ABSTRACT Seventy-one lactic-acid bacteria (LAB) were isolated from a sample of “Siahmazgi”, an Ir... more ABSTRACT Seventy-one lactic-acid bacteria (LAB) were isolated from a sample of “Siahmazgi”, an Iranian traditional cheese. Lactobacilli were then screened for some technological properties such as rapid and adequate production of lactic acid, growth in different salt concentrations, gas production from carbohydrates, catalase activity and antimicrobial activity. Finally, the selected lactobacilli were tested for their growth profile in a fluid model-medium modified according to the special conditions of fermented sausages. LSCD5, LSCD7, LSCD10, LSCD11 and LSCD14 showed high acidifying activity, and reduced the pH of MRS broth medium to ∼4.0 in 24 h at 30 °C and in 48 h at 20 °C. These strains were identified by biochemical and molecular methods (16s rDNA sequencing) as Lactobacillus plantarum. The screened lactobacilli, except LSCD11, were able to grow at a high salt concentration of 10%. They also showed antimicrobial activities against Listeria monocytogenes, Staphylococcus aureus and Escherichia coli O157:H7. Relatively acceptable souring properties and good growth properties in simulated fermented sausage (SFS) medium were found for LSCD7 and LSCD14, with maximum numbers of 7.21, and 7.99 log CFU/ml, respectively. As a result, LSCD7 and LSCD14 exhibited the best technological properties to act as starter cultures for manufacturing fermented meat products.
Abstract This study focused on the optimization of key process parameters for maximizing kefir gr... more Abstract This study focused on the optimization of key process parameters for maximizing kefir grain biomass yield using statistical methodology. A response surface methodology (RSM) was developed to describe the effects of whey lactose and yeast concentrations, temperature and pH on increases in kefir grain biomass using cheese whey as a fermentation medium. Initially, one factor at a time was applied to evaluate the effect of different nitrogen sources. The results showed that the concentration of yeast extract ...
Abstract This study focused on the optimization of key process parameters for maximizing kefir gr... more Abstract This study focused on the optimization of key process parameters for maximizing kefir grain biomass yield using statistical methodology. A response surface methodology (RSM) was developed to describe the effects of whey lactose and yeast concentrations, temperature and pH on increases in kefir grain biomass using cheese whey as a fermentation medium. Initially, one factor at a time was applied to evaluate the effect of different nitrogen sources. The results showed that the concentration of yeast extract ...
International Journal of Biological Macromolecules, 2014
In this study, we aimed to improve the physical, mechanical and water-vapor permeability (WVP) pr... more In this study, we aimed to improve the physical, mechanical and water-vapor permeability (WVP) properties of kappa-carrageenan (KC) films by including montmorillonite (MMT) nanoclay in the film-forming solution. To further improve these properties, the combined effect of Zataria multiflora Boiss essential oil (ZEO) and MMT was also investigated. The incorporation of MMT improved the physical and mechanical properties of KC film. Film made from KC alone had a tensile strength (TS) of 26.29MPa, while the KC film with 10% nanoclay had a TS of 34.67. Further analysis was provided by X-ray diffraction and scanning electron microscopy that confirmed the dispersion of MMT in the KC matrix. It was also shown that the combined effect of nanoclay and ZEO significantly improved the TS and EB of KC films. ZEO decreased the WVP of the nanocomposite films; for example, 3% ZEO reduced WVP by around 78%. The antimicrobial activity of nanocomposite films was also studied using the overlay and vapor-phase methods; the films effectively inhibited the growth of five pathogens tested. Thus, the incorporation of both nanoclay and ZEO into KC films is a promising way to manufacture films with better mechanical, antimicrobial and WVP properties.
Abstract Determination of physical and mechanical properties can facilitate the design calculatio... more Abstract Determination of physical and mechanical properties can facilitate the design calculations of harvesting, handling, sorting and processing equipments. In this study, these properties of mungbean have been evaluated as a function of seed moisture content varying from 8.72 to 27.41%(db). In this moisture range, the length, width, thickness, geometric mean diameter and surface area increased significantly (p< 0.05) from 4.32 to 5.10 mm, 3.33 to 3.54 mm, 3.30 to 3.59 mm, 3.62 to 4.01 mm and 41.1 to 50.6 mm 2, respectively, whereas ...
International Journal of Biological Macromolecules, 2013
Sodium caseinate composite films containing lipids-oleic acid (OA), stearic acid (SA), or Matrica... more Sodium caseinate composite films containing lipids-oleic acid (OA), stearic acid (SA), or Matricaria recutita essential oil (MEO) - were prepared through emulsification and their physical, thermal, mechanical, and barrier properties were evaluated and compared. Furthermore, their antimicrobial effectiveness against Listeria monocytogenes, Staphylococcus aureus, and Escherichia coli was studied. Emulsified films were softer, less rigid, and more stretchable than pure films. The films' water vapor barrier properties were found to decrease upon the addition of lipid content; this effect was greatly reduced when MEO was added. The presence of OA/SA and MEO decreased tensile strength and elastic modulus but increased the elongation at break. Thermal analysis of all emulsified films showed two endothermic peaks; these results confirmed those obtained by SEM studies, where a partial separation of the two phases occurred. The films' antimicrobial activities were increased by incorporating lipids, particularly those containing MEO, which were more effective against the studied bacteria. This work showed that when taking all the studied variables into account, films formulated with MEO were found most suitable for various food applications.
ABSTRACT Seventy-one lactic-acid bacteria (LAB) were isolated from a sample of “Siahmazgi”, an Ir... more ABSTRACT Seventy-one lactic-acid bacteria (LAB) were isolated from a sample of “Siahmazgi”, an Iranian traditional cheese. Lactobacilli were then screened for some technological properties such as rapid and adequate production of lactic acid, growth in different salt concentrations, gas production from carbohydrates, catalase activity and antimicrobial activity. Finally, the selected lactobacilli were tested for their growth profile in a fluid model-medium modified according to the special conditions of fermented sausages. LSCD5, LSCD7, LSCD10, LSCD11 and LSCD14 showed high acidifying activity, and reduced the pH of MRS broth medium to ∼4.0 in 24 h at 30 °C and in 48 h at 20 °C. These strains were identified by biochemical and molecular methods (16s rDNA sequencing) as Lactobacillus plantarum. The screened lactobacilli, except LSCD11, were able to grow at a high salt concentration of 10%. They also showed antimicrobial activities against Listeria monocytogenes, Staphylococcus aureus and Escherichia coli O157:H7. Relatively acceptable souring properties and good growth properties in simulated fermented sausage (SFS) medium were found for LSCD7 and LSCD14, with maximum numbers of 7.21, and 7.99 log CFU/ml, respectively. As a result, LSCD7 and LSCD14 exhibited the best technological properties to act as starter cultures for manufacturing fermented meat products.
Abstract This study focused on the optimization of key process parameters for maximizing kefir gr... more Abstract This study focused on the optimization of key process parameters for maximizing kefir grain biomass yield using statistical methodology. A response surface methodology (RSM) was developed to describe the effects of whey lactose and yeast concentrations, temperature and pH on increases in kefir grain biomass using cheese whey as a fermentation medium. Initially, one factor at a time was applied to evaluate the effect of different nitrogen sources. The results showed that the concentration of yeast extract ...
Abstract This study focused on the optimization of key process parameters for maximizing kefir gr... more Abstract This study focused on the optimization of key process parameters for maximizing kefir grain biomass yield using statistical methodology. A response surface methodology (RSM) was developed to describe the effects of whey lactose and yeast concentrations, temperature and pH on increases in kefir grain biomass using cheese whey as a fermentation medium. Initially, one factor at a time was applied to evaluate the effect of different nitrogen sources. The results showed that the concentration of yeast extract ...
International Journal of Biological Macromolecules, 2014
In this study, we aimed to improve the physical, mechanical and water-vapor permeability (WVP) pr... more In this study, we aimed to improve the physical, mechanical and water-vapor permeability (WVP) properties of kappa-carrageenan (KC) films by including montmorillonite (MMT) nanoclay in the film-forming solution. To further improve these properties, the combined effect of Zataria multiflora Boiss essential oil (ZEO) and MMT was also investigated. The incorporation of MMT improved the physical and mechanical properties of KC film. Film made from KC alone had a tensile strength (TS) of 26.29MPa, while the KC film with 10% nanoclay had a TS of 34.67. Further analysis was provided by X-ray diffraction and scanning electron microscopy that confirmed the dispersion of MMT in the KC matrix. It was also shown that the combined effect of nanoclay and ZEO significantly improved the TS and EB of KC films. ZEO decreased the WVP of the nanocomposite films; for example, 3% ZEO reduced WVP by around 78%. The antimicrobial activity of nanocomposite films was also studied using the overlay and vapor-phase methods; the films effectively inhibited the growth of five pathogens tested. Thus, the incorporation of both nanoclay and ZEO into KC films is a promising way to manufacture films with better mechanical, antimicrobial and WVP properties.
Abstract Determination of physical and mechanical properties can facilitate the design calculatio... more Abstract Determination of physical and mechanical properties can facilitate the design calculations of harvesting, handling, sorting and processing equipments. In this study, these properties of mungbean have been evaluated as a function of seed moisture content varying from 8.72 to 27.41%(db). In this moisture range, the length, width, thickness, geometric mean diameter and surface area increased significantly (p< 0.05) from 4.32 to 5.10 mm, 3.33 to 3.54 mm, 3.30 to 3.59 mm, 3.62 to 4.01 mm and 41.1 to 50.6 mm 2, respectively, whereas ...
International Journal of Biological Macromolecules, 2013
Sodium caseinate composite films containing lipids-oleic acid (OA), stearic acid (SA), or Matrica... more Sodium caseinate composite films containing lipids-oleic acid (OA), stearic acid (SA), or Matricaria recutita essential oil (MEO) - were prepared through emulsification and their physical, thermal, mechanical, and barrier properties were evaluated and compared. Furthermore, their antimicrobial effectiveness against Listeria monocytogenes, Staphylococcus aureus, and Escherichia coli was studied. Emulsified films were softer, less rigid, and more stretchable than pure films. The films' water vapor barrier properties were found to decrease upon the addition of lipid content; this effect was greatly reduced when MEO was added. The presence of OA/SA and MEO decreased tensile strength and elastic modulus but increased the elongation at break. Thermal analysis of all emulsified films showed two endothermic peaks; these results confirmed those obtained by SEM studies, where a partial separation of the two phases occurred. The films' antimicrobial activities were increased by incorporating lipids, particularly those containing MEO, which were more effective against the studied bacteria. This work showed that when taking all the studied variables into account, films formulated with MEO were found most suitable for various food applications.
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Papers by Mehran Ghasemlou