JOURNAL OF FOOD RESEARCH (UNIVERSITY OF TABRIZ)
Year:2018 | Volume:28 | Issue:3|Papers Count:15

In this study, effect of individual substance [ethanol 70%, colloidal silver Nano-particles (Nps) (0. 5 ppm), benomyl 15%, wax or methylcellulose-wax] or their combinations at 8 ° C was evaluated on prevalence of decay, textural and organo-leptic properties of Thomson novel oranges. Quality and sensory attributes were evaluated every two weeks for 16 weeks. After rinsing, fruits were treated by ethanol 70%, silver Nano-particles (0. 5 ppm), or Benomyl 15%. Fruits were coated by commercial wax or methylcellulose-wax [MC-lipid (9: 10, w/w)] using immersion method, and then were dried at ambient temperature. Uncoated fruits were used as the control ones. This research was performed using a factorial experimental model in a completely randomized design with 5 replications at an accuracy rate of 95%. During storage, the minimum and maximum of decay were observed for the fruits treated by nanosilver and ethanol, respectively. The percent of decay for the control fruits was smaller than that of the fruits treated by ethanol. No significant changes were observed between the fruits coated by wax and methylcellulose (P>0. 05). Texture analysis showed that the fruits coated by wax or methylcellulose-wax had much better firmness in comparison with the control or disinfected fruits (P<0. 05). The panelists reported that the highest and lowest organoleptic properties for methylcellulose and wax, respectively. No significant difference was observed between the two types of coatings in their appearances.

For many years, there have been concerns about side effects of sugar on human health, such as cardiovascular diseases, diabetes, obesity and tooth decay and the human mind is always to provide safe alternatives to replace sucrose. The aim of this study was production of dietetic chocolate cream using natural sugar substitutes. In dietetic chocolate cream different amounts of stevia (rebaudioside A), inulin and sucralose were used. Physicochemical and sensory characteristics of the samples were studied. The results showed that the lowest pH was related to control sample. Sample containing 0. 004 % stevia + 0. 17% inulin + 0. 47% sucralose had the highest viscosity. The highest dry matter was related to the control sample. The scores of flavor, color, texture and overall acceptability of control sample was significantly (P<0. 05) higher than other samples. Among dietetic cream samples, sample containing 0. 006 % stevia+0. 21% inulin+0. 47% sucralose was awarded the highest sensory scores. Therefore, this sample can be selected as the best treatment.

In this study, with the aim of increasing of butter aroma of industrial dough, tri-sodium citrate was used in dough formulation at concentrations of 10, 30 and 50 ppm, and the amount of phase separation, acidity and production of diacetyle during storage days (1-30day) was studied. The results showed that adding citrate reduced the acidity and by passing time, acidity increased. Minimum value of acidity for treatment was 50ppm and maximum amount was regarding for control treatment on the first day of storage. Also, the acidity was statically significant (P<0. 05). A significant difference in the phase separation between all treatments, there was in a 30-day maintenance period (P<0. 05). Minimum and maximum amount of phase separation was regarding to the treatment which was 50ppm concentration in the first day of storage period and control treatment in the 30th day, respectively. Also, by increasing the concentration of tri-sodium-citrate, phase separation during storage period decreased. The amount of diacetyl production induced up to 10ppm, by increasing tri-sodium-citrate concentration and maximum amount of diacetyl production was regarded to the 50ppm sample, which indicated a positive effect of tri-sodium-citrate on quality and aroma properties of the product.

Essential oils and extracts of medicinal plants with antimicrobial, anticancer and antioxidant activity are important as a new drug compounds in the field of health and protection of raw and processed foods or healthier food products. The aim of this study was to compare the antioxidant and antibacterial properties of ethanol extracts of Hypericum perforatum and Hibiscus gossypifolius. The antibacterial properties against pathogenic bacteria (Salmonella enterica, Bacillus cereus, Escherichia coli and Staphylococcus aureus) using well diffusion and antioxidant activity were also tested using Trolox Equivalent Antioxidant Capacity (TEAC) method with ABTS+● . The results revealed that Staphylococcus aureus was the most sensitive bacteria to Hypericum and Hibiscus extracts and there was no significant difference between two extracts (P≥ 0. 05). The results revealed that there was a significant difference between antioxidant activity of Hibiscus and Hypericum (P<0. 05). Evaluation of antioxidant activity showed that the IC50 of Hypericum and Hibiscus was 1. 56± 0. 31 mg/mL and 0. 78± 0. 2 mg/mL, respectively. Therefore, Hibiscus gossypifolius had higher antioxidant capacity than Hypericum perforatum. The results showed that ethanol extracts of Hypericum and hibiscus had antioxidant and antibacterial activity; therefore, they can be used in food and pharmaceutical industries as natural additive.

Today, the desire to use minced meat has grown as one of the available raw foods. Due to the economic value of meat, there is the likelihood of using unauthorized meat or other meat in minced meat. There are several methods to detect adulteration in ground meat. One of the best methods for detecting these adulterations is molecular tests like PCR. Today, this technique has been widely used because of its speed, simplicity, sensitivity and specificity. In this research, it was used of polymerase chain reaction (PCR) technique to detect adulteration in minced meats collected from Tabriz. The PCR primers were designed based on the ND2 sequence of mitochondrial genes of donkey and genome of cow. Amplification sizes were 145 and 274 bp for donkey and cow respectively. Screening of 98 commercial minced meats collected from different parts of Tabriz, 7 samples were showed which have contamination with donkey meat.

Meat consumption risk of cardiovascular disease and obesity increase, but the people who follow diets of plant origin, naturally the risk of type 2 diabetes, cardiovascular disease and cancer reduced. Soy burger is a non-meat substitutes which contains about 30% soy protein but soy protein has a high oil absorption capability. Application of gums in soy burger formulation improve the textural, color, oil absorption and organoleptic of final product. Hence, regarding the gums application in food systems, the effect of adding xanthan (0, 0. 4, 0. 6%) and caboxymethyl cellulose gums (0, 0. 4, 0. 6%) on textural, color and oil absorption properties of soya burger were evaluated. It was found that the samples with xanthan and carboxymethyl cellulose gums had significantly higher (P<0. 05) adherence, L* (lightness), b*(yellowness) and  E and significantly lower (p<0. 05) in a* (redness), firmness, elasticity and oil absorbance percentage. Scanning electron microscopy results showed that adding xanthan and carboxymethyl celluloses gums leads to more homogenous and coherence texture than control sample. Consequently, adding mixture of these two gums (0. 6+0. 6%) adding xanthan and carboxymethyl cellulose gums had a successful result in textural, color and oil absorption properties of soya burgers.

Starch-based active packaging which contain additives has been used to food preservation, significantly. Organic nano-clays such as montmorillonite cause to strength of these films and additives such as antioxidants reduces food spoilage rate. In this study starch-based films with different percentages of montmorillonite from 0 to 8% and the green tea extract from 0 to 2. 5 % were produced by casting method and physical properties of the films such as tensile strength, water absorption, water vapor permeability and solubility were investigated. Then flax seed oil was packaged in these films and some chemical properties of oil, peroxide index and acidity, were evaluated. Then the optimal point in the film production was determined with Minitab 17 software by response surface methodology. The results showed that low content of both independent factors caused to decrease of water absorption and solubility and addition of montmorillonite and green tea extract increased the tensile strength of films. It was seen in medium content of both factor water vapor permeability of films was the least. Montmorillonite in high and medium content caused to reduction of peroxide index and acidity, respectively. Organoleptic tests showed that edible films did not change the odor, flavor, color and overall acceptance of flax seed oil, too. The optimal point to justify was in 2. 42% of Montmorillonite and 0. 181% of green tea extract caused to increase shelf life of flax seed oil to 7 days.

The aim of this study was to investigate the possibility of using tarragon (Artemisia dracunculus) essential oil as an aromatic herb in preparing mayonnaise to replace artificial antioxidants. The oil of the fresh tarragon leaves was extracted by hydro-distillation technique using Clevenger apparatus and its volatile compounds were analyzed using GC/MS. The total phenol content of essential oil was measured by Folin-Ciocalteu reagent and the antiradical activity of essential oil was assessed by using ABTS and DPPH methods and compared with BHT as a synthetic antioxidant. The essential oil at different concentrations (500, 1000, 1500, and 2000 ppm) was added to mayonnaise and its antioxidant activity was evaluated under accelerated condition (90° C) during seven days by comparing peroxide and acid values and thiobarbituric acid with 100 and 200 ppm BHT. Twenty compounds were detected in tarragon essential oil by GC/MS. Results showed that estragole (83. 39%), (E)-β-ocimene (6. 47%), (Z)-β-ocimene (5. 41%), and limonene (2. 19%) were the main components of tarragon essential oil. Total phenol content of essential oil was determined to be 13. 996 mg gallic acid equivalent in 1 gr of dried sample and EC50 was 3. 15 mg/ml in DPPH test. ABTS test showed that 2000 ppm of essential oil had the highest antiradical activity. Peroxide, acid and thiobarbituric acid tests showed that the tarragon oil at high concentration could be replaced the synthetic antioxidant in mayonnaise. Also, the results of sensory evaluation test showed that different concentrations of essential oil had no significant effect on organoleptic characteristics of mayonnaise. In conclusion, tarragon essential oil can be recommended to inhibit the oil oxidation and increase the shelf life of mayonnaise as a natural antioxidant.

Polystyrene nanocomposites were prepared with varying amounts of nanotitanium dioxide and nanosilver by melt mixing process at 190° C. The nanocomposites structure was characterised by scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDS). The mechanical properties were obtained with tensile test. The influence of nanoparticles on the thermal properties of polystyrene matrix was examined using differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA). The results of the SEM showed that both nanoparticles were present in nanocomposite, and the distribution of nanoparticles in the polymer was relatively good, despite the fact that in some places aggregation (with maximum size of 55 nm) were observed. The EDS spectrum showed that the nanocomposite was non-impure and contained three elements of carbon, titanium and silver, and the amount of nanotitanium was about 10 times that of silver. The augment of nanoparticles leading to decrease Young’ s modules and stress at break point slightly. But, a point of view yield at break had not seen significantly different (P˃ 0. 05). The investigating of the thermal properties of the samplesshowed they did not differ significantly from the point of view of glass temperature and thermal stability of the polystyrene and nanocomposites.

Celiac Disease (CD) is a common lifelong disorder with small bowel malabsorption and gluten intolerance. The only effective treatment for CD is a strict adherence to a gluten free diet throughout the patient’ s lifetime. One of the main challenges in relation to the gluten free bread is to obtain a proper structure and quality. Gluten free breads require polymeric substances that mimic the viscoelastic properties of gluten to provide structure and retain gas. In this research effect of tragacanth in three concentrations (0. 5, 1. 25 and 2%) and pectin-tragacanth in concentration of 1. 5% (1: 1) was evaluated on the physicochemical, textural and sensory properties of corn-based gluten-free bread. Specific Volume of the breads was enlarged as the concentration of tragacanth increased compared to the control sample. The lowest weight loss of samples was belonged to the bread containing2% tragacanth that had not significant difference with the sample containing 1. 25% tragacanth. With increasing of tragacanth concentrations a significant )P<0. 01) increase in moisture content of the sample crumb was observed compared to the control bread. Crumb hardness increased during storage from first to third day and the effect of treatment on crumb hardness was significant )P<0. 01). Bread containing 1. 25% tragacanth had a softer texture compared with other breads containing hydrocolloids and control bread. However, this difference was not significant (P>0. 05). Also the results showed that treatment effect on the sensory properties was not significant (P>0. 05), and addition of different concentration of hydrocolloids improved the overall score of sensory evaluation. Generally, according to the results of different tests and statistical analysis which carried out in the present study, it was suggested that the addition of tragacanth in concentration of 1. 25% can improve the gluten-free bread quality.

Doughnut is one of the most important products in the world that frying in the oil, after the fermentation, dividing and shaping stages. Because of its high consumption in the country, its quality is of great importance. Today, additives such as gums, emulsifiers, enzymes and. . ., are used to improve the quality of baking products. Aware of the hazards of chemical additives, tend to use natural ones has increased. Therefore, the present study was conducted with the aim of investigating the effect of Basil and Tragacanth gums as natural additives on improvement of quality, sensory characteristics and shelf life of doughnut. For this purpose, Basil and Tragacanth gums in four levels (0, 0/3, 0/6 and 1%) has been added to the doughnut formulas, and moisture content, specific volume, texture and sensory properties of doughnuts were evaluated. The results showed that the use of Basil and Tragacanth gums at 1% increased moisture content and decreased firmness (two hours and one week after baking). Addition of Basil at 1% and Tragacanth at 0/6 %, together, increased the specific volume, shelf-life, sensory scores, color indexes and decreased firmness of doughnuts.

The present study was conducted to evaluate the effect of antimicrobial and antioxidant chitosan coating enriched with rice-bran extract on the shelf-life extension of trout fillet. Rice-bran extract was extracted with 80% methanol. Samples were separated into three groups; uncoated and without rice-bran extract (Control), coated with chitosan and coated with chitosan containing 2% rice-bran extract. Fish fillets were stored at refrigerated condition (4¡ ¾ 1¢ ª C) for 20 days. Lipid contents, chemical characteristics (peroxide value, thiobarbituric acid, free fatty acids, pH) and microbial (total bacteria and psychrophilic counts) and organoleptic properties (odor, color, texture, and general acceptability) were compared in fillets at various days of cold storage (0, 4, 8, 12, 16 and 20 days). Chitosan coating and chitosan coating containing rice-bran extract had positive effect in reducing the peroxide value, thiobarbituric acid, free fatty acids and pH. Microbial analysis indicated that coating enriched with rice-bran extract had a significant effect in the reducing the total bacteria and psychrophilic counts. Results showed that chitosan coatingand using rice-bran extract in coating had significant effects in reducing the chemical indices of spoilage and microbial properties and extension the shelf-life of trout fillets.

In this study, the effect of soaking pretreatment on kinetics of bioactive phenolic compound extraction from Eryngium caucasicum Trautv leaves using ultrasound-assisted extraction (UAE) under optimized conditions (50% amplitude, 42 º C temperature and 51 min sonication time) was investigated. The soaking pretreatment independent variables were time (30, 60 and 90 min) and temperature (25, 35, 45 and 55 º C). The kinetics of bioactive phenolic compounds extraction was studied using Pelegʼ s model. The high value of correlation coefficient (R2 > 0. 98) and low values of root mean square error (RMSE < 0. 160) and mean relative deviation modulus (E<0. 44) revealed that Pelegʼ s model could applied successfully to describe the kinetics of bioactive phenolic compounds extraction. The experimental results showed that soaking pretreatment had significant (P<0. 05) effect on improvement of UAE of bioactive phenolic compounds. Swelling index and total phenolic content obtained using the best conditions of soaking pretreatment (temperature of 45 º C and 60 min) were 14. 50 ± 0. 05 mL/g and 95. 50 ± 0. 11 mg GAE/g, respectively. Under these conditions, the radical scavenging activity of extract was 67. 20% ± 0. 15 of DPPH free radical scavenging activity and 36. 11% ± 0. 12 of OH free radicals scavenging activity. In addition, the Peleg rate constant (K1) was 0. 009639 min. g/mg under the best conditions.

The Conventional heat pasteurization systems, due to the slowness of heat transfer to the milk, are associated with energy losses. Sometimes by increasing the temperature for the adequate pasteurization of the highly contaminated milk, it is associated with formation of the milk stone; lack of adequate heat transfer to the milk would be inconsistent with the relevant standard of health characteristics. Also, with increasing the temperature of the pasteurization, the burnt layer of milk would be thicker together with the negative impact on flavor, color and nutritional value of milk and also addition of the toxic substances to the milk. The increase in temperature will follow the more energy consumption. The other side the increase in the temperature will follow the more energy consumption. While in the induction method, the resulting electromagnetic flow has no disadvantages of conventional pasteurization of milk due to the heat transfer rate. In this study, the pasteurized milk by induction current in the device with 1600 watt of electricity transmission and 30 seconds storage time in 84 ° C and the diameter of the supporting surface of heat transfer: 23 cm (the best conditions of selected sample) was compared to the conventional method in a similar situation in terms of energy consumption and the costs were determined before and after targeted subsidies. The results showed that energy losses in both conventional and induced pasteurization methods were 46. 15% and 32% respectively, and the percentage of saving energy consumption by using the induction method compared to the usual pasteurization method during the year before and after targeted subsidies, were 67% and 82. 9% respectively. So, the energy consumption of induced pasteurization of milk is preferable to conventional method.