IRANIAN JOURNAL OF FOOD SCIENCE AND TECHNOLOGY
Year:2017 | Volume:14 | Issue:62|Papers Count:20

The aim of this study was to investigate the effect of ultrasound and drying pretreatments on apparent density as well as modeling apparent density during deep-fat frying of potato slices. Ultrasound pretreatment was performed at 28 and 40 kHz for 15 min and drying pretreatment were conducted at 80oC for 8 and 15 min. Then, the frying process was done at 150, 170 and 190oC for 60, 120, 180 and 240 seconds. In order to model apparent density, experimental data were fitted with six empirical models proposed in this study. The results showed that apparent density of various samples decreased during deep-fat frying. In samples pretreated with ultrasound (28 and 40 kHz), the process time for 180 or 240 s, significantly reduced the apparent density compared to control samples. However, in samples pretreated with pre-drying (8 and 15 min), the decrease in apparent density was not statistically significant in comparison with control samples for the same process time. Furthermore, by increasing the temperature from 150 to 190oC, the reduction in apparent density increased. In addition, applied models were well fitted to experimental data with high R2 and low RMSE. Also, through multiple regression analysis, models with high R2 were proposed that are applicable to the different conditions in terms of time and temperature of the deep-fat frying process.

Sour orange juice has found application in various foods as alternative of lime juice, due to its desirable taste. Different thermal processes could be performed to improve safety and shelf life of this product. In this study, the sour orange juice was processed at four microwave power levels (170, 340, 510 & 680 W) in a various periods of time to reach the product temperature to 72oC. The aim of this study was to investigate the effect of heating processes on the some physicochemical properties of sour orange juice during come up time. Based on the results, different power levels of microwave have no significant effects on viscosity. The thermal destruction of Ascorbic acid and Pectin methyl esterase were found to follow first order kinetics. Destruction rate of these two compounds were also increased by increasing microwave power. Because of the effect of microwave power on chemicals especially ascorbic acid, the colorimetric parameters of the product changed as a result of changing in microwave power. By considering the high regression (R2>0.97) between two measuring methods (spectroscopy and image processing), the image processing method is suggested as browning index during thermal processing.

Skin, bones, frames, heads and tails are by-products produced during the processing of fish and prawn. These by-products can be enzymatically hydrolyzed and be converted products with beneficial functional properties. So, Protein hydrolysates were prepared from green tiger prawn (Penaeus semisulcatus) waste using flavourzyme and response surface methodology (RSM) based on 18 treatments was applied to study the effect of enzyme to substrate ratio, temperature and time on the protein. The antioxidant activities were measured using 2,2-diphenyl-1-picryl-hydrazyl (DPPH), hydroxyl radical-scavenging activity and ferric reducing antioxidant power. Totally, products have showen better response in 2,2-diphenyl-1-picryl-hydrazyl (DPPH) scavenging activity in comparison to hydroxyl radical-scavenging activity and Ferric (Fe3+) reducing antioxidant activity. Among the treatments produced, 7 treatment (hydrolysis temperature of 54.6oC together with enzyme to substrate ratio of 1.61% and hydrolysis time of 105.8 min) with degree of hydrolysis (33.5%) and protein (79.5%) were the optimum conditions to obtain the highest antioxidant properties. These results suggested that prawn waste protein hydrolysates could be useful in the food industry.

The effect of addition of a commercial enzyme derived from Bacillus Polymyxa type IX on Iranian UF-Feta cheese during a 60- day ripening period on chemical composition, pH and proteolysis of cheese samples was investigated. No Significant differences were observed in the chemical composition between experimental and control cheeses. In experimental cheese, pH values were significantly (P<0.05) higher throughout whole ripening period and at 60d it was 4.6 and 4.77 in control and experimental cheeses, respectively. Soluble nitrogen in pH=4.6 was significantly (P<0.05) higher in experimental cheese at 45 and 60d. At 60d, this index was 6.38 and 7.73% in the control and experimental treatments, respectively. Significant difference in the level of trichloroacetic acid (TCA) 12% was also observed at 45 and 60d. Urea- polyacrylamide gel electrophoresis of the pH 4.6-insoluble fractions showed that as1-casein was hydrolysed faster than the b-casein. Intact as1- casein values from 100% on the first day reached to 82.93% and 71.24% and in b- casein reached to 90.28 and 90.56% at 60d in control and experimental cheeses, respectively. The concentration of total free amino acids in whole ripening period was significantly (P<0.05) higher in experimental cheese and at the end of the ripening period was 0.68 versus 0.54 in control cheese (mg Glycine/g cheese). Levels of individual free amino acids were also different between treatments.

In this study, Response Surface Methodology (RSM) was used for optimization of the conditions for hot air drying of pear slices with osmosis pretreatment. The effects of two parameters including drying temperature (50-70oC) and drying time (240-360 minutes) as independent variables on moisture content, shrinkage percentage and rehydration ratio of pear slices as dependent variables (responses) were evaluated. The regression models for all responses were statistically significant at the 99% confidence level and lack of fit was not significant. All process variables had linear effect on all the responses (p<0.01). Also the quadratic term of drying temperature on rehydration ratio was significant. The optimum conditions obtained for minimum moisture content and shrinkage percentage and maximum rehydration ratio were: 39.60oC as drying temperature and the drying time of 360 minutes. In optimized condition, the moisture content, rehydration ratio and shrinkage percentage of dried pear slices were 26.17%, 1.62 and 77.31 respectively.

The sourdough is a paste that is made up of water and flour and yeasts and lactic acid bacteria are its key microorganisms. Sourdough fermentation process is based on lactic and alcoholic fermentation that is done by lactic acid bacteria and yeasts respectively. Also these microorganisms play an important role in improving the flavor, texture and shelf life of bakery products. In this research, samples of sourdough were collected from different regions of Iran to verify the yeast flora, were studied. To achieve this aim the yeasts isolated by the colony morphology method and then had reproduced 26S rRNA gene whit general primers for identification exactly. The sections that replicated sent to bioscience company UK for Sequencing. Then compare the resulting sequence whit sequences in the gene bank (NCBI), the yeast species studied were identified. The results showed that the yeasts isolated included Saccharomyces cerevisiae, Saccharomyces exiguous, Issatchenkiaorientalis, Torulasporafranciscae, Torulasporadelbrueckii, Pichiafermentans that dominantspecies related to Saccharomyces cerevisiae and Saccharomyces exiguous.

Roasting is the common shape of pistachio nuts processing and the purpose of this process is to increase the total acceptability of products. The aim of this study was the effects of hot air roasting temperatures (90, 120 and 150oC), times (20, 35 and 50 min) and air velocities (0.5, 1.5 and 2.5 m/s) on textural attributes (fracture force, hardness, apparent modulus of elasticity and compression energy) and stress relaxation behavior of pistachio kernels. Increasing the temperature of roasting decreased the fracture force (from 71.95 N to 43.10 N), hardness (from 78.15 N to 47.22 N) and compression energy (from 235.61 J to 130.80 J) of pistachio kernels (P<0.01). To increase the time and air velocity of roasting didn't show significant effects on fracture force, hardness and compression energy (P>0.05). Increasing the temperature, time and air velocity of roasting decreased the apparent modulus of elasticity (P<0.01). The triple interactions between three factors (temperature, time and air velocity of roasting) showed significant effects on fracture force (P<0.01). The regression equation showed that the linear effect of air velocity on fracture force is higher than other parameters. Fracture force, hardness, apparent modulus of elasticity and compression energy were at the range 25.54-82 N, 37.59-82.76 N, 101.18-280.73 J and 21.22-47 N/m, respectively. The results of stress relaxation test showed the roasted pistachio kernels have solid-viscoelastic behavior.

Dahi is a traditional Indian fermented milk product that is similar to plain yogurt in appearance and consistency. As compared to yogurt, dahi has lower acidity, consequently it seems to be more effective in production of probiotic or synbiotic foods. The aim of this study was optimization of the production process and evaluation of physicochemical and microbial properties of synbiotic dahi by response surface methodology (RSM) based on Box Benken Design. Inulin (0-2.5%), tragacanth gum (0-0.06%) and storage time (1-19 days) were the factors that their impacts on the dependent variables were evaluated. In order to optimize variables, three traits including firmness, syneresis and viability of probiotic Lactobacillus acidophilus (LA5) were considered as responses. Finally, the appropriate power and fit of model were indicated based on determination coefficient (R2), adjusted determination coefficient and coefficient of variation (CV). The determination coefficient (R2) for firmness, syneresis and microbial counting in synbiotic dahi was obtained 0.99, 0.91, and 0.98, respectively. The increase in the concentration of inulin and storage time led to improve of syneresis and firmness of the products. Also, the increase in concentration of tragacanth up to 0.03% increased firmness, while afterward up to 0.06% concentration caused negative effect and reduced firmness. The increase in concentration of tragacanth and inulin had positive effect on probiotic counting of the products, while storage time had deleterious effect on it. According to the results of optimization experiments, optimal conditions were 2.5% concentration of inulin with 0.03% concentration of tragacanth gum in 18-day holding period.

Nowadays, regarding to human need to functional and probiotic foods and the extend use of these foods, considerable attention is donated to production and development of probiotic products which eventually can play an important role in improvement of society health. Additionally, investigations have identified the chocolate as a proper carrier for probiotics. In the present study, probiotic chocolate containing Lactobacillus casei was manufactured and then some of physicochemical parameters including pH and water activity (aw) together with survival assessment of Lactobacilluscasei in chocolate were investigated. Addition of Lactobacillus casei to chocolate haven’t had any adverse and significant effects on physicochemical parameters such as pH and water activity during 6-month storage time at ambient and refrigerated temperatures (P>0.05). According to obtained results, the amount of water activity in probiotic chocolate was higher than control chocolate (P<0.05). Moreover, the survival of Lactobacillus casei in probiotic chocolate didn’t changed significantly during 6 months storage at two different temperatures of 4 and 22oC (P>0.05).The obtained results declared that the enriched chocolate with Lactobacillus casei can be stored at ambient temperature without having any unfavorable changes in its physicochemical properties such as pH and water activity. Also, even with slight decrease in population of probiotic bacteria of Lactobacillus casei during the 6-month storage time at temperatures of 4 and 22oC, but the final product which included 108 CFU/g probiotic cells can be considered as a functional probiotic foodstuff.

Today the nutritional value of the meals, including snacks has increased because of consumer demand for healthy food. So the aim of this study was to examine the effect of adding stabilized wheat germ on levels of 0, 3, 6, 9, 12 and 15% (based on flour weight) on the quantity and quality of the unextruded snacks. In order to measure the color values the image processing technique and Image J software was used. Results clearly showed that addition of wheat germ reduced the moisture content and L* value examples of samples. While the hardness, a* and b* values, and vitamin E of the final product increased by adding wheat germ. In addition evaluation of taste, tenderness, color and texture of the samples showed, the sample containing 9% wheat germ had the highest score of overall acceptability. Finally it can be concluded that processed wheat germ with saturated steam up to 9% increased the nutritional value, and could also maintain technological and sensory characteristics of snacks to offer to the market as a healthy product.

Identify and cultivate new oil seeds is an important step in the supply of required oil in our country. The aim of the present research was to evaluate the composition of physicochemical properties, fatty acids structure and the oxidative stability of Dill (DS) and Coriander (CS) seed oils. To produce oil, the seeds were mixed with n-hexane solvent in the ratio of 1:4 w/v. The physicochemical properties of DS and CS oils includeding acid value, peroxide value, iodine value, refractive index, wax compound content, viscosity, specific gravity, oxidative stability and fatty acids structure were examined. According to the results, the acid value (11.56 mg/g), iodine value (104 g/100g of oil), wax compound content (34.25%) and specific gravity (0.92 kg/m3) of DS oil was higher than CS oil. Also peroxide value (3.07 meq/kg), viscosity (20.94 cp), refractive index (1.55) and oxidative stability (16.3 h) of CS oil was higher than DS oil. DS oil contained 8.51% of saturated fatty acids that mainly composed of palmitic acid and stearic acid which is lower than CS oil (8.83%). DS oil contained 91.35% unsaturated fatty acids. The ratios of polyunsaturated fatty acids to mono-unsaturated fatty acids of DS and CS oils were 0.23 for both oils. Also the ratio of polyunsaturated fatty acids to saturated fatty acids of DS and CS oils were 2.07 and 1.94, respectively.

Mung bean (vigna radiata) is an annual crop belonging to Fabaceae family. Germination process is a conventional and inexpensive way to improve nutritional value of legumes. Mung bean sprout is one of the popular products. It is rich in protein (20-33%) and is excellent sources of essential fatty acids, tocopherols, esterols, sugars and organic acids. In this study, the change of chemical composition, antioxidant activity, total phenolic compounds, minerals, ascorbic acid and organic acids content were determined in raw, soaked and germinated mung bean. Also, the profile of fatty acids was recognized. The results showed an increase in moisture, protein and ash and a reduction in fat and carbohydrate due to the energy consumption during 4-day germination, significantly. Total phenolic content and antioxidant activity indicated 2.5 and 1.5 fold increase in mung bean sprout compared to raw seed. Ascorbic acid content varied from 8.9% to 19.6% and organic acids increased significantly during germination process. Analysis of fatty acids composition showed that mung bean sprout contained 17% and 36% linolenic and linoleic acids, respectively and so, this product can be introduced as an excellent source of omega-3. The results of this work revealed the high nutritional value and consumption importance of mung bean sprouts.

Frying technology is one of the oldest of food preparing that it used in household and industrial scale, widely. Due to the increasing tendency of consumers to use low-fat products, efforts to reduce oil uptake in fried products has been done. Eggplant absorbs high amount of oil during frying because of high amount moisture and porous texture. In this study effect of different frying times (90, 120, 150 and 180 seconds) and cooking times (1, 4, 7 and 10 minutes) on mass transfer kinetic (oil and moisture) eggplant samples during deep fat drying and cooling period was investigated. Results of analysis variance (ANOVA) showed that independent variables on oil and moisture content was significant (p<0.05). Results of this study showed that cooking pretreatment (hot water and atmospheric pressure) 60%, decreased oil content in comparison with which did not any pretreatment (control). In mention that cooking time 7 minutes had higher than effect on oil content decreasing (72%). To investigate the kinetic relationships, eggplant samples for 1, 3, 5, 8, 10, 12, 15, 30, 60, 75, 90, 120 and 150 seconds were fried and after each stage of oil and moisture were measured. In addition, at the end of each of these times, were immediately removed from the oil in order to measure the surface oil, immersed in ether, and the amount of oil absorbed (structural) and surface oil samples were measured. Results of mass transfer kinetic during deep fat frying at 180oC, showed that oil content fried eggplant had maximum value on the first time of deep fat frying process and then decreased. Also fried eggplant moisture content decreased, quickly and then velocity of reducing the moisture content of the samples, also declined.

Essential fatty acids (omega3/6) which are precursors of prostaglandins and leukotrienes and play an important rules in treatment of diseases. These fatty acids cannot be synthesized by human and should be obtained by nutritional dietary. Gamma linolenic acid (GLA) is one of the omega 6 fatty acids that is useful in cardiovascular and cancer diseases. Fungi especially zygomycetes are known as the best lipid producers containing essential fatty acids. The purpose of this research was using of several oil wastes as the renewable and cheap substrates to production of essential fatty acids by zygomycete fungi Mucor rouxii DSM1194.Five oil wastes were studied and the production of lipids, biomass, essential fatty acids like GLA, linoleate (omega6) and alpha linolenate (omega3) were determined.Since production of GLA was considerable, it was optimized by hierarchical experimental design, including a half fraction factorial and then design following by the response surface method (RSM). Yeast extract, ammonium sulphate and carbon source (oil wastes) were the significant factors on optimization of GLA production. Results showed after 72h growth of fungi in 28oC on R1 oil waste (obtained from restaurant), 56.4 mg/l GLA were produced which increased to 82.23 mg/l after optimization. The interaction of carbon and nitrogen sources was significant while yeast extract and ammonium sulphate didn’t have any interaction effects.

Pistachio has been considered as an ancient valuable nut, and is famous as the king of nuts. The nutritional value, taste, digestibility, high level of calories, vitamins and minerals are among characteristics which make pistachio superior to other nuts. Over the last five years, more than 50 percent of the pistachio all over the world, with the annual average of 120,000 tons, has had its source in Iran, with an estimated waste of 30,000 tons. This research used pistachio paste, date powder, milk powder, vanilla, and monoglyceride in different portions as the ingredients of chocolate breakfast. Following chocolate breakfast preparation, it was properly-packed. Rheological properties of the samples were evaluated. In this regard, the viscosity parameters, activation energy values, flow behavior index and consistency factor were measured in different treatments and appropriate statistical software was used for the statistical analysis. The results showed that chocolate breakfast is made of a pasty mixture the flow of which is dependent on the time and temperature; it has thixotropic property and its apparent viscosity decreases along with the increase in cutting time.

Charkhak (Launaea acanthodes) is one of the most common species of medical herbs in central Iran. In this study, the gum was extracted by alcoholic extraction method with 90% ethanol that the yield percentage was 40.4%. Then, emulsifying properties of the extracted gum were investigated. To do so, soybean oil emulsions (10% w/w) were prepared using 1, 2, 4, and 6% gum. Following tests were done for all emulsions: surface and interfacial tension, stability testing, particle size distribution, observing by light microscope and viscosity of the emulsion. Altogether, it was illustrated that polysaccharide efficiency of Launaea acanthodes gum is higher than other national gums in Iran. According to the results, increasing the gum concentration in emulsion led to decrease in surface and interfacial tension but an increase in viscosity. The particle size distribution reduced with increasing the concentration of gum in emulsion. Moreover, the gum had good overall stability in the past two months.

The present research work was aimed to evaluate the effects of whey protein concentrate (WPC) at different levels of 0, 2, and 4%, as a protein based fat replacer, soy protein isolate (SPI) (0, 1, and 2%) and microbial transglutaminase (MTG) (0, 1, and 2%) on some physical properties of a low fat vanilla ice cream (4% fat). Electrophoresis pattern of ice cream proteins and effect of MTG on proteins were analyzed by SDS-PAGE. Total solids of all formulations was adjusted on 34%. Results showed that application of WPC in formulation of low fat ice cream significantly increased hardness and melting values, while SPI significantly (P<0.01) increased hardness and reduced melting value. MTG decreased hardness and melting of ice cream samples compared to the control (P<0.01). Results showed that application of MTG in low fat ice cream was more useful than the utilization of SPI and WPC in terms of hardness and melting properties.