مجله علوم غذایی و تغذیه
سال یازدهم شماره 2 (بهار 1393)

Due to the consumers demand for high quality food، new safe and effective methods of food processing and preservation have been developed. The application of optical radiation in the food industry for preservation has been known as a new technology. This method is quite effective to inactivate a large number of microorganism’s particularly pathogenic microorganisms that often cause infection and food poisoning. However، when this kind of treatment is applied some changes might occur. Therefore the aim of this project is to understand the effect of such treatment on the physicochemical properties of eggalbumen. The effects of visible Continuous Waves (CW) lasers on structural changes (using SDS-PAGE) and physicochemical properties (organoleptic and pH) of egg Albumen were studied. The results of this investigation indicated that visible laser radiation even at the maximum power and highest time period (180 minute) did not affected the structural and organoleptic characteristic of egg white proteins. Evaluation of the pH values showed that there were not significant differences between the control and the treated samples. It can be concluded that visible continuous lasers radiation might be employed as a new safe sanitation method in egg industry، however further research is required to understand more about its precise and potent application.

It has been proved that certain dietary fat and cholesterol cause cardiovascular diseases and obesity and there is an increasing consumers’ demand for low fat and low calorie food products. Therefore the aim of this research work is to develop and formulate a low fat meat product namely the functional sausage. In order to reduce the fat and cholesterol contents of the product and produce a low fat and functional sausage، 25% of full fat meat (17% fat) in the formulation was replaced with 1. 2% and 1. 7% dietary fiber، (z-trim originated from corn) and calcium gluconate (20% RDA) as a calcium source. A series of physicochemical tests were carried out on the formulated product to understand the behavior of finished low fat، functional sausage. The results indicated that the fat، cholesterol and calorie contents were reduced by 34%-63%، 35%-51% and 27%-46% respectively as compared to the control. A combination of corn z-trim and calcium gluconate improves the physicochemical and nutritional properties as well as the emulsification quality of the formulated product. 1. 7% z-trim and calcium gluconate was selected as the best formulation.

Healthy Eating Index (HEI) was first developed to assess and monitor nutritional status of Americans by the United States Department of Agriculture (USDA) in 1989. HEI is one of the scoring systems in nutritional researches. Since prison is an isolated place and prisoner’s state of health to some degree depends on the food consumed، therefore the nutritional status by this index might have some implementations for the policy makers. In a cross sectional study 435 prisoners (48 females and 387 males) were recruited using stratified random sampling method proportional to the ward population. Food intake from different sources in prison was assessed by analysing prison food menu، measuring wasted foods and food bought and provided by prison supermarkets. HEI score in Mashhad Central Prison was 80 percent of the total calculated score. Scores for consumption of fruit، meat and poultry، dairy products and food variety were 0، 4، 9. 5 and 9 respectively. Other food groups concerned with vegetable and cereals had scores of 10. Sodium intake representing the salt consumption was not measured. The results of this study showed that eating pattern of prisoners is healthy but steps might be taken to improve the quality of the food consumed.

Evaluation of food contaminants particularly heavy metals in tuna and its products، that might be considered as an indicator of water pollution is quite important. In this study the concentrations of mercury، cadmium and lead in canned tuna produced in four countries measured and evaluated. Samples of canned tuna from Oman Sea، coasts of India، Seychelles and Ghana were obtained from one of the distributing companies in Iran. The concentration of mercury was measured by cold vapor technique using atomic absorption spectroscopy (AAS). The concentration of cadmium and lead were determined by inductively coupled plasma - atomic emission spectroscopy (ICP-AES). The results were compared with the national، european and international standards. Statistical analyses of the results were carried out using SPSS software and analyses of variance (ANOVA) were used to detect significant differences. The results indicated that the concentrations of mercury، for all the samples examined were within the standard limit while for cadmium and lead only 25% and 50% of the samples examined were within the defined standard limits respectively. it was conclude that Chabahar region of Oman Sea and Ghana coast had the highest and least concentrations of heavy metals as contaminants respectively.

Spices in addition to their flavor contribution are important sources of natural antioxidants. Therefore، due to the possible undesirable effects of synthetic antioxidants، the natural antioxidants that are present in fruits and vegetables and have been consumed by man for years are preferred. In this project the antioxidant activity of cinnamon extract a popular spice used as a flavoring agent is evaluated. Acetone and methanolic extracts of cinnamon were obtained by the application of cold solvent method. Extraction efficiency was determined and total content of phenolic compounds were measured using Folin Ciocalteau method. Different concentrations of extracts at 0. 02%، 0. 04%، 0. 06%، 0. 08% & 0. 1% were added to tallow a substrate free of natural antioxidant and the stabilities of the samples were determined. Peroxide value and induction period measurements were used as means to evaluate the antioxidant activities. The results were compared with a synthetic antioxidant; TBHQ at 0. 01% concentration. The best concentration of extracts having antioxidant activity (0. 1% concentration)، was examined forchelation of copper metal in tallow as the substrate. Extraction efficiency of cinnamon extract using methanol was higher than acetone، but the amount of phenolic compounds was higher when acetone was employed. The evaluation of the antioxidant activity of the extracts on tallow indicated that the activity was concentration dependent and the activity was increased as higher concentrations of the extracts were applied. The acetone extract at 0. 1% concentration showed the highest activity after the synthetic antioxidant، TBHQ at 0. 01% concentration. The addition of Cu in the formof its copper salt to tallow in combination with the extracts at 0. 1% concentration indicated that these compounds might be regarded as chelating agents and the extract obtained by acetone was more effective in term of chelating property. Cinnamon extract in addition to the antioxidant activity، has chelating property on copper، and might be employed as a source of natural antioxidant and metal chelating agents.

In Iran and some other countries bread is considered a staple food. Therefore by increasing the nutritional value، decreasing the wastage، improving the quality and shelf life، bread might provide the nutritional need of the consumer to a great extent. The addition of molasses as a good source of minerals and vitamins improves the nutritional quality and consequently affects the health of the people. This research is aimed to investigate the effects of molasses addition molasses on dough rheological properties and quality of Toast Bread. Molasses was added to wheat flour at 1، 3، 5 and 7 percent levels. Chemical properties of molasses and wheat flour were determined. Rheological properties of dough formulations were evaluated. Specific volume and firmness of bread were measured over the periods of 0، 2، 4، 6 days. Sensory characteristics of breads were evaluated after the periods of 24، 48 and 72 hours. The results indicated that the dough made with molasses was more stable than the control that was made from wheat flour. The bread that contained molasses showed an increase in specific volume and higher acceptability. During the storage breads supplemented with molasses maintained higher degree of softness. It was concluded that the addition of %5 molasses improved dough rheological properties and shelf life of the produced bread، Therefore molasses might be employed as a quality improver in production of bread.

Overweight and obesity are major risk factors for cardiovascular morbidity and mortality، that is associated with increased oxidative stress statues. Moreover، despite of many studies that indicated regular exercise training is associated with numerous health benefits، it has been shown that acute exercise might give rise to increased oxidative stress. Therefore، natural supplementation might attenuate oxidative stress in exercise. The present study is conducted to assess the effect of blackberry extract on the total antioxidant capacity and lipid peroxidation after acute resistance exercise in obese men. In a randomized double-blind design، twenty obese men (BMIS 30) were assigned into one of two placebo (n = 10) and supplement (n = 10) groups. Supplement group received 100 mg blackberry daily for seven days while other group consumed placebo. All subjects underwent resistance exercise that included nine exercises with 60% 1-RM. Venous blood samples to determine plasma malondialdehyde (MDA) as an index to lipid peroxidation and total antioxidant capacity were obtained one week prior to the exercise، immediately before the exercise and 24 hours after the exercise. The results indicated that MDA concentration significantly increased after resistance exercise in placebo group as compared to the supplement group (P<0. 05). Moreover، the mean of total antioxidant capacity remained unchanged in both groups in immediately preexercise and 24 h post exercise (P>0. 005). The results of this study indicated that acute resistance exercise give rise to increased MDA concentration in obese men. The application of blackberry extract employed as an antioxidant supplement might ameliorate this marker and prevent the oxidative stress damage.

Dehydration of food particularly fruits and vegetables have been carried out for decades. In this research، thin layer drying of zucchini was performed by convective hot air dryer. The aim of this study is to investigate the effect of temperature and drying kinetic on zucchini and present the best kinetic model concerned with changes in moisture with respect to the time.

All the tests were carried out in three temperature environments، (60، 70 and 80°C) with zucchini cuts of 10 mm thickness in three replicate order. Ten mathematical kinetic models were processed on experimental data and evaluation of models were analyzed by four criteria such as Determination of Coefficient (R2)، Root Mean Square Error (RMSE)، Chi-square (X2)، and Mean Bias Error (MBE). Second Fick''s Law was used for evaluation of diffusion coefficient and Arhenius equation was employed for activation energy (Ea).

The results showed that Hii، Law & Cloke model evaluates drying of thin layer zucchini more appropriate than other models. The activation energy value was determined (85. 45 kJ/mol).

The Hii، Law & Cloke model might be considered as the most suitable mathematical model for thin layer drying of zucchini by hot air displacement method.

Mayonnaise sauce is consumed by a large number of people. Producing symbiotic mayonnaise sauce with probiotic bacteria has probably an important impact in human health promotion. Recently، Microencapsulation of probiotic bacteria is the newest method for increasing the survival ability of probiotics in food products. In this study، Lactobacillus acidophilus ATCC 43121، Lactobacillus casei ATCC 39392 and Bifidobacterium bifidum ATCC 29521 were encapsulated by calcium alginate and resistant starch under the emulsion procedure. These were added to the mayonnaise sauce either as free cells or encapsulated form. The survival of probiotic was evaluated during storage after 30 days at 4 ºC. The morphologicalcharacteristics of capsules were indicated by optical microscope and scanning electron microscope. The survival of encapsulated probiotic bacteria was higher than the free state in mayonnaise sauce. There were not detectable differences in the morphological characteristics of the capsules with resistant starch employing scanning electron microscope and optical microscopy. Sensory evaluation of mayonnaise sauce was improved by the addition of encapsulated probiotic bacteria. The microencapsulation significantly increased the survival of probiotic bacteria and synbiotic mayonnaise sauce with an acceptable quality characteristic might be introduced for the production.

Apple is one of the most important horticultural crop that storage and post-harvest problems attract the growing interest of researchers and industry’s authorities. In this study، the effect of 1 - methyl cyclopropene (1-MCP) and ethylene nano-absorbent (potassium permanganat) as a new combination، effective and low cast treatment on the durability of apple and its storage was investigated. Two commercial apple cultivars، Wealthy and the native Dirras-e Mashhad، present in National Horticultural Research Station، kamalshahr-karaj were selected. The samples were harvested according to the starch index (2-2. 5) and were pre-cooled for 24 hours and then treated with 1 ppm concentration of 1-methyl cyclopropene by spraying in an impenetrable atmosphere and maintained for 8 hours at room temperature and finally transferred into the cold room. Ethylene treatment was performed by placing the nano absorbent packets of 5 gr within the cardboard containers together with the non treated fruits as control. The samples were stored at 0. 5 °C and 90% of relative humidity. Series of tests consisting of fruit weight، flesh firmness، ascorbic acid concentration، total soluble solids (TSS)، titrable acidity (TA) and pH measurement were carried out on the sampls once a month in triplicate order. Sensory evaluations were carried out at the end of five months of storage period، comparing the treated samples of both cultivars with the control. The experiment was organized as completely randomized design and the collected data were analyzed by SAS software. weight loss and flesh firmness in both experimental samples demonstrated less reduction as compared to the control the use of 1-MCP affected TSS، pH and TA significantly (p<0. 05) and inhibited the rise pH and reduced also acidity TA during storage، while no significant effect (p>0/05) was noted by the use of nano-absorbent. The native ''Dirras-e Mashhad'' showed higher pH value than ''Wealthy'' under the combination of ENA and 1-MCP. The results showed that this technique can increase most characteristics of apples duringthe storage.