فصلنامه پژوهش های صنایع غذایی
سال سی و چهارم شماره 2 (تابستان 1403)

Spices are used as one of the most common flavors in preparing food stuff .Spices represent a prevalent category of natural flavors extensively employed in culinary practices and food formulation. To increase food's nutritional and sensory quality while simultaneously ensuring the products' microbiological safety, one of the key targets is finding alternatives to current food processing and preservation technologies. Preparing, storing and consuming food safely and while preserving nutrients is one of the most important parts of maintaining food health and hygiene. The suitability of food for the growth of microbes can lead to spoilage and ultimately pathogenicity. Emerging innovations in food science and engineering have developed consistently and quickly over the past 20 years. The innovative food processing method called "cold plasma" uses energetic reactive gases to inactivate contaminating bacteria in spices. Ginger is an edible plant, a spice and a medicinal plant. Ginger is one of the medicinal plants that is used as a spice with strong antibacterial and antioxidant properties around the world. In addition to treating indigestion, ginger is used as a pleasant and appetizing spice in the food industry.Sumac (Rhus coriaria L.) is a pistachio genus of small shrubs 1 to 5 meters high, with 9 to 15 leaflets, covered with hairs and toothed. Employing thermal processes for spices sterilization may cause in destruction of bioactive materials, so it is necessary to recommend employing non-thermal processes which preserve the most amount of bioactive ingredients and cause less alternation. One of these techniques is cold plasma which is a non-thermal process providing microbial safety with minimum destruction. Cold plasma decontamination techniques are significantly safer and more efficient than previous ones .The purpose of this investigation is to study the influence of atmospheric cold plasma (DBD), with the use of argon gas, on chemical and microbial features of ginger and sumac in 3 minutes' time.

The examined elements of these spices were: color, scanning electron microscopy(SEM), counting coliform, mold, and counting total microbial. In order to show the proficiency of plasma influence, the prepared samples were compared to the controlled sample(non-plasma). In order to prepare samples for plasma treatment, DBD plasma device of Faculty of Physics, Faculty of Science and Research, Azad University of Tehran was used in this process. By adjusting the gas current and voltage by 10 kV and frequency of 40 kHz and power of 100 watts, plasma irradiation was performed for 3 minutes using argon gas. Samples were stirred several times during treatment Antioxidant capacity was measured using 2 and 2 diphenyl 2 picryl hydrazyl solution (DPPH).In a test tube, 600 μl of DPPH solution was poured and 60 μl of the spice extract was added and 5.34 ml of methanol was added to the tube.After 15 minutes at room temperature and in a dark environment, the absorbance of both test tubes was read by a spectrophotometer at 517 nm, zeroing the device with methanol solvent.The morphological study of the cross section of the spice sample was performed using SEM (manufactured by Tescan, Czech Republic).Bombarding the sample causes electrons to be released from the sample toward the positively charged plate, where these electrons become signals. The movement of the beam on the sample provides a set of signals on the basis of which the microscope can display an image of the sample surface on a computer screen.To evaluate the microbial load of the samples, including total count from PCA sterile culture medium, coliform count from VRB culture medium, mold count from DG18 culture medium were used. 2 replicates were cultured from each treatment. After incubation, the plates were counted. ). In this study, Sumac and ginger spices were exposed to cold plasma processing with argon gas to examine their microbiological, chemical, physical, and organoleptic qualities.

The results demonstrated that, with the use of plasma, the reduction of mold growth in sumac was 5/8 and in ginger 5/2. The reduction of coliform was 92% in the treated ginger sample and 91% in the treated sumac sample compared to the control. The total count was significant at the 5% probability level(p<0.05). In both treated spices, compared to the control samples, a 20-fold reduction in the microbial population was observed. In investigating the antimicrobial effect of Enterococous, Salmonella and saffron mold mold, similar results showed that the rate of decrease in saffron mold population was less than Enterococous, Salmonella. Plasma had no effect on the antioxidant capacity of control samples. Scanning electron microscopy images to examine the morphology of the samples before plasma exposure showed a rough, prominent, and inhomogeneous surface and after exposure to plasma with argon gas with a smooth and uniform surface, which increased the solubility. In the study of the effect of plasma on onion powder, it was reported that the samples treated with cold air plasma had a smoother surface than the samples treated with hot air . Also, no organoleptic changes were observed in the samples. In a study, they reported that the type of gas used did not differ significantly from the color indices of turmeric samples.

The non-thermal nature of cold plasma makes it a valuable alternative to traditional chemical methods, offering an option that minimizes the use of chemical substances while maintaining the quality of the food ingredients. This presents an innovative and potentially more sustainable approach to ensure food safety and longevity without compromising the essential characteristics of spices.1-In both types of spices, by applying 3 minutes of treatment time, the total number of bacteria and also the amount of mold count was significantly reduced. This reduction in the total bacterial count and the amount of mold count for sumac spice is more than ginger spice.2- Examination of coliform counts showed that by applying plasma for 3 minutes in two spices (ginger, sumac), it was reduced by 92%.3- Changes in the level of inhibition of antioxidant compounds after exposure to cold plasma have been reported for a long time in other studies. The reasons for the lack of change in antioxidant capacity in this study can be attributed to the short plasma time.4-Morphological evaluation of control and cold plasma treated samples shows that the treated sumac has a smooth structure and a smooth surface and the treated ginger is rougher and spongy compared to sumac.5- The results of color parameter analysis showed that there is no color reduction in control samples and after treatment.

In recent years, researchers have focused on production of active and smart packaging due to the increasing interest of consumers in biodegradable packaging (Hashem et al., 2022; Zhang et al., 2022). Smart films are a category of biodegradable films that convey visual information to consumers (Dong et al., 2020). Anthocyanins are a group of flavonoids that are responsible for the red, blue and purple colors of plants. The color of anthocyanins changes in different pH (Wang et al., 2021). Common poppy belongs to the poppy family, which have several health benefits. Common poppy petals are red in color due to the anthocyanins in their composition (Katarzyna et al., 2021). The use of anthocyanins from different plants in combination with biopolymers has attracted increasing interest in the food industry. One of these biopolymers is gelatin (Xu et al., 2022). Gelatin is widely used in food packaging due to its abundant resources, non-toxicity and inexpensive price (Wang et al., 2022). However, gelatin is used in combination with other biopolymers or nanofillers due to its high-water solubility and poor mechanical properties (Rangaraj et al., 2022). One of these nanofillers is chitosan nanofibers. Chitosan nanofibers are used to improve the properties of films due to their biodegradability, non-toxicity, antibacterial properties and biocompatibility (Amjadi et al., 2019).

In this study, common poppy extract was prepared using the solvent extraction method. Then, the obtained extract was used to prepare a smart film based on gelatin/chitosan nanofibers. Afterward, Surface morphology was analyzed using scanning electron microscope, chemical structure using Fourier transmission infrared spectrometer and crystal structure using X-ray diffractometer. The antioxidant property of the films was tested using the DPPH method. Also, UV-vis absorption and transmission in the range of 200-800 nm was evaluated using a spectrophotometer. In addition, the samples were cut in a dumbbell shape and investigated using a tissue analyzer to evaluate the mechanical properties of the films. The sensitivity of films to ammonia and acidic vapors was evaluated using ammonia and acetic acid solutions. Also, the transparency of smart films was evaluated at a wavelength of 600 nm using a spectrophotometer. In addition, the package containing the indicator film and shrimp was kept in the refrigerator for 7 days in order to monitor shrimp spoilage. The color changes of smart film at the beginning and end of storage were recorded using a digital camera in order to investigate shrimp spoilage.

The addition of common poppy extract increased the thickness of the smart film due to the increase in solid content. Also, the pure gelatin film had the highest transparency, which significantly decreased the transparency of the films by adding chitosan nanofibers and common poppy extract. In addition, the color change of common poppy extract at different pH was evaluated. The color changes at different pH values were as follows: red at pH = 2, coral at pH = 4, peach puff at pH = 6-8, goldenrod at pH = 10 and dark goldenrod at pH = 12. In addition, the color change of the smart film at different pH was also evaluated. The results showed that the smart film at pH = 2 has a crimson color, at pH = 4 it has an indian red color, at pH 6, 7 and 8 it has a coral color, at pH = 10 it is dark salmon color and at pH = 12 it has It was dark goldenrod color. Furthermore, the results of UV-Vis light absorption and transmission characteristics of the films showed that pure gelatin film and gelatin/chitosan nanofibers have low UV-Vis absorption and high transmission. However, the addition of common poppy extract significantly increased the UV-Vis absorption and decreased the transmission of the films, which could be due to the light absorbing property of common poppy anthocyanins. Also, X-ray diffraction results showed that the pure gelatin film had a peak at 2θ = 12.16°, which did not change significantly with the addition of common poppy. In addition, the results of the food packaging showed that the color of the smart film changed from bright coral to goldenrod after 7 days, which was caused by the increase in pH from 8.3 to 10.5 and the production of ammonia compounds. Also, the SRGB of the smart film increased to 13.20%.

Smart film based on gelatin/chitosan nanofiber containing common poppy extract was produced by casting method. The results showed that the smart film had the lowest amount of transparency. Also, the smart film had the lowest UV-Vis transmission and the highest absorption, which indicated the film's potential to be used for light-sensitive food packaging. In addition, the smart film color changed from coral to dark red, and its SRGB reached 38.17%, when it was exposed to acid vapors. Moreover, when the smart film was exposed to ammonia vapor, its color changed from coral to dark olive and the SRGB of the film reached 61.14%. The results of the food packaging showed that the color of the smart film changed from coral to goldenrod, which was caused by the decomposition of shrimp tissues and the production of ammonia-containing compounds and the increase in pH from 8.3 to 10.5. This result showed that smart film has the potential to be used to monitor food (shrimp) spoilage.

Lentil is one of the five major pulses produced in the world, and the annual production is around 4.5 million tonnes (Chelladurai and Erkinbaev 2020). Lentils have a relatively higher protein, carbohydrate, and energy content than other legumes. Lentil seeds are composed of about two-thirds carbohydrates and 24–30% protein. In addition, lentils are also a good source of certain amino acids, such as lysine and arginine (Lee et al. 2007). In many of the developing countries, lentil is considered as a stable source of protein due to its higher dietary protein and complex carbohydrate content (Chelladurai and Erkinbaev 2020). Sprouting process involves changes in the nutritional, biochemical, and sensory characteristics which improve the quality of legumes (El-Adawy et al. 2003). Ultrasound pre-treatment as non-thermal food processing technology could be a better pre-treatment technique for food processing, due to its benefits which comprise energy saving, preservation of original freshness and nutritional contents, keeping bioactive compounds, the decline in processing duration, and cost. Ultrasound pre-treatment accelerates the mass transfer in dehydration and drying of fruit and vegetable slices mostly due to the breakdown of cells and the creation of microchannels (Awad et al. 2012; Ghorbani et al. 2013). One of the best methods for the preservation of agricultural product is drying, which consists in removing water from the manufactured goods. One of the best ways to decreasing in drying time is to provide heat by infrared radiation. Infrared heating has many advantages including high heat transfer rate, uniform heating, low processing time, high efficiency, low energy consumption, low energy costs, and improving final product structure, porosity and quality (Salehi 2020). We found no report on the effects of ultrasound pretreatment on the hot-air and infrared drying kinetics of sprouted lentils in the literature. Hence, the purpose of this study was to estimate the impacts of ultrasound pretreatment and drying approaches on the drying time, mass transfer kinetic, effective moisture diffusivity (Deff), and rehydration of sprouted lentils. In addition, the moisture ratio changes of sprouted lentils during drying were modeled.

Lentil seeds were washed and soaked in tap water for 24 hr at room temperature (25±1°C). Soaked seeds were kept inside a polyethylene container covered with a clean kitchen towel and allowed to germinate for 48 hr in the dark at room temperature (25±1°C). In this research, the effect of ultrasound time and dryer type (hot-air and infrared) on the drying time, effective moisture diffusivity coefficient and rehydration of lentil sprouts were investigated and drying kinetics were modeled. To apply the sonication treatments on the germinated lentils, a Backer vCLEAN1-L6 ultrasonic bath (Iran) was employed with a frequency of 40 kHz and a power of 150 watts. The tank of the device was filled with 6L of distilled water and, then, after the temperature of the water reached to 25°C, the germinated lentils were placed directly in the bath. To apply ultrasound pre-treatment, the sprouts were placed inside the ultrasonic bath machine for 0, 3, 6, and 9 minutes, and after leaving the machine and removing extra moisture, the samples in thin layers were placed in the hot-air (with a temperature of 70°C) and infrared (power of 250 W) dryers. The dehydration kinetics of sprouted lentils has been explained using 4 simplified drying equations (Henderson and Pabis, Newton, Page, and Wang and Singh). Fick's second law of diffusion using spherical coordinates was used to calculate the moisture diffusivity of germinated lentils at various hot-air and infrared drying conditions. The rehydration tests were conducted with a water bath (R.J42, Pars Azma Co. , Iran). Dried sprouted lentils were weighed and immersed for 30 min in distillated water in a 250 ml glass beaker at 50°C.

The results showed that sonication treatment, causes an increase in moisture removal rate from the sprouts, an increase in the effective moisture diffusivity coefficient, and as a result, reduces the drying time. By increasing sonication time from zero to 9 min, the average drying time of sprouts in the hot-air and infrared dryers decreased from 156.7 min to 103.3 min, and from 32.7 min to 24.3 min, respectively. The average drying time of the samples in the hot-air dryer was 134.2 min and in the infrared dryer was 28.8 min. Also, the average effective moisture diffusivity coefficient calculated for the samples placed in the hot-air dryer was equal to 3.76×10-10 m2/s and for the infrared dryer it was equal to 1.6×10-9 m2/s. The time of ultrasound and drying treatment had significant effects on the rehydration of samples, and the value of this parameter was higher for samples dried in the hot-air dryer.

Kinetic modeling of lentil sprouts weight changes during drying was carried out by models in the sources, followed the Page model was selected as the best model to predict moisture ratio changes under the selected experimental conditions. Generally, 9 minutes pre-treatment by ultrasound and then using an infrared dryer is the best condition for drying lentil sprouts.

The frequent and long-term use of a significant amount of frying oil at temperatures between 150 °C and 190 °C to heat and immerse food is called deep frying. This method of food preparation due to the creation of attractive sensory and organoleptic features, including texture crispness, good taste, increasing the speed of cooking, and producing food products with a unique aroma,taste and brown color has been noticed by all the people of the society, especially the youth (Asokapandian et al., 2020). In the process of deep frying, as a result of the interaction between oil and other factors such as moisture, oxygen and heat, the main and complex chemical reactions of hydrolysis, oxidation, denaturization, isomerization and polymerization occur, by transferring moisture from the food to oil and absorption of oil into food leads to the production of harmful compounds and the reduction of oil quality, as well as chemical changes and mechanical deformations such as wrinkling, expansion and crust formation in fried food products (Dash et al., 2022). The extent of these changes depends on various factors, such as the characteristics of food and oil, the type of fryer, the type of heating process, the increase in factors such as the rate of integration of air and oil, the number of times of frying, and the duration of immersion of the food. Considering the very unfavorable effects of these reactions on oil quality, in order to reduce corruption and to identify and determine the point of oil disposal during the deep-frying process, various important indicators have been determined. The most important of these indicators are polar compounds, anisidine value, peroxide, volatile and non-volatile compounds, peroxide number, free fatty acids, acid value, iodine number, and smoke point. This study aimed to investigate the possibility of determining and predicting the tipping point of frying oil during deep frying (Xu et al., 2019).

For this purpose, on four consecutive days for 6 h with 45 minintervals, 100 g of semi-prepared potatoes from the Paris brand for 8 to 10 min in a fryer containing 4 L of Aftab brand oil. It was fried at a temperature of 180 oC, at the end of 6 hours of work, the fryer was turned off and some of the oil inside the fryer was removed in a container, after cooling the oil inside the container, 3 Falcon tubes of 50 ml (total 150) of the oil sample was separated to evaluate and perform various tests, and after labeling, it was placed in the freezer at -10 oC. To evaluate the changes in the oil used on the 4 day samples and the control sample (total of 5 samples), tests of anisidine, peroxide, acidity, polar compounds, and absorption in the region of 200 to 900 nm at a wavelength of 380 nm were performed. Suitable kinetic modeling was performed using MATLAB software, and these changes were interpreted using SPSS software with a confidence level of 95%. In previous studies, the changes in the oil factors of trade and industry were evaluated and investigated, but the amount of absorption in a certain spectrum and the use of this factor to determine and predict the tipping point of oil have received less attention (Senanayake 2018).

In this study, it was found that with the increase in the time of frying potatoes, the amount of acidity, polar compounds, anisidine value and absorption in the fried oil increased, and statistically, these changes were significantly different from they also have (p≤0.05). Thus, the lowest level of acidity was related to the control treatment, and the highest level of acidity was related to the fourth-day sample. The peroxide changes first increased and then decreased, and the changes in this treatment were different from those of the other treatments. The acidity and anisidine values passed the point of corruption of these factors, but polar compounds and peroxide did not reach this point. The anisidine values were significantly different between the treatment and control samples (p≤0.05). As the number of days passed, the amount of anisidine in the fried oil increased, which was statistically significant (p≥0.05). Thus, the lowest number of anisidines was related to the control treatment, and the highest number of anisidines was related to the fourth-day sample. There was a significant difference in polar compounds between the treatment and control sample (p≤0.05). As the number of days elapsed, the number of polar compounds in fried oil increased, with a statistically significant difference (p≤0.05).Thus, the lowest amount of polar compounds was related to the control treatment, and the highest amount was related to the sample on the fourth day. The absorption at in 200-900 nm was significantly different between the treatment and control samples (p≤0.05). With the passage of time, the amount of absorption in 200-900 nm range in fried oil increased, which was statistically significantly different (p≤0.05). Therefore, the lowest absorbance at 200-900 nm was related to the control treatment and the highest absorbance at 200-900 nm was related to the fourth-day sample. Researchers believe that the measurement of polar compounds is the most important test in oil decomposition. The amount of polar compounds during a certain period of margarine heating is a function of the amount of moisture and oil phase used (including the resistance of the oil to oxidation, the amount of mono- and diglycerides, free fatty acids and oxidized triglycerides).

Measuring and checking the changes in oil factors, as well as using the intensity of absorption of polar compounds at different intervals in determining the spoilage and waste of industrial frying oils is a very suitable and practical method. The results of this research show that theabsorption index of polar compounds can be used to determine the pour point of oils used in frying.

Probiotics are live microorganisms that have beneficial effects on human health when consumed in sufficient quantities (Fuller 1989). Kefir beverage is a natural complex probiotic and one of the oldest fermented milk products. This microbial symbiotic is obtained by fermenting milk with kefir grains. Consumption of kefir is effective in promoting health and increases the body's immune system, balances blood pressure, treats digestive diseases and reduces serum cholesterol levels, and also has antibacterial, antifungal and antitumor activities (Farnworth 2005). The microflora of kefir grains contains a group of specific microbes that exist in a complex symbiotic relationship, including species of yeasts, lactic acid bacteria (Lactobacillus and Lactococcus), and acetic acid bacteria (Garbers 2004). Kefir is a complex probiotic, from a microbial symbiotic that is obtained from milk fermentation by kefir grains, and its consumption is effective in promoting health. The main raw material for making kefir beverage is cow's milk. For various reasons, some people do not consume cow's (animal) milk: they may be vegetarians or have health problems such as lactose intolerance or a casein allergy (Bau et al., 2015). The purpose of this study is to investigate the antibacterial activity of kefir samples prepared with soy milk against 10 pathogenic bacteria.

The regeneration and fermentation process of grains was done with successive subcultures in milk according to the method presented by Ajam and Koohsari (2020). Activated kefir grains were added to soy milk (with 2% and without sucrose) and the fermentation process was performed at 25°C and 37°C. After fermentation, kefir grains were separated from kefir extract and the antibacterial activity of kefir extract against 10 pathogenic bacteria including Staphylococcus aureus, Bacillus cereus, Shigella dysenteriae, Enterococcus faecalis, Pseudomonas aeruginosa, Salmonella typhimurium, Escherichia coli (native isolate and standard strain) and Klebsiella pneumoniae (native isolate and standard strain), was evaluated based on diffusion in agar and by the well method. For this purpose, the method presented by Weinstein et al., 2018 was used. Regarding sensory tests, in order to compare with kefir samples prepared from soy milk, kefir samples with cow's milk were also prepared, so that a comparison can be made between these samples. In order to study this comparison, indicators of overall appearance, color, fragrance, taste and mouthfeel and total score were measured.

The results of the effect of fermentation temperature (25°C and 37°C) and the presence of sucrose in kefir samples prepared with soy milk on the antibacterial activity against the tested bacteria, except for the gram-positive bacteria E. faecalis and S. aureus, indicate a significant difference between treatments (P>0.05). The presence of sucrose and fermentation temperature had a significant effect on antibacterial activity against all tested bacteria except E. faecalis and S. aureus. And kefir samples prepared with soy milk containing sucrose showed more antibacterial activity. The highest antibacterial activity of kefir samples prepared with soy milk against P. aeruginosa was related to kefir samples prepared with soy milk containing sucrose at fermentation temperatures of 25°C and 37°C with mean of diameter of inhibition zone of 20 mm. The highest antibacterial activity of the kefir samples prepared with soy milk against E. faecalis is related to the samples prepared with soy milk without sucrose and at the fermentation temperature of 25°C with mean of diameter of inhibition zone of 18.5 mm and the highest antibacterial activity of the samples against S. aureus was related to the samples of soy milk without sucrose at the fermentation temperature of 37°C with mean of diameter of inhibition zone of 16 mm. The highest antibacterial activity against S. dysenteriae and S. typhimurium was observed in kefir samples prepared with soy milk containing sucrose at fermentation temperatures of 25°C and 37°C. The highest antibacterial activity of kefir samples prepared with soy milk against the native isolate and standard strain of K. pneumoniae was related to kefir samples prepared with soy milk containing sucrose at fermentation temperatures of 37 with mean of diameter of inhibition zone of 21 and 18 mm, respectively. Compared to other tested bacteria, E. coli and especially the standard strain of this bacteria, showed more resistance than kefir samples prepared with kefir soy milk. In this regard, B. cereus showed resistance to all treatments and no antibacterial activity was seen against this spore bearing bacteria bacterium. Based on the results of sensory tests, no significant difference was observed between the treatments in any of the indicators (P<0.05), but nevertheless, the sensory evaluations indicated low sensory acceptability of kefir samples prepared with soy milk, so compared to kefir samples obtained from cow's milk, it obtained a lower overall score. Antibacterial activity of fermented beverage is related to the compounds present in this beverage. It has also been reported that the compounds in kefir drink are affected by the type of substrate or milk (soy milk in the present study), fermentation conditions, kefir grain origin and storage conditions (Rosa et al., 2017). Soy milk has different carbohydrates, the most important of which are sucrose, raffinose and stachyose, while lactose is the main carbohydrate in cow's milk (Pinthong et al., 1980). Among the mechanisms of antibacterial activity of kefir extracts, we can mention acidic pH, as a result of lactose fermentation or alternative substrates, increasing the content of organic acids, such as lactic acid, acetic acid, etc., by microorganisms in kefir grains (Kourkoutas et al., 2007). Addition of carbohydrates (including sucrose) improves the ability of kefir grain microorganisms to produce lactic acid in soy milk. In addition to the role of organic acids, the antimicrobial activity of kefir beverage is related to the production of peptides (bacteriocins), carbon dioxide, hydrogen peroxide, ethanol and diacetyl (Oliveira Leite et al., 2013). In addition to these compounds, the exopolysaccharide produced by kefir grains called kefiran also has antibacterial activities (Wang et al., 2008 and Prado et al., 2015).

The results indicated significant antibacterial activity of kefir samples prepared with soy milk against the tested bacteria except for B. cereus and the standard strain of E. coli. The remarkable effect of kefir samples prepared with soy milk against Gram-negative bacteria such as P. aeruginosa, K. pneumoniae, both native isolates and standard strains, and S. dysenteriae was very interesting.

Yogurt is one of the most popular fermented milk products, which affords an excellent source of essential nutrients such as vitamins, calcium, and proteins. It also provides valuable lactic acid bacteria that are beneficial to the function of human gut microbiota. However, plain yogurt lacks a variety of health-beneficial antioxidant substances particularly phenolic compounds, flavonoids, anthocyanins, and vitamin C. Therefore, incorporation of natural functional ingredients such as fruits (Alirezalu et al., 2014; Raikos et al., 2019; Arslaner et al., 2021) and vegetables (Kim et al., 2010; Yang et al., 2012; Hong et al., 2020; Momenzadeh et al., 2021) can boost the chemical composition and health benefits of the yogurt. Most of these investigations revealed that adding natural edible ingredients to yogurt improved its chemical composition, biological activity, and quality characteristics. Fortification with these bioactive constituents is one of various methods to preclude the syndromes associated with dietary deficiencies. In addition to antioxidant activities, these compounds exert other beneficial health effects such as antimicrobial, antidiabetic, anticancer, anti-obesity, anti-inflammatory, and cardioprotective properties. The aim of this study was therefore to evaluate the the effect of addition of concentrated bell pepper extract (CBPE) with three different colors on the physicochemical and color properties of set yogurt.

Bell peppers with yellow, orange, and red colors were washed and crushed by a blender. After straining for pulp extraction, the total soluble solids of juices were adjusted up to 30% by a rotary evaporator. The set-style yogurt samples were produced on a laboratory scale according to the method described by Yademellat et al. (2017) and Jooyandeh et al. (2023) with some modifications. For yogurt production, the milk was heated at 90 ◦C for 10 min and after the temperature reduction up to 65 ◦C, the CBPEs were added. After inoculation with 0.05% starter cultures (lyophilized powder) at 44-45 ◦C, the samples were incubated at 42 ◦C until the pH reached to 4.6. The yogurt samples were kept at refrigerator and analyzed for physicochemical characteristics (pH, total solids, syneresis and water holding capacity (WHC)) and color values (L*, a*, and b* indexes) during 21 (1, 11 and 21) days of storage. The yogurt sample without CBPE was prepared and considered as the control. For performing analysis, data were analyzed by a completely randomized factorial design using SPSS software, version 20. The mean of treatments was compared with Duncan test at 95% confidence level.

Results showed that incorporation of CBPE in the yogurt samples and the storage perid had significant impact on the studied parameters. With incorporation of CBPE in the yogurt samples and with the passage of storage time, the amounts of pH, syneresis and lightness significantly decreased, while the amounts of total solids, WHC and a* and b* values increased. The amounts of pH of yellow CBPE was slightly higher than other fortified samples, but these differences were not significant (p>0.05). The red CBPE sample had higher total solids and syneresis than orange and yellow CBPE samples but these differences were also not significant (p>0.05). The control sample (yogurt without CBPE) had higher L* value (87.87) than yellow (85.36), orange (83.87) and red (80.32) CBPE samples. The red CBPE sample had higher a* value particularly at the end of 21 days of storage period as compare to other samples probably due to the higher anthocyanins content. The amount of a* value in red, yellow and orange CBPE samples were recorded as 8.94, -2.52 and -0.96, respectively. As the time of storage increased, the amount of redness particularly in the red CBPE yogurt increased probably due to the lower syneresis (Kim et al., 2010). Like a* values, results showed that fortified yogurt samples especially orange CBPE sample had higher b* value probably due to the higher carotenoids compounds. With agreement with our results, Kim et al. (2016) reported the higher amount of carotenoid substances in orange bell pepper (62.57 mg/100 g) as compare with yellow (35.32 mg/100 g) and red bell pepper (55.80 mg/100 g) on dry basis. Furthermore, in control sample with the passage of storage time, b* value increased slightly while in fortified samples decreased to some extent (p>0.05). The increase in b* value in control yogurt is probably due to destabilizing of casein micelles because of pH reduction during the storage (Garcia et al., 2005). The decrease in b* value in the fortified yogurts is undoubtedly due to disintegration of pigments mainly Xanthophylls during the storage period (Suwannasang et al., 2022).

Based on the results of the current study, incorporation of bell peppers in the form of concentrated extract had significant effect on physicochemical and color characteristics of set yogurts. One of the most common defects in set type yogurts is syneresis. The results revealed that by application of CBPE in yogurt formulation, the syneresis reduced and WHC increased significantly. Therefore, by incorporation of CBPE, a functional yogurt with a higher antioxidant substances and a lower syneresis could be produced. Based on sensory and antioxidant activities (results are not shown), the yogurt sample having orange CBPE was selected as the best functional product.

Probiotics are living microorganisms that, when consumed in food, provide health benefits to the host. In the past, probiotics were used as substances consumed by microorganisms that stimulate the growth of other microorganisms. The composition of probiotics is defined as microbial supplements that create a positive effect by modifying the composition of the microbial flora (Joyande et al. 2021). Among the effects of probiotics on human health, we can mention the improvement of milk digestibility in people with lactose intolerance, the enhancement of the immune system through antimicrobial peptide production, the synthesis of group B vitamins, the boost in the body's immunity, and the prevention of cell carcinogenesis (Fallah et al. 2019). Due to the conversion of fermentable sugars into organic acids, ethanol, and other metabolites with antimicrobial potential, these microorganisms create unfavorable conditions for the growth of potentially pathogenic microorganisms or agents of spoilage (Alizadeh Behbahani & Noshad. 2021). Native strains of lactic acid bacteria have found special importance in the dairy industry because these strains, in addition to being compatible with the conditions of the region, possess a unique ability to produce the desired taste and aroma in various types of fermented products. Additionally, these strains exhibit characteristics such as inherent resistance to destructive phages and antimicrobial effects (Rokhtabnak et al. 2015). The aim of this research was to investigate the functional potential and antimicrobial activity of the Levilactobacillus brevisNKN55 strain isolated from local yogurt in Tashan (Behbahan). If it exhibits desirable functional and antimicrobial properties, it can be utilized in the production of dairy products either as a complementary culture or as a natural preservative.

Firstly, the strain was isolated and identified using molecular methods. Subsequently, the strain was evaluated for probiotic properties such as acid resistance (pH 2.5, 3.5, and 4.5), hydrophobicity, and bile resistance (0.3, 0.5, and 0.7). Cholesterol absorption was also assessed. Additionally, the strain underwent evaluation for biogenic amine production, hemolytic and DNase properties. The antioxidant property of the isolated strain (measured using DPPH and ABTS assays) was determined, and its antimicrobial activity against 6 key pathogens (Escherichia coli, Bacillus cereus, Salmonella typhimurium, Klebsiella aerogenes, Staphylococcus aureus, and Listeria monocytogenes) was investigated using disc diffusion and agar well diffusion methods. Furthermore, adhesion potential to Caco-2 cells, anti-adhesion properties, auto-aggregation capacity, and co-aggregation of the strain were also evaluated.

The maximum reduction in strain viability is associated with a shelf life of 3 hours at pH 2.5. As the pH decreased from 4 to 2, a significant decrease in the number of viable cells was observed, dropping from 7.8 to 6.90 Log CFU/mL. In this study, the growth of the strain decreased by 0.7% with an increase in bile salt percentage. The hydrophobicity of the strain was 58.4±0.40%. For the investigated strain, DNase, biogenic amine production, and hemolytic activity were negative. The cholesterol absorption rate was 10.39, while DPPH and ABTS free radical capacity were 33.46 and 38.5, respectively. The auto-aggregation potential was 33.8, and Co-aggregation was 21.45. Adhesion potential to Caco-2 cell was 10.50, and anti-adhesion potential against K. aerogenes was 38.90 in competition, 31.20 in ability, and 19.8 in displacement. One of the important characteristics of lactic acid bacteria, crucial in their role in the food industry, is resistance to exposure to acidic conditions in products such as yogurt or buttermilk. For this purpose, the survival of these bacteria was tested at pH 2.5, 3.5, and 4.5. The results showed that the Lev. brevisNKN55 strain has a favorable shelf life under the investigated conditions.To produce beneficial effects in the body, probiotics must be able to grow in the stomach and intestines and have the ability to live there. For this purpose, they must have the necessary resistance to face hydrochloric acid in the stomach and bile salts in the intestine (Alizadeh Behbahani et al. 2020). The results showed that Lev. brevis NKN55 has good resistance to different concentrations of bile salts. In this study, the growth of the tested strain was inhibited by 0.7% with an increase in the percentage of bile salt. However, the growth rate depends on the concentration of bile salts. These results are similar to other studies that have shown lactobacilli can survive in high bile levels. Surface hydrophobicity can be used as a primary way to identify probiotic bacteria with adhesion properties and suitable characteristics for commercial purposes (Vasechi et al. 2020). The presence of hydrophobic molecules on the cell surface, such as surface proteins, cell wall proteins, cytoplasmic membrane proteins, and lipids, increases the cell's hydrophobicity. There is always concern about the commercial use of these bacteria because it is possible to transfer this gene to pathogenic bacteria and create resistance against them. The significant sensitivity of the isolated strain to multiple antibiotics indicates that this strain may not possess genes that cause antibiotic resistance. One critical aspect of probiotic bacteria that should be considered during evaluation is their antibacterial effect, attributed to metabolites such as organic acids, hydrogen peroxide, diacetyl, ethanol, phenols, and protein compounds that inhibit growth (Barzegar et al. 2020). The most common antimicrobial compounds reported to be produced by probiotic bacteria include bacteriocins, hydrogen peroxide, and organic acids (especially lactic and acetic acids). Auto-aggregation is directly related to the adhesion potential of probiotic bacteria, while aggregation has a close interaction with pathogens (Patel et al., 2011). The auto-aggregation property helps bacteria adhere to intestinal cells and mucosal surfaces. Cell aggregation may enable bacteria to form a barrier that prevents colonization and biofilm formation by pathogenic bacteria. The ability of bacterial cells to attach to intestinal mucosa is called adhesion (Jena et al. 2013). In case of damage to the epithelial tissue, the probability of bacterial cell adhesion decreases. Probiotic bacteria are used to treat damage to the digestive system and replace its lost flora. By correcting the microbial balance inside the intestine, damaged tissue is improved, and the ability of microorganisms to bind to the surface of intestinal cells increases (Fontana et al., 2013).

The process of collecting and identifying native strains from fermentation products in any part of the country can cause Preservation of microbial and genetic reserves and provides useful information for scientific and commercial applications, especially in the field of dairy industries and the discussion of probiotics and functional foods. In this study, Lev. brevisNKN55 strain isolated from Behbahan yogurt was evaluated for its probiotic and antimicrobial potential. The results showed that this strain has a high ability to inhibit pathogenic bacteria. This bacterium tolerates different concentrations of bile salts well. It also has the ability to survive in acidic conditions. This bacterium tolerates different concentrations of bile salts well. It also has the ability to survive in acidic conditions. The studied strain was sensitive to common antibiotics and showed acceptable adhesion, hydrophobicity, auto-aggregation and accumulation. According to the results, it is suggested to use this strain as a probiotic supplement in fermentation cultures or as a co-culture in the production process of fermented food products after conducting more confirmatory tests. The results showed that this strain has a high ability to inhibit pathogenic bacteria. This bacterium tolerates different concentrations of bile salts well. It also has the ability to survive in acidic conditions. This bacterium tolerates different concentrations of bile salts well. It also has the ability to survive in acidic conditions. The studied strain was sensitive to common antibiotics and showed acceptable adhesion, hydrophobicity, auto-aggregation and accumulation. According to the results, it is suggested to use this strain as a probiotic supplement in fermentation cultures or as a co-culture in the production process of fermented food products after conducting more confirmatory tests. The results showed that this strain has a high ability to inhibit pathogenic bacteria. This bacterium tolerates different concentrations of bile salts well. It also has the ability to survive in acidic conditions. This bacterium tolerates different concentrations of bile salts well. It also has the ability to survive in acidic conditions. The studied strain was sensitive to common antibiotics and showed acceptable adhesion, hydrophobicity, auto-aggregation and accumulation. According to the results, it is suggested to use this strain as a probiotic supplement in fermentation cultures or as a co-culture in the production process of fermented food products after conducting more confirmatory tests.The results showed that this strain has a high ability to inhibit pathogenic bacteria. This bacterium tolerates different concentrations of bile salts well. It also has the ability to survive in acidic conditions. This bacterium tolerates different concentrations of bile salts well. It also has the ability to survive in acidic conditions. The studied strain was sensitive to common antibiotics and showed acceptable adhesion, hydrophobicity, auto-aggregation and accumulation. According to the results, it is suggested to use this strain as a probiotic supplement in fermentation cultures or as a co-culture in the production process of fermented food products after conducting more confirmatory tests.

The saffron plant is native to Iran. About 90% of the world's saffron is produced in Iran. Drying saffron has a great effect on the qualitative and sensory characteristics of saffron. Saffron drying is done in different ways. In choosing the optimal method and conditions for drying saffron, one should pay attention to points such as regional conditions, pollution level, efficiency, final moisture and product quality indicators. Drying saffron at a temperature of 25 to 60 degrees Celsius will reduce the amount of crocin pigment and the intensity of coloring due to the enzymatic decomposition of crocin (Tsimidou and Biliaderis 1997). Using a temperature higher than 90°C will reduce the intensity of saffron coloring due to the increase in the thermal decomposition and oxidation of crocin (Gregory et al., 2005).The saffron plant is native to Iran. About 90% of the world's saffron is produced in Iran. Drying saffron has a great effect on the qualitative and sensory characteristics of saffron. Saffron drying is done in different ways. In choosing the optimal method and conditions for drying saffron, one should pay attention to points such as regional conditions, pollution level, efficiency, final moisture and product quality indicators. Drying saffron at a temperature of 25 to 60 degrees Celsius will reduce the amount of crocin pigment and the intensity of coloring due to the enzymatic decomposition of crocin (Tsimidou and Biliaderis 1997). Using a temperature higher than 90°C will reduce the intensity of saffron coloring due to the increase in the thermal decomposition and oxidation of crocin (Gregory et al., 2005). The saffron plant is native to Iran. About 90% of the world's saffron is produced in Iran. Drying saffron has a great effect on the qualitative and sensory characteristics of saffron. Saffron drying is done in different ways. In choosing the optimal method and conditions for drying saffron, one should pay attention to points such as regional conditions, pollution level, efficiency, final moisture and product quality indicators. Drying saffron at a temperature of 25 to 60 degrees Celsius will reduce the amount of crocin pigment and the intensity of coloring due to the enzymatic decomposition of crocin (Tsimidou and Biliaderis 1997). Using a temperature higher than 90°C will reduce the intensity of saffron coloring due to the increase in the thermal decomposition and oxidation of crocin (Gregory et al., 2005).International and national standards recommended minimum humidity of 12% and 10% respectively for saffron in order to increase its shelf life. Moisture absorbent materials are based on the principle of moisture transfer due to the difference in vapor pressure between the absorbent material and air. The absorbent material with low moisture content absorbs moisture from the air and reaches a balance with it. The saffron plant is native to Iran. About 90% of the world's saffron is produced in Iran. Drying saffron has a great effect on the qualitative and sensory characteristics of saffron. Saffron drying is done in different ways. In choosing the optimal method and conditions for drying saffron, one should pay attention to points such as regional conditions, pollution level, efficiency, final moisture and product quality indicators. Drying saffron at a temperature of 25 to 60 degrees Celsius will reduce the amount of crocin pigment and the intensity of coloring due to the enzymatic decomposition of crocin (Tsimidou and Biliaderis 1997). Using a temperature higher than 90°C will reduce the intensity of saffron coloring due to the increase in the thermal decomposition and oxidation of crocin (Gregory et al., 2005). International and national standards recommended minimum humidity of 12% and 10% respectively for saffron in order to increase its shelf life. Moisture absorbent materials are based on the principle of moisture transfer due to the difference in vapor pressure between the absorbent material and air. The absorbent material with low moisture content absorbs moisture from the air and reaches a balance with it.The advantages of moisture absorbent materials in drying, in addition to low energy consumption, include continuous drying even in non-sunny hours, increased drying rate due to hot and dry air, very uniform drying, and higher product quality, especially for heat-sensitive products (Dorouzi et al., 2017). There is no research available in the field of using moisture absorbing compounds in drying saffron. The purpose of the research was to investigate the effectiveness of moisture absorbent material on drying saffron and the effect of the characteristics of the air entering the dryer containing moisture absorbent material on the quality indicators (color, aroma and taste) of saffron. The stigmas were separated from the saffron petals and prepared for drying. The usual index and sufficiency of saffron drying was considered equal to 10% moisture based on national standard No: 259-2. After drying and reaching laboratory conditions in terms of temperature and humidity, the samples were packed in glass containers and kept at 4 °C for evaluation tests. In the first phase, moisture absorbent materials including silica gel, natural zeolite, clay and bentonite were compared in terms of their effect on the drying speed of saffron. At this stage, these materials were placed in the drying machine and under constant drying conditions (inlet air temperature 40°C and inlet air velocity 0.4 m/s) the time for saffron moisture to reach 10% of the initial value was measured. . To determine the time to reach 10% moisture, direct weighing during drying and comparing it with the moisture content of the original product was used. The adsorbent selected from this step was used in the next step. Then, with the aim of determining the optimal conditions of the incoming air in the drying method using the moisture absorbent material selected from the previous phase, the incoming air with 3 speeds of 0.2, 0.4 and 0.6 m/s and three temperatures of 30, 40 and 50 degrees Celsius after passing through the (selected) moisture absorbent layer, it entered the dryer and the effect of the treatments on the amount of picrocrocin, safranal and crocin of saffron was checked and the optimal speed and temperature of the inlet air was selected. Also, the effect of drying method on the quality of saffron was investigated. In this experiment, saffron was dried using three Spanish methods, dry shade (traditional) and drying with moisture absorbent materials, and the effect of drying method on picrocrocin, safranal and crocin of saffron was investigated. Drying methods included the traditional, Spanish method and the use of moisture absorbent materials. Saffron quality evaluation tests including measuring the values of saffron quality indicators, i.e. picrocrocin, safranal and crocin, were determined based on national standard number 259-2 and with a spectrophotometer and ultraviolet-visible spectrophotometric method. The drying of saffron continued until the moisture content reached 10%. The results showed a significant difference between the effects of moisture absorbent materials on the drying time of saffron under the same temperature conditions. The highest drying speed was related to silica gel and the lowest was related to clay. An important issue is the ability to stabilize silica gel in the drying bed and the possibility of reusing it without contamination. The results showed that as the temperature increased from 30°C to 50°C, the amount of picrocrocin gradually decreased. Also, at a constant temperature, the amount of picrocrocin increased with the increase of the inlet air speed. Decreasing the drying temperature along with increasing the incoming air speed can produce saffron with a better aroma. The studied temperature range for drying saffron, i.e. the temperature range of 30°C to 50°C, the amount of crocin increased with increasing temperature. The quality of saffron obtained by drying saffron with moisture absorbent was in competition with the traditional drying method. Among the three methods of drying saffron, by measuring the qualitative indicators of saffron, the traditional drying method produces saffron with an aroma index (safranal) (48 ± 2.7 unit), taste index (picrocrocin) (96 ± 2.1).The drying method with silica gel moisture absorbent material was after the traditional method in terms of taste index (86.7 ± 1 unit). In terms of saffron color index (crocin), the Spanish method (211.37±3 unit) scored the highest. The use of moisture absorbent materials in the process of drying saffron can significantly help in drying saffron with high quality (taste and aroma). The use of air speed of 0.2 m/s was chosen due to economic efficiency. The highest amount of crocin (235.7±5 unit) was obtained at a temperature of 50 °C and an air velocity of 0.2 m/s. Drying saffron at 30 °C produced saffron with better taste and aroma. To create crocin or more color in saffron, after drying saffron at a temperature of 30°C, at the end of the drying process, it is better to use a high temperature of 50°C.

Kefir is a dairy that contains lactic acid, carbon dioxide, and other volatile aromatics traditionally produced by the activity of kefir dunkers (Gaware et al., 2011). One of the constituent components of kefir grain are mucoid substances that are produced by the microbial flora of this grain, and exopolysaccharide called kefiran is one of them. Radhouani et al. (2018) showed that kefir is a suitable material for use in the field of biomaterials production, film and tissue formation. The most prominent biodegradable biopolymers used in food packaging from the group of biopolymers produced by microorganisms are bacterial cellulose and kefir (Rhim et al., 2013 and Sabatino et al., 2020). Kefiran is able to produce transparent films with relatively good mechanical resistance. Recently, the antimicrobial effect of postbiotics has attracted the attention of researchers. Postbiotics are actually a byproduct of the fermentation process done by probiotics (Moradi et al., 2019). Silver nanoparticle is one of the nanomaterials that has been mentioned in many studies for its antimicrobial effect as well as the effect of improving the mechanical and barrier properties of biodegradable films (Ajitha et al., 2021; Blosi et al., 2021; Li et al., 2023). One of the new methods in the production of biopolymer films that has recently attracted the attention of researchers is the electrospinning method. Electrospinning is a process in which continuous polymer fibers with diameters in the sub-micrometer range are produced through the action of a high-voltage electric field applied to a solution.

To cultivate kefir seeds, kefir grains were first cultured in fresh cow's milk for activation and growth. In order to increase the activation speed, greenhouse was used at a temperature of 27°C. To extract kefir from kefir grains, kefir grains were mixed with distilled water at a ratio of 1:10 at a temperature of 81°C and then the resulting mixture was centrifuged at a temperature of 20°C for 20 minutes. Then, kefirs using 96% ethanol were centrifuged at a temperature of 4°C for 20 minutes, and the obtained precipitates were mixed with distilled water at a temperature of 80°C in a ratio of 1:5. This washing step was repeated twice until a white deposit of kefir was obtained and then, was dried.In order to extract the postbiotic extract, first, 5 g of kefir seeds were inoculated in the milk culture medium and placed in a greenhouse at 35°C for 48 hours. Then the culture medium was centrifuged and the supernatant was filtered with a needle filter. In this study, a concentration of 4% kefir was used to produce electrospun nanofibers. In this way, 0.04 g of kefir was added to 10 ml of postbiotic extract and electrospuned (Ethnaashri et al. 2024). To prepare the next treatments, three levels of silver nanoparticles (1, 2.5, and 4% by weight of kefir) were added to the previous solution and treated with an ultrasonic probe for 5 minutes (40 kHz, 100W).Also, in order to study the properties of the nanofibers, FTIR, XRD, DSC and SEM analysis were performed and the contact angle, antioxidant activity and antimicrobial activity of them were studied.

This research was designed and implemented with the aim of developing an active electrospun nanofiber substrate for use in food preservation. Kefiran nanofibers containing kefir postbiotics in constant concentration and silver nanoparticles in different concentrations were prepared and their structural, morphological and functional properties were evaluated. Comparison of FTIR spectra of nanofibers containing nanosilver shows that the addition of nanoparticles had no effect on the chemical structure of nanofibers. Due to the small amount of nanosilver in the formulation of nanofibers, the peak related to the nanoparticles itself was not observed. The lack of change in the spectrum of kefir chemical groups due to the addition of nanosilver means that the nanoparticles are physically bound in the polymer network of kefir nanofibers. SEM images show tha nanofibers had a uniform cylindrical shape with a smooth surface and no knots. The average diameter of kefiran nanofibers without nanosilver was about 245 nm. Also, by increasing the concentration of silver nanoparticles to 2.5%, the size of nanoparticle clusters on the surface of nanofibers increased and the average diameter of kefir nanofibers decreased to 205 nm. XRD analisys of kefiran nanofibers showed a sharp peak at the angle of 2θ=44.5°. The results indicate the semi-crystalline nature of kefir nanofibers. With the increase of silver nanoparticles, there is no change in the intensity and location of the main peak at the angle of 44.5°, but a new peak is created at the angle of 2θ = 1.38° and the highest intensity is observed in the sample containing 4% nanosilver. The control nanofibers of kefir containing postbiotics showed three ranges of changes in the DSC test. The main melting peak of this nanofiber was observed at 73°C. By adding silver nanoparticles, the thermal properties of kefir nanofibers were weakened. The results show that silver nanoparticles affected the thermal properties of kefir and reduced its resistance to temperature. The contact angle of nanofibers by adding of silver nanoparticles at a concentration of 1%, shwed no significant change (p>0.05). But when the amount of silver nanoparticles reached 2.5% and 4%, the contact angle decreased significantly (p<0.05) and in fact the hydrophilic property of nanofibers increased. The antibacterial activity of electrospun kefir nanofibers containing postbiotics and nanosilver was investigated against E. coli and S. aureus. By increasing the amount of silver nanoparticles, the antimicrobial property increased and the sample containing 4% nanosilver showed the highest antibacterial activity against both bacteria. In this research, kefir nanofibers containing postbiotic showed an antioxidant activity of 5.65%, which is due to the low amount of postbiotic in the nanofiber formulation. By increasing the concentration of silver nanoparticles, the antioxidant activity increased significantly, and the highest inhibitory activity was observed at a concentration of 4% with a power of 59.21%.

The results of the FTIR test proved the physical connection and the lack of chemical bonding between silver nanoparticles and nanofibers. Good and uniform surface morphology was observed in kefir nanofibers in SEM test, but silver nanoparticles were observed in aggregated form. The XRD test showed no effect of nanosilver on the structure of kefiran nanofibers, but in the DSC test, the weakening of the thermal properties of kefiran nanofibers was reported with an increase in the concentration of nanosilver. The control nanofibers of kefirs that had only postbiotics also had antioxidant and antimicrobial properties, but these functional properties were enhanced by increasing the concentration of silver nanoparticles, and nanofibers containing 4% nanosilver showed the best antimicrobial and antioxidant properties. In general, the results of this study showed that kefir nanofibers containing postbiotic kefir and silver nanoparticles have favorable physical and functional characteristics and can be used as active food packaging and can be used for the purposes of increasing the shelf life of food and preventing microbial and oxidative spoilage.