فصلنامه پژوهش های صنایع غذایی
سال بیست و پنجم شماره 3 (پاییز 1394)

In this research، effect of yeast types on aflatoxin B1 content during bread making process was studied. For this purpose، the dry aflatoxin was added to flour and then bread was prepared. For dough preparation three yeast types in market (active dry yeast، instant dry yeast and compressed yeast) were used. Presence of aflatoxin in flour، dough، and bread was measured by High Performance Liquid Chromatography with fluorescence detector size. Aflatoxin content in the dough، in two steps; first and final proof was measured. The results showed that most of aflatoxin reduction was seen at the first proof. Moreover، Instant dry yeast had the greatest impact on the aflatoxin B1 and the least effect was seen for compressed/wet yeast. In relation to bread making processes، the fermentation process has the most impact and the combined effect of fermentation and baking on aflatoxin B1 destruction has not been significant.

Drying of foods is one of the most important preserving methods due to reduction of microorganism’s activities which lead to longer shelf life. Shrinkage during drying plays an important role in determining the quality of the dried product. In this paper، a method based on computer vision was used to analyze the effect of Osmotic dehydration on shrinkage of potato slices dried with hot air. The effect of osmotic dehydration in different concentrations (5 and 10% w/w) of salt solutions، temperatures (30، 40، 50 and 60 0C) and different time (30، 60 and 90 min) on parameters related to shape of samples was studied. Potato slices were dried at temperatures of 60، 70، 80 0C and air velocities of 1. 0 m/s. Changes in area، perimeter، major and minor diameters and elongation of the slice were measured continuously during drying. Results showed Shrinkage and elongation of samples increase with decreasing of temperature، time and concentration of osmotic solution. Also، Elongation increased with decreasing of moisture content ratio.

Apple pomace is a byproduct of apple processing plants which can be used as a good source for bioactive materials like phenolic compounds. In this research the 2 sub verities of Rhizopus oligosporus was used for production of Antioxidative bioactive compounds from Whey Proteine Concentrate (WPC) and apple pomace. Total Phenolic compounds، free radical scavenging ability by DPPH، Antioxidative Protection Factor (APF) and total count of molds were evaluated in 48 determined treatments. Effect of Incubation temperature in three levels 23،27،31°C، incubation time at 3،8،13 days، and Apple pomace/WPC ratio at three levels of 50:50، 70:30، 90:10 were studied. The polyphenol content، precent of DPPH inhibitation، APF and count of fungi of the extracts was found to be in the range of 6. 01-11. 12 mg GAE/g Dry Matter، 65. 8%-95. 2%، 1. 18-1. 55 and 2. 2*10^8-3. 13*10^10 of samples respectively، depending on the ratio of Apple/WPC، time of incubation، type of fungi and temperature. The highest efficiency obtained was related to Rhizopus oligosporus PTCC NO. 5287 and the results showed that the time of incubation had the most effect on measured parameters.

Molds have the ability to produce different pigments with consumption as food color. This study aimed to investigate the effect of the factors affecting the production of pigment by the Penicillium aculeatum. In this study، the combined effect of pH (5، 6. 5 and 8)، temperatures (25، 30 and35) and agitation speed levels (100 and 150 rpm) on pigment production and mycelial growth of Penicillium aculeatum was investigated in submerged whey media. After ten days of incubation، the produced pigment was isolated and purified using filtration، centrifugation and ethyl acetate solvent. All experi-ments were conducted in a completely randomized factorial design with three replications. The data were compared using the mean Tukey’s test and data analysis was performed using the statistical soft-ware JUMP V 8. 0. 1. The best production of pigment (1. 38 g/L) was obtained with pH value of 6. 5، temperature of 30 ˚C and agitation speed of 150 rpm. In contrast، the maximal biomass concentration (11. 12 g/L) was obtained at pH value of 8، temperature of 30˚C and agitation speed of 100rpm. These results demonstrated that biomass and pigment production were not directly associated. This study showed that the effect of pH and temperature on pigment production are significant (p<0. 05) but agita-tion speed not significant (p≥0. 05). pH has no significant effect of growth (p≥0. 05)، In contrast، tem-perature and agitation speed have a significant effect on the growth (p<0. 05).

Evaluation of physical and chemical properties of fruit can help to optimal design and operation of processing، and safe and secure handling. In this study، the textural، physical and chemical characteristics of sweet cherry (cv. Syaahe Mashhad) in the period of ripening were investigated. Changes in the amount of soluble solid، stemming force، firmness، hardness، cohesiveness، resilience،gumminess، chewiness and color indices i. e. lightness (L*)، a*، the total color difference (ΔE)، a*/b*، Chroma (C)، hue angle were measured. Simultaneously with increasing °Brix، magnitude of true density increased from 0. 995±1. 13 g/cm3 (for fruits with green color) to 1. 032±0. 33 g/cm3 (for red color fruits). During ripening period، the force required to stemming، firmness and hardness values decreased with a positive significant correlation (confidence level of 0. 95). Changes in the stemming force، firmness and hardness were obtained by 4. 89±1. 92 N، 1. 3± 0. 54 N/mm، 3. 8± 1. 18 N، respectively، from first harvest date (47th day after anthesis(to last harvest date (68th day after anthesis(. Variations in cohesiveness and resilience were relatively insignificant، but gumminess and chewiness decreased. Results showed that during the final days of fruit development، L* and Hue angle parameters decreased، but total color differences) ΔE(and a*/b* increased.

Samanu is a traditional Iranian dessert with high nutritional value that using it as substitute of high-calorie and high-consumption foods such as breakfast chocolates and other fat spreads is important. Hence، in order to evaluate of low-fat samanu spread formulation total oil (10-30%)، vegetable oil to butter ratio (50:50-80:20%) and stabilizer content (0. 1-0. 5%) parameters were used. Effect of each parameter was studied on physicochemical properties of the spread namely moisture، pH، acidity، emulsion stability and color difference using by response surface methodology and factorial during storage at 4 ͦϹ for 14 days. Moisture، pH، emulsion stability and color difference of the spread were significantly decreased during storage however، the acidity was decreased. Carrageenan increasing in the spread formulation revealed that the sample contained more carrgeenan has less moisture and acidity but much pH، emulsion stability and color difference. As well as increasing butter compared to vegetable oil increased the all studied properties.

Milk as a strategic commodity was directly related to public health and food security of the country. The annual per capita consumption of milk in Iran in 1388 from 61. 7 kg decreased to 38. 73 in 1391. The main objective of this study was investigation of effect of consumer characteristics on consumer preferences for milk in Tabriz. The research population is Tabriz households. The data were collected through questionnaires completed by 158 heads of households in Tabriz. To achieve the objective of research multinomial logit model is used. The calculated results of marginal effect of each variables show that، age of household head، household size، monthly household income، child less than 6 years of age in household، health of the unpacked milk and indirect use of milk variables have positive effect and importance of shelf-life of milk variable has negative effect on the probability of choosing of unpacked milk. Age of household head، importance of shelf-life of milk and indirect use of milk variables have positive effect and household size، monthly household income، child less than 6 years of age in household، health of the unpacked milk variables have negative effect on the probability of choosing of pasteurized milk. Also، household size، monthly household income، health of the unpacked milk and importance of shelf-life of milk variables have positive effect and age of household head، child less than 6 years of age in household and indirect use of milk variables have negative effect on the probability of choosing of sterilized milk.

Polyphenols by antioxidant properties in tea are responsible for the health. One of the major alkaloids witch found in tea leaves is caffeine. The purpose of this study was to compare the total polyphenols and caffeine contents in the varieties of green and black tea and instant types of them، which provided from tea garden of Lahijan from north of Iran. Caffeine contents of tea samples were extracted with chloroform as a solvent. Results showed that the average amount of total polyphenols within the range of 4. 8027 to 21. 6510 (g/100g dm)، decrease in green tea، instant black tea and black tea، respectively and comparison of the results showed that although there are differences between the obtained values، but the difference of the total amount of polyphenols in green tea and instant black tea is not significant (p<0/05). According to the results the average amount of caffeine decrease in the instant black tea، instant green tea، black tea and green tea، respectively and the difference of the amount of caffeine (2. 2026 to 5. 3232 g/100g dm)، in samples is significant (P<0/05).

Acceleration of cheese ripening is interesting for researchers in the field of food technology. The purpose of this study was encapsulation of Flavourzyme in liposome by heating method and evaluation of its kinetic properties before and after encapsulation. The impact of temperature (12-62°C) and pH (7-9) was investigated on enzyme activity by central composite with 13 treatments. Liposome was prepared by modification of heating method and by phosphatidil choline، Flavourzyme and cholestrol in the amount of 4. 500، 0. 675 and 0. 225 (%w/w)، respectively. Enzyme activity was measured base on enzyme reaction with initial material of L-Leucin P nitroanilid. Kinetic studies indicated an increase in both Michaelis–Menten constant and maximum velocity in encapsulated Flavourzyme (P<0. 05). Optimum incubation temperature and pH of encapsulated enzyme did not show any significant difference in compare to free enzyme. Evaluation of the thermal stability (at 35، 45 and 55°C) showed that encapsulated enzyme was stable at 35°C during 6 h. Also a decrease of stability of encapsulated enzyme has been observed at 65 and 75°C in 1 h. The results showed increased stability of encapsulated enzymes in pH 7 and 8 (7 h)، while it was decreased in acidic condition. The results showed that liposomal encapsulation by heating method did not cause any significant difference on kinetic characteristics of enzyme Flavourzyme but comparison of proteolysis in sample and control indicated gradually proteolysis of casein in the case of liposomal enzyme application. So، it can be concluded that preparation of liposome by heating method is a suitable approach for encapsulation of protease for acceleration of cheese ripening.

Conjugated linoleic acid (CLA) is a type of nutraceuticals which can be used in functional food development however، it is sensitive to oxidation. Nanostructured lipid carriers (NLC) were used for the encapsulation of conjugated linoleic acid by hot homogenization method. Among four different solid lipids used in the production of this system (precirol ATO-5، Compritol ATO-888، Cacao butter and lauric acid) only precirol was able to produce acceptable particle size and structure. On the next step، on the basis of response surface method and central composite design، various concentrations of precirol and aqueous phase surfactant (poloxamer) and different ratios of liquid to solid lipid (conjugated linoleic acid to precirol) were used to find the optimum sample of CLA bearing NLC. The particle size and particle size distribution (Span) were in the range of 75-2040 nanometer and 0. 44-5. 16، respectively and it was observed that by increasing the concentrations of solid lipid and aqueous phase surfactant، the particle size increased considerably. Also، increment in liquid to solid lipid ratio enhanced particle size stability. The NLC formulation containing 2% (w/v) surfactant، 2% (w/v) precirol solid lipid and 50% of CLA to solid lipid ratio was chosen as optimum sample by 93 nm particle size and was stable at 4˚C during 45 days of preservation.

In this research، effects of different concentrations of carbon dioxide (to reach pHs 10. 5، 10. 2، 9. 9، 9. 6، 9. 3، 9، 8. 7، 8. 4 and 8. 1) and different temperatures (90، 95 and 100℃) on quality characteristics of the first carbonation juice were studied. For this purpose، stability of formed calcium carbonate crystals during the process of the first carbonation juice were evaluated by measuring effective alkalinity، total hardness، color، purity and conductivity total ash of the second carbonation juice. The appropriate effective alkalinity (1. 2 g CaO/100 mL) and lowest total hardness (30 gCaO/100 mL at 100 ℃) obtained at pH 9. 3 and 9 for the second carbonation، respectively. It was also observed that the color value of 2th carbonation juice decreased by reduction of pH and the lowest color value (1121. 15 IU at 100 ℃) obtained at pH 8. 7. The lowest conductivity total ash (90. 81 IU at 100 ℃) and highest purity of the second carbonation juice obtained at pHs 9. 3، respectively. By regarding the different physicochemical parameters at different pHs، it could be concluded that higher temperature (100℃) had more effects on studied characteristics. Finally it could be mention that most effective treatment was pH 9. 3 at 100 ℃. According to results of the research، pH≥9. 3 were suggested for stability of formed calcium carbonate crystals (stable form) because at pH≤9. 3 resulted in formation of calcium bicarbonate (unstable form) from calcium carbonate (stable form).

The main object of this study was comparison of quality and staling of bread baked in convention، microwave and convection- microwave combination ovens. Crumb and crust moisture content، hardness values، specific volume، height to diameter ratio، crumb to crust ratio، oven spring، porous، and starch retrogradation enthalpy of the breads were measured during the study. Also، micro - structure of breads were investigate، and sensory attributes of the samples by seven people evaluated. In combination oven height to diameter ratio، crumb to crust ratio and oven spring samples were comparable with breads baked in convection oven. Specific volume of bread baked in combination oven was lowest. Convection- microwave combination oven was partially solved retrogradation enthalpy of sample and decreased problem staling of bread baked in microwave، but still crumb moisture content breads baked in convection- microwave oven was low and hardness values of them was high Result of sensory evaluation showed formation and porosity of sample baked in convection oven insignificant difference (P≤0. 05) with ones baked in convection- microwave combination oven.

In this study، the antimicrobial effects of Portulaca oleracea leaves essence and extract on Staphylococcus aureus to reduce nitrate used in meat products is investigated. For this purpose، methanol extract and essential oil of Portulaca Oleracea leaves were prepared and chemical composition were determined. Antimicrobial activity of them were investigated with different concentrations (500، 1000، 5000 and 10000 ppm) and 50ppm nitrate solution on Staphylococcus aureus count in sausage at different time intervals: storage for 15، 30 and 45 day at -12°C. The results showed that 83% and 93. 4% of main constituents of the extracts and essence were phenolic compounds and flavonoids، respectively، which exhibit significant bactericidal activity. The results also indicated that MIC of the extract was 10000 ppm and it did not show any bactericidal effect on S. aureus. While the MIC and MBC of essence were respectively 500 and 10000 ppm was considered. Also nitrate concentration used did not show inhibitory effects on the growth of S. aureus. These data indicate that Portulaca Oleracea leaves essence and extract can exhibit antimicrobial activity against Staphylococcus aureus; so it can be considered as an alternative natural preservative in food products.

“Date Arde” is energetic new product that traditional was produced in countryside area of the mount zagros in Iran. This product formed from mixed arde (roasted، decorated and milled sesame seed) with dates paste in portion (25%w/w). The average oil of “Date Arde” is around 9-10%. This study was carried out for investigation the effects of flavor compounds (cumin، cinnamon، ginger) and coatings (chocolate، gelatin، roasted flour with confectionary fat) on the physical (Color، texture)، microbial (Total count، yeast mold) and organoleptic (Softness، flavor، color and over all acceptance) characteristic of “Date Arde” that include berhi dates variety. Analysis of data showed that maximum levels of flavoring for good acceptance was 1% (w/w) of dates، also this level (1%) influenced significantly (p≤0. 05) on texture of product. On the other hand، cumin flavor was accepted with the highest degree. Analysis of findings showed that coating of “Date Arde” flavoring with cumin affected significantly (p≤0. 05) the texture، color and total acceptance. So that chocolate coating showed the best acceptance.

In recent years demand for organic and minimally processed foods with superior quality and extended shelf life has been increased. Introducing novel disinfecting processes instead of chlorine treatment in fruits and vegetable processing is of great importance for food technologists. In this study disinfecting effect of ozonized water and chlorine treatments on nutritional، microbial، sensory and shelf life fresh cut basil was investigated. The results showed that although both ozonation and chlorination led to a noticeable reduction in basil vitamin C and β-carotene; however، the amount of these nutritional substances were higher in treated samples compared to those of control after one week storage. Ozone treatment led to increase lightness and greenness and increased yellowness in samples. Both chorine and ozone treatments significantly (p<0. 05) reduced aerobic mesophylls، psycrotrophs، entrobacteriacea، molds and yeasts، although ozone was more effective in this respect. Ozone treated basil received higher sensorial scores compared to those of chlorine treated and control samples. Considering the fact that ozone preserved nutritional and sensorial quality and effectively reduced the microbial count and improved the shelf life of basil، its application as a novel disinfecting factor in vegetables processing is strongly recommended.