نشریه فرآوری و نگهداری مواد غذایی
سال چهاردهم شماره 1 (پیاپی 33، بهار 1401)

Spices and medicinal plants, like other agricultural products, have been contaminated with bacteria, soil, and insects during the process of planting, harvesting, transporting, and processing. One way to remove contamination is to use gamma radiation. Therefore, the aims of the present study were to evaluate the effect of gamma irradiation (0, 5, 10, and 15 kGy) on color parameters and microbial population of Mentha longifolia L. plant packaged under modified atmosphere (MAP), vacuum, and aerobic conditions, and also its effect on chemical composition and antioxidant and antimicrobial properties of M. longifolia essential oil.

M. longifolia L. plant was collected in spring (April-May) 2020 from Gilanegharb, located in Kermanshah, Iran. Irradiation of the packaged M. longifolia plant samples was performed under MAP (N2 = 100%), vacuum and aerobic conditions using doses of 5, 10, and 15 kGy (radiation source = 60 cobalt and dose rate = 4.18 kGy h-1) in the Atomic Energy Organization of Iran. After irradiation, the color parameters and microbial population of the packaged samples were evaluated. Moreover, the chemical composition of M. longifolia essential oil using gas chromatography–mass spectrometry and antioxidant property via 2, 2-diphenyl-1-picrylhydrazyl radical scavenging and Beta-carotene bleaching inhibition were evaluated. Study on the antimicrobial activity of M. longifolia essential oil against Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, and Bacillus subtilis using disk diffusion method was performed.

Results of this study indicated that gamma irradiation under 5 and 10 kGy (aerobic condition) and 15 kGy (aerobic, vacuum, and modified atmosphere conditions) resulted in significant reducing a and b parameters and increasing L parameter in comparison with control group (P < 0.05). The gamma irradiation under 10 and 15 kGy inhibited the growth of total viable bacteria, coliforms as well as yeast and mold in packaged samples into lower than the count limit of 1 log CFU g-1. Based on our findings, nineteen chemical compounds were identified in Mentha longifolia essential oil. Eucalyptol (18.23%-19.55%), menthone (12.36%-13.55%), and pulegone (47.69%-49.55%) were the main identified chemical constituents in Mentha longifolia essential oil. Moreover, gamma irradiation (0, 5, 10, and 15 kGy) and types of packaging (aerobic, vacuum, and modified atmosphere conditions) hadn’t effects on the change of chemical compounds, as well as antimicrobial and antioxidant properties of Mentha longifolia essential oil (P > 0.05).

The results of this study showed that the use of gamma radiation at doses of 10 and 15 kGy is a suitable method for disinfection of packaged M. longifolia under aerobic, vacuum and MAP conditions, without affecting their chemical composition and antimicrobial and antioxidant properties.

The Persian sturgeon (Acipenser persicus) is a species of fish in the family Acipenseridae. It is found in the Caspian Sea. Globally, sturgeon fisheries are of great economical value, primarily as a source for caviar, but also for the flesh, and several species of sturgeon are harvested for their roes. Caviar is composed of different types including pressed caviar. It is composed of damaged or fragile eggs and can be a combination of several different roes. Besides wild species, in some countries such as Iran sturgeons are sustainably farmed to produce caviar. In the present study, farmed Persian sturgeon packing pressed caviar was evaluated by tube packaging through assessing its quality and shelf life under cold storage. An unpublished report on pressed caviar packaging in tubes was not found in other countries, but in Iran, the present study is the only study performed on pressed caviar packaging in tubes.

Four treatments were considered including caviar packed in laminated tubes with an aluminum coating (Treatment 1), without coating (Treatment 2), metal tubes of aluminum type (Treatment 3), and metal cans made of stainless steel sheets (Treatment 4 and control). Treatments were packed in the amount of 50 g and stored at - 3 ° C for 7 months. Microbiological tests include the total bacterial counts, Staphylococcus bacteria, Clostridium, coliform, Escherichia coli, Psychrophilic and mold and yeast, chemical tests such as peroxide, thiobarbituric acid, free fatty acid, and total volatile nitrogen bases, physical (pH), and sensory tests including texture, odor, color, taste, salinity, and overall acceptance were performed to evaluate the quality of experimental and control treatments.

Psychrophilic, yeasts and molds, Clostridium, Coliform, and Escherichia coli were not observed in experimental and control samples. Total bacterial counts, Staphylococcus, peroxide value and physical properties (e.g. pH) were in acceptable limits in both experimental and control samples. Protein, fat, moisture, ash, and pH were %29.81, 18.00, 48.96, 3.24, and 6.98 – 7.42 in these samples. TVB-N and pH showed significant differences in treatments 3 and 4 as compared with the other treatments which were higher than the standard level. Sensory properties and overall acceptance (1.14) and free fatty acids (3.17 %) were significantly different in treatment 3 as compared with the other treatments and control (4.47 and 2.15 %) (it was not in the allowable range). Changes of pH (6.98), peroxide (0.76 meq/kg oil), TVB-N (17.64 mg/100g), free fatty acids (2.13%), total bacterial counts and Staphylococcus (1.85 and 1.11 logCFU/g), and overall acceptance (4.70) were better in treatment 2. The quality superiority of these samples was confirmed. Treatments 3 and 4 for six months, while other experimental treatments were of good quality until the end of the storage period in the cold room.

Since the chemical, microbial and sensory quality in treatment 2 was better than other treatments, so aluminum-coated laminate tubes recommended for packing of pressed caviar.

The formation of free radicals in aerobic organs is inevitable. These radicals cause cells and tissues damages. Oxidation of lipids by producing harmful compounds and as a result spoilage of food products, is one of the most important concerns of the food industry. The use of synthetic antioxidants is tightly controlled due to their harmful effects on human health. Therefore, scientists' research has turned to identification and extraction of natural antioxidants compounds. Bioactive peptides are specific protein components that are inactive at the primary protein source and produced by enzymatic hydrolysis, microbial fermentation, and chemical synthesis. These peptides have different health-promoting properties such as antihypertensive, anti-cholesterol, anti-cancer, strengthening the immune system and antioxidant properties that are influenced by their amino acid composition and sequence. The aim of this study was to investigate the effect of molecular weight and amino acid composition on the antioxidant properties (DPPH radical scavenging activity, Fe reducing power and ABTS radical scavenging activity) of peptide components of pumpkin seed protein hydrolysate.

Pumpkin seed protein hydrolysate was prepared under optimum conditions based on the results of previous research and then the effect of molecular weight distribution on the bioactive properties of the resulting fractions and also the relationship between amino acid composition of these peptides and their antioxidant properties after separation and purification by size exclusion chromatography (SEC) and reverse phase high pressure liquid chromatography (RP-HPLC) was examined.

The results of size exclusion chromatography showed that fractions 49 to 56 and 49 to 63 with a molecular weight in range of 9000 to 13,000 daltons have highest DPPH and ABTA radical scavenging activity and after further purification of these fractions by RP-HPC, this ability in fractions with a holding time of 22 minutes showed the highest level. The results of amino acid analysis showed that fractions with high antioxidant capacity contain high amounts of hydrophobic amino acids (about 33.5%), which include non-polar aliphatic groups (such as valine, isoleucine, proline, leucine, tryptophan, and tyrosine). In other words, low molecular weight peptides, with aromatic and hydrophobic amino acids have higher antioxidant activity.

Pumpkin seed protein hydrolysate with peptide components with significant antioxidant properties, can compete with synthetic antioxidants used in the food industry, so it can be used as a natural preservative in food formulations to produce functional products with the aim of increasing public health level and also in medicinal purposes.

Among the various hot air drying methods, fluidized bed drying has significant advantages such as high heat and mass transfer, uniform moisture reduction of products with short time and high drying rate and uniform process at entire surface of the product due to efficient mixing with the drying air and high efficiency of process. In recent years, usage of infrared drying to dry food products has increased over conventional drying methods due to higher product quality, uniform heat distribution, high energy efficiency, high heat transfer rate and less processing time, facilitating the control of raw material temperature, reduced necessity for air flow across and the high ability to control process parameters in infrared heating. In this study, kinetics of carrot cubes drying by infrared-fluidized bed dryer were investigated.

Fresh carrot were washed with tap water and peeled manually then diced by dicer. To drying carrot cubes by combined infrared- fluidized bed method a laboratory scale dryer was designed and performed. In this study, drying of carrot cubes (0.5 and 1 cm3) was performed in factorial design experiments using air temperatures of 50, 60 and 70 °C and three levels of infrared power (200, 400 and 600 W) in three replications. To describing the infrared-fluidized bed drying behavior of carrot cubes, five mathematical models (Page, Modified Page, Henderson & Pabis, Midilli and Logarithmic) were evaluated.

The results demonstrated that the change in inlet air temperature, size of carrot cubes and infrared power had a significant effect (P <0.05) on water withdrawal from the sample and drying time decreased with increasing air temperature and infrared power and decreasing carrot cubes size. Therefore, the energy consumption was also reduced considerably, decreasing from 12.63 Kwh/kg in bed fluidized method (without infrared power) to 2.28 Kwh/kg using infrared -fluidized bed drying. The Page model was identified as the suitable model to describe the drying kinetics of carrot cubes by infrared-fluidized bed dryer that showed a good agreement with experimental data.

The statistical analysis of variance showed that air temperature, sample size and infrared power had a significant effect on water withdrawal rate of samples and therefore drying time. According to the results, using infrared-fluidized bed drying as a combined method in comparison with conventional hot air drying methods can reduce drying time and energy consumption and costs considerably.

Salad is one of the most consumed products that is used as an appetizer, with a meal or a meal. Salad dressing is one of the seasonings are used for flavoring or appetizing foods. However, due to the use of eggs in the formulation of most salad dressings, there is a possibility of the entry of harmful microorganisms as well as amounts of cholesterol in the diet. Therefore, making salad dressing without egg yolk is benefical for health. In this study, oil-in-water emulsions were prepared with balsamic vinegar and extra virgin olive oil and then stabilized with zedo or Persian gum. One of the main characteristics of salad stabilizers is viscosity, which is related to the suspension of particulates, emulsion stability, pourability, etc. Control separation is also directly or indirectly related to viscosity and suspending power, which is related directly to gum concentration. Zedo gum is secreted from the Amygdalus scoparia tree. Balsamic vinegar has been considered a source of antioxidant compounds. The most representative antioxidants found in balsamic vinegar are phenolic acids, flavanols, polymeric tannins, and high molecular weight melanoidins. The presence of phenolics in vinegar has positive health effects because these products maintain a good portion of the phenolics present in the grapes, expressing a significant antioxidant capacity. Also Using palm syrup in the production of this product instead of sucrose, reduces the amount of calories in the product.

In this study, the quality characteristics of oil-in-water emulsion salad dressing were investigated using Zedo gum, palm syrup, balsamic vinegar and olive oil. Zedo gum (1, 2.5, and 4%) concentration was used for stable salad dressing. Chemical and physical properties including phase separation, pH, acidity, free fatty acids, total phenolic compounds, antioxidant activity and the sensory properties of the prepared balsamic salad dressing within 90 days’ preservation were evaluated.

During storage, pH, acidity and free fatty acid of all samples were in the range of Iranian National Standard. Samples containing zedo gums were not observed phase separation. Their physical stability increases during storage of balsamic sauce samples. The highest and lowest levels of antioxidant activity and phenol of total diet salad were related to the control sample and the sample containing 4% zedo gum, respectively. The total phenolic content and antioxidant activity of samples decreased with increasing storage time. Samples containing 1% Zedo gum and control received the best sensory evaluation.

Formulation of salad dressing with virgin olive oil, balsamic vinegar, and palm syrup with 1% zedo or Persian gum, had the optimum physicochemical, antioxidant and sensory properties among the samples, which can be used to produce a useful and healthy sauce with optimum physical, chemical, oxidation, and rheology properties and customer-friendly.

Bacillus cereus is one of the foodborne pathogens in food. Today, by international standards, post-baking foods have to be cooled to less than 10 degrees Celsius for 60 hours. In this study, the effects of this parameter on cooling duration, moisture content, percentage of broken rice and rice sensory evaluation and the extent of Bacillus cereus growth were investigated.

Iranian rice (Tarom) and foreign rice (Thai rice) were cooked under the same conditions. Four trays with various dimensions were prepared to achieve the rice's thicknesses of interest (i.e. 5, 7, 9, and 11 cm). Grains of rice with foregoing thicknesses were weighted using the scale and then cooled in the blast chiller fitted with a data logger. Two strains of mesophilic Bacillus cereus lyophilized (Code: FORC-005) were purchased from Takgene Co. (TAKGENE PROBIOTIC PRODUCTS). Bacteria were grown on the MYP medium to be activated according to the manufacturer's instructions. Probably occurred Bacillus cereus cells were counted per each plate following confirmation of chosen colonies. Data were analyzed through performing a one-way ANOVA in SPSS using DUNCAN post-hoc test.

The results showed that increases in the thickness of rice layer increased the population of Bacillus cereus but not beyond the standard range (0.5 cfu / g). Moreover, the highest bacterial populations in Iranian and foreign rice with layer thickness of 11 cm were 0.41 and 0.3 cfu/g, respectively. In addition, increases in the thickness of layer of the studied rice exponentially increased the cooling duration. Since the cooling duration of foreign rice with the thickness of 11 cm (267 min) exceeded the required standard of 4 h, rice layer thickness greater than 11 cm will not be acceptable for cooling foreign rice. It should be noted that increases in the thickness of the samples of rice layers reduced the percentage of broken rice (by 8 and 4/9%) and the percentage of moisture loss (by 48.7 and 47.2%) in Iranian and foreign rice, respectively. In sensory evaluation, the Iranian and foreign rice received the scores of 9 and 7.9, respectively. which indicated that the Iranian rice had higher quality than the foreign rice in this evaluation.

Generally, the results revealed that the size of the Bacillus cereus population (colonies) expands with an increase in the thickness of rice samples (Tarom and Thai rice), but it did not exceed the standard threshold. When exceeding the standard cooling time of 4 hours, thicknesses greater than 11 cm will not be admissible for the cooling process. Importantly, as the rice thickness rises, taste characteristics in cooked rice will be less affected and more acceptable. In this study, Iranian rice (Tarom) missed less moisture content than foreign rice (Thai rice) due to textural and strain-related characteristics and ultimately was more acceptable

Dairy Spreads are solid and spreadable food products that merely made from milk or milk products that contain 10 to 80% milk fat. samanou is a traditional Iranian dessert that is prepared by cooking a mixture of wheat flour and green malt extract. The aim of this study was to assessment the effect of adding xanthan gum (0, 0.5 and 1%) and chia seed (0, 0.5 and 1%) on physical stability and textural and rheological properties dairy spread containing samanou powder.

In the present study, the frequency sweep rheological test was performed by a rheometer. During this test, first the linear viscoelastic range is determined and then in the frequency range of 0.1 to 100 Hz, temperature of 10 ° C and constant strain of 1%, the rheological properties of the spread including storage modulus (G′), loss modulus (G′′) and loss tangent (G′′ /G′) were measured. Emulsion stability was measured using a centrifuge based on oil separation (g). texture evaluation was performed by backward extrusion and spreadability tests with a texture analyzer to determine of firmness (N), cohesievness (N), consistency (Ns) and spreadability (N) parameters.

The results showed that the effect of adding xanthan gum and chia seed flour on increasing the cohesievness, consistency, firmness and reducing the spreadability of the produced spread was significant (p<0.05). Increasing the concentration of xanthan and chia seed flour from zero to 1% increased the cohesiveness and firmness and also redused the spreadability of the produced spread compared to the control sample. The treatment containing 1% xanthan and 1% chia seed flour had the highest firmness and the least spreadability, respectively. spreads containing xanthan were more consistency than spreads containing chia seed flour, so the highest and lowest consistency were in the treatment containing 1% xanthan and without chia seed flour (67.53±12.66 N.s) and the treatment prepared from 1% Chia seeds flour without xanthan of (37.36±17.5 Ns), respectively. The lowest and highest cohesievness were in the treatment containing 0.5% xanthan (-0.05±0.22 N) and the treatment containing 1% xanthan and 0.5% chia seed flour with a score of -0.31±0.39 N respectively. Spreads containing xanthan gum and chia seed flour were more stable than the control sample, so that the control sample had the highest oil separation and the lowest physical stability (0.476±0.13 gr). In frequency sweep test, 1% strain was determined as the best strain corresponding to the linear viscoelastic range. by simultaneous increasing the concentration of xanthan and chia seed flour, the amount G′, G′′ and G′′ /G′ decreased. The presence of chia seed flour in the spread formulation, unlike xanthan gum, increased the amount of G′ and G′′. The maximum amount of G′ and G′′, as a result of the highest elasticity, , consistency and , firmness belonged to the treatment containing 0.5% xanthan and the treatment containing 1% xanthan and 0.5% chia had the lowest amount of G′ and G′′ Dedicated to himself.

application minimum concentrations of xanthan (0.5%) and chia seed flour (0.5%) improved the textural properties of dairy spreads containing samanou powder. Increasing the concentration of chia seed flour, unlike xanthan, weakened the internal bonds and reduced the consistency of the product. The presence of xanthan compared to chia seed flour had a greater effect on preventing phase separation and increasing the stability of dairy spread containing of samanou powder. In all frequency ranges, the amount of storage modulus was greater than the drop modulus, and the spreads produced behaved like a gel viscoelastic solid.