مجله علوم غذایی و تغذیه
سال هفدهم شماره 1 (زمستان 1398)

Wheat bran is a concentrated source of diatery fibre, protein, minerals, unsaturated fatty acids and vitamins. Existence of some technological and nutritional difficulties containing high amount of phytic acid and unappropriate sensory characteristics has coused limitation of its application in food formulation. In this study the effect of formulation and extrusion conditions containing feed moisture content, tempreture and screw speed were evaluated on chemical, functional and nutitional properties of texturized wheat bran.

In order to improve the nutriotional and technological properties of wheat bran, the effects of different concentration of feed moisture content (18, 21 and 25%), tempreture (120, 160 and 200°C) and screw speed (170, 235 and 300 rpm) were examined on functional charactristics (water adsorbtion index; WAI, soluability index; SI and oil adsorbtion index; OAI, soluble and insoluble fiber), and the nutritional values (phytic acid) of processed wheat bran.

Based on results the maximum and minimum level of WAI and SI were obtained at 25% moisture content, 120°C and 170 rpm. However the maximum level of SI and OAI were demonstrated at 18% moisture content, 200°C and 300 rpm. The least Phytic acid content (3.09 mg/100g) was shown in 21% moisture content, 120°C and 300 rpm. Extrusion process had significant effect on enhancement of soluble fiber fraction (55%) and decreased the insoluble fiber (6%).

The results indicated that, optimized condition of processing method could enhance the quality of processed wheat bran.

Alga Cystoseria is a brown macroalga belonging to the Phaeophyta family. This alga with irregular branches is found in tropical, sub-tropical waters near rocks and wetlands. The aim of the study was to identify the bioactive compounds of Cystoseria brown algae extract and to evaluate the physicochemical and sensory properties of the edible jelly fortified with algae.

The chemical compositions of the Cystoseria alga extract were detected by the GC-MS method, and the extracts were added to the jelly formulation at concentrations of 50, 100 and 150 mg, then the effects on sensory properties and synereses were studied. Sensory evaluations of oral jelly were carried out by ten evaluators and using a five-point hedonic test to examine the color, taste, texture and general acceptance of the prepared jelly.

The GC-MS analysis identified twelve biologically active compounds effective in food and drugs. The study indicated that the color score increased with the addition of algae extract. According to the results of acceptability, adding 50 mg of the extract to the jelly had the most effects on color, taste and texture factors. The syneresis reduction in treatments was an indication of high water content within the jelly, resulting in improving the appearance of edible jelly.

It can be concluded that the addition of 50 mg of Cystoseria alga extract can be as criteria for the selection of the best formulation that can be used for its high nutritional value.

Pasta products have been identified as healthy foods but due to the minute content of omega-3, scientists have been encouraged to fortify this product with long chain (LC) omega-3 polyunsaturated fatty acids (PUFAs) in order to improve its qualitative effects.

Microencapsulated omega-3 powder that containing %9 LC n-3 PUFA was prepared. After enrichment (%1.2) and drying at different temperatures (55 °C, 75°C, 90°C), the stabilities of the Ecosapentaenoic acid(EPA) and docosahexaenoic acid (DHA) were determined by methyl esters of fatty acids during 18 months. The qualitative characteristics of spaghetti concerned with stickiness, looking loses and cooking weight were also investigated the highest reduction of long chain omega-3 fatty acids after cooking was observed at 75°C.

The results indicate that drying the spaghetti under the different temperature conditions was effective for the stability of long chain omega-3 fatty acids before and after cooking (P<0/01). So that drying at 90Ċ in comparison with 55°C and 75°C decreased omega-3 stability in fortified spaghetti. Most content of long chains omega-3 fatty acids after cooking the spaghetti was observed at 75°C. 

It might be concluded that fortification of this kinds of food at optimal conditions improving its qualitative factors and the nutritional needs.

Grape seed oil is important to human health due to its very pleasant taste, odor, as well as its high nutritional values. Consumption of the grape seed oil in the diet has been increasing in recent years. Long periods of heating will deteriorate the oil and fried products due to oxidative and hydrolytic changes and reactions. Therefore, accurate control of the frying processes and changes are quiet essential.

In this study, the effects of deep frying at 180 °C (24 and 48 hours) on some chemical characteristics of grape seed oil namely sterol profile and fatty acid composition have been studied using chromatography techniques.

The results indicated that, the predominant fatty acid was linoleic acid, and by increasing the heating period, more unsaturated fatty acids namely linoleic acid was decreased due to oxidation. The phytosterols study showed that beta-sitosterol was the predominant phytosterol and deep fat frying did not affect its concentration.

Due to the high concentration of linoleic acid and beta-sitosterol in grape seed oil, it might be stated that the oil has a high nutritional value, but considering the changes during frying it might not be recommended for frying practices.

The amount of heavey metal elements in tea mighg have significant impact on human health. In the present study, the amount of heavy metal elements such as cadmium (Cd), lead (Pb), zinc (Zn), iron (Fe), aluminum (Al) and copper (Cu) in some imported tea samples and local tea samples cultivated in Iran have been evaluated.

The Tea samples were prepared by three different methods including Digestion, Brew and Infusion and the concentration of heavy metals in the prepared samples were measured by ICP-OES and ICP-MS.

Aluminum with a concentration of 853.9 µg/g and the cadmium element with the concentration of 0.99 µg/g were found to be the highest and lowest in the samples examind, respectively. Among the extraction methods, the concentration of extracted elements in digestion method was significantly higher than other methods. The statistical analysis of the obtained results by ICP-OES and ICP-MS revealed that there is no significant difference between the detected concentrations of Al, Zn, Fe, Cu and Cd eighter in the local or imported tea samples in each of the extraction methods. The obtained result showed that the amount of detected Pb in the ICP-MS technique for both internal and imported tea samples is significantly higher than those of ICP-OES technique.

Concentrations of all metal elements in the studied tea samples were significantly higher than of standard reference (NIESNO.7). However, the estimated daily intake of all elements for each adult person is still within the allowable level of the World Health Organization.

One of the new techniques in the drying of food is the application of infrared radiation that increases the drying rate, enhanced the final product quality, and decreases the costs of the process.

In this study, drying kinetic modeling of strawberry in an infrared dryer was investigated. The effect of radiation lamp power (150, 250 and 375 W) and distance of the lamp from the sample (5, 7.5 and 10 cm), on drying time, and moisture diffusion coefficients during the drying process of strawberry were evaluated. For measuring the weight of the samples during experimentation without taking them out of the dryer, the tray with samples was suspended on the digital balance. Standard models (Wang and Singh, Henderson and Pabis, Approximation of diffusion, Page, Modified Page –II, Newton, Midilli and Logarithmic) were fitted to experimental data to study the drying kinetics and fitting quality (coefficient of determination and standard error) of them was analyzed.

By increasing infrared lamp power from 150 to 375 W, the drying time of strawberry is reduced by 79.8%. Decreasing the distance of the lamp from a sample from 10 to 5 cm, 40.1 % of drying time is reduced. The effective diffusivity coefficient was increased by increasing heat source power and decreasing distance. Moisture effective diffusivity coefficient of strawberry was between 1.54×10-9 to 13.83×10-9 m2/s.

The effect of radiation lamp power and distance on the drying process of strawberry is significant. Modeling of strawberry drying process showed that all the models led to proper results, but in total, the Page model, compared to other studied models, with the biggest coefficient of determination (R2=0.999) and the smallest error (<0.011), had closer results to the experimental data.