IRANIAN JOURNAL OF FOOD SCIENCE AND TECHNOLOGY
Year:2005 | Volume:2 | Issue:1|Papers Count:11

In the present study, the effect of variety and oil extraction method on the chemical composition (protein, glucosinolate and phytic acid) of hexane-extracted and two-phase solvent (methanol-water/hexane) meals from double-zero canola varieties (Brassica napus, cv. Quantum, PF 7045.91 and Hyola 401) were investigated. The suitable conditions for the extraction of proteins and phytic acid as well as protein perceptibility of meals were determined. Two methods were applied to prepare of meals: Oil extraction with hexane or with methanol- water/hexane. The effect of oil extraction method on protein, glucosinolate and phytic acid content of meals was investigated. Alkaline extraction at pH between 9.5 and 12.0 and isoelectric precipitation at pH between 3.5 and 7.5, both of them in increments of 0.5 were examined. Variety and oil extraction method had reasonable significant effect (P<0.01) on protein and glucosinolate content. The Two-phase method brought about an increase in the protein content (15%) and decrease in the glucosinolate (50%). Although, it had no significant effect (P<0.05) on the phytic acid content. The optimum pH for protein extraction of all meals tested was 12.0. Oil extraction method had significant effect (P<0.01) on nitrogen solubility. The maximum yield of protein extraction was 60.7% (PF, Hexane-extracted meal). The phytic acid extractability at pH 12.0 was observed between 11.5 (PF, Single phase) and 16.2 (Hyola, Single and Two-phase). The effect of pH on protein precipitation was very significant (P<0.01). The maximum yield of protein precipitation was observed at pH-values between 4.5 and 5.5. Almost 60% of the proteins were recovered in two usable products: precipitated protein isolate and the meal residue with about 35% protein, suitable for animal feed. The glucosinolate content of precipitated protein isolates was below the detection limit (<0.2 mg/g). Precipitated protein isolates had about 85% protein, and there was not significant differences (P<0.01) among them, although significant differences (P<0.01) was observed among their phytic acid content.

Pistachio nut is an edible seed produced by the pistachio tree. Drying is an important operation in pistachio processing. The moisture content of pistachio nuts decreases from 37-40 % (w.b.) to 5-6 % during drying process. The high quality of pistachio nuts depends on fast and efficient handling and drying operation. Drying conditions (drying air temperature, air velocity, relative humidity and initial moisture content) of pistachio nut affect on quality, chemical and microbial attributes of dried nuts. Thus the drying process must be understood and controlled. This requires an accurate description of the drying mechanism. In this study the finite element formulation and solution of diffusive moisture transfer equations to improve grain drying simulation of axisymmetric bodies is presented. Model was solved with improvement moisture diffusivity (7.5E-10 m2/s for 70°C and 5E-10 m2/s for 55 °C). For experiment, thin layer pistachio nut, ‘ohadi’, was dried with two drying air temperature (55 and 70°C) and during drying air velocity and relative humidity were 1.5 m/s and 20%, respectively. During drying, moisture was measured every minute. Good agreement has been observed when the output of model was compared to experimental data. Relative deviance average that calculated of improvement model for air temperature 55 and 70°C  with experimental data, respectively were 5.3% and 8.4%. This result shows that simulation model is near experimental data. Model is used for moisture simulation of pistachio nut drying. The simulated moisture profile and gradient are directly usable for stress cracking analyses of  pistachio nut. The results of the finite element analysis can be used for pistachio nut quality evaluation and drying simulation studies.

The role of processing technology on carrot juice stability was studied in laboratory-scale pressing technique. To do so, the acidification and blanching conditions were changed. To assess the effect of acidification, different amounts of citric acid were added to the mash (i.e. 0.5 and 1 g citric acid/kg whole sample) and blanched at 60, 70, 80°C for 10 min and compared untreated sample (without added acid). Acidifying with 0.5 g/kg showed significant effect on cloud stability. Although, the mash acidification improved the cloud stability, acidification following juice extraction even enhanced sedimentation rate. The mash blanching after acidification at 70°C for 10 min concidreably inactivated of pectin esterase and intensified β - carotene extraction.

Honey is the natural sweet substance produced by honey bees from nectar of plants or from secretions of living parts of plants or excretions of plant sucking insects on the living pans of plants. Physico-chemical properties of honeys in each region are related to kind of plant and flower. Therefore, knowing of component is very important. In this study, sixty samples of honey were collected from throughout of Garmsar city in Semnan Province of Iran in 2003. Honey samples were sent to the food chemistry laboratory. Then, some physico-chemical parameters such as humidity percent, specific weight of twenty percent solution, solid matter, ash, acidity and pH was determined. The results were showed which humidity percent, specific weight of twenty percent solution, solution solid matter, ash, acidity and pH of honeys are 16.32 %, 83.68, 1.323018, 0.287%,  16.33 meq/kg, and 4.54, respectively.

Campylobacter jejuni infectious are one of the most important foodborne diseases in many countries  and causing of diarrhea in more contries. A total of 400 liver samples in order to detection of Campylobacter jejuni in liver of broilers chickens during summer 2001 to spring 2002 in slaughterhouse and retail market broilers of Shahr-e- Kord township. All of the samples were culture in enrichment and specific bacteriological media for C.jejuni. Out of 400 samples, 64.75%were positive due to C. jejuni. From 200 samples taken from slaughter house 64.5% and from 200 samples taken from retail markets, 65% were positive. In comparison of the infection rate in different seasons, autumn 2001 with 80% was highest rate and spring 2002 with [45%] was lowest rate. According to the bacteriological findings of this study, Therefore the consumption of infected livers to C. jejuni constitutes a major health hazard for human in this city.

In recent years several experimental studies have been carride out about beneficial effects of  L. casei, one of the probiotic bacteria, on animals and human. The first step for the use of microorganisms in order to producing probiotic milk products is to recognize their growth conditions in milk and effective elements on it. In this research, the effects of dextrose, glycine, thiamine and different temperatures on growth rate of L. casei in milk have been studied. A series of 38, 40, 42 and 440C incubators were used to choose the best incubation temperature. The acidity of milk samples were measured as the growth index of the microoganism prior and during incubation. The amounts of 0, 5, 10 and 15ppm of vitamin B1; 0, 0.4, 0.6, 0.8 and 1 percent of dextrose; 0, 30, 60, 90 and 120ppm of valine and glycine were used to evaluate their effects on the growth rate of L. casei and acidity of milk samples were measured in 0, 1, 2, 3, 4 and 5 hourse of incubation at 420C. The increase of acidity rate at 440C and 420C was significantly higher than other temperatures (p<0.05). The addition of dextrose, valine, glycine had no significant effect on the acidity rate of the milk samples (p<0.05). Although the addition of thiamine did not have significant effect on the acidity but it improved the ability of enzyme and gas production.

At this study, growth and production of carotenoid (torularhodin and β- carotene) by a new isolated strain (Sporobolomyces ruberimus H110) were studied using technical glycerol and ammonium sulfate as souces of carbon and nitrogen, respectively. Experiment was carried out in a 3L reactor batch in which glycerol concentration was kept constant but three different concentration of ammonium sulfacte (3, 20 and 30 g/l) were used at 23ºC and pH=6. The maximum yield of toularhodin (2.70mg/l) and β- carotene (0.10 mg/l) was obtained using 20 g/l ammonium sulfate. The highest amount of μmax (0.096 h-1 ) obtained with supplying of 30g/l ammonium sulfate. The optimum production (growth  yield as a function of glycerol consumption for different intial sulfate ammonium concentrations) was 0.52±0.01 g/g in all of the experiments.    

In this study, a total number of 48 samples of the white cheese, that produced by different  factories with different dates of production, selected via randomly sampling method and then the levels of aflatoxins B1, B2, G1,G2 and M1 were analysed by thin layer chromatography. AFM1 was found in 37 (70.08%) of 48 of the cheese samples examined. AFM1 content of 75.6% of the positive samples were higher than the maximum tolerance limit (0.25 ppb) accepted by some of the European countries. The range of contamination levels varied among different months. AFM1 in January, February, March, April, May and June, ranged from 159 to 747, 197 to 720, 185 to 1047, 232 to 761, 218 to 627 and 176 to 495 ng/kg, respectively. While the mean values were 390.87, 496.12, 553.50, 287.12, 258.25 and 213.87 ng/kg,  respectively. The highest mean concentration of aflatoxin M1 (AFM1) was registered in March's samples (553.5 ng/kg). The lowest mean concentration of aflatoxin M1 was registered in June samples (213.87 ng/kg). Statistical evaluation showed that there were not significant differences (P>0.05) between the mean concentration of AFM1 of cheese samples taken in January, February, March, April, May and June. However, mean concentration of AFM1 of cheese samples in winter was significantly higher than spring (p = 0.004). Aflatoxins B1, B2, G1 and G2 were not found in all samples. It was therefore concluded that, widespread occurrence of AFM1 in cheese samples were considered to be possible hazards for human health.