مجله علوم و صنایع غذایی ایران
سال چهارم شماره 1 (پیاپی 11، بهار 1386)

In this research with respect to results arising from dietary absorption of heavy metals such as increase in heart and blood vessels disease، disorder in immunity and nervous system، reduction of fertility rate، increase in children death rate، and most important of all، automatic absorption and the point that cheese is one of the chosen food for feeding children and other age groups، level and source of pollution of Yazd''s saline cheese to some metals was evaluated. In this research from milk send to company، water used in process، used salt، packaging container PS+ AL (polystyrene + Aluminum) and cheese، 6 of each sample and totally 90 sample from 3 company A، B، C randomly was sampled; samples got ready for evaluation of metals such a lead، cadmium، arsenic، iron، zinc، copper and tin By slurry method، and final measurement of 2 metal iron and zinc by Flow Injection Analysis Atomic Absorption Spectrometry (FIA-AAS) and of other metals by Electro thermal Atomization Atomic Absorption Spectrometry (ETA – AAS) took place. Should be mentioned that 3 companies produced cheese was quarantined for 45 days in lacquered tin and 7 days in packaging containers and then was evaluated، Results of test show that highest rate of pollution by iron and cadmium belongs to A Company''s cheese، highest rate of pollution by copper، zinc and Lead belongs to C company''s cheese، highest rate of pollution by Tin and arsenic belongs to cheese produced by company named B. By the way، highest level of fat، moisture and protein belong to A، C، B cheese. Findings reveal that affinity of tin and arsenic to protein and affinity of cadmium and iron to fat is higher than other metals. Statistic analysis by SPSS software and Dunnett، Scheffe and Tukey tests was done and level of mentioned metal was less than normal.

Mass transfer between packaging and its contents during the storage mainly affects physical and chemical properties of foods. Possible interaction between HDPE container and soft drink basis was studied in this work. GC-HS analysis was applied to identify the possible reactants of HDPE. Basis packaged in HDPE containers was stored at different storage temperatures; 4، 25 and 48 C. Specific migration of n-Octane as possible reactant was determined by headspace chromatography coupled with mass spectrometer. Quality parameters of basis were measured during storage time at different temperatures. N-Octane was not detected in the samples stored at 4 and 25 C، and at 48 C was 0. 7ppb، which is much smaller than permitted level of FDA (300ppm). The best storage condition was recognized at HDPE container and darkness condition in 4 C. So the temperature was recognized as an important attribute in basis storage.

Nowadays foods are preserved with using some methods to minimize contamination. One of these methods is food preservatives. Food preservatives with antagonistic effect usually interfere with cell membrane، enzyme action or genetic structure of microorganisms. In this investigation the effects of some preservatives were studied on the growth curve of Listeria monocytogenes that is isolated from dairy products. First the growth curve of bacteria was drawn when the preservatives were absent. Then the growth curve of bacteria was drawn when citric acid، which is a chemical preservative and nisin، which is a natural preservative، were present at sub-MIC concentrations. Next the growth curve of bacteria was drawn at the presence of both acetic acid and sodium citrate at different concentrations and in this period the changes of pH were measured. Listeria monocytogenes did not grow against citric acid at any sub-MIC concentrations which shows the sensitivity of bacteria to citric acid. Although this bacterium was sensitive to MIC concentrations of nisin، but it was significantly resistant to nisin after 18 hours. Also acetic acid and sodium citrate together can have more effect against this bacterium. This study showed that food isolated Listeria monocytogenes is resistant to sub-MIC concentrations of some preservatives، so it is suggested not to apply less concentration of MIC concentrations.

Four varieties of Iranian wheat (Chamran of Ahvaz، Rooshan of Yazd، Zarrine of Aurmieh and Zagross of Ahvaz) were selected. These varieties are selected for high production and their suitable quantity and quality of protein. Phytic acid content in whole flour of these wheat varieties was analyzed. The effects of different leavening agents (2% of yeast، 20 % of sourdough and 1. 5% of soda) and various fermentation times (45، 55، 75 min and 65 min for blank) in loaf bread samples (from 70% extraction flour baked at 260 for 20 min) were investigated. Then phytic acid content of these bread samples was compared. The statistical results showed significant differences on phytic acid content for all of varieties (P<0. 05). With increasing of fermentation time and using of sourdough as a leavening agent phytic acid content were decreased. The decreasing percent in four mentioned varieties of wheat was 95. 5، 95. 13، 91. 4 and 90. 96%، respectively، after 75 min fermentation. Significant differences were observed on interaction between variety، fermentation time and kind of leavening agent (P<0. 05). No significant differences were observed between fermentation time and kind of leavening agent.

One of the most important step in the edible oil refining is the elimination of free fatty acids or the acidification. This step is important not only for consumer acceptance، but also because it has the maximum economic impact on production. The good operation of this step can decrease the loss of edible oil in process and affect strongly the final price of production. Industrially the most commonly used method for deacidification is alkali neutralization known mainly as caustic refining. In this method، there is considerable oil loss due to the hydrolysis of neutral oil by caustic. In addition، loss of oil also occurs in the form of occlusion in soapstock، thereby reducing the overall yield of refined product. In the present paper، we have measured these excessive losses of neutral oil in the refinery units of JAHAN vegetable oil Company (Karaj، Iran). Caustic refining units were studied several times in different dates. The samples were withdrawn from input and outputs of each centrifugal separator. The flowrates and operational conditions of each unit were also recorded. The results showed a very variable excessive loss which changes from 0. 75 to 2. 4 times of sum of free fatty acids and phosphatide contents of crude oil. The crude oil mainly used in the refinery units was degummed soybean oil. Regarding this result، it was concluded that the optimization and control of operation conditions in caustic refining is essential for diminishing the oil losses significantly.

In this study، the effect of olive variety (Kroneiki، Iranian native oleaginous and mission) and enzyme concentration on yield، acidity، peroxide value، iodine value، turbidity، integral color index and total polyphenols of extracted oil was investigated. The statistical analysis was carried out using factorial experiment 3×3 in Completely Randomized Design (CRD) with three replicates. Our results showed that the effect of variety on all of examined factors was significant (P>0. 01). The effect of enzyme concentration on extraction yield، color، turbidity and total polyphenol showed significant difference (P>0. 01). Althought، there was not significant effect (P>0. 05) on acidity، peroxide value and iodine value. Color and phenolic content in extracted oil produced by aqueous enzymatic process as compared with those in control showed significant difference (P>0. 01) between 13 to 62. 2 and 13. 9 to 72. 6 percent،respectively. Turbidity showed significant (P>0. 01) reduction between 29. 6 to 67. 4 percent. On the basis of our result، the yield of oil extraction by processing aid was significantly (P>0. 01) higher (1. 3-2. 4 percent) than that of control. It was concluded that application of enzymatic pretreatment increases quantity and quality of extracted oil and it is applicable as a processing aid in oil extraction unit operation.

Regarding the vast applications of amino acids such as glutamic acid in food industry، chemistry، pharmacology and cosmetics on one and the effort to over come the problem of date wastes in Iran on the other hand، the production of amino acids such as glutamic acid from date fruit wastes was studied. Two mutants corynebacterium glutamicum CECT690 & CECT77 were used to study of possible producing of amino acids from date wastes. Results of date fruit wastes analysis indicated that these wastes are nutritious to bacterial growth. Since date fruit wastes are complex and unknown medium for bacterial growth، in this study some effective variables on production of the amino acids using screen design (used as an experimental design) including 7 independent variables in 2 levels (minimum and maximum) were investigated. Results of amino acids measured by high performance liquid chromatography showed that threonine and glutamic acid are produced more than other amino acids. According to the statistical analysis، the most effective variables on glutamic acid production are the amount of date fruit wastes، time of penicillin addition، phosphate amount and type of microorganism respectively and the least effective variables on glutamic acid production are biotin amount، temperature and nitrogen source. Among interaction effects variables، interaction effect of date wastes amount and time of penicillin addition is the most effective of variable on glutamic acid production. Results of statistical analysis of threonine production showed that the most effective variables on threonine production are time of penicillin addition، the amount of date fruit wastes and type of microorganism. The results from HPLC also showed that many amino acids such as alanine، valine، lysine، proline، tyrosine، phenylalanine، leucine and isoleucine a part from glutamic acid and threonine are produced.

Vegetable oils contain a little amount of phospholipids or phosphatides and in soybean oil compared with other oils usually more phosphatides exists. In the oil refining process، phosphatides exert adverse effects on the quantity and quality of the oil and their presence in the oil distributed in supermarkets could also create undesirable effects during consumption. If، however، phosphatides are extracted properly from the oil، they could have valuable applications such as emulsification in many food systems. Five varieties of soybean cultivated in Iran (Sahar، Williams، Gorgan، Simes and Hill) were selected for this investigation. Hexane could be used to extract oil and phosphatides but the output of the extracted phosphatides is low. This is due to the polar nature of phosphatides which does not allow these compounds to be completely dissolved in a non-polar solvent like hexane. In fact، the proper solvent for this purpose is a mixture of chloroform and methanol، but such a solvent is expensive and its recovery is costly as well. Thus، a kind of hexane، containing some polar compounds and manufactured in Iran was used for the extraction of oil. With this solvent and relatively severe conditions for the extraction، the amount of the extracted phosphatides increased to 1. 72%. Considering that the phosphatides، constituents could affect the process of their separation from the oil and also their functional characteristics، the amounts of individual phophatides form each varieties were determined. The results indicated statistical significant difference among different varieties (P< 0. 05). Although، for fatty acid composition، relatively considerable difference was observed among oils from different varieties، this difference was less on the fatty acid composition of their phosphatides.

Aflatoxin M­1 is a result fungal secondary metabolite in ruminants. this toxin remains in milk as one the most important contaminants. In this work we modified the methods described by other researchers and presented it as a validated method for monitoring aflatoxin M1 in Iranian white cheese for the first time. At first، toxin was extracted from a polar solution (dichloromethane) and then the extract was dried and dissolved in hexan، methanol and water solution. in the third step water phase separated and purified using immunoaffinity liquid chromatography. for method validation we calculated accuracy، precision and sensitivity factors. Measurement of accuracy of method was performed by fortification of conventional blank samples. For precision measurement method was evaluated in six working days under repeatability condition and calculated the mean، variance and relative standard deviation (RSD). Limit of detection in our method was 55 ppt and limit of quantification was 183 ppt.