Food Technology
Shahab Naghdi; Masoud Rezaei; Mehdi Abdollahi; Mehdi Tabarsa
Abstract
[1]Introduction: Bioactive compounds are substances found in small amounts in food. In addition to their influence on human development, these compounds also play a crucial role in reducing diseases in human. Polysaccharides are a group of bioactive compounds that come from a variety of sources. Polysaccharides ...
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[1]Introduction: Bioactive compounds are substances found in small amounts in food. In addition to their influence on human development, these compounds also play a crucial role in reducing diseases in human. Polysaccharides are a group of bioactive compounds that come from a variety of sources. Polysaccharides are macromolecules that are usually composed of more than ten monosaccharides. The constituent monosaccharides are arranged linearly or branched together through glycoside bonds, depending on the length of the chain and the number of constituent monosaccharides. They also have different molecular weight. Polysaccharides, like other essential macromolecules such as proteins and poly-nucleotides in the body, are essential for the flaxseed body's daily activities and play an influential role in cell-cell communication, cell adhesion, and the identification of molecules in the immune system. A group of polysaccharides derived from marine sources are sulfated polysaccharides. These polysaccharides are a broad branch of the resulting polysaccharides. In industrial quantities, sulfated polysaccharides are produced from pig skin and pig bone, and there are some restrictions on the use of these products in some countries. The limitations on the use of these products made from pig waste are the risks of transmitting influenza, as well as the prohibition of pork in some Islāmic countries. In this regard, by-products from seafood processing, which account for about 20 to 50 percent of the initial weight of raw material, are one of the sources that researchers are considering to extract these compounds. Material and Method: After preparation of the by-product, it was covered with ice in a ratio of 1 to 3 and transferred to the laboratory of Tarbiat Modares University. The sample was then washed and then ground. Finally, it was packed in plastic bags and kept in the freezer at -18 ° C until the day of experiment. Then, the enzymatic hydrolysis method and precipitation by ethanol were used to get sulfated polysaccharides. Chemical analyses were performed to determine carbohydrates, sulfates, proteins, and uronic acid content. The FTIR spectrum of extracted sulfate polysaccharide was determined using an FTIR spectrophotometer in the range of 400-4000 cm-1. Evaluation of antioxidant properties of obtained sulfate polysaccharide was assessed by DPPH free radical scavenging activity, ABTS free radical scavenging activity, and ferrozine tests. Emulsifying and foaming properties were also evaluated as functional properties. Results and Discussion: In the present study, sulfated polysaccharide was extracted from Rainbow trout (Oncorhynchus mykiss) skin by pepsin enzyme and its FTIR spectrum, carbohydrate, sulfate, uronic acid and protein were analyzed. The results of the chemical analysis of the extracted polysaccharide showed that the extraction efficiency was 3.23± 0.02%, as well as the percentage of carbohydrate and protein of the obtained polysaccharide was 57.03± 2 2.56, 7.78± 0.43% respectively. Also, the amount of sulfate and uronic acid were 6.54± 0.77 and 3.86± 0.43, respectively. The results of infrared spectroscopy showed the presence of a broad peak in the range between 3350 and 3450 cm-1 for the –OH group and the S=O sulfate flexural band in the range of 1245 cm-1. An increasing and significant trend was observed in different concentrations used for the DPPH test (p <0.05) which had the highest neutralizing power (38.85%) at a concentration of 2 mg/ml. The highest percentage of ABTS radical chelating was observed at a concentration of 4 mg/mm of distilled water with 71.70% (p <0.05). The chelating results of the extracted polysaccharide against ferrous ions showed that the highest chelating percentage was 98.43% (p <0.05). The foaming capacity, stability properties of the foam, and the emulsifying ability of the studied sample showed a trend of increasing the concentration coefficient of the sample (p <0.05), and the concentration of 10% used sulfated polysaccharide had the highest foaming percentage (72/22%) and foam stability (62.22%) (p <0.05). The emulsifying property of extracted sulfate polysaccharide against soybean oil was higher in all concentrations used than sunflower oil (p <0.05), and the highest value of that was related to the concentration of 10% with 86.57% and 92.59% against sunflower oil and soybean oil (p <0.05). The obtained results demonstrated that the fish skin extracted polysaccharide can serve as a natural antioxidant and functional agent in the food industry
Narjes Badfar; Seyed Ali Jafarpour; Mehdi Abdollahi
Abstract
Introduction: There is an expanding market for surimi in the world, and much interest in surimi throughout the seafood and food industry by the rapid growth in popularity of surimi-based products. This interest justifies an investigation into the applicability of freshwater fish species such as Silver ...
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Introduction: There is an expanding market for surimi in the world, and much interest in surimi throughout the seafood and food industry by the rapid growth in popularity of surimi-based products. This interest justifies an investigation into the applicability of freshwater fish species such as Silver carp, as an alternative fish resource, for surimi and surimi based products. Rheology concerns the flow and deformation of substances and, in particular, to their behavior in the transient area between solids and fluids. Moreover, rheology attempts to define a relationship between the stress acting on a given material and the resulting deformation and/or flow that takes place. Rheological properties are determined by measuring force and deformation as a function of time. Rheological evaluation is a useful technique for gathering information on the textural characteristics of surimi and kamaboko. It describes the surimi dynamic characteristics in the form of storage modulus (G′), loss modulus (G″), and phase angle (δ). Materials and methods: Whole Silver carp fish were gutted and the head removed, Fillets were minced by a meat mincer with a mesh size of 3 mm, then mince washed one, two and three times at ratio of 1:3 and 1:2 (mince: water) and dewatered. The mince was turned into surimi in a food processor operated for 2 min. salt (2%) was sprinkled over the mince. Ice water was also sprinkled over the mince to adjust the moisture content of the paste to 80 mL/ 100 g.Dynamic tests using a rheometer (MCR-301, Anton Paar- Germany) were carried out on the surimi gel after setting. The region of linear viscoelasticity of the surimi paste was determined by both stress and frequency sweep tests. The thermorheological behavior of Silver carp surimi was evaluated using a temperature sweep test and reported using sol-gel transition thermographs. The stress of 100 Pa was considered as the stress and the frequency of 1 Hz was considered as the frequency in the frequency sweep test, then Temperature sweep test involved heating the surimi samples from 10 to 90°C. Also Crip-recovery test was performed on the surimi in 300 seconds. Results & discussion: Rheological tests: Frequency sweep, Stress sweep and Temperature sweep graphs were relatively similar and in all samples affected by H2O2 and the control sample, the lowest value of G' was recorded between 50 and 52°C. Then, with increasing temperature from 52 to 62°C, the curve G' increased and the curve was stable at temperatures up to 80°C. Changes in the G' graphs can be attributed to the process of forming the gel by heating. Changes in the G" graph showed a similar trend with G’. In the creep-recovery test, the lowest and most strain were belonged to the control and sample 5 (1% H2O2, 1: 2, twice washing). Studying the figure of Creep-recovery test showed the samples affected by H2O2 had more resistance against applied stress in compression with control sample which expressed the effect of H2O2 on creating more and effective covalence cross-linking resulting more stable and constant gel network. During Surimi's heating, there are several reactions that involve various mechanisms, such as protein gelation. About Surimi, the observed macroscopic changes are related to the effect of temperature on proteins. The presence of H2O2 during the washing process did not have a significant negative effect on rheological properties of Surimi.
Seyed Mahdi Ojagh; Akbar Vejdan Taleshmikaeil; Mehdi Abdollahi
Abstract
Introduction: Natural polymers have gained increasing attention for the development of packaging to reduce ecologically-related problems caused by plastic packaging (environmental pollution). Among these natural polymers, proteins such as gelatin is considered a good candidate for food packaging. However, ...
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Introduction: Natural polymers have gained increasing attention for the development of packaging to reduce ecologically-related problems caused by plastic packaging (environmental pollution). Among these natural polymers, proteins such as gelatin is considered a good candidate for food packaging. However, several studies have shown that gelatin films are brittle, and their hydrophilic nature connotes high water vapor permeability and water solubility. Different solutions have been suggested to overcome these weaknesses, including adding crosslinking agents and chemical modification, adding nanoparticles and developing bio-film blends and bilayers with polysaccharides. Agar is a polysaccharide extracted from marine red algae, which is biocompatible, has good mechanical properties and possesses good film-forming properties. Preventing food spoilage from light and oxygen-induced oxidation is one of the greatest concerns in the food industry. Despite having good mechanical and relatively good water vapor permeability properties, protein- or polysaccharide-based films don't have sufficient barrier properties against oxygen and UV light that can't properly prevent the oxidation of food products. Among nanoparticles, metal oxides like TiO2 (such as antiradiation and antimicrobial activities) and Montmorillonite (such as improved mechanical and barrier properties against moisture, WVP and gases) have evidenced good potential to improve functional properties of bio-films. Thus, the present study aimed to develop a new biodegradable bilayer agar/gelatin film incorporating nanoclay and TiO2 for food packaging, with maximum water sensitivity and maximum UV light and oxygen barrier properties.
Materials and Methods: Agar/gelatin bilayer films were prepared by a two-step casting technique. First, the agar layer was produced by solubilization of 1.5 g of agar powder (agar-agar analytical grade were obtained from Merck Co., Germany) in 100 mL of distilled water. Then, glycerol (obtained from Merck Co., Germany) was added as plasticizer. The agar film-forming solution was casted onto petri-dish. In the next step, the gelatin (obtained from cold water fish skin was purchased from Sigma-Aldrich, St. Louis, MO, USA) solutions were prepared by dissolving 4 g of the fish gelatin in 100 mL of distilled water. Glycerol was also added as plasticizer. The TiO2 dispersions (in ratios of 0 and 2% of the gelatin) and MMT (Na+–montmorillonite (in ratios of 0, 3, 5 and 10% of the gelatin)) were added to the gelatin solution and stirred and sonnicated. Finally, produced solutions were then casted. The agar/gelatin films, with or without TiO2 and MMT, were characterized using SEM analysis. Film transparency, water vapor permeability, water solubility, swelling, surface color and mechanical properties of the bilayer films were also examined.
Results and Discussion: In this study, bilayer films based on agar and gelatin incorporated with TiO2-MMT nanoparticles have been successfully developed. Results demonstrated that some properties of the bilayer films were greatly influenced by TiO2 and MMT nanoparticle content. So that, the addition of TiO2 decreased water vapor permeability of the bilayers more than 15%, upon increasing TiO2 content to 2%. However, swelling ratio and moisture content increased with the increase in the nano-TiO2 content, probably due to the hydrophilic nature of the TiO2 nanoparticles. Also, whiteness index (WI) increased by adding 2% of TiO2 nanoparticles. As shown in the surface photograph of the bilayer films, TiO2 generated more opaque and whiter films, which might be related to the white color of TiO2 nanoparticles in solution form. Also, the addition of MMT (0, 3, 5, and 10%) to bilayer-2% TiO2 significantly decreased water vapor permeability and transmission of UV light of the bilayer films. However, tensile strength (TS) decreased with further increase of the nanoparticle concentration. Increasing the concentration of nanoparticles' MMT to 5%, the tensile TS of the agar/gelatin films increased from 12.86 to 20.54 MPa; it might also be related to the interactions between sulphydryl and carboxylic groups from certain amino acids in the gelatin structure with MMT and TiO2 nanoparticles. However, the TS decreased again with further increase of the filler content up to 10% MMT. Also, the addition of MMT from 3%-10% concentration significantly reduced the elongation at break value (EB) of the bilayer films from 41.77 to 28.90% for the bilayer films (p
Fatemeh Tabari kouchaksaraei; Masoud Rezaei; Peyman Aryaee; Mehdi Abdollahi
Abstract
Introduction: An edible film is a thin layer, made of edible materials, which once formed can be placed on, or between food components. Protecting the product from mechanical, physical and chemical damages, as well as microbiological activities, are some of its functions (Falguera et al, 2011). The main ...
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Introduction: An edible film is a thin layer, made of edible materials, which once formed can be placed on, or between food components. Protecting the product from mechanical, physical and chemical damages, as well as microbiological activities, are some of its functions (Falguera et al, 2011). The main materials made of these films are proteins, lipids and polysaccharides which are able to be used as alone or in blending form (Hernandez et al, 2008 ;Gennadios, 2004). Carboxymethylcellulose (CMC), is a linear polysaccharide that its natural and biodegradable features cause to exhibit excellent film-forming properties (De Moura et al, 2011). Films prepared with these polymers, generally have good gas barrier properties and moderate to propriate mechanical features (Gutierrez et al, 2012). Using the edible, biodegradable films, due to the sensibility to moisture and poor mechanical properties particularly in moist status, is almost limited (Wang et al, 2009; Silva et al, 2009). Because of high hydrophilic property, CMC films also have a low resistant rate to water vapor permeability (Mohanty et al, 2000). Gum Tragacanth (Astragalus sp.) is another polysaccharide used to produce edible films and coatings. This gum can be widely used as a stabilizer, emulsifier and thickener in food industry, pharmaceutics and cosmetics (Azarikia & Abbasi, 2010). Tragacanth also has a prominent effect on physical and mechanical properties of the potato starch-based edible films (Fazel et al., 2002). It has also a proper blending potential in blending with other hydrocolloids, carbohydrates and most of proteins and lipids (Farahnaki et al., 2009). Yet, not any researches has made about the effect of blending tragacanth gum with other carbohydrate polymers. Blending of polymers can enhance the functional properties of the produced films (Bourtoom, 2008). Hereby, the current study has been done in order to preparate the best edible film with suitable physical, mechanical and biodegradable properties and has tried to introduce an ideal blend film made of different rates of carboxy methyl cellulose and tragacanth. Material and methods: In this research in order to improve the physico-chemical characteristics of biodegradable edible films, blending two polymers of carboxymethyl cellulose (CMC) and tragacanth (Astragalus sp.) was studied. At first, it was tried to making the film. For this purpose in laboratory the solubles of CMC 1% w/w and tragacanth of 0/75% w/w were prepared. In order to dissolute the polymers, both polymers subjected to heat (75 օC) and following the temperature decrease (~ 40 օC), glycerol (20% of the polymer) was added to each one. Therefore, CMC and tragacanth were blended to each other at proportions of 25:75, 50:50, and 75:25 (v/v) and water vapor permeability, solubility, mechanical properties and microstructure were evaluated. Microstructure of the produced films was assigned by an electronic microscope (Philips, made in Netherlands). Thickness of samples was determined by a digital balance (0/0001 mm, Mitutoyo- made in Japan) via measuring in five points of each sample. Water vapor permeability, moisture content and solubility rate were conducted by standard. Tensile strength (TS) and elongation at break (EAB) were determined using an Instron universal testing machine (Model TVT 300 Xp, Sweden) operated according to the ASTM standard method D882-01(ASTM, 2002). Statistical Analysis performed by software of SPSS, ver. 20. Normality of data and homogeneity of data were conducted by Kolmogorov-Smirnov and Levene tests, respectively. For significance of treatments effect One-Way Anova and for statistical comparison of data Duncan test were performed. Results and discussion: The results showed that blended film of 50:50, as well as pure CMC film, had a smooth, flat surface without crack, showing that both polymers were properly blended. Among three blend proportions of two polymers, tensile strength was greatest in 50:50 whereas this amount in proportions of 50:50, 75:25 and 25:75 was recorded 44.59, 32.82 and 26.59 MPa, respectively. These results were in line with Ghanbarzadeh et al. (2011), who indicated the quality of maize starch-based films was suited by CMC and citric acid. With decrease of CMC content in blended films the elongation rate of films significantly decreased. This can be attributed to suitable interactions of the two polymers. This is in accordance with report of Tongdeesoontorn et al. (2011) and Mu et al. (2012), who found the different contents of CMC positively affected the films properties. Water vapor permeability was of better status at 50:50 and 25:75 than at 75:25. Solubility in water did not differ among three blend films but it had better conditions in pure CMC film whereas the blend films showed a decrease about 52 to 58% in solubility compared to the pure CMC film. The results of our research is consistent with findings of Tong et al. (2008), who investigated preparation and properties of pullulan -alginate- CMC blend films. The decrease of solubility can probably be due to proper interactions between CMC and tragacanth. Likewise, blending two polymers at different proportions decreased the moisture content of films. It can be stated that because of the linkages between tragacanth and carboxymethyl cellulose polymer chains, a compact structure has been created that not allows water molecules to presence and thus leads to a reduction in moisture content of films. This is in accordance with findings of Gutierrez et al. (2012), who reported that the increase of leaf extract in plant of murta improved the quality properties of the CMC films. Generally, from this investigation it is deduced that blending the two polymers in different proportions can improve some physico-chemical properties of the CMC- tragacanth edible film.
Mehdi Abdollahi; Masoud Rezaei; Gholam Ali Farzi
Abstract
A bionanocomposite film was developed by nanoclay incorporation to chitosan films, using a solution casting method and the effects of nanoclay concentration (0.5, 1.0, and 3% w/w) on the physical and mechanical properties of the chitosan films were evaluated. Moreover, X-ray diffraction (XRD), scanning ...
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A bionanocomposite film was developed by nanoclay incorporation to chitosan films, using a solution casting method and the effects of nanoclay concentration (0.5, 1.0, and 3% w/w) on the physical and mechanical properties of the chitosan films were evaluated. Moreover, X-ray diffraction (XRD), scanning electron microscopy, and fourier transform infrared spectra (FTIR) were used for studying microstructure and internal interaction of the chitosan-based films. It was found that the water vapor permeability and the water gain of the chitosan films decreased more than 45% with nanoclay incorporation up to 3%. Moreover nanoclay improved the tensile strength of the chitosan films about 20%. XRD and FTIR results confirmed that the improvements in the nanocomposite properties may be due to the exfoliation of the nanoparticles, good interaction between nanoclay and the functional groups of chitosan chains, and good cross links in polymeric matrix.
Keywords: Nonocomposite, Chitosan, Nanoclay, Mechanical properties
