IRANIAN JOURNAL OF FOOD SCIENCE AND TECHNOLOGY
Year:2007 | Volume:4 | Issue:3|Papers Count:11

In this work, the effect of type and concentration of some sweeteners (sucrose, glucose, fructose, aspartame, acesulfame k and neotame) on the rheological properties of locust bean gum solutions in model system include sweeteners and hydrocolloid has been investigated. Two level of sweetener concentrations were used (10, 20% w/v for sucrose, glucose, fructose, and 0.1, 0.2% w/v for aspartame, acesulfame k, and 0.001, 0.002% w/v for neotame). The rheological properties were measured by oscillatory rheometer (model MCR-300). The results showed that the effect of sweeteners on rheological properties of locust bean gum depend on type and concentration of sweeteners. In these concentrations, the synthetic sweeteners had no effect on rheological properties of locust bean gum solution.

The main goal of this study was to evaluate the antimicrobial activity of Ziziphora clinopodioides against some food spoilage and pathogenic bacteria and determine Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC). Extract of Ziziphora was tested for its growth inhibitory and bactericidal effect on 6 Gram-negetive (Enterobacter aerogenes, Escherichia coli, Klebsiella pneumoniae, Salmonella enteriticlis, Shigella dysenteria and Pseudomonas aeroginosa) and 3 Gram-positive (Listeria monocytogenes, Staphylococcus aureus and Bacillus cereus) species. Minimum inhibitory Concentration (MIC) was determined using dilution method and minimum bactericidal concentration (MBC) was taken from the concentration of the lowest dosed test tube showing no growth on subcultured. All of microorganisms were inhibited by the extract of Ziziphora clinopodioides except Pseudomonas aeroginosa. The MIC and MBC for Gram-negetive bacteria, including Enterobacter aerogenes, Escherichia coil, Klebsiella pneumoniae, Salmonella enteriticlis and Shigella dysenteria were 1000-2000 mg/L. The MIC and MBC for Gram-positive bacteria, including Listeria monocytogenes, Staphylococcus aureus and Bacillus cereus, were 1000-4000 mg/L. Acording to the results of this study; It is applicable to use extract of Ziziphora as the natural preservatives and flavoring agents in food products.

In this investigation starch gelatinization in Barbari bread was studied. Starch gelatinization was examined by XRD and reducing sugars.Intensity and the hights of peaks of XRD (X-ray Diffraction) in breads with different weights (400, 500 and 600 gr) followed V pattern which showe gelatinization of starch in Brbari bread.Results of diffractograms obtained at the third and fifth days was showed that in Barbari bread crystallization appear very slowly, It seems to be due to high moisture in it. Statistical results indicate that samples weights have no effect in gelatinization and baking have same effect on all samples.

There are two reasons for measuring mechanical properties of cereal, at first determination of grain texture for classification, and second, in modification of harvesting and processing machinery. Therefore, this research was accomplished on sardary wheat variety. For this purpose, exactly 160 simple compression tests were conducted including four levels of moisture content and two types of wheat (good and sunn pest- damaged) at twenty replications. According to the research, it is possible to distinguish sunn pest and good grains from each other. Results of this study were defined which able to us on basis of mechanical. The best moisture contents for separation are 12 and %14 (w.b.) based on toughness and maximum force respectively. The results of analysis of variance indicated that two types of wheat at three attributes (toughness, maximum force and initial tangent of the curve) were different, significantly. The maximum force to rupture for good grain is higher than sunn pest-damaged grain, but, sunn pest-damaged grains were more tougher than good grains. This phenomenon is due to porosity of sunn pest-damaged grain tissue. Also its maximum strain is twice as many as of good grains. Among the mechanical parameters which extracted from the tests, it was shown that the toughness is from most suitable factor to recognize sunn pest-damaged grain from other grain. Also the results of this study indicate which maximum and minimum force to rupture of sunn pest-damaged grain are 90.6 and 7.35 N respectively. Whereas, the similar values for good grain are 121.8 and 28.34 N respectively. Also, there are no significant differences between sunn pest-damaged and good wheat kernels based on physical parameters.

According to the statistics, consumption of the bread has the highest value in Iran. Regarding the high wastage of different breads, which is mainly due to low quality, low shelf life and staling, we will answer one of the most important nutritional problems of our country , if reduce or at least retard its rate by means of research. This research was carried out to determine the effect of different levels of sodium stearoyl lactylate (SSL) on dough rheological properties and quality of Taftoon. So SSL was mixed with flour at levels of 0.25%,.0.50% and0.75%and the rheological properties of the resulting doughs were determined by Farinograph and Extensograph and optimum level of SSL addition was determined ,regarding the results. Different treatments of breads were baked and sensory analysis was done in days1,2 and 3 by means of trained panel of referees. The texture of breads were evaluated by krummer, compression and rubber tests in days 1,2,3 and4 with Instron. Moisture content of the breads was determined in days 1, 2 and3.Results of Farinograph and Extensograph , showed that SSL improved dough properties .The results indicated that bread containing 0.75%SSL had the best quality and was the one to mostly retard the staling rate and improve the texture of bread, but there was no significant difference between breads containing 0.50 % and 0.75%SSL.

The use of sodium and potassium nitrite as preservative and color stabilizer in meat products like sausages is common. High concentrations of these Salts in meat products increases the likelihood of cancer, malignancy and teratogenesis amongst consumers, whilst low concentrations increases the risk of c.botolinum growth during storage and the production of lethal toxin of botulism. Therefore, the use of these salts shuld be cotroled during the production and storage of meat products. The purpose of this study, was to plot the decreasing curve of nitrite in sausages containing 40, 60 and 90 percent meat during storage and then to compare them in order to evaluate the effect of meat concentration on nitrite decrease. In this study, 10 kg of each type of sausages containing 40, 60 and 90 percent meat were produced from the same meat source and 120 PPM of nitrite was added to all of them. Three samples were taken from each sausage type daily and, consecutively, on the first week, every other day during the second week and in 2 day interval during the third and fourth weeks and the nitrite levels were measured using the spectrophotometric technique and the mean of three samples recorded as the nitrite residue level on that day. The results indicated that nitrite residues decreases during storage and the pearson correlation coefficient between storage time and nitrite residues in three sausage types containing 40,60 and 90 percent meat, respectively, was r=-0.91, r=-0.89 and r=-0.86 which is significant (p<0.01). The results also indicated that nitrite residues in sausage containing 40 percent meat was significantly higher than sausages containing 60 and 90 percent meat on different time intervals and also these residues were significantly higher in sausage containing 60 percent meat than sausage containing 90 percent meat (P<0.05).

Moisture desorption isotherms are useful in food dehydration, storage and packaging. Due to the complex food composition, theoretical prediction of the isotherms is not possible and experimental measurements are necessary. Moisture desorption isotherms of Thompson seedless raisins were determined at 30, 40, 50, 60, 70 and 80oC, using the standard static gravimetric method developed by the European cooperation project COST 90. GAB, Smith, Oswin, Halsey, Henderson and D’Arcy-Watt equation were fit the data. The experimental data were fitted well with Halsey equation at 30oC and 40 to 80oC, with D’Arcy-Watt equation. So, Isosteric heat of desorption data obtained at different moisture content.

In or to evaluation the effects of milk total solids on the growth of starter bacteria during fermentation, pastorizied skim milk concentrated to 4 levels of total solids (14, 18, 23 and 27%) using a vaccume evaporator. Concentrated milk samples inoculated with a yoghurt starter culture (CH1) and incubated at 43oC for 6 hours. At intervals of 1 hour tow samples removed from the incubator and cultured in BGWA medium. The results showed that increasing milk total solids, increased the lag phase time for both of starter bacteria but increased growth coefficient. The acidity increased and syneresis decreased with increasing total solids. Increasing total solids to 23% had no significant effect on the flavour scores but increasing of them more than this level decreased the flavour scores significantly. The texture scores increased with increasing of total solids.

Listeria spp. has been isolated from poultry, red meat and meat products and fish in many countries around the world. According to the reports of isolation of Literia monocytogenes in water and ice used for retaining freshness of food products and possibility of the increasing of bacterial contamination of poultry carcass after cooling in water chiller in poultry slaughter house, the effects of water chiller on Listeria monocytogenes contamination of poultry carcasses before and after chilling process in four industrial slaughter houses of western Azerbaijan province was investigated.Ninety poultry carcasses from 4 industrial slaughter houses in western Azerbaijan was investigated for Listeria monocytogenes before and after chilling process using the modified Canadian version of U.S. Food and Drug Administration (FDA) Listeria isolation method. Listeria monocytogenes contamination was 4.9 MPN g-1 in one sample before chilling process in water chiller. The result of Listeria monocytogenes contamination in the same positive sample and 6 other samples which did not show positive result before chilling process were 18, 43, 28, 21, 14, and 92, respectively. All of the isolated belongs to the serogroup 1. Paired-samples T test indicated significant difference (P<0.05) between the contamination levels before and after chilling process.Free available chlorine content of water in water chiller of these slaughter houses was not measurable.