IRANIAN JOURNAL OF FOOD SCIENCE AND TECHNOLOGY
Year:2016 | Volume:13 | Issue:50|Papers Count:18

One of the most important enzymes in bakery industry is alpha-amylase. The commercial wheat varieties grown in Iran are generally low in amylase activity especially in alpha amylase. The cereal technologists have recommended the use of diastase enzyme for bread production. In this study 4 varieties of Iranian wheat (Falat, Gods, Gaskogen and Ghamran) with different amylase activity were selected and milled then malt flour used at 5 leveles (0, 1, 1.5, 2 and 2.5%). Specific volume, texture properties and sensory paramers of bread were evaluated. Data were subjected to statistical analysis with factorial design. Results showed that doses of malt flour addition must be determined and if it was used in extra dose not only has good effect on volume, texture properties and sensory of bread, but also destroyed them. Best treatments were: Falat with 2%, Gods with 2.5 %, Gaskogen with 2.5% and Chamran with 2.5 % malt flour.

Wheat bran is one of the most important dietary fibers that have physiological and therapeutic properties. Hence in recent years has been considered its for use in foods. In this investigation, has been studied effects of adding 5, 7, 10 and 12 percent of wheat bran on rheological properties of dough, mechanical proerties, tissue, sensory, porosity properties and color of barbary bread. The results of farinograph showed that adding of wheat bran increase water absorption and reduce dough strength. Also the results of mechanical test (penetration tests, cutting and texture profile analysis) and colorimetric showed that with increasing level of bran, bread become more rigid, its chewing ability and elasticity and L factor Decreases. As well as the results of the test Cutting shows that adding bran bread delayed the staling of bread. About investigation of tissue morphology bread that analyzed by ImageJ software, determined increasing level bran decrease porosity and increase pore size of bread. The overall in a lot of tests, not only didn’t cause satanically different, increasing level of bran to 7%, but also bread better than blank bread of sensory analyses due to delay in the staling process and production of appropriate aroma and taste in heating process.

The aim of this study was to investigate the influence of Tragacanth and Salep gums on the dough rheological properties and Barbari bread quality. Dough was prepared by straight method with gums in two levels (0.5, 1%). Farinograph and extensograph tests were carried out on dough samples. After baking bread and sensory evaluation, the bread samples were stored for 1-5 day in polyethylene bags in order to do staling tests. According to farinogaraph results, water absorption of samples containing gums was significantly higher than control. Dough development time increased significantly by 1% Tragacanth. There was significant difference in dough stability between control and samples containing Tragacanth. Extensograph results showed significant differences in energy changes, resistance to extension and extension ratio of samples containing Tragacanth and control. Data obtained from sensory evaluation showed, gums had no significant effect on quality characteristics of bread samples, however in case of taste and aroma salap containing breads presented lower score. Both hydrocolloids didn't have any effect on bread staling, however salep was more effective. Overall results reveal that Tragacanth may improve dough rheological characteristics.

This research was investigated effect of rosemary extract, as rich source of antioxidant compounds, on physicochemical properties and stability of butter from sour cream. Rosemary extract was added to butter from samples at concentrations, 0 (control), 0.05, 0.1, 0.3 and 0.5% and after vacuum packaging, samples were stored in refrigerator for 60 days. Acid and peroxide values, polyphenol content, hardness, oxidative stability, sensory characteristics of samples including flavor, textural and apparent characteristics of samples and DPPH radical scavenging assay of rosemary extract were evaluated. Results showed that samples which contained rosemary extract had higher acid value, higher oxidative stability and plyphenol content and peroxide value than control sample. During storage, acid value of all samples increased but extract enriched samples showed lower increase. Peroxide value and polyphenol content of samples were decreased during storage. DPPH radical scavenging assay proved that antioxidant activity of rosemary extract is lower than quercetin. Moreover, sensory characteristics evaluation showed that samples containing more than 0.5% rosemary extract in comparison with control sample had significant difference in extract flavor (P<0.05). The results showed that adding rosemary extract to the butter could devolve a new butter formula enriched with phenolic substances and higher stability and introduce a new product with high shelf-life to the market.

Annatto color is one of the oldest of natural carotenoids that have wide applications in food technology. Annatto color is the second natural color additives used in world industry, of economic. It is predicted that demand for it is increasing day by day. Color extraction from annatto seed is done by conventional methods, mainly. Little information is available about the use of new techniques such as response surface methodology of ultrasound technology in the extraction of annatto color. The subject of this study was to optimize the ultrasound-assistant extraction process of annatto color and determination of the best process conditions by using response surface methodology and central square design. The central composite design was used in order to evaluate the effect of extraction temperature (80-20OC), extraction time (10-2 min), seed to solvent ratio (5-20%) and duty cycle (0.2-0.8 s), on efficiency of dye extraction from annatto seed and to optimize the extraction process. ANOVA shows the seed to solvent ratio variable (X4) and it square effect (X42) have the greatest impact on dye extraction from the annatto seeds. In temperature of 72.7OC, extraction time of 7.25 min, the seed to solvent ratio of 14 percent and duty cycle of 0.8 s were found as the optimum conditions of the ultrasound-assistant extraction process in order to obtain the maximum efficiency of color under which the absorbance value and extraction efficiency was determined as 0.865 and 6.35 percent of annatto seed, respectively.

The main target of this research is drying raspberries in a Microwave assisted fluidized bed dryer. In order to evaluate and predict the quality properties of this fruit, Response Surface Methodology (RSM) was used. In this research, the effects of five variables: power of microwave (0, 300 and 600 W), temperature (55, 70 and 85 C), air flow rate (15, 20 and 25 m/s), starting time of microwave input (from the moment when the moisture content decreased until 334, 400 and 466 g water per 100 g dry matter) and amount of material (50, 100 and 150 g) on the rehydration capacity and loss of anthocyanins content were studied. Experiments were designed according to Central Composite Rotatable Design with these five factors each at three different levels, including central and axial points. With respect to the dependent variables, both linear and quadratic effects of all of the five independent variables on Rehydration Capacity and loss of anthocyanins content were found to be significant. For each response, second order polynomial models were developed using multiple linear regression analysis. Analysis of variance (ANOVA) was performed to check the adequacy and accuracy of the fitted models. According to our results, the optimal point for both characteristics were as follows: microwave power 600 W, temperature 74, the air flow rate 3.22 meters per second and 53 grams of the substance, starting from the moment the microwave 466 percent moisture content was reduced. Model to predict the dependent variables with empirical results obtained were very close.

In this study, the effects of some processing parameters on drying yield, moisture content, solubility and bulk density of spray dried cornelian cherry (Cournus mas L.) juice powders were investigated. A pilot-scale spray dryer was employed for the spray drying process and maltodextrin and gum Arabic were used as carrier agent. Experimental design involved the use of Box-behnken design and response surface statistical method. Independent variables were inlet air temperature (110, 140, and 170 C), concentration of drying aids (0, 7.5, and 15 %) and feed flow rate (6, 9, and 12 %). Results show that increasing in concentration of drying aids, increases drying yield and the solubility and reduces the moisture content and bulk density of powder; also increasing in inlet air temperature, increases drying yield and reduce solubility, moisture content and bulk density of powder. Optimization carried out using response surface methodology and optimum conditions were inlet air temperature of 140oC, maltodextrin concentration of 7% and feed flow rate of 9%.

By changing consumers’ tendency to use low-fat healthy food products, reducing oil content in fried foods by maintaining sensory quality is inevitable. In this study, ultrasound pretreatment at two frequencies of 20 and 40 kHz for 15 minutes as well as osmotic dehydration pretreatment using 2 and 4% salt solution concentration for 3 hours applied on the potato pieces and then deep-fat frying was performed at 150, 170 and 190oC for 60, 120, 180 and 240 seconds. The effect of the pretreatments on oil uptake and sensory characteristics were analyzed. To optimize and improve process equipment and frying conditions, oil uptake in potato pieces pretreated with ultrasound and osmotic dehydration was also investigated. Oil uptake in the fried potato pieces was significantly decreased (P<0.05) using osmotic dehydration pretreatment. The use of ultrasound together with osmotic dehydration, led to further reduction in oil uptake compared to the other samples. Proposed experimental models in this study fitted well with experimental data. In addition, osmotic dehydration and its combination with ultrasound pretreatment improved sensory characteristics of the fried potato slices.

Milk as a unique source of elements is important in bone formation and its growth. In addition, it contains valuable proteins, minerals and vitamins. Considering the nutritional importance of this food and its role in personal health, microbial quality status of pasteurized milk was studied. In this research, microbiological quality of 60 pasteurized milk samples collected from western part of Tehran was evaluated by enumeration of aerobic mesophilic microorganisms, coliforms and detection of Escherichia coli. According to Iran's National Standard limits, aerobic mesophilic microorganisms and coliforms counts must not exceed 7.5×104 CFU/ml and 10 MPN/ml in pasteurized milk, respectively. Besides, Escherichia coli must be absent. Eighty five percent of the samples had satisfactory qualities. Escherichia coli was not isolated from any sample. The aerobic mesophilic microorganisms and coliforms counts were not in accordance with Iran's National Standard limits in 5% and 10.3% of the studied samples. Aerobic mesophilic microorganisms and coliforms average counts were 1.8×104 CFU/ml and 1.1 MPN/ml in the studied samples, respectively. The results confirmed satisfactory microbial quality of studied pasteurized milk samples.

In this study investigated the use of modified atmosphere packaging (MAP) to extend the shelf life of two kinds of Iranian flat bread including Barbari and Sangak breads. Four treatments of atmospheres including 100% CO2, 70% CO2-30% N2, 30% CO2-70% N2, normal air and a coveraged samples as a control were used. The bread samples were packaged in pouches of polyamid / polyethilen (PA/PE). The shelf life was determined by appearance of molds and yeasts (M+Y) in bread samples stored at 25±1oC. Sensory analysis of bread achieved with scoring method by trained panels. The textural properties of the breads were determined by Instron and DSC apparatuses. Results showed that it is possible to prolong the shelf life of breads to about 17 days by using modified atmosphere packaging with high carbon dioxide concentration and high-barrier laminated. However, significant differences (P<0.05) were obtained in the firmness of control bread compared to another treatment. In addition, firmness rate of breads packaged in normal air during storage was more than that compared to the samples stored in MAP, but there were not significant differences between samples packaged under atmospheres 100% CO2, 70% CO2-30% N2 and 30% CO2-70% N2. Enthalpy changes had not a regular and documentary trend in breads during storage , when extent of staling and starch retrogradation measured by differential scanning calorimetry (DSC), so this method was not suitable for evaluation of extent of staling in Barbari and sangak breads.

The tendency to use natural preservatives for food security has spread. The objective of this study was to compare the antimicrobial properties of orange peel essential oils with potassium sorbate as a chemical preservative in cupcakes. In order to extract the essential oils from orange peel ultrasound was used at 70% and 90% at 3 and 5 minutes. The results showed that by increasing the time and intensity of sound for extraction of essential oils, efficiency of extraction was increased and extraction time decreased, and also by using essential oils significant changes on dough pH reduction, increasing specific volume and firmness of the final product were observed. However, the reduction of L* and b* values and increasing a* value were observed in this condition. It should be noted that the negative effect of potassium sorbate on the technological properties of cakes and reducing its quality was more than orange peel extract. Samples containing extracted orange oil by 70% ultrasound over 3 minutes, had significant results on technological characteristics and sensory properties especially texture and flavor. The results showed that microbial inhibitory of orange peel essential oils on the growth of mold and yeast was comparable with potassium sorbate. By increasing the time and intensity of sound antimicrobial effect of essential oils was increased.

Rehydration typically composes of three simultaneous processes: the imbibition of water into dried material, the swelling of the rehydrated products and the leaching of soluble solids to rehydration medium. In this research, squash (Cucurbita pepo) fruits were cut into 0.4 cm thick and 4 cm diameter slices. Then, squash slices were blanched in a steam chamber for 4 min. After cooling to room temperature, squash slices were dehydrated up to moisture content of 0.1065 kg H2O per kg d.m. Dehydrated samples were stored at 4°C. Squash slices with specified weight were rehydrated by immersion in distilled water at different temperatures (25, 50, and 75oC), various dry matter-water ratios (1:25, 1:50, and 1:100), which was agitated at 100 rpm. At specified time intervals, up to 300 min, the squash samples were removed from the water, and the weight, moisture content and rehydration indices of the sample were determined. The texture characteristics were examined over a 180 min period. The results showed that moisture content, water absorption capacity (WAC) and rehydration ability (RA) of squash slices increased, whereas dry matter holding capacity (DHC) and texture firmness (maximum force and stress) decreased with rehydration time. The maximum WAC was achieved in squash slices rehydrated into 75oC water at 1:100 dry matter-water ratio. The lowest force and stress were observed in squash slices which were rehydrated into 75oC water after 180 minute. These squash slices had the maximum moisture content and RA and the minimum DHC. The lowest moisture content and RA and the highest DHC, force and stress, were observed in squash slices immersed in water at 1:100 dry matter-water ratio. In general, for all rehydration conditions of squash slices, the highest water absorption rate occurred during the first minuts of process. Then, this rate decreased. The highest rehydration rate and amount of water absorption occurred in 75oC.

Whitecheek shark (Carcharhinus dussumieri) meat was washed two times by 0.1 M NaCl and then hydrolysed using Alcalase in 50oC for 120 minutes. The hydrolysate was dried by spray dryer. Functional properties includes, solubility, bulk density, oil-holding capacity, sorption isotherm, kinematic viscosity and antioxidant activities such as DPPH radical-scavenging activity and the oxidative stability of soybean oil with protein hydrolysate were investigated. Kinematic viscosity and DPPH radical-scavenging activity were measure in different concentration of protein hydrolysates. The results showed that protein hydrolysate of whitecheeck shark has high solubility (>83.6%) at different pH. Bulk density, oil-holding capacity were 113.46 (mg/l), 131.15 (mg/50mg of sample), respectively. The more the protein concentration, the more the kinematic viscosity (P<0.05). The values of DPPH and Induction period were 96.47% and 2.38 hours, respectively. Results showed that whitecheeck shark protein hydrolysate has desirable functional properties and antioxidant activity that could be use as natural antioxidant in food and pharmaceutical industries.

Nowadays the edible mushroom has got a great consideration as a high protein and low calorie food source and also its medicinal consumption. As the production of edible mushrooms increases, it is necessary to notice on its storability, waste decreasing and usage of dried mushrooms. For this reason drying of this crop as a practical way has been considered. Nowadays advantages of artificial neural network are noticeable for simulation and prediction of necessary parameters in drying processes. The objective of this study is moisture content prediction of edible mushroom with arithmetic neural network during drying process. In this study the thin layers of edible mushroom were dried by hot air dryer in three temperature levels: 40, 50, 60oC and three air flow speed levels: 0.5, 0.7, 1 m/s until the moisture content reached to 10% (d.b.). Regression models and feed forward neural network with Levenberg-Marquardt learning algorithms were used to estimate and predict the moisture content of mushroom thin layers. The results showed that the quadratic degree regression model with determination coefficient of 97.0 and the error sum of the squares of 0.071 and also the neural network with 3-20-18-1 structure with sigmoid threshold and logarithmic function in comparison with other topologies had better results to predict the moisture content of mushroom thin layer during drying.

White bread is a staple food in the human diet in many countries, including Iran; but it is a poor source of prebiotic dietary fiber, containing typically less than 2.5% fiber content. So a demand exists for enrichment bread with prebiotic ingredients that exert a health and quality-promoting effect. In this study, effect of different amount of b-glucan (0.8%, 1% and 1.2% w/w) and resistant starch (5.5%, 8% and 10.5%) and one sample with 4%BG and 0.5% RS on the dough rheological properties has been investigated. The results revealed that the rheological behavior of enriched doughs depend on kind of prebiotic substance, and its concentration. The farinograph water absorption of doughs increased with increasing BG and RS amounts. The development time and farinograph quality number of b-glucan-enriched doughs remained similar to the control while the stability of dough decreased and also all of these values decreased when the RS was added to the dough formula. BG was more effective in increasing dough softening than RS. The addition of RS or BG to the dough formula increased; the resistance to deformation, energy, but their extensibility values had decreased compared to the control. Formulation containing BG/ RS combination showed the best farinograph (development time, stability) and extansograph (resistance and extensibility) parameters.

With the aim of using plant essential oils (EOs) as natural antibacterial in the bioactive zein film, the chemical composition of Zataria multiflora Boiss. was analyzed by GC-MS. Minimum inhibitory concentration and minimum bactericidal concentration of Zataria multiflora EOs were evaluated against for Listeria monocytogenes and Escherchia coli by using the method of micro-well dilution and head space phase. Zein based films containing 5 and 10% of Zataria multiflora Boiss. (ZEO) were developed. The antimicrobial activity of the films was investigated in a vapor phase and liquid media. Carvacrol and thymol were detected as the major components. MIC and MBC were obtained from above components against for Listeria monocytogenes (500 mg/l and 1000 respectively) compared to Escherchia coli were more effective. Listeria monocytogenes was more sensitive to ZEO on vapors phase. A highest inhibition zone was observed against for Listeria monocytogenes by incorporating 10% (v/v) ZEO in the vapor phase. zein film containing 5% ZEO had no inhibitory ability on bacteria in addition to in concentration of 10% just reduced the density of bacteria, Log reduction value of bioactive film of zein against Listeria monocytogenes and Escherchia coli were increased the direct-contact. These results revealed that ZEO as natural food additive has good potential to be incorporated into zein to make antimicrobial for food applications.