مجله علوم غذایی و تغذیه
سال نوزدهم شماره 1 (زمستان 1400)

Nowadays, use of non-additive food products has become a fundamental issue and a general demand for consumers. On the other hand, the rheological properties and viscosity of beverage products are one of the important factors that impacts acceptability of these products. Hence, it is essential to find a way to solve this problem and improve the quality properties of juices.

In this study, the effect of homogenization with 5,000 and 10,000 rpm at 5 and 10 minutes was studied on the physico-chemical and rheological properties of peach nectar.

Homogenization significantly increased the apparent viscosity of the samples by 5% level, therefor from 10.6 mPa in the control sample, it was 16.67 mPa in the homogenized sample at 10,000 rpm and 5 min. On the other hand, homogenization improved color characteristics and peach nectar sedimentation as compared to the control sample. In addition, homogenization increased pH, brix, formalin index, and turbidity significantly. However, acidity of the samples increased insignificantly. Besides that, the particle size decreased significantly by the homogenization procedure.

According to the results of this study, it might be concluded that the application of homogenization improves the viscosity and stability of treatments and therefore the homogenization process can be used as a substitute for viscous additives.

Fats and oils play important sensory and functional roles in food products. They are responsible for enhancing and releasing flavor components that react with other components to enhance the texture and mouthfeel of fried foods. Fat is a natural factor in making the food delicious. When frying food, hot oil penetrates into it, replaces its water content and makes it significantly more pleasant. This absorbed fat makes the crust crispy and affects the taste. In this study, the effect of deep frying process in sesame, canola and frying oils on nutrients and bioactive compounds of onions and potatoes and evaluation of their antioxidant activity were investigated.

Slices of potato and onion were fried in sesame oil, canola and special frying oils for 8 minutes and 4 minutes, respectively. Deep frying was carried out in three separate steps (for new samples but in that oils) with an interval of three hours between each step. Slices of fried potatoes and onions were evaluated by measuring total polyphenol factors, fatty acid composition and antioxidant activity.

During frying, elaidic acid is produced in canola oil (1.14-1.53% in the first and third stages of frying, respectively), but no significant difference was observed between the first stage and the third one. Due to the oxidation of linoleic acid in all fried onion and potato samples the content of linoleic acid decreased palmitic acid content was increased. The height amount of total poly phenols in fried potato slices were found in potatoes fried in sesame oil followed by potatoes fried in canola and finally in frying oils. The same observations were made for onion slices fried.The amount of polyphenols in fried samples showed a significant difference as compared to pre-frying (P <0.05). The highest oxidation resistance as indicated by Rancimat test was observed in potato slices fried with sesame oil, followed by special frying and finally canola oils. The same observation was made for onion slices.

It might be concluded that sesame oil probably due to its fatty acid composition and oxidational contents might be regarded as a better media for deep frying applications as completion to canola and frying oils.

Considering the increasing consumption of fat-rich foods over the last decades and its relationship with prevalence of cardiovascular diseases, development of low-fat food formulations is of special importance. Hydrocolloids such as gums have great potential for imitating the role of fat in foodstuff. The aim of the present study was to explore the capability of konjac gum to replace the fat in mayonnaise.

Different concentrations of konjac gum (0.25, 0.5, 0.75 and 1%) were incorporated into the formulation of mayonnaise with 20, 30, 40 and 50% oil reductions, respectively. The static (flow behavior) and dynamic (strain sweep and frequency sweep) rheological properties were measured using a rheometer and sensory chracteristics were evaluated by a 10-member sensory panel. The rheological and sensory properties of low-fat mayonnaise containing different concentrations of konjac gum were compared with each other and low-fat control (30% fat) using a completely randomized design at 95% confidence interval.

The results of fitting the rheological data to Power-Law and Herschel-Bulkley models showed that all samples had pseudoplastic behavior. The low-fat samples containing different concentrations of konjac gum had lower flow index and higher consistency index than the control sample. Similarly, the yield stress was enhanced with gum concentration up to 0.5% but decreased after that. The finding of oscillating frequency sweep test showed that all samples had storage modulus larger than loss modulus and loss tangent lower than 1, confirming the viscoelastic characteristics of the samples. Furthermore, the loss tangent steadily decreased with increase in konjac concentration. It was observed that konjac gum had a significantly improving impact on stability index of reduced-fat mayonnaise in a concentration-dependent manner. The results of sensory analysis revealed that konjac gum significantly improved the texture, viscosity and overall acceptability but did not have any significant effect on odor and flavor of low-fat mayonnaise.

It is concluded that the low-fat mayonnaise sample containing 0.5% konjac gum was the best formulation in terms of rheological and sensory properties.

Heavy metal pollution, is one of the most important environmental problems and one of the concerns of food hygiene. Rice, especially white rice is the most important food in the diet of people in various asian countries and is the second staple food of the people of Iran.

This study was designed to determine the concentrations of cadmium, lead and arsenic in Anbarboo rice samples in areas of Khoozestan province. Seven Anbarboo rice samples and samples of cultivated soils were collected. The samples were prepared and subjected to ICP apparatus to analyze and determine the concentrations of cadmium, lead and arsenic. The obtained data was analyzed by SPSS statistical software and compared with the national standard.

The results indicated that the mean concentrations of cadmium, lead and arsenic in the rice samples were 0.0292, 0.0075 and 0.0072 ppm respectively while the concentrations of these elements in the related soils were 0.0071, 187.09 and 16.110 ppm respectively.

It is therefore concluded that the concentrations of studied elements in the Anbarboo rice samples were less than the concentration defined by the national standard. It also may be concluded that many factors namely the nature of the soil and irrigation might affect and the concentrations of these elements in the rice samples.

Today, due to the increasing public awareness of the harms of consuming carbonated beverages, the tendency to consume natural beverages such as drinking yoghurt is increasing, but despite the observance of health standards, the sensory and physical characteristics of this product that are very important have not been confident. One of the main problems in this drink is the two-phase formation, that is due to the acidic conditions, where the casein proteins of yogurt accumulate and precipitate and eventually create an undesirable appearance and condition.

In order to prevent this problem, hydrocolloids can be used. In this study, the effects of adding carob seed gum at concentrations of 0.1, 0.15, 0.2 and 0.25% to buttermilk were investigated. The physicochemical, rheological, activation energy, potential, two-phase formation and organoleptic properties of this populate drink was studied thoroughly.

The potential in dough samples is from -17.96 to -31.89 mV, respectively. Changes in the flow behavior of dough from Newton to dilute by shear were observed during the addition of carob seed gum and a suitable mathematical model to predict the flow behavior of the product. Fermented milk fermented with carob seed gum was the law of power. Activation energy in dough samples ranged from 13.82 to 24.98 kj/mol, respectively. The best sample in terms of sensory evaluations was reported for the sample with a concentration of 0.2% carob seed gum.

The use of carob seed gum had a favorable effect on the physicochemical, sensory and rheological properties of dough.

Food industry has an important value all over the would. Tomatoes and it’s other products are one of the important agricultural products in food industry. Transgenic plants and seeds are one of the important achievements of modern biotechnology in field of agriculture that have captured a part of food marketing in recent years. Therefore, identify and examine whether transgenic agricultural products are transgenic or not, it is necessary because there are still many opinions for and against the use of these products in the world.

In this study, 10 types of tomatoes along with sepals were collected by simple sampling method from Tajrish bazaar, Shahrvand-e farmaniyeh, vegetable market East and West of Tehran and were examined. At first, P35S F/R, NOS-1/NOS-3, RBCLF/R and NPTǁ F/R primers were used. Nucleotide fragments were amplified respectively at 195bp and 180bp.

Amplified nucleotide fragments confirmed 100% similarity of the nucleotide sequence to the samples in the gene bank that the studied products were genetically engineered. Also, in order to identify transgenic tomatoes, aspecific PG F/R primer pair was used to amplify the antigens of polygalacturonase gene. All specimens that had P35S promoter band or NOS terminator, or both, amplified the 384bp band associated with part of the PG gene antisense, and found a 100% similarity in the gene sequence registered in the gene bank.

The results of this investigation showed that transgenic tomatoes exist in Iran’s market without consumer awareness.

Staling is one of the main causes of reduced bread shelf life. In this study, the effect of using green tea hydroalcoholic extract as a beneficial herbal compound on dough rheological properties and staling of barbari bread was investigated.

In order to prepare the hydroalcoholic extract, first, green tea was extracted with 30% ethanol and then concentrated and powdered by spray dryer. The product was subjected to qualitative analysis and then was added at the 0, 0.5, 1.5, 2.5 and 3.5% concentrations (based on flour weight) in the formulation of consumable dough followed by performing the dough rheological properties and bread quality tests, staling, bread crumb hardness (by TPA device) and the samples thermal properties (by DSC device) were evaluated in one, three and five days after cooking.  

The results of dough rheological tests showed that the green tea hydroalcoholic extract increased flour quality and improved the dough rheological properties and also, increased the moisture and total polyphenol contents in bread, at all concentrations. In all three time periods, 0.5 and 1.5% treatments had the highest soft tissue as compared to other treatments and the control samples. The results of thermal properties indicated that 1.5% treatment reduced the starch retrogradation in the short- term (one day after baking) and possibly long-term (more than five days after baking).

In this study, green tea hydroalcoholic extract acts as an oxidizing improver and improved the dough rheological properties, and also, 0.5 and 1.5% treatments had the most effect on reduces the bread crumb hardness by delaying the staling of barbari bread.

Biscuits are one of the most important flour products, that are very popular due to its ease of production, storage, and consumption. In biscuits production using an emulsifier has increased the ability to spread fat in the flour and sugar system. The objective of this research was to investigate the effect of three emulsifier SSL, DMG, DATEM in the hydrated form in soft biscuits and optimization of the formulation.

The range of use of each emulsifier is 0.1-0.5 percent based on the weight of flour. The RSM was used to determine treatments and 22 treatments were identified. The experiments performed included measuring the long and short diameter, thickness, hardness, browning index and overall acceptability. The data were then analyzed and optimization performed.

The SSL has the most effect on the diameter than the other two emulsifiers and at 0.5% concentration has increased by 2mm in diameter. But, by increasing SSL, the thickness has decreased. The DMG on diameter has a positive effect and its effect is greater on long diameter. DATEM is the most effective factor on the texture and as it increases, the texture becomes softer. The use of hydrated emulsifiers reduces browning index. Increasing DATEM, causes dough adhesion to rotary moulding and the appearance of biscuits is unacceptable.

By optimization, the formulation of the combination of emulsifiers was determined that included: 0.37 SSL, 0.45 DMG, 0.5 DATEM.