Journal of food science and technology
Year:2021 | Volume:18 | Issue:114|Papers Count:30

One of the problems with the processed meat products shelf life is the formation of yellow spots in sausages. The aim of this study was to isolate and identify the microbial agents causing yellow stain from sausage by molecular-and culturebased methods. For this purpose, 15 samples from yellow spot and separation areas of chicken sausages were sampled. A total of 44 colonies grown on the MRS, M17, YGC, and PDB culture medium were inoculated into pre-packaged cutting sausages to induce the yellow spot. Yellow spots appearance9 samples and they were characterized by both culture-based methods and sequencing of a 350 bp fragment from 16S rRNA V3 region and a 800bp fragment from 18S rRNA ITS4 region. The results of the culture-based and molecular assay showed that the main causes of the yellow spots in the chicken sausage packaged under vacuum were Enterococcus faecium, Enterococcus faecalis, Streptococcus faecium and Candida saitoana. In addition, one species of Enterococcus and one species of Candida were also identified at the genus level. Examination of yellow spotted samples also showed that the microorganisms that cause yellow spotting cause changes in pH, color indices L*, a* and b*, and syneresis compared to the control sample but the rate of change is only in the syneresis quantity and a* was significant.

Milk, from its production to consumption, is exposed to a variety of microbial and chemical contaminants. Aflatoxin M1 (AFM1) is one of the most important contaminants in milk, which has always received attention due to its carcinogenic and destructive effects on the consumer. Accordingly, the rapid, sensitive, and costeffective identification of AFM1 in milk is essential. In the present paper, an electrochemical aptasensor based on screen printed electrode (SPE) modified with magnetic nanoparticles (MNPs) and gold nanoparticles (AuNPs) was proposed to identify AFM1 in cow milk samples. SPE was activated by applying a potential within the range of-1. 5 to +1 V versus the reference electrode at a scan rate of 200 mV/s for 5 continuous cycles in the 0. 5 M sulfuric acid and 0. 1 M potassium chloride solution. Changes of the electrode surface at different stages of preparation were assessed using cyclic voltammetry (CV) technique. Using CV in optimal conditions, it was found that the aptasensor presents a concentration range of 100-700 ng/l and a limit of detection (LOD) of 50 ng/l. There was a linear relationship between changes of the current peak (Δ I) and analyte concentration. This relationship follows the regression equation of Δ I=0. 0209C+2. 14 (R² =0. 9897). Calculation of the relative standard deviation (RSD=3. 2%) indicated the acceptable repeatability of the electrochemical aptasensor. The current peak was obtained to be 7. 4% in the investigation of RSD reproducibility, indicating the good reproducibility of the electrochemical aptasensor. The obtained results showed that the aptasensor response after 8 days has only reduced by 7% compared to the first day, indicating the desirable stability of the aptasensor. The recovery percentage range for cow milk samples at concentrations of 100 and 200 ng/l was obtained to be 86. 5 and 93%, respectively, showing the acceptable recovery percentage of the electrochemical aptasensor.

In this study, the antifungal activity of Boswellia sacra essential oil was evaluated against fungi species causing strawberry rot (Botrytis cinerea, Aspergillus niger, and Rhizopus stolonifer), via well diffusion agar, disk diffusion agar, microdilution broth, and minimum fungicidal concentration methods. Extraction yield, total phenolic and flavonoid contents, and antioxidant activity (DPPH and ABTS radical scavenging methods) of the essential oil were also determined. The extraction yield of the oil was 1. 30% w/w and its total phenolic and flavonoid contents were 69. 37 mg GAE/g and 38. 40 mg QE/g, respectively. The antioxidant activity of B. sacra essential oil, based on the DPPH-and ABTS-radical scavenging activity, were found to be 57. 50% and 48. 66%, respectively. According to the results of disk/well diffusion agar tests, B. cinerea andR. stolonifer were the most sensitive (the highest inhibition zone) and resistant (the lowest inhibition zone) fungal species to the B. sacra essential oil, respectively. The minimum inhibitory concentration and minimum fungicidal concentration were, respectively, ranged from 25-50 and 200-400 mg/ml. Based on the results, the B. sacraessential oil contains bioactive compounds with appropriate antioxidant and antimicrobial properties, and it could be therefore used as a natural preservative agent to increase the shelf-life of various food products.

In this work, the physicochemical properties of commercial guar gum powder were investigated after air atmospheric pressure cold plasma treatment at three different times (5, 10 and 15 min). The results of steady shear flow test showed that behavior of both control and cold plasma treated samples was pseudoplastic. Among the rheological models, the Hershel bulkley model had higher coefficient of determination (R2). The nH in the control and treated samples was less than 1. Also, KH decreased significantly with time (except 5 minutes). In strain sweep, storage module G′ and loss module G″ decreased significantly as the time increased. The crossover point (G′ =G″ ) of 5 minutes treated sample for 5 minutes was higher than the control samples, which decreased with increasing the treatment time. In the low frequency range of frequency sweep, G″ module of the control and treated samples was higher than G′ module. From the frequency of 0. 1 to 1 Hz, the G′ and G″ modules depended on the frequency. After crossover, the G″ module prevailed over the G′ module and the guar gum showed weak gel behavior. The value of tanδ in samples was less than 1 and higher than 0. 1. The complex viscosity (η *) significantly decreased, as the time of treatment increased. The slope of complex viscosity decreased with the increasing time. The FTIR data demonstrated that the absorption spectrum of the treated samples was similar to the control one.

Nowadays, the food industry is looking for new technologies to increase the shelf life of various products. Furthermore, as consumer's demand for more “ healthier” meals (free of conventional chemical preservatives) has increased in the last decade. In this study, edible sago starch coating containing leave extract of Withania Somnifera (0. 125 and 0. 25 mg/ml, 1 and 2 times MIC, respectively) was applied onto chicken fillet to extend its shelf life at 4 ˚ C. Examination of coated chicken fillets showed that active film of sago starch inhibited the microbial load (aerobic bacteria, coliform and Staphylococcus aureus bacteria) of chicken fillets. The results of chemical analysis of chicken fillet also showed that the coated samples had less volatile nitrogen compounds, thiobarbituric acid index and peroxide value than control. In general, the results of this study showed that the edible film produced from sago starch containing Withania Somnifera extract increases the shelf life of chicken fillets.

Utilization of dairy products assumed to be the first option for the phrmaceutical purposes. Hence, in this project, we have been following to produce a functional product, which is fortified with malt extract (5%, 10% and 15%), and inulin (0. 5%, 1% and 2%) and containing Lactobacillus casei. Microbial survival, physicochemical, textural and sensorial properties investigated during 28 days. The results showed that storage of treatments for up to 28 days at 4 ° C significantly reduced the activity of probiotic microorganisms (p≤ 0. 05). Physicochemical properties of ice cream, showed an alteration, so that pH of treatments decreased significantly while acidity increased (p≤ 0. 05). Color parameters induced as malt extract and inulin increased (p≤ 0. 05). Functional properties including melting stability and over run also improved dramatically, however, in treatments with 15 percent of malt extract a reverse trend observed (p≤ 0. 05). Increase in inulin and malt extract revealed with an upward trend in hardness and adhesiveness of treatments. In addition, treatments with 15 percent of malt extract weakened the textural properties, eventually end up in sensorial evaluation of treatments led to selection of sample D (treatment with 5 percent malt extract, 1 percent inulin), which is recommended for probiotic ice cream fortification.

Plant essential oils are frequently used as natural preservatives to decrease the toxicity of synthetic fungicides and environmental pollution. This study was aimed to investigate the antifungal effect of Vitex agnus-castus essential oil on Penicillium digitatum and Penicillium italicum causing orange rot. The essential oil of V. agnuscastus was extracted by the hydrodistillation method and the extraction yield was 0. 95% w/w. The total phenol and flavonoids content of the essential oil were also measured and the results showed that the essential oil is rich in phenolics (91. 74 mg GAE/g) and flavonoids (52. 32 mg QE/g). The evaluation of antioxidant activity of the V. agnus-castus essential oil showed that the bioactive compound is able to effectively scavenge DPPH (IC50 = 48. 62 μ g/mL) and ABTS (IC50 = 40. 50 μ g/mL) free radicals. The antifungal activity of the V. agnus-castus essential oil was evaluated against P. digitatum and P. italicum, based on disk diffusion agar, well diffusion agar, and minimum inhibitory/fungicidal concentration methods. And P. digitatum was more sensitive to the essential oil and lower concentration of the bioactive compound was able to inhibit the growth of or kill the species. In general, the results of this study showed that the V. agnus-castus essential oil is rich in bioactive compounds with remarkable antioxidant and antifungal activities, and it could be applied as a natural preservative to increase the shelf-life of food products.

The aim of this work was to develop an enriched apple jelly with Spirulina sp. Four formulations were developed: C, J1, J2, J3 with 0, 0. 75, 1. 5 and 3% Spirulina sp. and their rheological, textural, color and sensorial properties were evaluated. The results showed that all samples presented predominant behavior of the elastic solid. Also, the non-intersection of the loss and storage modulus curves at the applied frequencies showed the behavior of a typical gel. Also, in all samples, the dependence of the storage modulus on the frequency was not observed, but in larger frequencies, especially the storage modulus of sample with higher percentage of spirulina algae, decreased, indicating a more liquid behavior. Indicators n and m also confirmed such behavior, decreasing the strength of gel structure with increasing spirulina concentration. The data obtained from the force-time curve showed that even though the variables of all samples were within the range of a typical jelly, but increasing spirulina algae content decreased the hardness, adhesiveness elasticity, gumminess and increased cohesiveness. These results follow the trend of those obtained by dynamic rheology. Also, the results related to the sample color showed that the addition of spirulina in 1. 5 and 3% percentages significantly decrease the variables L*, b* and C* especially in the sample with 3% algae, presenting a darker sample. The overall color difference between the samples also was more than 6 degrees, which detected different color groups. Sensorial scores of samples, mainly color and overall acceptance also reduced with increasing the percentage of microalgae. In general, it can be concluded that incorporating of Spirulina in the apple jelly regarding to its negative effect on the most evaluated parameters, requires further research and a better understanding of its gel formation mechanism to optimize the formulation and process treatments.

Increasing consumer awareness of the dangers of chemicals and the effect of heat treatment on the foods nutritional value, lead to increase of the demand for the production and use of fresh or minimaly processed foods. In this study, the ability of cumin, fennel and clove essential oils (concentrations of 50, 75, 100, 200 ppm and pure form) in non-thermal inactivation of courgette peroxidase enzyme were investigated. The results showed that only pure form and concentration of 200 ppm of cumin essential oil and also pure form and high concentrations (100 and 200 ppm) of fennel essential oil were able to reduce the peroxidase enzyme activity in courgette but using concentrations of 50 and 75 ppm of fennel essential oil leads to increase peroxidase enzyme activity. Clove essential oil in all studied concentrations reduced the peroxidase enzyme activity, which indicates the ability of clove essential oil to react with oxygen and inhibit the reaction of enzyme peroxidase and polyphenol oxidase (enzymatic browning reaction). The best conditions for inactivation of peroxidase enzyme under the influence of cumin essential oil included a concentration of 194. 5 ppm essential oil and an enzymatic activity time of 0. 02 seconds, while the optimal conditions for achieving the lowest peroxidase activity included using 200 ppm fennel essential oil and enzyme activity time of 0 second, and 200 ppm of clove essential oil and enzymatic activity time of 1. 7 second.

The aim of this study was to investigate the effect of probiotic bacteria and trypsin enzyme on the physicochemical, microbial and sensory properties of dough. For this purpose, bioactive peptides of 1. 5 and 3 mg /100 ml were added to the probiotic dough formulation, which were inoculated separately with 108 cfu / ml of Lactobacillus acidophilus and Lactobacillus helveticus. PH tests, mold and yeast counts, coliform counting, probiotic bacterial survival, antioxidant activity evaluation, gamma amino butyric acid measurement and sensory evaluation were performed on dough. The results showed that the use of probiotic bacteria with trypsin enzyme and increasing its concentration was maintained viability increase, probiotic bacteria, antioxidant properties, GABA production rate, and sensory evaluation score after 60 days. It also reduced pH, mold and coliforms in dough. Using Lactobacillus acidophilus and the enzyme trypsin 3 mg / 100 ml can produce high-yielding dough containing GABA with lower microbial load and higher antioxidant and sensory properties.

The aim of this study was to investigate the changes in color parameters (L*, a*, b* and Δ E) and the area of eggplant slices coated with different concentrations of wild sage seed gum during deep fat frying. In this study, eggplant slices in a cylindrical shape with a thickness of 1 cm were coated using wild sage seed gum in four concentrations of 0. 0, 0. 5, 0. 5 and 1. 5%. Then they were placed in the fryer and the effects of frying temperature at three levels of 150, 175 and 200 ° C on the appearance characteristics of the samples were investigated. To examine the changes in color indexes including lightness (L*), redness (a*), yellowness (b*) and color changes (Δ E) as well as changes in the area of the samples, images were taken continuously during the frying time. The L* index calculated for the frying process of eggplant samples showed that the coated samples were brighter in terms of lightness and eggplants coated with wild sage seed gum with a concentration of 1. 5% had higher L* values. With increasing the concentration of wild sage seed gum from 0. 5 to 1. 5%, the redness of the samples decreased from 11. 77 to 8. 38. In terms of color change index (Δ E), eggplants coated with wild sage seed gum showed the least color changes during frying. The mean Δ E values for the control sample, 0. 5%, 1% and 1. 5% of wild sage seed gum were 44. 66, 46. 25, 45. 85 and 39. 80, respectively. For modeling the color change index, the MMF model had less error compared to the Power, Quadratic, Gompertz, Logistic, Richards, and Weibull models and it fitted well with the experimental data. The average area changes calculated for the control sample, 0. 5%, 1% and 1. 5% of wild sage seed gum were 42. 99, 40. 49, 39. 70 and 38. 53, respectively. The results showed that coating of eggplant slices with 1. 5% of wild sage seed gum preserves the appearance of the fried product and also the least area changes were observed in these samples in the frying time at different temperatures.

Plants are rich source of phenolic compounds, which are the most important natural antioxidants. The aim of this study was to investigate the effect of extraction methods and different solvents on extraction yield, total phenolic content (TPC), total flavonoid content (TFC) and free radicals scavenging activity of DPPH in Moringa oleifera leaf extract. For this, the leaves were grinding after dried followed by different extraction techniques like soaking, Soxhlet and ultrasound (Frequency: 70 kHz) using distilled water, acetone and methanol as solvent. TPC and TFC were measured using Folin– Ciocalteu method and colorimetric assay. Antioxidant activity of resulted extracts was measured using 2, 2-Diphenyl-1-picryl-hydrazyl (DPPH). The antioxidant activity of the extracts was compared with ascorbic acid. The highest extraction efficiency was obtained in Soxhlet method use acetone as solvent (24. 40± 0. 34%). Methanol in Soxhlet extraction method showed the highest effect on TPC (24. 79± 1. 35 mg GAE/g dry sample) and TFC (81. 14± 1. 45 mg QU/g dry sample). In all samples, increased DPPH free radical scavenging when increased concentration of the extracts. The highest radical scavenging was observed in methanol extracts obtained by Soxhlet (IC50=49. 97± 0. 65). Finally, it could be concluded that, methanol was the best solvent and Soxhlet was the best method for extraction of phenolic and flavonoid compounds in in the leaves of Moringa oleifera.

In order to prevent the growth of pathogenic and spoilage bacteria in food, various chemical preservatives are used. However, due to health problems of these compounds, most food consumers demand the use of natural derived compounds from plant sources as an antimicrobial agent. The aim of this study was to investigate the possibility of replacing sodium benzoate and potassium sorbate preservatives with peppermint essential oil and malva sylvestris extract at two levels of 0. 5 and 1% and combination of these compounds at two levels of 0. 25: 0. 25% and 0. 5: 0. 5% as well as study the effect of these compounds on chemical (peroxide value, acidity), sensory and microbial properties of mayonnaise. According to the obtained results; samples containing malva sylvestris extract revealed better antioxidant activity, however, samples containing peppermint had better antimicrobial properties. Additionally, by increasing the concentration of peppermint essential oil up to 1%, the sensory scores of mayonnaise samples decreased. Moreover, the results also showed good antioxidant and antimicrobial activity as well as higher sensory scores of mayonnaise samples containing peppermint essential oil and malva sylvestris extract in combination (0. 5: 0. 5%). In conclusion, mayonnaise sample containing 0. 5% peppermint essential oil and 0. 5% malva sylvestris extract was determined as the optimal sample with favorable chemical, antioxidant, sensory and microbial properties.

Due to the progressive consumption of fried food products in the country, the increase of quality and oil uptake reduction is necessary. As a potent human toxicant, acrylamide is present in different heated food products, with unexpectedly high levels in potato products such as french fries. Prevention of acrylamide formation in food could minimize its dietary exposure and decrease its potential health risks to humans. For this purpose, blanched potato slices were immersed in curcumin extracts (0, 5, and 10% w/w) for 15 minutes, followed by frying in oil. Water content, oil uptake, shrinkage, color (L*, a*, b*), acrylamide content, and sensory properties were analyzed. The results showed that increasing curcumin concentration increased the water content and decreased the oil uptake and shrinkage in all samples. Color parameters indicated that L* and a*of the potatoes decreased by increasing curcumin extract concentrations, but b* was increased. The immersion in a solution of curcumin extract reduced the content of acrylamide in french fries significantly. As the increasing concentration of curcumin up to 10%, the amount of acrylamide decreased by 47% compared to the control sample. Sensory characteristics (appearance, smell, taste) except flavor at a concentration of 10% curcumin extract improved with increasing extract concentration. Using curcumin extract and improving the quality and sensory properties led to a significant reduction in fried potatoes' acrylamide formation. They could be suggested as a method to reduce the construction of this toxic compound.

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.

Shelf life is the amount of time that corresponds to an acceptable reduction in food quality under certain conditions. This feature depends on various intrinsic and environmental factors such as the nature of the food, storage processes, coating and the type of packaging, and it affects the stability of the product. The ability to estimate shelf life is of considerable commercial value, but there is no reliable method for this purpose for fresh pistachios. The aim of this study was to create mathematical models to predict the shelf life of food, using Badami's fresh pistachio samples coated with chitosan edible coating in different concentrations (0, 1, and 1. 5%) under three atmospheres including ambient atmospheric condition, passive MAP, and active MAP. The shelf life study was performed at 5° C and a multivariate prediction of instrumental and sensorial firmness was performed through kinetic models. In this study, fresh pistachios coated with 1. 5% chitosan under active MAP had the highest estimated shelf life (86 days). Also, obtained models were able to estimate the softening time to the end-point of shelf life in different conditions of coating and packaging of fresh pistachios.

In this study, the effect of a grape syrup and storage time on the physicochemical, microbial, and sensory properties of yogurt were evaluated using the response surface method. The amount of grape syrup and storage time were in the range of 0-5% and 1-21 days, respectively. The results of the statical analysis showed that with increasing the amount of grape syrup and storage time, the number of Lactobacillus casei were increased and decreased, respectively (p<0. 05). With increasing grape syrup, the moisture content and acidity decreased and ash, pH, and syneresis increased (p<0. 05). During storage time, pH decreased and acidity and syneresis increased (p<0. 05). The results of the microbial test showed that with increasing grape syrup and storage time, the molds count was decreased (p<0. 05). The results of sensory evaluation also showed that by increasing the amount of grape syrup, the score of color, flavor, and texture increased (p< 0. 05). According to the obtained results, for producing bio-yogurt, grape syrup at 5% and the storage time about 7 days found to be the optimal processing conditions.

One of the practical and inexpensive solutions in improving the characteristics of the bakery and reducing the waste of this category of products is to use sourdough. Therefore, in this study, the possiblity to use kombucha beverage and soybean milk as a water substitute in sourdough formulations prepared from Lactobacillus fermentum and Lactobacillus plantarum separately and to evaluate the physicochemical and sensory properties of toast samples prepared from this Sourdoughs were examined. The results showed that by adding sourdough prepared from kombucha beverage and soybean milk, the moisture content and acidity of the final product increased and the pH decreased. On the other hand, Lactobacillus fermentum was more effective than Lactobacillus plantarum in reducing pH and increasing acidity. In addition, after examining the amount of lactic acid and acetic acid in the product, it was found that the amount of lactic acid in samples prepared from sourdough containing kombucha beverage and kombucha beverage was maximum while the amount of more acetic acid in samples prepared from sourdough containing kombucha beverage and Lactobacillus fermentum was higher. Samples containing kombucha beverage had the lowest amount of firmness and the highest amount of specific volume and porosity, and the type of primer used in the sourdough had no effect on the amount of these parameters. On the other hand, the study of the crust color values showed that by adding kombucha beverage and soybean milk in sourdough formulation, the amount of L* and a* values was decreased and increased respectively. Finally, sensory evaluators gave the highest score to two samples of sourdough containing kombucha beverage in the presence of both Lactobacillus plantarum and Lactobacillus fermentum. Therefore, these compounds can be used to produce sourdough with better performance properties.

Ice milk is a low-fat frozen dairy product, which is much cheaper than ice cream. The texture of low-fat products is one of the most important issues in the marketing of these products. There has been a lot of research on the use of surfactants in ice cream formulations, which shows the ability of these compounds to increase consistency and agitation and aeration, improve melting resistance, create a softer and creamier texture, and increase the overrun. The present study investigated the effect of adding Chubak root extract powder to ice milk on the quality of this product. Ice milk mixture was produced with different concentrations of Chubak extract powder (0, 0. 015, 0. 030 and 0. 045 g/kg) and the changes in physicochemical and sensory properties of ice milk were investigated. The results showed that increasing the concentration of the extract in ice milk increased the consistency coefficient, overrun, melting resistance, creaminess and overall acceptance, while the values of flow behavior index, hardness, adhesiveness, roughness and coldness decreased. These results can be related to increased water absorption, improved agitation, increased fat instability and smaller ice crystals. Sensory evaluation showed that ice milk containing 0. 045 g/kg Chubak root extract powder had the highest overall acceptance and gained more scores. It can be concluded that the use of Chubak root extract powder in the preparation of ice milk can improve the functional characteristics of the product so that it can achieve a higher position in the group of frozen dairy products.

Drying is one of the oldest methods of food preservation, which usually have adverse effect on the physicochemical properties and nutritional value of the final product too. Today, the demand for application of rapid drying methods such as using microwave and infrared beams has increased to prevent or reduce undesirable changes in foods. In this study, the effect of infrared drying process condition (drying temperature and time) on weight loss, vitamin C and color properties of Shahsavar Yazdi pomegranate arils were investigated and optimized by response surface method. The results showed that the amount of weight loss and L* value of pomegranate samples, increased with increasing drying time and temperature, while the amount of vitamin C decreased. Drying temperature had a greater effect on weight loss and vitamin C changes compared to drying time; however, variation of L* value under the influence of infrared drying time are more severe than the drying temperature. The amount of a* and b* value increased with increasing drying temperature while decreased with increasing infrared drying time. The best conditions for infrared drying of pomegranate arils are using drying temprature of 55 ° C for 600 minutes and by applying the optimal conditions, the amount of weight loss, vitamin C and the total color difference ( E) of the produced pomegranate arils are equal to 69. 5, 12. 89 and 5. 79 respectively. The results of the optimal conditions validation test showed that by applying the obtained conditions from the optimization process, the quality attributes of pomegranate such as weight loss, amount of vitamin C and the total color difference ( E) of the produced samples were 70, 12. 45 and 7. 75 respectively, which are very similar to the obtained results from the optimal conditions predicted by the response surface method.

Nowadays, gums are used in cereal and flour products to replace gluten by optimizing physicochemical and rheological properties. In this study, with the aim of improving the rheological properties of the dough compared to the control sample, the effect of different concentrations of guar gum, xanthan and pectin gums (0. 3, 0. 6 and 0. 9%) in terms of weight / weight percentage based on rice flour of Nemat and Neda cultivars was examined. Based on the results of the viscosity properties, the highest Peak viscosity is in Nemat and Neda cultivars with the addition of guar (0. 9%) and the lowest Peak viscosity is in Nemat cultivar without adding gum or control sample. The results show that with increasing guar and increasing the concentration of added guar, the tendency to absorb water increases and the volumetric expansion of the dough will increase. The greatest effect on the rate of breakdown viscosity was observed in Nemat cultivar with the addition of xanthan gum and the highest rate of breakdown viscosity was observed in Neda cultivar with increasing guar (0. 9%). Due to the decreasing trend on the rate of breakdown, we find that xanthan is not a suitable hydrocolloid to improve the rheological properties of rice flour paste of Nemat cultivar. The highest rate of setback viscosity was observed in both Nemat and Neda cultivars with an increase of 0. 3% and the lowest rate was in the control sample. Comparison of the average of statistical data shows that the highest final viscosity in both Nemat and Neda cultivars with an increase in guar 0. 9% and the lowest in the control sample. It can be concluded that increasing the gums used in this study increases the tendency of the final product or product to dry after cooling.

Drying is an important method of preservation of wet materials and is applicable to a wide range of industrial and agricultural products. Dried products have limited deterioration rates, due to the low water activity, are easily transported and stored because of the reduced volume, and have no need of refrigeration, representing energy economy. The purpose of the present study was to develop a model to describe the heat and mass transfer during the drying of beetroot. Temperature, moisture content, and shrinkage of a beetroot disc were simulated during drying at three different air temperatures (50, 60, and 70 ° C). Simultaneous heat and moisture diffusion equations were solved along with convective boundary conditions, using a simulation language, MATLAB, based on finite difference technique. Shrinkage, variable thermal properties and moisture diffusivity were considered in the simulation. The simulated results matched satisfactorily with measured temperature and moisture content of the beetroot during drying.

In the present study, the effect of different concentration of flaxseed flour (0. 0. 5, 1, 1. 5%) and storage time (1, 7, 14, 21 days) have studied on physicochemical, microbial and sensory properties. The target of this study was production of functional low-fat yogurt that pontificated with flaxseed flour. The results have showed that increasing in flaxseed flour had no significant effect on pH and acidity, while synergies and dry matter have increased significantly. Viscosity decreased with increasing in flaxseed flour and with increasing in storage time, pH and Acidity increased and decreased respectively. Dry matter and viscosity showed increase and decrease with increasing in storage time. And the peroxide value increased significantly. Different levels of flaxseed flour had no significant effect on growing mold and yeast, while it has showed significant increase with increasing in storage time. In opinion of sensory properties, the most scores were for blank samples and samples with 0. 5% flaxseed flour. with increasing in storage time, scores reduced. According to nutritional properties of flaxseed flour and present essential fatty acids, using of this compound In addition to preserving yogurt chemical and physical properties, help to produce functional yogurt.

The impact of aw (0. 65-0. 9), temperature (15-30° C) and their interaction on the germination and radius growth of Aspergillus fumigatus isolated from cake was surveyed on Yeast Extract Glucose Chloramphenicol Agar (YGC-Agar) during 60 days as well as the capabilities of Gompertz and Logistic models for fitting data were explored. Rising aw (from 0. 65 to 0. 9) and temperature (from 15 to 25° C) caused significant enhancing of germination and growth rate of A. fumigatus (P < 0. 05). However, in constant aws, further increasing of temperature (up to 30° C) led to meaningful decreasing of these parameters (P < 0. 05). A. fumigatus did not germinate at aw 0. 65. In addition, germination was observed at aw 0. 7 and 0. 75 only when the temperature was 15 and 25° C while the mycelium growth was not occurred at these conditions. Although the germination rate was relatively high at aw 0. 8, the mycelium growth was very limited. The most amount of germination and radius growth was for aw 0. 85-0. 9 and temperature 15-25° C (P < 0. 05). Consequently, the optimum growth of A. fumigatus was seen at aw 0. 9 and temperature 25° C and the best shelf life of cake proved at aw < 0. 7. Furthermore, fitting the growth curves demonstrated the more accuracy of Logistic model rather than Gomperts model.

In this research, in order to optimize the extraction process of Ethanolic extract of barberry fruit, the increase and optimization of the conditions for the extraction of anthocyanin's and bioactive compounds by means of intermittent electric field pretreatment from three levels of electric field intensity (0. 5, 1. 75 and 3 kV / cm) and 3 levels of number of pulses (15, 30 and 45); then with ethanol solvent was used to extract their extracts and the amount of flavonoids, total anthocyanin, DPPH, total phenolic compounds, iron regeneration capacity, vitamin C and acidity compared to control (no treatment) Was studied. The results showed that the total phenol content of the extract decreased by increasing the number of pulses and reducing the intensity of the pulsed electric field applied to the sample. The increase in the electric field strength and the number of pulses initially increased the flavonoid content, DPPH and iron ion recovery capacity, but with the increase of these variables, these three parameters decreased. Also, with increasing of these parameters, the anthocyanin level and vitamin C content increased. The acidity of the sample was reduced and then increased by increasing the electric field strength and applied pulse number. Regarding the results of the process optimization, it can be concluded that the electrical field intensity of 2. 003 kV / cm and applying 29 pulses can increases the antioxidant properties of the produced product compared with the control sample.

Honey is a natural product that has long been used for treatment in addition to nutrition. In this regard, the antimicrobial effect of some Iranian kinds of honey against antibiotic-resistant bacterial strains and the relationship between this effect and the enzymatic activity of honey samples were evaluated. In this study, the protein content of 20 honey samples before and after extraction was determined and analyzed by SDS-PAGE technique. Then the activity of glucose oxidase, amylase, invertase, and catalase enzymes of each honey was measured. Inhibition of the tested bacterial strains in the presence of honey was investigated by ager well diffusion method and the relationship between enzymatic activity with antibacterial effect and freshness of honey was evaluated. The protein content of the samples before extraction ranged from 0. 4 06 0. 06 to 1. 0 64 64. 19 mg/g honey and after extraction this amount decreased by about 50% or less. In the protein profile of all kinds of honey after electrophoresis, 3 bands related to amylase, invertase, and glucosidase enzymes were visible. The activity of enzymes was assigned to glucose oxidase> invertase> amylase> catalase, respectively. The selected honey samples did not affect Staphylococcus epidermidis and had the least effect on Pseudomonas aeruginosa. After honey inoculation, the inhibitory pattern of Escherichia coli and Enterococcus faecalis were similar, but a different inhibitory pattern was observed from Staphylococcus aureus strain. This study showed that glucose oxidase plays an important role in bacterial inhibition, but this role fluctuates in catalase-positive strains. Also, Amylase and invertase enzymes can be a measure of the freshness of honey.

Nowadays, increasing the level of awareness among consumers of dietary drinks has led to the preparation and formulation of new products. The production of Kombucha using 0, 1, 3 and 5 % of green tea extract and stevia in levels 0, 2, 4 and 6% were prepared. Kombucha tests such as acidity, pH, viscosity, colorimetric indices, soluble protein, lactic acid and acetic acid measurements, antioxidant activity were monitored during days zero, seven and fourteen. The use of stevia in pH and colorimetry was significant at 0. 05. The results showed that the addition of stevia significantly increased acidity, increased acetic acid and lactic acid, increased soluble protein and increased antioxidant activity compared to the control sample. The highest score of the final overal acceptability belonged to the treatments blank containing 10% sucrose, free stevia and free green tea extract, Treatment containing 10%sucrose, free stevia and 1% green tea extract, Treatment containing 10%sucrose, free stevia and 3% green tea extract, Treatment containing 8%sucrose, 2%stevia and of 3% green tea extract, Treatment containing 8% sucrose +2% stevia and 5 % green tea extract. The highest antioxidant activity was determined by treatment with 8% sucrose + 2% stevia + 5% green tea extract and the treatment containing 6% sucrose + 4% stevia + 5% green tea extract. According to the results, in order to increase the functional properties of Kumbucha and reduce the amount of sucrose sugar in this product, the use of stevia and green tea extract is recommended.

Yogurt is popular because of its high levels of calcium, vitamins, minerals and low levels of fat, as well as its health-promoting effects and inhibiting harmful bacteria and helping to prolong life. Pumpkin is a good source of β-carotene, water-soluble vitamins and amino acids. In this study, syneresis, pH, acidity and rheological properties of yogurt (1. 5% fat) containing 0, 2. 5, 5 and 7. 5% pumpkin powder were investigated. The results showed that the highest amount of acidity (74° Dornic) was related to the control sample. The results showed that by adding 2. 5% pumpkin powder to the control sample, the strength of the formed gel decreased and with increasing concentration up to 7. 5%, this property was increased. In the study of the viscoelastic behavior of the samples, it was found that by adding a concentration of 2. 5% powder to the control sample, the ratio of viscous to elastic component increases, but with further increase in concentration, this ratio remains almost the same and therefore the viscoelastic behavior remains balanced. The values of loss tangent in the viscoelastic region for the control sample, 2. 5%, 5% and 7. 5%, were 0. 173, 0. 308, 0. 317 and 0. 319, respectively. Therefore, with greater structural cohesion, the consumer feels the same flexibility of the gel regardless of the gel concentration. Also, in all samples, in the whole frequency range, the elastic behavior prevailed over the viscous behavior, which increased by adding 2. 5% powder to the control sample, the type of gel structure (b) increased, and the strength of the structure (a) decreased. This means that the yogurt gel becomes weaker and with increasing concentration of the powder, b decreases and a increases; Therefore, the strength of our structure increases.

Rice is the staple food of the Iranian people and its pollution with heavy metals has irreparable dangers for consumers. The aim of this study is to find a way to reduce the absorption of heavy metals from rice. To study the effect of nitrogen fertilizer and parboiling process on heavy metals, a factorial experiment was conducted in a randomized complete block design with three replications. In this study, nitrogen fertilizer at three levels (N1: 60, N2: 80 and N3: 100 KgN /Ha) and parboiling at two levels of soaking temperature (C1: 50 and C2: 80 ° C) and two levels of steaming time (T1: 10 And T2: 15 min) were applied. Induced plasma mass spectrometry (ICP-MS) was used to determine heavy metals. Increasing the soaking temperature and steaming time reduced all heavy metals, but changes in fertilizer levels had no significant effect on heavy metals. The interaction effects of the treatments showed that N3C1T1 treatment had the highest percentage of weekly allowance for Cr and Ni (99% and 58%, respectively) and N2C1T1 treatment had the highest percentage of weekly allowance for Mg and Cd (11% and 9. 5%, respectively). Increasing the soaking temperature and steaming time minimizes the weekly intake of all heavy metals so that the N2C2T2 treatment shows the lowest weekly intake of all heavy metals. In less heat and time, the remaining heavy metals cannot be ignored, so parboiling at higher temperatures and times is recommended to maintain consumer safety and health.

Currently, the consumption of meat products has been rising due to their high protein content, and because of the relative disadvantages of synthetic preservatives, it has always been attempted to use natural preservatives with antioxidant and antibacterial properties in food and meat products. Coatings and edible films have increased their customers' desire for fresh and refreshing food products. In this study, antioxidant, antibacterial and anti-fungal effects of 5 different treatments including Artemisia scoparia waldst & Kit extract at 5% concentration (Asw 0. 05), gelatin and glycerol (GG), edible coatings of gelatin and glycerol In addition, 5% of the extract (GG + Asw 0. 05), starch and glycerol (SG), edible coating of starch and glycerol with 5% of extract (SG + Asw 0. 05) were mixed in the paste at 4 ° C Centigrade was maintained for 8 days. During this time, the moisture content, pH and color of the treatments were measured. In the TBARS antioxidant test, malondialdehyde was measured on days 0, 4 and 8, and it was found that in all treatments, malondialdehyde increased with increasing time, and the antioxidant activity of the treatments in These terms were (GG + Asw 0. 05), (SG + Asw 0. 05), (Asw 0. 05), (GG) and (SG) respectively. In addition, the antibacterial and anti-fungal strength of the treatments was the same, and the antibacterial activity of the treatments against mesophilic bacteria was higher than coliform bacterial. In the case of color and moisture, all treatments had a decreasing trend over time, but in the case of PH there was an increasing trend. Also, after the 8th day, the moisture content of the treatments was the highest to the lowest (GG + Asw 0. 05), (SG + Asw 0. 05), (GG), (SG) and (Asw 0. 05) and all tests in the form of the design Completely randomized at 5% level.