مجله علوم غذایی و تغذیه
سال بیستم شماره 4 (پاییز 1402)

Due to their high moisture content, cherries have a very high rate of spoilage and require the use of some post-harvest treatments in order to be effectively preserved. Drying is one of these preservation methods. Drying time can be shortened by using ultrasonic waves as a pretreatment before drying agricultural products. The genetic algorithm–artificial neural network method has a high ability to find the optimal value of a complex objective function. In this study, the effect of sonication treatment for 0, 3, 6, and 9 minutes on drying time, weight changes, and rehydration of cherries was investigated. In the next step, this process was modeled by genetic algorithm–artificial neural network method with 2 inputs (drying time and ultrasonic pretreatment time) and 1 output (weight loss percentage). The results of this research showed that sonication for up to 3 min increased the rate of moisture removal from cherries and thus reduced drying time. 3-min treatment with ultrasound increased the rehydration of dried cherries; but as the treatment time increased to 6 min and 9 min, the amount of rehydration decreased. Genetic algorithm–artificial neural network modeling results showed that a network with a 1-4-2 structure in one hidden layer and using the hyperbolic tangent activation function can predict the weight loss percentage of cherries during drying with a high correlation coefficient and a low error value. According to the results of sensitivity analysis test, drying time was the most effective factor in changing the weight loss percentage of cherries during the drying process. In general, the best conditions for drying cherries are pretreatment with ultrasound for 3 minutes followed by drying the product with hot-air. Based on the modeling results, the genetic algorithm–artificial neural network method can also be used to predict the parameters of the cherry drying process.

  The quality of fresh fruits and vegetables, and thus their shelf life, is reduced due to changes such as moisture loss, enzymatic browning, tissue decay, and microbial growth. The use of an edible coating on fruits and vegetables during storage will increase shelf life by controlling the moisture migration, respiration rate, and oxidation. As apple is one of the most important raw materials for many foods and is grown in many countries around the world, it is important to keep apples fresh. The use of methylcellulose and Carnauba wax coating with Modified Atmosphere Packaging for maintaining the quality and prolonging the shelf life of Red Delicious apples.

 In this study, fresh apples (Red Delicious) were coated by two types of coating materials (methyl cellulose and carnauba wax) then samples packed in three layers bags (PE/PA/PE) with normal air condition (control), active modified atmosphere and inactive (passive) modified atmosphere, Samples stored at 2°C for 3 month. Thereafter, their quality characteristics such as Weight losses, color changes, hardness and change in packaging gas percentage, were tested and evaluated.  

Data showed coated samples had better properties as compared to the uncoated samples. The property was more obvious in samples coated by methylcellulose. In coating samples, weight losses were significantly (P≤0.05) less than uncoated samples, and also weight loss was slower.  At the end of the storage time, the highest firmness (958.2) was related to the sample with methyl cellulose coating and the lowest firmness (780.2) was related to the sample without coating (control). In the methyl cellulose coated samples, the weight loss of the samples was significantly lower than the other samples and the weight loss occurred at a slower rate (p≤0.05). At the end of the third month, the highest (7.6) and the lowest (4.7) weight loss was related to the sample without coating and the sample with methylcellulose coating, respectively. At the end of the sample storage time, the uncoated sample (control) had the highest Brix (17.2) and the sample coated with carnauba wax (16.1) had the lowest Brix. In all samples, the amount of L* decreased at the end of the storage time. During the entire storage period of apples, the amount of L* of the coated samples was higher than that of the control samples. The amount of L* in the control samples decreased and reached (19.2), while it reached (25.6) in the samples with methyl cellulose coating.  

  The results of the present study showed that Methylcellulose was an appropriate coating to maintain the quality and increase the shelf-life of apples (Red Delicious).

The super-beneficial food contains compounds with biological activity that promote health. Pasta is a suitable carrier for adding nutrients from various agricultural wastes. Nowadays, the use of synthetic antioxidants is limited due to the risks they have for health, therefore, the effort to find natural antioxidants of plant origin has increased.

Based on the formulation, the effect of adding 0 to 0.5 percent of saffron residues, including petals, yellow stamens, and white roots, on the physicochemical, antioxidant, texture, and sensory properties by comparing averages using Duncan's test was performed at a confidence level of 95% using SPSS version 19 software and the analysis of the data obtained from the treatments of di-optimal mixed design was carried out using Design Expert software. The standard was checked in the form of di-optimal mixed design.

During the analysis of the results after optimization, from the total of 0.5% of the remaining saffron, the values ​​of 0.072% of the petal share, 0.028% of the white root share and 0.4% of the flag share were suggested by the software.

The addition of saffron residue had no significant effect on the amount of moisture, water-soluble solids, weight and pH after cooking, while a significant effect was observed on the amount of total phenol, antioxidant, and anthocyanin, as well as the pasta texture. Enriched had less strength than the control sample and no significant difference was observed in sensory properties. Therefore, the addition of saffron residues while maintaining the physicochemical and sensory properties is important in the production of beneficial pasta.

In this study, the effect of an aqueous extract of grape microencapsulated in chitosan nanoparticles (0.5 / 1) was used to evaluate the shelf life of surimi prepared from Kilka fish by ionic gelation method.

Grape was extracted aqueously, and total phenol content was detected by spectrophotometry and phenolic acids of the extract by HPLC method.  Physical properties of nanoparticles including particle size, zeta potentia and PDI were determined with zeta-sizer, and microencapsulation efficiency was determined by spectrophotometer and loading capacity of nanoparticles by HPLC method. Antioxidant activity of free extract and chitosan nanoparticles with / without extract (by DPPH test) was determined.  The total count was determined by cryophilic, mesophilic, pseudomonas, mold, and yeast and inhibition capacity (MIC, MBC and IZ) of selected Gram positive and Gram negative bacteria and mold and yeast in different treatments days (0 , 1 , 3 , 6  and 9 ) at refrigeration temperature.

The data showed that the produced nanoparticles were in a favorable condition (particle size, zeta potential and PDI: 177.5 nm, +32.95 mV and 0.385 and the efficiency of microencapsulation and loading of nanoparticles were 48.95 and 6.19 percent, respectively). The phenolic content of the extract was 2896 ±18 mg/g and the extract in the loaded state showed a higher percentage of antioxidant activity (42.1%). Growth inhibition in microorganisms (gram positive and negative) is also increased and the overall amounts of bacteria and mold and yeast decreased, and the total values of cryophilic bacteria (6.35 ± 0.29 CFU/g), mesophilic bacteria (6.18 ± 0.27 CFU/g), Pseudomonas (5.41 ± 0.14 CFU/g), and mold and yeast (2.45 ± 0.26 CFU/ /g) in the last day of experiment, showed a significant decrease in the growth of microorganisms.   

According to the results, the use of chitosan nanoparticles containing extract in surimi of Kilka fish can delay microbial decay and increase the product resistance to free radicals and thus increase the shelf life of the product during the storage period in the refrigerator.

Listeriolysin (LLO) is a sulfhydryl-activated hemolysin bound to cholesterol, that is encoded by the hlyA gene of Listeria monocytogenes. The aim of this study was to detect and determine the frequency of Listeria monocytogenes in food samples through molecular analysis of the hlyA gene.

The present study was a descriptive cross-sectional assay conducted from the middle of October 2018 to the end of January of the same year. One hundred sixty-five samples of different types of meat, vegetables, hamburgers and shrimps were examined. Samples were randomly collected from restaurants, delicatessens, prepared food places, and different supermarkets. All samples were analyzed with phenotypic and biochemical tests. The samples suspected of Listeria monocytogenes, after DNA extraction, were evaluated by PCR with specific primers for the hlyA gene. Then the data and results were evaluated with using SPSS v.23 software and Excel software.

Phenotypic methods (microbial culture and biochemical investigation) confirmed 18 positive samples for Listeria monocytogenes, of which 10 (6.06%) samples were positive for Listeria monocytogenes by PCR of the hlyA gene. The rate of contamination in pounded kebab was 37.9%, chicken meat 4.4%, local hamburger 16.66% and lettuce 13.33%. Compared to other studies, these findings were more prevalent in some foods (e.g., local hamburger) and less in others (e.g., chicken meat).

The use of biochemical methods for determining the frequency of Listeria monocytogenes in food samples in Sanandaj had a high percentage of false positives.

Replacement of fluids excreted during exercise play an important role in in the success of athletes. However, according to the studies, knowledge and attitude about fluid intake are insufficient, and sometimes this lack of awareness leads to death. Therefore, this study was conducted to investigate the knowledge and behavior of athletes about sport drinks.

In a cross-sectional study, 18 sports clubs in Qom were randomly selected and 272 researcher-made questionnaires were distributed among the athletes. The questionnaire contained demographic questions and also included 14 questions about knowledge, 9 questions about attitude and 7 questions about practice. The validity and reliability of the questionnaire were determined by assessment experts and Cronbach's alpha (N=24, α=0.83). Data were analyzed by ANOVA test.

In this study, 48% of the people know thirst is the best index for drinking water during exercise and 63% were unaware of the positive effects of sugary drinks on athletic performance. The number of athletes that preferred water to other beverages was 75% and about 70% had no attitude about adding carbohydrates. Also, age and education did not have correlations with level of awareness.

The findings of this study show that athletes had incorrect attitude about fluid intake and it has caused dangerous consequences such as death. Therefore, education and training for athletes and their coaches to increase their sport activity with respect to nutritional awareness is essential.

The food industry is faced with a great demand to produce new products that meet consumer needs for a healthy lifestyle. Thus, functional foods enriched with plant materials play an important role in this field. Therefore, this study investigated the effect of different plant powders (thyme, moringa, quinoa, black seed and coriander seeds) on physicochemical, antioxidant and microbial properties of cheese. Plant powders were added to cheese at 0.5, 1 and 1.5% concentrations. Cheese samples were subjected to sensory evaluation, followed by tests concerned with acidity, pH, moisture content, L*, a* and b*color factors, phenolic contents, antioxidant activity, total bacterial and mold and yeast counts. The highest acidity was related to the control sample and the lowest acidity was observed in the samples containing thyme, black seed, quinoa and coriander seed powders. The highest amount of moisture was related to treatment containing moringa and the lowest amount was observed in control. By adding powders to cheese, L* decreased and a* and b* increased as compared to control. The highest amount of total phenolic compounds and antiradical activity was related to sample containing quinoa and the lowest amount was related to control. Samples containing plant powders had lower total bacterial, mold and yeast counts than control. The addition of plant powders to cheese improved physicochemical and increased antioxidant properties, and reduced microbial population, and the use of these plant powders is recommended to create diversity and produce products with high nutritional value.

Awareness of proper nutrition leads to people's health, therefore if low-fat and low-sugar foods is produced, this can lead to an increase in the health of the society. Foman traditional cookie is one of the popular confectionery products in the north of Iran, which is made from wheat flour, butter, sugar, cinnamon and walnuts. This research deals with the feasibility of producing traditional Foman cookies by removing white sugar from cookie's cream and replacing it brown sugar and stevia natural sweetener powder.

The changes in the levels of moisture, total sugar, calories and acidity were measured after substituting brown sugar and stevia powder (in terms of flavoring) instead of white sugar in cookie dough during a 14-day storage period at 25 degrees Celsius. In this method, brown sugar was replaced by 40, 50 and 60% of the removed white sugar in cookie core, and stevia was used to compensate sweetness taste. The changes of moisture, total sugar, calories and acidity after this replacement was measured during the 14-day storage period at 25°C.The color, taste, texture hardness and general acceptability of the cookies were investigated by sensory evaluation.

The results show that the replacement of brown sugar and stevia in cookie core has caused significant changes in dependent variables such as moisture, total sugar, acidity, calories, and kernel color, therefore kernel color and moisture have increased, but total sugar has a decreasing trend, calorie of cookies has increased as compared to the control sample due to the replacement of dry matter instead of white sugar. There is no significant change in taste, hardness of texture and overall acceptance.   

In the examination of the samples in the selected intervals, the highest agreement with the control sample in terms of changes in dependent variables such as moisture, total sugar, acidity, color can be observed in the sample with 40% brown sugar and 60% stevia. Substitution of stevia and brown sugar instead of white sugar led to a decrease in total sugar, but there was no visible effect on taste, texture hardness, and overall acceptance, although time had a negative effect on most of the studied parameters. By increasing the amount of brown sugar, the agreement with the control sample decreases, but the amount of calories has a reverse trend due to the change of dry matter in the core.