مجله علوم غذایی و تغذیه
سال نهم شماره 1 (زمستان 1390)

Acrylamide was recognized as a potential carcinogen for human being by the international cancer research organization. As far as the present study is concerned, no research has been carried out concerning the presence of acrylamide in food products particularly in potato chips produced Iran. Different potato chips from five major Iranian potato chips producers were randomly chosen and the amounts of acrylamide were measured by GC-MS. The object of the present study is to verify the safety of Iranian potato chips for acrylamide content and compare the results with the international standard. The amounts of acrylamide in all the samples examined were higher than the amount recommended by WHO and FDA. The minimum amount of acrylamide was 1512 ppb for salty flavor potato chips and the maximum amount was 2877 ppb for potato chips with ketchup flavor. The amount of acrylamide in a 65g packaged potato chips varies from 98.3 to 187 microgram. The intake of acrylamide by consuming a package of potato chips with minimum amount of acrylamide is 98.3 microgram which is 2.5 and 1.4 times more than maximum daily intake level recommended by wHO for the people weighing 40 and 70 kg respectively. The high amount of acrylamide in Iranian potato chips recommended quick measures to be taken by relative organizations to control and reduce this substance.

One of the factors affecting national health of a society is the healthy eating and the way the food is consumed. This will promote the growth, repair body tissues and regulate body processes. Human nutrition and the consumption of food in general might be based and related to the geographical, historical, economical, political, cultural and social conditions of a society. These factors affect the health of a society at any times. The object of this study is to investigate the factors mentioned earlier. This study was carried out through various related research papers, books, registered documents and patents which are officially published by the research centers, institutes and government bodies. The results indicated that in some present societies, nutrition might not be regarded as the only tool and factor to provide the need of a society as this used to be the case in the past history. However the economical, social, cultural, historical, geographical and political characteristics of a society might affect the nutritional need of that society. The nutritional habit of a society might be affected by various factors related to that society. Lack of some or all of these factors might partially or totally affect the nutritional changes and might create unpredicted results.

The aim of this study was to determine the types and amounts of phenolic compounds present in the grapefruit seeds as a source of natural antioxidant and to examine the antioxidant activity of grapefruit seed extract (GSE) in anchovy oil. Free and bound phenolic compounds of grapefruit seeds were extracted by methanol and alkaline hydrolysis respectively and then were measured by HPLC method. Antioxidant activities of GSE at different concentrations were compared with the synthetic antioxidant; TBHQ.The antioxidant activity was assessed by determination of peroxide value (PV), Thiobarbitoric Acid value (TBA) and induction periods (IP) measurements using Rancimat apparatus. Phenolic acids (Coumaric, Ferulic, Caffeic and Sinapic) and lutein, naringin and flavonoids were identified as the main phenolic compounds in grapefruit seeds. Total amount of phenolic compounds in grapefruit seeds was 485 ppm. The antioxidant activity increased with the increase in GSE level. GSE at 2000 ppm exhibited the highest antioxidant activity and the activity was better than TBHQ at 100 ppm. This study indicated that GSE is an antioxidant which might be used as an alternative to TBHQ to preserve the oil at low temperature. GSE might be suggested as a substitute for synthetic antioxidants for oils stored for a long time at room temperature.

Lipid oxidation is an important deteriorative reaction. Different factors have affected formation and decomposition of hydroperoxides. In this project, the effects of temperature, time and temperature variations on the formation and decomposition of hydroperoxides in canola and soybean oils with added 100ppm TBHQ have been studied. The oils were heated at 70, 80, 100, 120, 140 and 160°C for different time intervals. Peroxide values and fatty acid compositions have been employed as means to investigate the changes during heat treatment. The results indicated that the increase in temperature reduced peroxide value due to hydroperoxides decomposition. Fatty acid composition, presence of synthetic antioxidants were the major factors to stabilize the substrate by preventing both oxidation and consequently hydroperoxide decomposition during the heat treatment. The rate of formation and decomposition of hydroperoxides in canola oil were less than soybean oil due to less linoleic and more oleic acids in canola. Canola Oil, Fatty Acid, Oxidation, Production and Decomposition Hydroperoxides, Soy bean Oil.

There are some evidences indicating that free radicals cause oxidative damage to lipids, proteins and nucleic acids. Some fruits and vegetables are rich in antioxidants, that might inhibit or delay the oxidation of substrate and would therefore seem to be very important in the prevention of some disease. In order to determine phenolic compounds and antioxidant activity of plum extract, four different varieties of Iranian plum (Bokhara, Torghabe, Shams and Khorasani) were selected and extraction was carried out by using four different solvents namely water, methanol, ethanol and acetone. Additionally antimicrobial activity of plum extract against Staphylococcuse aureus and Escherichia coli in 35°C was studied. Methanol was the best choice between the selected solvents to extract the phenolic compounds of plum. Bokhara plum was the richest and had the highest amount of phenolic compounds. Regarding the antimicrobial activity, the extract can reduce E. coli and S. aureus growth and the higher the concentration of the extract, the less the growth of bacteria. The results showed that, significant correlation existed between antimicrobial effects and concentration of extract. There is a significant correlation between the total phenolic compounds and antioxidant activity. In future plum extract might be used as a source of natural antioxidant and antimicrobial in food processing.

Oak tree (Quercus) is a predominant plant genus in northern and central regions of Iran. Acorn fruit is a good source of phenolic compounds especially gallic acid and tannin. This study was designed to determine the phenolic compounds and evaluate the antiradical and antibacterial activities of ethanolic extracts from Q.branti var. persica and Q.castaneifolia var.castaneifolia fruit. After removal of internal husk and grounding the fruit, the ethanolic (70%) extracts were prepared according to re-extraction method. Polyphenol and flavonoid contents were measured spectrophotometrically. Antiradical activity was evaluated against DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals. Phenolic compounds were determind by the application of HPLC system equipped with a diode array detector. The antibacterial effects of the extracts were assessed on three gram positive and five gram negative bacteria by micro broth dilution technique using ELISA reader. Total phenolic and flavonoid contents of ethanolic extract of castaneifolia variety were significantly higher than that of the extract of persica variety. The two extracts showed good antiradical activities that were comparable to BHA and BHT. Gallic, caffeic and cholorogenic acids were found in the two extracts while vanillin was detected only in extract of castaneifolia variety. The extracts showed good inhibitory and bactericidal effects against all investigated bacteria. The ranges of minimum bactericidal concentration (MBC) of the extracts were 0.615-5 and 1.25-5 mg/ml for castaneifolia and persica respectively. This study suggested that ethanolic extract of acorn fruit can be used potentially as a source of natural antioxidants and antimicrobial.

The Ochratoxin are produced by Aspergillus ochraceus, A. niger, Penicillium viridicatum and P. verrucosum. The Ochratoxin is the most important mycotoxin which might cause some disorders in human health and condition. The object of this research was to evaluate and study the ochratoxin content in 100 samples of grape juice and 100 samples of raisins by competitive ELISA. The ochratoxin determination was conducted on the grape juice and raisin samples collected from the market by application of ELISA method. 32 samples of grape juice and 4 samples of raisins out of 100 samples examined contained Ochratoxin above the European community limit and regulation (10μg/kg). The concentration of Ochratoxin in grape juice and raisin samples were 2.1-18.4 and 0.1-11.4 μg/kg with the average concentrations of 8.14 and 4.7μg/kg respectively. Due to the deteriorating effects of Ochratoxin, some measures should be taken in to account in processing production and storage of grape juice and raisin.

Essential oils have many applications in food industry. Their antimicrobial activity affects different classes of microorganisms. This study was designed to evaluate the antimicrobial activity of the essential oil of Ziziphora clinopodioids on Kluyveromyces marxianus. The essential oil was analysed by GC/MS. For the evaluation of the antimicrobial effect of the oil, different concentrations (3%, 2%, 1%, 0.75%, 0.50%, 0.25%, 0.20%) were added to the subculture (YM agar) and the antimicrobial activity was evaluated. GC analysis revealed 33 different compounds in the essential oil. Six of the identified compounds comprised more than 64% of the compounds present in the oil, pulegone (27.15%), alpha-terpinyl acetate (10.83%), geraniol (8.26%), menthone (6.82%), thymol(6.71%) and alpha terpineol (4.44%) were present in respective decreasing order. Minimum inhibitory concentration (MIC) of the essential oil of Ziziphora clinopodioides was 0.25% for Kluyveromyces marxianus. The plant Ziziphora clinopodioids has antimicrobial activity. The antimicrobial activity of the essensial oil might be partially due to phenolic compounds present in the oil.