JOURNAL OF FOOD RESEARCH (UNIVERSITY OF TABRIZ)
Year:2016 | Volume:26 | Issue:3|Papers Count:14

With regard to important bread on supply the high mass of energy and protein human, improvement quality and save nice quality product is essential. This experiment was carried out to evaluate the effect of hydrocolloids on pan bread crumb. In this study the effect of Qudome shahri (Leidium perfoliatum) and Xanthan gums (0.5 and 1 %) on crumb structure by use fractal dimensions, image texture (energy, entropy, contrast and homogeneity) and crumb characteristic (mean cell area and void fraction) was investigated. The results showed that with increasing concentrations of Xanthan gum and Qudome shahri, fractal dimensions, entropy, contrast and size of cell decrease. However, with increasing concentrations of hydrocolloids, energy, homogeneity, total cell and total cell area increased. The deduction of this work could be regarded as rapid, non-destructive, objective and inexpensive method for quality evaluation of bread crumb. Also based on the results, functional characteristics of Qudome shahri is similar Xanthan gum characteristics, thus enabling the use of a Qudome shahri gum as well local hydrocolloid is to improve the quality of pan bread.

The purpose of this study was to model water loss during deep-fat frying of potato slices pretreated with ultrasound (frequency of 40 kHz for 10 and 30 min), microwave (power of 5 W/g for 5 min) and osmotic dehydration (sodium chloride solution at concentrations of 1 and 3% and temperature of 40oC for 3 hours). Diffusion Fick's law was used to model water loss during the frying process. Ultrasound pretreatment for 10 min decreased the effective moisture diffusion coefficient and water loss rate from the potatoes. Moreover, a number of experimental models were used to model water loss during the process. Also, using the Arrhenius equation, effect of temperature on the effective moisture diffusion coefficient was investigated. With increasing frying temperature, effective moisture diffusion coefficient increased logarithmically. On the other hand, using multivariate regression analysis, the water loss model constants as a function of various process conditions (concentration of osmotic solution, ultrasound time, microwave power and frying temperature) were obtained. In general, application of microwave and osmotic dehydration pretreatments as well as the combination of these pretreatments with ultrasound decreased the initial moisture content of the potatoe strips.

In this paper, the effect of nanoemulsion produced from high pressure homogenization process on properties of microcapsuls resulted from microencapsulation by spray drying was studied. For this purpose, oil-in-water emulsions containing 5% limonene (wall material basis) in a solution of 10, 15 and 20% whey protein concentrate (WPC) using high pressure homogenizer at pressures of 20, 50, 80 and 110 MPa was prepared and their quality attributes such as mean diameter of droplets and size distribution, polydispersity index and viscosity was studied as a function of wall material concentration and pressure of homogenization. Moreover, the influence of these parameters on the properties of spray-dried microcapsules such as particle size, percent of oil retention, encapsulation efficiency and also on the quality indexes of reconstituted emulsions was evaluated. The results indicated that an increase in the pressure of homogenization and wall material concentration increase the size of microcapsules and efficiency of microencapsulation while decrease surface oil content of microcapsules. However, increasing the concentration of WPC and homogenization time of fresh emulsions decreased significantly the difference between particle size of fresh and reconstituted emulsions.

In this study, nano-complex production based on two biopolymers, casein and Arabic gum was studied for developing of a carrier system for β-carotene. For this purpose, complex formation was investigated by different techniques. The first the sodium caseinate solutions at the levels of 0.1 and 0.5 (w/v%) and Arabic gum at three levels of concentrations 0.1, 0.5, and 1% (w/v%) were prepared. Then beta-carotene was loaded to the sodium casein solutions and Arabic Gum was added to it at different levels. The electrostatic interaction between biopolymers was induced by the adjustment of the pH.The complex formation between two biopolymer and bcarotene-caseinate was evaluated by Infrared spectroscopy (FT-IR), differential scanning calorimetry (DSC), turbidiometry and rheometry. The FT-IR curves of nano-complexes showed that the spectrum of specific nano-complex containing beta-carotene in a given region of is different from the specific spectrum of every one of the biopolymers and beta-carotene. In the DSC test thermogram pattern of the biopolymeric nano-complex containing beta-carotene differed with the every one of single biopolymers and beta-carotene. This is possibly confirming the b-arotene encapsulation in nano-complexes. The results of turbidity measurement of solutions showed that the increasing of Arabic gum caused to increase in turbidity and maximum turbidity (134 NTU) observed in the caseinate 0.1 - Arabic Gum 1% (w/v). Investigating the rheological properties of nano-particles showed that increasing the concentration of Arabic gum from 0.1 to 1% caused to increase in the viscosity of aqueous nano-complex solutions which attributed to increasing of complex particle numbers.

Environmental pollutions and limitation of petroleum resource were brought about development of biobased polymers and progress in reducing dependence to fossil fuels. In current study, the functional properties of modified starch by photochemical reactions as a biodegradable food packaging material were investigated. Starch film-forming solutions were exposed to ultraviolet C (UV-C) ray with a wavelength range 100 to 280 nm for different times (1, 6, 12, and 24 h). Tensile strength and Young’s modulus of the film specimens were decreased with increasing irradiation time. Elongation at break, and tensile energy to break of the film specimens were increased, simultaneously. Hydrophobicity, moisture sensitivities, and water vapor permeability of starch films, were improved with UV-C irradiation. It can be concluded, UV-C is an easy and accessible process to modify starch-based biodegradable films.

Tragacanth gum and EPSs have properties that they can be fat replacers in cheese. The effect of tragacanth gum and EPS producing starter on physicochemical, textural and microstructure properties of low-fat cheddar cheese was investigated during ripening. Cheddar cheese was produced in 5 treatments, including: low fat and full fat control, containing 0.06 % tragacanth gum, containing EPS producing starter and containing combination of 0.06 % tragacanth gum and EPS producing starter. Samples were vacuum packed and stored for 6 months in 6 ± 1oC. The results of ANOVA showed that with addition of tragacanth gum, dry matter and fat in dry matter of cheeses decreased and salt and cheese production yield increased in comparison to full- fat control sample (P<0.05). But addition of EPS producing starter had no significant effect on these properties. Regarding the texture analysis results, EPS producing starter increased hardness and cohesiveness considerably in comparison to full- fat control cheese (P<0.05). But the effect of tragacanth gum on TPA parameters was not significant (P>0.05). In images of samples containing tragacanth gum obtained by scanning electron microscopy, a protein matrix with many holes was observed while the samples containing EPS producing starter, had more homogeneous structure and samples containing both fat replacers, were between two conditions. The results of sensory evaluation also showed that adding of tragacanth gum and EPS producing starter had no significant effect on sensory factors (P>0.05). The results of this research showed that tragacanth gum and EPS producing starter can be used as fat replacers with desirable textural properties in cheddar cheese production.

Osmotic drying process is application of hypertonic solution (osmotic) for the disposal of water from the product. The aim of this study was investigation on the different concentrations of osmotic solution, different temperatures and times of treatment for drying of apricot and chooses the best treatment. Water loss (WL %) and solid gain (SG %) at different temperatures and three different osmotic solutions (sucrose-salt) for 5 hours were used to choose the best osmotic treatment to produce dried apricots. The used treatments were including of different osmotic solutions (sucrose-salt %55-5, %50-10 and %45-15, respectively) and different temperatures (at 50°C and 60°C) during 5 hours (1, 3 and 5 hours). The results showed that the best treatment among the 18 different treatments was the treatment containing osmotic solution of %50 sucrose and %10 sodium chloride and treatment time of 5 hours at 60°C with respect to the lowest SG/WL which made better drying of apricots in comparison with the other treatments and was known as the best treatment. Among the measured parameters, the lowest solid gain and the highest water loss were related to treatment containing osmotic solution of %55 sucrose and %5 sodium chloride and treatment time of 5 hours at 50°C and the treatment containing osmotic solution of %55 sucrose and %5 sodium chloride and treatment time of 5 hours at 60°C, respectively. The results showed that among the three different osmotic solutions, the dried samples with solution 1 (sucrose-salt with %55-5) and solution 2 (sucrose-salt %50-10) had the highest amount of total sugar. The highest and the lowest amount of vitamin C were related to the dried samples with the osmotic solution 1 (sucrose-salt 55-5%) (8.75mg /100g) and the osmotic solution 3 (salt sucrose- 45-15%) (7.39 mg/100g), respectively. The results showed that vitamin C content was significantly (P<0.05) reduced in the higher temperatures and also during the much immersion times. Also, the highest amount of salt was in the dried samples with the osmotic solution 3 (sucrose-salt 45-15%). Therefore, among the different sensory characteristics, the osmotic dried apricot samples in the different treatments had no significant differences (P>0.05) except in the flavor.

Foaming is one of the most important functional properties of egg white proteins. In this study, the effect of transglutaminase-induced cross-linking of egg white proteins and contamination of egg white with yolk on the foaming properties of egg white, were investigated and polysorbate 20 was used accompanied with transglutaminase in order to compensate for the deteriorative effects of the yolk on foaming ability of egg white. Enzymatic treatment increased foam stability; the longer the treatment, the higher was the stability of foam. Optical microscopy images revealed that air bubbles coalesced much lesser in enzyme-treated egg white compared with non-treated counterpart. Nevertheless, enzymatic treatment decreased foam volume. It was argued based on apparent viscosity measurements that in enzyme-treated whites, air incorporation into the foam during white beating is decreased due to the higher consistency coefficient (K) resulting in lower foam volumes.A considerable decrease in foaming ability was observed when egg white was contaminated with yolk. Polysorbate 20 although increased the foam volume of yolk-contaminated egg white, influenced foam stability negatively. Simultaneous addition of surfactant and enzymatic treatment could compensate the weakening effect of polysorbate to some extent; however, caused a decrease in foam volume. Preferential adsorption of surfactant molecules into the air-water interface and/or evacuation of egg white proteins from the interface by surfactants might account for the observed effect of polysorbate.

In recent years, acid coagulation method of cheese production has spread in the Iran cheese industry; furthermore, low-fat products are the demand of a part of consumers due to health concerns. The cow milk was concentrated with milk protein concentrate (MPC) to produce of low-fat lactic cheese. Then, the effect of concentration (0, 25 and 50% increasing of solids) on the yield, chemical (fat, solids, protein, acidity, pH and salt), sensory (taste, color and texture) and textural (hardness, gumminess, chewiness, springiness and cohesiveness) characteristics of cheese was investigated. The results showed yield was increased significantly (p≤0.05) as a result of concentration with MPC. Increasing of the total solids of cheese milk resulted in fat reduction in cheese samples so 50% increasing of cheese milk solids leaded to decreasing of cheese fat content to below 10%. Increasing of cheese milk solids resulted in significant (p≤0.05) increase in solids, protein and salt of cheeses. On the other hand, instrumental texture analysis showed that MPC increasing resulted in increasing of hardness, cohesiveness, gumminess and chewiness of cheese samples. Finally, ripening with Lactobacillus paracasei in 30 days was applied to improve texture properties of the low-fat cheese. The results showed that hardness, gumminess and chewiness decreased due to ripening, as a result texture score of cheese increased.

Today, fish consumption, to provide nutrients and also maintain human health, is increasing worldwide. In this work, green back mullet fish was firstly divided into three groups: the first group was kept as raw sample and other two groups were cooked by two methods of frying and oven baking (with and without fennel extract) and then transferred to the freezer (-18°C), stored for 5 months. In defined intervals, the samples were defrosted using oven and microwave methods. In different processing methods, physiochemical characteristics and fatty acids profile of treated and raw fish were analyzed. The results revealed that oven-baked sample had the lowest moisture (51.97%) and highest protein (39.69%) over cooking. The fried sample due to oil absorption during frying had the highest fat content (8.6%). The most amounts of fatty acids in green back mullet were related to myristic, oleic and myristoleic acids. The omega-6 to omega-3 ratio in the oven baking did not differ with raw sample while this ratio in fried samples due to frying oil absorption increased. The content of EPA and DHA was reduced from 7.9 and 3.6% to 2.4 and 1.3%, respectively. Between reheating methods, there was no significant difference in fatty acids profile. In samples treated with fennel extract, the least changes in content of polyunsaturated fatty acids were observed during 5-month storage.

“Ready to eat” pomegranate arils in addition to unique sensory and nutritional properties, provides the possibility of increasing the pomegranate consumption. The pomegranate fruit is native to Iran, so it is important pay attention to the pomegranate processing industry. The present study investigated the effect of modified atmosphere packaging and vacuum packaging on some quality properties of pomegranate arils with response surface methodology. The extracted pomegranate arils packed with three gas concentrations of oxygen includes vacuum packaging (%0), modified atmosphere (%10) and normal atmosphere packaging (%21) and kept them in storage temperatures (4, 12 and 20oC (for 16 days. Measurement of total soluble solids, titratable acidity, total anthocyanin, antioxidant activity and microbial load was performed on samples in intervals of 4, 10 and 16 days after packaging. Antioxidant activity decreased with storage temperature and time increasing that had direct relation with anthocyanin decreasing during storage period. The highest of total anthocyanin content and soluble solids was in modified atmosphere packaging. Also, antioxidant activity by acidity increasing in normal atmosphere packaging (control) showed a significant increase. Microbial quality is an important parameter in determining the shelf life of foods. The lowest and highest of microbial load was, respectively, in vaccum and normal atmosphere packaging (control) that titratable acidity increasing and soluble solids decreasing was due to microbial activity increasing in normal atmosphere packaging. After final optimization, the best of gas oxygen concentration, storage temperature and time for maintaining of pomegranate arils was, respectively, %7, 5oC and 11days. At the optimal point, acidity, maximum total soluble solids, maximum antioxidant activity and total anthocyanin content, minimum total count and yeast-mold was determined 1.13 (gr/100ml), 17.6 (°Brix), %56.7, 224 (mgL-1), 2.98 Log cfu/g and 2.95 Log cfu/g respectively.

Using of natural antioxidants instead of synthetic compounds is a novel approach in food processing and preservation. The aim of this work was to compare the antioxidant activities of ethanol extracts of nettle (Urtica dioica L.) in stabilizing soybean oil in two forms of direct addition to oil and using of extract loaded starch based active film. At first, the phenolic composition and antioxidant capacity of nettle extract (NE) were measured. Afterward, protective effects of NE and active film in stabilizing soybean oil were compared to synthetic antioxidant (tert-butyl hydroquinone, TBHQ), by measuring their peroxide values, 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and oxidative stability index (OSI) during 60 days storage at 25oC. DPPH radical scavenging activity and OSI of oils enriched with 800 ppm of NE at day 60 had not significant difference with those of sample containing 100 ppm TBHQ. Results of these experiments in the oils contacted with active films revealed that the increasing of migrated antioxidant during storage time, caused to increase of antioxidant activity and OSI. Peroxide value (PV) of soybean oil increased by increasing storage time, but the both of direct addition and using of active film were able to control the increasing rate of PV in oil and in the long storage periods, the effect of active film was more than direct addition of NE. Nevertheless, NE exhibited negative effects on color properties of soybean oil and green color of oil was increased by increasing of loaded NE and also increasing of migration rate from active films. The results of this research indicated that the using of active film containing nettle extract is able to preserve the oxidative stability of soybean oil during storage.

In the present study the phytochemical component, antioxidant and antimicrobial effects of citron essential oil (EO) on shelf life of trout fish in refrigerator temperature was investigated. A number of muscle fish samples were classified in 4 treatment groups including control and 3 treatments with different concentration of Citron essential (0.5, 1.5 and 3%) and stored at 4oC. Microbiological assessment including total aerobic (TAC) and psychrophilic (TVC) bacteria and chemical parameter including peroxide value (PV), free fatty acid (FFA) and thiobarbituric acid (TA) analysis have been implemented. The GC/MS analysis showed that the major compound was limonene (33.6%), Benzodioxol (29.7%), phenol (8.1%), beta-bisabolene (4.4%), citral (4.3%) and zheraniol (2.15%). The chemical and bacterial index in EO treated samples had the minimum significant change under the storage period compared with control group. The TAC, TVC, FFA values and PV index in treatment groups containing 1 and 1.5% Citron EO have shown the minimum significant change and TA in 3% Citron EO (P<0.05). TA values in all treatments increased over time, However in 3% EO treatments was significantly (P<0.05) slower than other treatments.

Black tea is the most important beverage, which is consumed alone or with different additives. The present study tries to investigate the effect of different concentrations (0.5, 1, and 2 g) of some brewing additives (clove, cinnamon, coriander, saffron, and ginger) on the antioxidant activity of black tea. Total antioxidant capacity, total phenols, and flavonoid compounds were measured respectively, by FRAP, folin ciocalteu, and aluminum chloride colorimetric methods, for fresh tea extracts and with different additives. As the result of addition of different concentrations of these additives to black tea, maximum total antioxidant capacity (9067.36 mmol/L FRAP) was observed by adding 2 g of clove to tea and the maximum polyphenols compounds was gained by adding 0.5gr clove (1894.66 mg Galic acid/L) and 0.5 ginger (1844/66 mg/L) to black tea, respectively. In addition, the maximum total flavonoid compounds content was gained by adding 2 grams saffron (728.93 mg quercetin/L) and 0.5 grams clove (678.16mg/ L) to black tea, correspondingly. Tea is a proper source of natural antioxidants supply for body, on behalf of its phenolic and flavonoid compounds, and adding the additives used in this research resulted in an increase in antioxidant activities of black tea. Totally, the effect of adding clove on the antioxidant properties of black tea was more effective than other additives.