سمانه فرجی کفشگری

Passive packaging has an almost neutral mechanism in dealing with external and internal packaging factors such as gas penetration, cellular respiration and gas production, water loss or gain, ethylene production, production of oxidation compounds and possibly microbial contamination of food. While active packaging, by changing the packaging conditions, increases the shelf life of packaged food and improves its safety and sensory characteristics, while maintaining the quality of food. Among the types of active packaging applications, antimicrobial packaging is one of the most common technological applications of active packaging. Antimicrobial packaging is a system that is able to destroy or inhibit the growth of microorganisms and thereby increases the shelf life and safety level of food products. In antimicrobial packaging, the activity of an antimicrobial agent is carried out through the contact of the microorganism with the inner surface of the packaging material or the gradual release of the antimicrobial agent from the packaging material to the food. The controlled release of antimicrobial substances during the shelf life of food improves the safety of food and increases its shelf life. Antimicrobial substances increase the shelf life of food products by slowing down the growth rate and prolonging the lag phase of microorganisms or by inactivating and destroying them. Antimicrobial agents may be of natural or unnatural origin. The origin of natural antimicrobial substances can be plant, animal or microbial. In the design of antimicrobial systems, in addition to the characteristics of antimicrobial substances, the methods of adding antimicrobial substances, their penetration and evaporation, and many other factors such as the resistance of microorganisms, controlled release, release mechanisms, the chemical nature of antimicrobial substances and Foodstuffs, storage and distribution conditions, physical and mechanical properties of antimicrobial packaging materials, organoleptic properties and toxicity of antimicrobial materials should also be taken into consideration.

Nowadays due to the harmfulness of chemical preservatives, the use of natural preservatives has increased. Bacteriophages are bacterial mandatory parasites that are harmless for human and animals and can, therefore, be used as appropriate antimicrobial agents in food. The aim of this study was to isolate the Escherichia coli lytic phage from wastewater, identify and evaluate its efficiency in controlling E. coli infection in chicken meat.

E. coli (PTCC: 1330) was obtained from Iranian Science and Technology Research organization. Phage isolated from the wastewater of Malayer dairy factory and its antimicrobial effect was investigated through plaque formation. TEM microscopy was used to observe the phage morphology and to determine its possible family. Host spectrum against 6 E. coli strains and its effect? against Salmonella enterica, Staphylococcus aureus and Yersinia enterocolitica were also evaluated .The effect of E. coli lytic phage on the amount of inoculated E. coli to contaminate the chicken meat was examined.

The isolated phage was tailless and had round capsid, possibly belonging to the Tectiviridae family. The target phage had antimicrobial activity against 5 selected E. coli strains, unlike the other genera tested. The effect of the phage on the E. coli contamination in chicken meat showed that the bacterial count was reduced from 3 log10   to 1.8 log10 after 24 h and reached less than 1 log cycle after 4 days.

The isolated phage had strong antimicrobial effect against E. coli. Therefore, it can be a good preservative candidate for use in foods.

Bacteriophages are mandatory bacterial parasites that are harmless to human and animal, which are used by dipping or spraying in food as natural antimicrobial agents. The use of these methods leads to wasting or trapping of phage in food, but its immobilization on the polymer surface facilitates the contact of phage with the host cell at the food surface. Therefore, the aim of this study was to immobilize the lytic phage of Escherichia coli on the cellulose acetate film and investigate of its antimicrobial effect. Escherichia.coli bacteria was incubated at 37°C for 24 hours, and the antimicrobial effect of phages was evaluated through plaque forming. The cellulose acetate film was prepared by casting, then modificated by plasma, and immersed in a suspension of phage (1010 PFU/ml) and incubated at 37 °C for 24 hours with slow shaking, then the number of immobilized phages was estimated. To confirm the immobilization, FESEM was done. The antimicrobial effect of the active film was evaluated by disk diffusion and the release rate and antimicrobial activity of immobilized phages were investigated in 14 days. Phages formed clear plaques against E.coli. Modification of film by plasma resulted in uniform immobilization (108 PFU/ml) that FESEM revealed it. The active film (with zone diameter 12 mm) showed stronger antimicrobial effect than the antibiotic ampicillin (positive control sample with zone diameter 8 mm). 11 days after the immobilization, the number of immobilized phages decreased from 108 to 106 (PFU/ml) and released from the film surface, afterwards did not release. The antimicrobial activity of active film was decreased due to the absence of host bacteria continuously in 15 days, so that the host bacteria population increased from 3 to 5.3 LOG CFU/ml. In spite of reducing the antimicrobial activity of cellulose acetate active film over the time, due to the presence of host bacteria at food surface and its high potential in destroying the host bacteria, it can be used to increase of food safety in food packaging.

The present research work was aimed to evaluate the effects of whey protein concentrate (WPC) at different levels of 0, 2, and 4%, as a protein based fat replacer, soy protein isolate (SPI) (0, 1, and 2%) and microbial transglutaminase (MTG) (0, 1, and 2%) on some physical properties of a low fat vanilla ice cream (4% fat). Electrophoresis pattern of ice cream proteins and effect of MTG on proteins were analyzed by SDS-PAGE. Total solids of all formulations was adjusted on 34%. Results showed that application of WPC in formulation of low fat ice cream significantly increased hardness and melting values, while SPI significantly (P

Plants produce a diverse range of bioactive molecules, making them rich source of different types of medicines. Combinational technology is method which combination two or more technology (Conventional or advanced(to transfer heat and humidity. The purpose of this study was to investigate the effect of microwave pretreatment in drying roots nutmeg on Antimicrobial activity in the against disease bacteria and spoilage mold. In this study, two methods, oven and microwave oven with pre-treatment has been used for drying the roots nutmeg and antibacterial effects of extracts produced by both methods against pathogenic bacteria and spoilage mold was studied by disk diffusion method and dilution in the wells. The results of the comparison and analysis of data showed that the methods of drying of the Hindi roots nutmeg was significant at the 99% level (p<0.01). Also the results showed that extract of roots nutmeg had the most antimicrobial effect on Salmonella enterica among the bacteria studied and Trichoderma viride among spoilage molds studied in this research. The results showed that extracts of roots nutmeg avoid the growth of spoilage mold and pathogenic bacteria. Also, The results showed that using of microwave pretreatment in drying of Hindi roots nutmeg, increase antimicrobial properties.

The aim of this study was to evaluate the quality characteristics of bread produced by yeasts and lactobacillus isolated from native Iranian sourdough. Initially for the preparation sourdough, fresh microbial cells with certain number of colonies, by centrifugation were isolated of initial culturing bacteria and yeasts. Then equivalent 10% weight flour, microbial cells mixed with equal amounts of water and flour. After processing identical samples to assess the quality characteristics of bread used of sensory evaluation test, image processing and Texture analysis. The experiments in a completely randomized design and completely randomized block with three replications were performed. The results showed that the samples significant effect on the quality characteristics. The results indicate that sourdough can be increasing the porosity of the sample So that e treat with 42 percent had the highest degree of porosity also sourdough delaying staling. According to the results from this study, treatment of Lactobacillus reuteri and Saccharomyces cerevisiae had best Sensory evaluation, porosity and texture.

In this study whey protein concentrate (WPC) at levels (0.1and 4%), soy protein isolate (SPI) at levels (0.1and 2%) and microbial transglutaminase (MTG) at levels (0.1and 2%) were used in low fat ice cream formulation (4% fat) and their effects were evaluated on the physicochemical and overall acceptance and their optimum amount was determined using response surface methodology. The amount of total solids in all samples was the same 34%). According to the results formulations containing WPC had higher viscosity and acidity but lower overrun, melting resistant and overall acceptance compared to the control sample (P<0.01). SPI resulted in greater viscosity and melting resistance but lower overrun and overall acceptance (P<0.01). MTG resulted in greater melting resistance, overrun and viscosity of the ice cream samples in comparison to control sample (P<0.01). But had no significant effects on overall acceptance and acidity (P>0.05). The result of optimization showed that the best levels of SPI, WPC and MTG were 0.06, 1.37 and 1.19 % respectively. Also in optimum levels, the amount of viscosity, melting resistance, overrun, acidity and overall acceptance were obtained 1700 cp, 52%, 49/54%, 28/5 dornik and 4.25, respectively.

Considering the importance of quality and bacterial contamination in food products، a rapid، accurate and able method to deliver consistent results for counting bacteria is an essential. Application of image processing in the measurement of quality is one of important research topics. This method is very accurate and non-destructive with constant results. The aim of this study was the use of image processing in bacterial count (Quail flora، sourdough and drinks kefir) and comparison with Colony Counter method. First، of intestinal microbial flora Quail، sourdough and drink kefir، Dilutions were prepared from 10 -1 to 10-9. Then respectively in plate count agar، YGC agar and MRS agar were cultured surface (Quail flora and lactic acid bacteria in drink kefir at 37 ° C and yeast in sourdough at 25 °C). After 24 hours، colonies grown by Colony Counter and Image J software were counted in triplicate. The results showed that in dilutions of 10-5 to 10-9، don’t difference between the numbers reported by the two methods but in dilutions of 10 -1 to 10-4، there were significant difference between the numbers reported by the two methods. According to the results of this research can be introduced image processing an accurate and rapid method for bacterial count.