جستجوی مقالات مرتبط با کلیدواژه « zinc oxide » در نشریات گروه « صنایع غذایی »

In this study, the effect of nanoparticles on oxide at three levels of 1, 3 and 5% was added to polylactic acid and chitosan nanocomposites and the results of its SEM (electron microscope) evaluation were evaluated and showed films containing polylactic acid and chitosan. It had an irregular and compact structure and with the addition of nanoparticles on oxide, it had a regular and cohesive structure. And water vapor permeability showed a significant effect (P <0.05). The results of histometry showed that with increasing the concentration of nanoparticles, the tensile strength of the film and the nanocomposite coating was significantly lower than the control treatment (P <0.05). Also, large changes in length to break point did not show a statistically significant difference. The results of tissue stiffness of this study also showed that during the 15-day storage time, the test treatment had the highest amount of stiffness. The effect of film and coating of nanocomposites based on polylactic acid and chitosan containing nanoparticles on zinc oxide on microbial properties indicated that during the shelf life of bread containing polylactic acid and chitosan dimers has an inhibitory effect on fungal growth by increasing nanoparticles on zinc oxide. Increases significantly. It also showed that the shelf life of seven sliced ​​toast containing the mentioned variables was higher at 5% level compared to the control treatment.

In food industries, nanotechnology can potentially provide solutions to food packaging with short shelf life. Nowadays, there has been an increasing interest in nanocomposites for many advantages in food packaging. Polymers have a wide range of applications in food packaging, and many studies have been conducted on the simultaneous use of nanoparticles and polymers in food packaging, which can be attributed to the synergistic effect of these nanoparticles. One of the most important goals is to increase the safety and quality of food during storage, transportation and protection against adverse factors such as chemical, moisture, light and external forces. The aim of this study was to investigate the effect of film prepared from PET containing nanoparticles of ZnO, TiO2 and TiO2 + ZnO nanoparticles in quantities 0.25, 2 and 2.25%. Weight is based on the physicochemical properties of mayonnaise.

The PET-based nanocomposites containing 2% by weight of TiO2 nanoparticles and 0.25% by weight of ZnO nanoparticles were prepared by melt mixing using an extruder. Mixtures of PET nanoparticles were dried in the oven at 170 ° C before loading in the extruder and fed simultaneously from the feeder to the extruder. The material was melted and thoroughly mixed as it passed through the extruder. The melt from the extruder was cooled by passing through a pool of cold water and entered the granule mill to make granules. Pure PET samples were molded as control and PET-based preforms containing nanoparticles. At the end of the molding stage, chillers were used to cool the preforms. PET-based bottles containing nanoparticles were produced by blowing preforms at appropriate temperatures and pressures for 120 to 140 seconds. The morphology and particle size of the bottle layers were investigated using FE-SEM. Then physicochemical properties including colorimetry, pH and acidity of mayonnaise, oxidative and peroxide stability, acidity of the extracted oil and migration of Zn +2 and Ti +2 ions from mayonnaise during 90 days at room temperature (22 ± 2 ° C) Celsius) was examined.

Based on FE-SEM images, the films of polymer bottles containing ZnO and TiO2 nanoparticles showed a smoother surface than the films of polymer bottles of ZnO + TiO2 nanoparticles. Moreover, the results of physicochemical properties showed that the reduction of brightness index as well as pH, acidity number, peroxide number and oxidative stability of mayonnaise sample during 90 days of storage in a bottle containing nanoparticles had a significant decrease compared to the control sample. According to the results of the present study, mayonnaise shelf life indices can be increased.

Due to the importance of food emulsions such as mayonnaise, it is necessary to pay attention to the quality characteristics and shelf life of this popular condiment. The use of these nanocomposites could be a promising approach to creating new active packaging in the food industry.

Strawberry (Fragaria x ananassa) as one of the most widely consumed fruits in the world is produced in 73 countries worldwide (Muzzaffar et al., 2016). Strawberry is mainly grown in Kordestan, Golestan, Mazandaran and Gilan provinces of Iran with Kordestan, Paros, Queen Eliza, Selva, Camarosa and Pajero as the most important cultivars. Since strawberry is very perishable fruit, requires careful harvesting and handling to maintain its quality after harvesting. Considering its sensitivity to physical injuries and fungal invasion besides rapid softening and susceptibility to rots, strawberry fruit has a short postharvest life. Gray mold, caused by Botrytis cinerea is considered as the most important strawberry disease with many negative impacts on ripening, marketing and postharvest life of the fruit (Abd-Alla et al., 2011). No strawberry cultivar is resistant to gray mold. The pathogen is able to infect stored strawberries because mycelia spread from infected fruit to adjacent healthy fruit. Several technologies have been used to reduce postharvest losses and extend the storage life of strawberries. These technologies include chemical control, low temperature storage, control atmosphere packaging, essential oils and irradiation (Marjanlo et al., 2009; Maraei and Elsawy 2017). Most of these techniques could be effective for shelf life extension of strawberry fruit. However, many reports documented harmful effects of chemical fungicides on human health and environment besides causing fungi resistance. Some compounds and methods may also have adverse effect on color, flavor or texture of the fruit. Thus, in the past few decades, research has focused on the use of safe and natural preservatives. It was reported that the storage life of strawberry fruit increased by application of cumin essential oil (Marjanlo et al., 2009). Among the various alternatives, metal oxides such as magnesium oxide and zinc oxide are catching the attention of scientists worldwide. These oxides render antimicrobial activity with higher stability in comparison to organic antimicrobials. Zinc oxide nanoparticles are less toxic than other nanoparticles such as silver nanoparticles. In addition, they are safer for human beings in comparison to other metal oxides (Al-Naamani et al., 2018). Al-Naamani et al. (2018) proved the efficiency of chitosan-znic oxide nanocomposite coatings in extending the shelf life of the packed okra. The application of nanocomposite film containing 2% zinc oxide nanoparticles maintained the qualitative characteristics of Mazafati date during cold storage (Sadeghipour et al., 2019). The aim of this study was to investigate the effect of different concentrations of zinc oxide solution on quality and shelf life of strawberry fruits (camarosa cultivar) during ambient and cold storage.

Zinc oxide solution with brand name Eimen Jav was purchased from Eimen Novin Pushan Pak Company. “Camarosa” strawberries at commercial maturity stage were harvested from a greenhouse located in Hashtgerd, Alborz province, Iran and then transported to Agricultural Engineering Research Institute. Fruits of uniform size without any defect were selected and used for the experiments. Strawberries were dipped in the solution at different concentrations (0.31%, 0.63%, 0.94%, 1.25%) for 1, 2 and 3 minutes. Then, the fruits were air dried at room temperature, put in plastic fruit boxes and stored at ambient temperature (25 oC, 30% RH) for 6 days and cold room (4 oC, 85-90% RH) for 21 days. The sampling was done on day 0, 2, 4, and 6 through ambient temperature and on day 0, 7, 14, and 21 through cold storage. Decay percent was calculated by visual observation of each sample. Fruits with visible brown spot and softened area were regarded as decayed fruit. Texture evaluation was performed by a texturometer. Firmness values of each individual strawberry were measured at two points of the equatorial regions using a 5 mm diameter probe and 500 load cell, at 2 mm/sec-1. Total soluble solids content was measured using a refractometer, Titratable acidity (TA) was calculated by titrating of clear juice of strawberry against 0.1 N NaOH solution and the results were expressed as citric acid %. Ascorbic acid content was determined by using 2,6-dichlorophenol indophenols titration method. A five-point hedonic scale was used for conducting the sensory evaluation of the samples. A panel of 15 judges was selected to evaluate the treatments for various sensorial parameters like appearance, texture, taste, and overall acceptability. Plain water was given to the judges to rinse their mouth between the evaluations of samples. The study was conducted as a factorial experiment in randomized complete design. All determinations were carried out in triplicates and the means were separated by Duncan Multiple Range test. All statistical tests were done by SPSS ver. 22 and were meaningful at 5%.

Ascorbic acid content was significantly affected by zinc oxide solution at different concentrations and immersion times. The ascorbic acid value of the control was significantly lower than the treated fruits. Ascorbic acid content decreased through the storage time as observed in all treatments and the control. Zinc oxide treated strawberries at 0.31% concentration for 3 minutes had higher firmness values and better qualitative characteristic with increased shelf life up to 2 weeks during cold storage. Additionally, this treatment reduced fungal decay up to 50% compared to the control during cold storage. Zinc oxide solution at 0.63% concentration for 3 minutes increased the shelf life of strawberry fruits up to 48 hours under ambient temperature. In this condition, fungal decay reduced up to 70% as compared to the control. Zinc oxide solution had no effect on sensory attributes of the fruits.

This study showed that strawberry fruits treated with zinc oxide solution (Eimen Jav solution) at recommended concentration and under storage in cold room had better quality and less decay than the control. The results introduce zinc oxide solution as a useful method for maintaining strawberry quality and extending its storage life.

Owning to drawbacks of synthetic polymers, biodegradable packaging materials (biopolymers) have received more attention both in studies and industrial applications. However, compared to conventional packaging, the biodegradable materials have some limitation must be eliminated either by using composite preparation method or introduction of nanotechnology. Inclusion of metal nanoparticles and their oxides are of the new approaches to improve the properties of packaging films. Therefore, the present study attempted to investigate the effect of ZnO (0, 2.5 and 5%) and β-glucan (0, 10 and 20%) incorporation on chemical and microbial properties of gelatin based biodegradable film over storage of chicken fillet. Results showed that incorporation the both of ZnO and β-glucan have significantly (p<0.01) improved the barrier properties against both of moisture absorption and water vapor permeability and the best properties obtained with film containing 5% of ZnO and 20% β-glucan. In addition, based on microbial tests result, it was obvious that the ZnO loaded films have antimicrobial properties and the highest inhibition activity obtained with 5% of ZnO against the all of studied pathogenic bacteria. Accordingly, the film containing 5% ZnO and 20% β-glucan is introduced as the most effective film for packaging of chicken fillets.

Metal oxide nanoparticles have unique physical and chemical properties. These components have shown antimicrobial effects against a wide range of microorganisms. In order to improve the physical properties of metal oxide nanoparticles, doping other elements with metal oxide nanoparticles is an effective way. Bacillus cereus is a gram-positive bacteria causing food-borne diseases. In this study, the antimicrobial effects of doped zinc oxide nanoparticles with manganese or iron on Bacillus cereus have been studied. To investigate the synergistic effects of the combined nanoparticles with two common biocides, including hydrogen peroxide and sodium hypochlorite, have been used. Co- precipitation method was used to prepare nanoparticles of manganese-zinc oxide and iron-zinc oxide. In this method, zinc sulfate and manganese sulfate were used to prepare manganese-zinc oxide  and iron sulfate and zinc sulfate are used for Zn- Fe doped nanoparticles. After preparing the sulfate solutions, the sulfate solutions were mixed and placed in an ultrasonic apparatus at a frequency of 57 kHz for 2 hours at 50ºC. Then, it was stirred at 80°C. A solution of NaOH was added until the pH of the solution reached 12. In these conditions, the mixing was done for 30 minutes. The solution was placed at ambient temperature for 18 hours. Then the centrifuge was performed to separate the sediment. Purification was done through washing with distilled water and ethanol. The precipitates were dried in the vacuum oven. In this way, the doped nanoparticles of manganese-zinc oxide and iron-zinc oxide were obtained. The Fourier transform infrared spectrum (FTIR) was carried out by the Perkin-Elmer apparatus of the Spectroma2 model, using a dry potassium bromide tablet at a frequency range of 4500-4000 cm-1. The X-ray diffraction was tested using the Phillips PW1820 from 2º to 80º. Structure of produced nanoparticles was assessed by the HITACHI electron microscope, the H-7500 model, by placing a drop of nanoparticles dissolved in methanol on a special lining with carbon coating and air drying, and performing microscopic images using an electron microscope in 100kv. The bacteria used in this study included Bacillus cereus (PTCC 1665) was purchased from the Iranian Scientific and Industrial Research Center and was transferred to the BHI medium in sterile condition and incubated for 32 hours at a temperature of 32°C. Microbial cells were isolated by centrifugation at 4000 rpm. McFarland's method was used for determining the bacterial population. Dilution was carried out to reach a population of about 106 CFU/ml. Agar disc diffusion method was used for assessing the antimicrobial effect of the doped nanoparticles alone or in combination with tested biocides (hydrogen peroxide, sodium hypochlorite). At first, 106 CFU/ml of Bacillus cereus were inoculated on the surface of Blood Agar. Then, 5, 10, 20, 30, 50, 100 and 200 mg/L of each of the nanoparticles were placed on the surface of the culture medium and then the plates was incubated at 37°C for 24 hours. Inhibition zone was considered as antibacterial activity. In order to investigate synergistic effects, inhibitory fraction index test was calculated. All experiments were performed in three replications. Statistical analyzes were performed using STATISTICA software. Results obtained from X-ray and FTIR analysis of doped nanoparticles confirmed that co- precipitation is a suitable method for producing doped nanoparticles of zinc oxide. TEM analysis of produced nanoparticles also affirm formation of doped nanoparticles of zinc oxide with manganese and iron. The results of antimicrobial tests showed that Mn-Zn oxide nanoparticles have more antimicrobial effects on Bacillus cereus than zinc oxide (32mm inhibition zone) whereas Fe- Zn oxide nanoparticles cause inhibition zone about 12 mm. In addition, both doped nanoparticles have more antimicrobial effects than zinc oxide nanoparticles alone, resulted in doping process improves antimicrobial properties of zinc oxide. The synergistic effects of synthetic nanoparticles in the combination of two common antimicrobial agents, including hydrogen peroxide and sodium hypochlorite, have been identified. Both nanoparticles show synergistic effects in combination with two tested biocides (especially in high concentrations). A mixture of two biocides with nanoparticles increases their antimicrobial properties. Manganese-zinc oxide nanoparticles with hydrogen peroxide and sodium hypochlorite showed a partial synergistic effect at low concentrations (5 + 20) and a complete synergistic effect at higher concentrations. In the case of iron-zinc oxide, combination of this nanoparticle with hydrogen peroxide and sodium hypochlorite, has complete synergistic effects at high concentration (100 + 200) and at other conditions, shows partial synergistic effects.

In this research, polypyrrole (PPy) and polypyrrole-zinc oxide (PPy-ZnO) nanocomposites were synthesized by chemical method on the bacterial cellulose film in the presence of Iron chloride ΙΙΙ. The size, shape and morphology of the synthesized particles were studied using scanning electron microscopy. The results showed that the polypyrrole particles (60-150 nm) are spherical in shape, while the nanoparticles of polypyrrole-Zinc oxide are granular in shape and are in the range of 30-120 nm. Mechanical properties including, strain to break and tensile strength and antimicrobial-antifungal properties, as well as antioxidant properties and electrical conductivity of the films were studied. The results showed that the addition of polypyrrole decreased the electrical resistance, resulting in an increase in the electrical current of the film. The addition of nanoparticles reduced the mechanical properties and decreased the tensile strength. The inhibitory power of free radicals of the film increased with the addition of zinc oxide. The synthesis and increase of the polypyrrole synthesis time on a cellulose film had a positive effect on the antimicrobial and antifungal properties of films, but zinc oxide nanoparticles were more effective on antifungal properties.

Date fruit (Phoenix dactylifera L.) is a rich source of sugar, fiber, some vitamins, minerals and antioxidant phenolic compounds. The physico-chemical, biochemical and microbial changes occurring in this fruit reduce its quality properties during storage time. In the present study, the effects of polyethylene film containing 1 and 2% zinc oxide nanoparticles as nanocomposite packaging and film without nanoparticles as a control were evaluated in order to maintain some quality characteristics of Mazafati date fruit in two storage temperatures of 4 and 25 °C for 120 days. The results of analysis of variance showed that the effects of nanocomposite film, temperature and storage time on the studied parameters of Mazafati date were significant (p <0.05). The least changes in quality parameters of weight loss, pH, titratable acidity, total soluble solids, total phenolic content and total and reducing sugar contents were observed in date samples packed in 2% nanocomposite film stored at 4 °C. The change in control sample stored at 25 °C was significantly higher than other samples. In addition, the use of nanocomposite packaging reduced the microbial growth rate (total aerobic mesophilic bacteria, and mold and yeast) compared to the control sample. With increasing storage temperature from 4 to 25 °C, an increasing trend was observed in microbial growth and changes in the quality parameters of all samples, which indicated a decrease in the quality characteristics of the date fruit. Considering the studied parameters, nanocomposite packaging containing 2% zinc oxide had better performance than nanocomposite packaging containing 1% zinc oxide. In general, the use of nanocomposite film containing 2% zinc oxide nanoparticles is suggested to maintain the quality characteristics of Mazatifi dates at a temperature of 4 °C.

This study aimed to evaluate the antimicrobial effect of nano-fluids based on Eremurus spectabiils extracts against Staphilococcus aureus, Escherichia coli and Salmonella enterica in in-vitro condition. The extract was obtained by maceration. Disc diffusion method was used for determining the antibacterial activity of the extract at three concentrations: 200, 250, 300 mg/ml and zinc oxide nanoparticles at 1000 ppm. Results showed no inhibition zones for the alone extract while ZnO nanoparticles led to clear zone up to 23mm. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) was determined using micro broth dilution method. The highest MIC and MBC was gained for the extract containing ZnO nanoparticles respectively at 12.5 and 25 mg/ml for Staphilococcus aureus. According to the findings, although the ethanolic extract had no inhibitory activity, yet addition of nanoparticles improved the antimicrobial activity which enables the extract to be used as a natural preservative in food and pharmaceutical industries.