مجله علوم غذایی و تغذیه
سال پانزدهم شماره 3 (تابستان 1397)

Food packaging is a vital approach for ensuring food safety. Due to the high importance of food packaging, nanotechnology can improve packaging quality and consequently ensure the safety.
Nanosilver particles were synthesized and starch-based nanocomposite films, chitosan with the content of 0, 250 and 500 ppm nanosilver particles were produced and their properties including mechanical properties, water vapour permeability, solubility, swelling and anti-microbial properties of the produced films were studied by measuring the diameter of the bright area in the disk permeability test. In this test, four types of bacteria including Staphylococcus aureus, Escherichia coli, Aspergillus niger and Candida albicans were employed. The colour changes in the films after the addition of nanosilver were examined and the size of synthesized nanosilver particles was determined by using DLS.
The addition of nanosilver to the films increased the water vapour permeability. Tensile strength was increased and this increase in the case of chitosan films was significant whereas in the case of starch film was not significant. Elongation at break was also increased in all the films. Although the addition of nanosilver increased the solubility and swelling, this increase was not significant. Films containing nanosilver has an antimicrobial effect on all the microorganisms that were investigated (p In general, the properties of the films produced by nanosilver particles were completely affected by the concentration of the used nanosilver except for water vapour permeability where this led to improvement of the properties of the films.

Increasing the cooking quality of rice is one of the most important initiatives in rice breeding goals. In this study, in order to determine the rheological properties of instant rice prepared from Hashemi variety, the effects of three precooking under boiling, under steam and under pressure were investigated and compared.
In all three methods, cooking continued up to 90 percent of fully cooking samples. The product was dried in an oven at 50° C. The viscosity of the samples were evaluated in three replications with rapid Visco Analyzer. The results were analyzed using SPSS software and significantly Tukey test was evaluated at the level of 95%.
The results indicated the maximum, minimum and final viscosities, breakdown, setback and time to reach maximum viscosity and pasting temperature. The effect of precooking methods on all the rheological characteristics of rice except the maximum viscosity and setback were significant at the level of 95%. It was concluded that the rheological properties of cooking under pressure showed significant difference in the level of 95% as compared to the other two methods. The study indicated that the swelling of the starch granules in instant rice prepared under pressure occurred earlier than the other methods. The maximum viscosity has relation with grain elongation during cooking.
Instant rice samples prepared under pressure will remain softer after cooking for a longer time and can be prepared in shorter time.

The application of using nanotechnology in food packaging is mixing nanoparticles with packaging material to prevent bacterial deterioration and loss of nutriants in order to improve the shelf life. The aim of this study is to extend the shelf life of milk by the application of the antibacterial polyethylene packaging that consists of copper nanoparticles.
Nanocomposite film consisted of copper nanoparticles was prepared by using industrial extruder for milk packaging at 4ºC. Microbial stability, pH variation, thermal stability and nanoparticle release at zero, 7 to 45 days of storing and water vapour permability for the nanocomposite were analyzed in triplicate order.
Microbial analysis indicated that the growth rate in nanocomposite consisted of copper nanoparticles decreased significantly by 38 days of storage. pH variations and acid production due to milk deterioration indicated the quality during storage. Thermal analysis of milk after 38 days of packaging in nanocopper packaging confirmed the level of deterioration during storage. The amount of copper released in milk was within permitted level (2.1ppb). SEM and TEM images indicated the presence of copper nanoparticles in polymer base and its hemogeneous distribution in polymer matrix. The application of nanoparticle in milk caused an increase in shelf life. The results showed that by increasing the concentrations of copper nanoparticles, moisture absorption of the film is decreased.
The results indicated that synthesized copper/polyethylen composite increased the shelf life of milk during storage.

Unsaturated fatty acids such as DHA (Docosa-hexaenoic acid) and EPA (Eicosa-pentaenoic acid,) might be considered important unsaturated fatty acids with several double bonds and have important role in human health. Research shows strong evidence that the omega-3s EPA and DHA can help to lower triglycerides and blood pressure. Panulirus homarus, is the most important lobster in Asian fishery.
A total of 20 male and female lobsters (Panulirus homarus) were randomly collected from Abadan (Khuzestan Province) in spring 2016. Chemical composition (protein, fat, moisture, ash) and polyunsaturated fatty acids after biometry were determined according to the standard methods of analysis.
According to the results, protein and fat contents in lobster meat was 23 and 4%, respectively. Chemical composition of lobsters indicated that protein, fat, moisture and ash contents of male and female lobsters were not significantly different (P> 0.05). Oleic acid was one of the major unsaturated fatty acids and found to be 17.11 and 17.93% in the male and female lobsters, respectively. Palmitic acid was also present in high concentration. The results indicated that palmitic, oleic and docosahexaenoic acids were the predominant fatty acids present.
Lobster; Panulirus homarus with more than 23% protein and 4 % fat is a good source of Omega-3, EPA, DHA that has high nutritional value for human consumption. Therefore, its usage is recommended along with other aquatic animals.

Fish is known as a perishable food because of its high amounts of polyunsaturated fatty acids and neutral pH. Accordingly, natural preservatives are employed to delay the spoilage and increase the shelf life of fish. The aim of this research is to study the antibacterial and antioxidative effects of Chlorella vulgaris algae extract on the quality of rainbow trout during storage at 4 °C.
In this study, trout fillets were treated with 4 concentrations of algae extract (0, 0.1, 0.2 and 0.3 %), then they were subjected to chemical (PV, TBA, TVB-N, pH), microbial tests (total count, psychrotrophs count) and sensory evaluation during 9 days of storage at 4 °C at 0, 3, 6 and 9 day intervals.
Based on the results obtained, the levels of lipid oxidation and microbial degradation were significantly lower in the fish treated with algae extract than the control sample. According to sensory analysis results, treatments with algae extract had better quality as compared to other treatments at the last day of storage.
The findings indicated that Chlorella vulgaris extract exerted antioxidant and antibacterial effects on rainbow trout during storage and increased the shelf life.

Grape is one of the most cultivated fruit in the world. Recently various methods have been employed to improve the efficiency of juice extraction. In this research project Gizil Ozom variety (red grape) in the form of paste is used as raw material to extract the juice.
Grape mash is subjected to ohmic heating, microwave heating and conventional thermal treatment before pressing. The juice samples were pasteurized at 88°C for 2 minutes. After production of the juice the effects of ohmic, microwave and conventional heating on the yield of grape juice, anthocyanin content, total phenolics, viscosity, pH, brix and total acidity were determined before and after pasteurization.
The results showed that the highest yields were obtained when microwave and ohmic treatments were applied to the samples and the yields were 8% and 13.2% for ohmic and microwave heated samples, respectively. Application of ohmic and microwave operations prior to pressing step, caused increases in anthocyanin and phenolic contents of grape juice in contrast to the control samples (P The results of this study showed that microwave and ohmic heating can be used as pretreatments for the production of grape juice.

Cream structure consists of various quantities of short chained fatty acids. Some of the fatty acids are branched and some are conjugated and some are nonconjugated with even or odd carbon numbers. A number of unusual fatty acids namely cyclohexyl fatty acids among others have been identified.
In this research cream with 30% fat content was produced, pasteurized and packed from the milk delivered to three plants on southern part of Iran. Samples were collected every three hours after production and three and six days later and investigated regarding the fatty acid composition and profile using gas liquid chromatography.
The results indicated that the fatty acid composition of the samples differentiated from each other based on the diet and feed consumed. However differences were observed among some fatty acids namely palmitic, conjugated and tran acids.
The fatty acid composition of creams indicated differences at p ≤ 0.05 level. This study showed that among the species, composition of fat and fatty acids are not constant and uniform.

In preparation of set yogurt, the aim is not only to provide a product with optimal spoonability, but also to obtain an attractive appearance, softness and texture free of coarse particles with least synersis. In this study the effect of long-chain inulin (Since the long-chain inulin has nutritional properties) and carboxymethyl cellulose on the physicochemical and sensory characteristics of low fat yogurt during 15 days have been investigated in order to determine the most appropriate treatment for future studies.
In this study, the experiment was designed with the use of two independent variables of long-chain inulin (DP≥22) and carboxymethyl cellulose in the form of 5 treatments of yogurt. Tests concerned with pH, acidity, synersis, water holding capacity, viscosity and colorimetric were carried out 24 hours, 5 and 7 days after the preparation of the samples.
The results showed that there were no significant differences concerning acidity, pH, L* and a* between control and other treatments containing carboxymethyl cellulose and inulin but synersis decreased, water holding capacity and viscosity increased and sensory properties (except odor) improved.
According to the results, sample containing 0.75% inulin and 0.25% carboxymethyl cellulose and sample containing 0.5% inulin and 0.5% carboxymethyl cellulose were introduced as the chosen prebiotic and functional yoghurt samples with superior physicochemical and sensory characteristics.

Various absorbents have been studied for removing heavy metals from water. One of the most effective removals is iron oxide nanoparticles. In recent years many studies have been carried out for modifying the surface of the nanoparticles and increasing its effectiveness and efficiency.
In this paper coated iron oxide nanoparticles were prepared using Polylophium involucratum extract. To examine the structure of the absorbent the infrared spectrometer instrument and SEM were used to check the size of nanoparticles. the average size of them were determined 60 nm.
The synthesized coated nanoparticles were used to eliminate lead and cadmium after optimization conditions (pH of 6, absorbent weight of 20 mg, and time of 4 minutes) in water samples. Magnetic green coated nanoparticles have many advantages such as non-toxicity, biocompatibility, shorter extraction time, avoiding the use of organic solvents, low cost, ease of use, high accuracy, recovery and adsorption capacity due to the nanostructure and high ratio of surface to volume.
Functionalized nanoparticles by extract of the plant is able to link up with heavy metal ions and increase the efficiency of the nanoparticles in the removal of these two heavy metals.

Decrease of moisture content to safe level in order to reach maximum maintenance is the principle goal of drying agricultural products. Parameters of temperature and air velocity are considered the main important factors in drying process. Mathematical modeling of drying process is used to design and improve available drying system and also to control the process.
In this research, the effect of temperature (40, 50, 60 and 70 ºC) and air velocity (2 and 3 m.s-1) changes on drying time and rate of drying peanut using hot air dryer has been studied. Moisture variations during drying process under different conditions were fitted using various mathematical models including Newton, Two-term, Midili, Page, Modified Page and Logarithmic.
Factors of temperature and air velocity had significant effects on the drying time and the rate of drying (P Effect of temperature on the drying process was considerable, therefore an increase in this parameter led to a 67.8% decrease in time and a 109% increase in drying rate. The maximum influence of air velocity on drying time and rate was 37.3 and 20.9%, respectively. Moisture variations during the drying process were well fitted to a two-term model(R=0.999).