understanding of the changes in viscoelastic and textural characteristics that occur due to different types of fat replacers and sweeteners. Frequency, temperature, and time sweep analysis and also back extrusion and texture profile analysis tests were performed. The magnitudes of dynamic moduli increased in the frequency sweep test with loss tan values <1. The elastic structure of all samples changed to viscous behavior with increasing temperature (5-65°C), regardless of the type of fat replacers and sweeteners level. The temperature sweep test on heating and cooling samples resulted in higher viscoelastic properties and more solid-like behavior. There was no time dependency for loss tan at 45°C. A modified Cox-Merz rule could superimpose the steady and complex viscosity data. There was a good agreement between the results of G′ and hardness in small and large deformation tests. Copyright © Taylor & Francis Group, LLC.

Shahbazi M.,Research Institute of Food Science and Technology RIFST | Ahmadi S.J.,Nuclear Science and Technology Research Institute, Iran | Seif A.,Bu - Ali Sina University | Rajabzadeh G.,Research Institute of Food Science and Technology RIFST
Food Hydrocolloids | Year: 2016

A comparative study between the combined effects of UV irradiation/sodium benzoate and glutaraldehyde vapor/gelatin on carboxymethyl cellulose (CMC) film with low degrees of substitution was performed. The kinetics of the surface photo-crosslinking and chemical crosslinking treatments were evaluated through determination of the film fraction and swelling rate in the crosslinked CMC networks. It was found that sodium benzoate and gelatin concentrations were dominant factors compared with UV irradiation and glutaraldehyde vapor induced times. The results of surface hydrophobicity, water barrier and mechanical properties were found to be a function of both treatments, among which photo-crosslinking treatment was more effective than the chemical crosslinking process. The pronounced peaks of CMC were disappeared in the fingerprint region after both crosslinking reactions. The cold-crystallization exothermic peak of CMC shifted to the lower temperature after the crosslinking treatments, indicating that more decrease belonged to the photo-crosslinked film. X-ray diffraction pattern of the modified films revealed the emergence of new pronounced peaks, coinciding with an increase in the CMC crystallinity. Many micro-cracks were recognized on the neat CMC surface, while the crosslinking treatments eliminated the cracks. Finally, the conformity of the crosslinked films with the actual food regulations on the biodegradable materials was verified by cytotoxicity test to study the possibility of utilizing in the food packaging sector. Both crosslinked films did not show any evidence of the cytotoxic effects since it could not increase the cytoplasmic lactate dehydrogenase release from L-929 fibroblast cells in contact with the films. © 2016 Elsevier Ltd

Shahidi Noghabi M.,Research Institute of Food Science and Technology RIFST | Razavi S.M.A.,Ferdowsi University of Mashhad
Journal of Food Processing and Preservation | Year: 2015

Interest in membrane filtration in the sugar industry is increasing. Sugar, as the final product of technology of sugar production, has to satisfy rigorous quality demands. Among others, it means low content of nonsucrose compounds, as well as the smallest possible share of colored matter. This work aimed to investigate the performance of ultrafiltration in purification of thin sugar beet juice. Thin juice was processed using polysulfonamide spiral wound membrane module of 20kDa molecular weight cutoff on a pilot plant under different operating conditions including; temperature at three levels of 30, 40 and 50C, transmembrane pressure at three levels of 1, 2 and 3 bar and operation time at levels of 15, 30 and 45min. The trials displayed satisfactory separation with an average purity rise of 0.72 unit, 7% lower CaO content, 86.9% lower turbidity and 10% lower color in the permeate on a 45-min operation and at different TMP and temperature. The average flux was 21.84kg/m2h. © 2015 Wiley Periodicals, Inc.

Rafe A.,Research Institute of Food Science and Technology RIFST | Razavi S.M.A.,Ferdowsi University of Mashhad
International Journal of Food Properties | Year: 2015

Attenuated total reflection Fourier transform infrared spectroscopy was used to compare the structure of β-lactoglobulin, basil seed gum, and β-lactoglobulin-basil seed gum mixtures, at different states (powder, solution, and gel). The effects of heating and different ratios of β-lactoglobulin-basil seed gum were also investigated to determine their impact on chemical structure and understand their interaction. The results showed that gelification process proved a pronounced effect upon β-lactoglobulin secondary structure, leading to the formation of intermolecular hydrogen-bonding β-sheet structure. These results confirmed that this structure may be necessary for the formation of a gel network. Basil seed gum had a distinct peak at around 1603 cm-1 that relates to -COO-1 stretching of carboxylate salts, probably uronic acids, which approved its anionic structure. The Fourier transform infrared spectroscopy findings strongly suggested that these two polymers are thermodynamic incompatible as amide I peak was increased in the β-lactoglobulin-basil seed gum mixed system and carbon-nitrogen (CN) stretching peak was observed at 2125 cm-1. On the basis of these findings, it was possible to modify the ability of β-lactoglobulin-basil seed gum to form a gel and as a consequence to control the gelling and emulsifying properties. © 2015 Taylor & Francis Group, LLC.

Rafe A.,Research Institute of Food Science and Technology RIFST | Razavi S.M.A.,Ferdowsi University of Mashhad
International Journal of Food Science and Technology | Year: 2013

Summary: Effect of pH (4.5-7.5) and Ca2+ (0.01-0.5 m) on gelation of single and mixed systems of 10% β-lactoglobulin (BLG) and 1% basil seed gum (BSG) was investigated. The gelling point of BLG and BSG gels was strongly pH-dependent, and stiffer gels formed at higher pH. The BLG gels were formed upon heating to 90 °C and reinforced on cooling to 20 °C; however, the gelation of BSG occurred at temperatures below 70 °C. By increasing Ca2+ concentration, storage modulus of BLG and BSG gels were increased, although pH had a greater effect than Ca2+. In contrast, mixed systems showed two distinct types of behaviour: BLG gel formation and BSG network, suggesting that phase-separated gels were formed. In addition, higher strength was obtained for BLG-BSG mixture at higher Ca2+ concentration. © 2013 Institute of Food Science and Technology.

Mohammadzadeh H.,Ferdowsi University of Mashhad | Koocheki A.,Ferdowsi University of Mashhad | Kadkhodaee R.,Research Institute of Food Science and Technology RIFST | Razavi S.M.A.,Ferdowsi University of Mashhad
Food Research International | Year: 2013

The effect of varying concentrations of whey protein concentrate (WPC, 5-15% w/v) and wild sage seed gum (SSG, 0-0.3% w/v) on interfacial tension, zeta potential, physical stability, droplet size, flow properties and viscosity of d-limonene-in-water emulsions at pH. 7 was investigated. The results indicated that the addition of SSG had no significant effect on zeta potential while the interfacial tension decreased with increasing gum concentration. For freshly prepared emulsions, the mean diameter of droplets slightly decreased as gum concentration increased from 0.0% to 0.3%. In contrast, protein concentration in the range of 5-15% showed no particular effect on the size of droplets. Storage of samples for a period of 4. weeks resulted in an increase in the size of droplets. This was substantially noticeable for the emulsions containing no SSG and negligible for those prepared with 0.3% SSG and 15% WPC. The presence of SSG in these emulsions increased the emulsion stability indices, evidently because of the higher viscosity it imparted to the aqueous phase. The emulsions containing only WPC showed Newtonian behavior, while those consisting of both protein and gum exhibited shear thinning characteristics. Various time-independent rheological models 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. © 2013 Elsevier Ltd.

Ahmadian-Kouchaksaraie Z.,Research Institute of Food Science and Technology RIFST | Niazmand R.,Research Institute of Food Science and Technology RIFST | Najafi M.N.,Agricultural and Natural Resources Research Center of Iran
Innovative Food Science and Emerging Technologies | Year: 2016

Subcritical water extraction was investigated as a green technology for the extraction of phenolic compounds from Crocus sativus petals. A Box-Behnken design was utilized to determine the optimal extraction conditions. Extraction temperature (120–160 °C), extraction time (20–60 min) and water to solid (W/S) ratio (20–40 mL/g) were considered as the variables for the extraction of phenolic compounds. A second order polynomial model was fitted to each response and the regression coefficients were determined using least square methodology. There was a good correspondence between the experimental data and their predicted counterparts. The optimum conditions of extraction were estimated to be W/S ratio of 36 mL/g, temperature of 159 °C and time of 54 min. Extraction using these optimized conditions achieved the best TPC (1616 mg/100 g), TFC (239 mg/100 g), %DPPHsc (86.05%) and FRAP value (5.1 mM). Principal components analysis (PCA) allowed a better understanding of interactions between properties of extracted phenolic antioxidants. Industrial relevance Application of subcritical water was shown to be a practical technique to extract the phenolic compounds of saffron petals as an underutilized bulk agro-waste. The higher phenolic antioxidants obtained in extractions carried out by this technique is of major interest from an industrial point of view, since solvent amounts were reduced and extraction times shortened. Thus, the application of this emerging technology for extraction uses and low-cost raw materials is an economical alternative to conventional extraction methods according to industry demands and a sustainable development. © 2016 Elsevier Ltd

Ghorani B.,Research Institute of Food Science and Technology RIFST | Tucker N.,University of Lincoln
Food Hydrocolloids | Year: 2015

Encapsulation of bioactive compounds and probiotic bacteria within prebiotic substances to protect or even enhance their survival whilst passing upper gastro-intestinal tract, is an area of great interest for both academia and the food industries. Different methods have been suggested, examined and applied to encapsulate and dry probiotics and bioactive compounds, for example spray drying. However, the harsh processing conditions of these methods can significantly reduce the viability of bacteria or damage the structure of the target molecules. Electrospinning (and the related process of electrospraying) both show promise as a novel delivery vehicle for supplementary food compounds because the process can work with an aqueous solution, at room temperature and without coagulation chemistry to produce matrices in the micro- and nano-range. The production of nanofibers (fiber diameters less than 1μm) is a commonplace. Nanofiber materials produced by electrospinning have attracted particular attention in the food industry because of their potential as vehicles for sustained and controlled release. The room temperature process route is compatible with food grade polymers and biopolymers, and allows efficient encapsulation by reducing denaturation, and enhancing stability of bioactives. Consequently, there is clear potential to develop electrospun fibrous assemblies to advance the design and performance of novel products and delivery systems for supplementary food compounds. To optimize production conditions and maximize throughput, a clear understanding the mechanism of electrospinning is essential. This paper presents a comprehensive review of the fundamentals of electrospinning to produce nanofibers suitable for food technology application particularly for use in encapsulation and as nano-carriers. © 2015 Elsevier Ltd.

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