مجله علوم و صنایع غذایی ایران
سال پنجم شماره 1 (پیاپی 15، بهار 1387)

Over the past few decades، microwave processing and its high potential capabilities has attracted food scientists where they preferred to replace the old and time-bearing prevalent methods with this swift and simple method. Application of microwaves for microencapsulation is an innovative and new method in which the core and shell were combined at an appropriate ratio and treated by microwaves in order to microencapsulate the core material by coating one. In this research، the citric acid powder at two various size (100–500 and <100 micron) was microencapsulated at different ratios (1:5 and 1:10) by casein and inulin، at various microwave powers (up to 1200 W) for 50 to 250 seconds. Findings of qualitative evaluation of microcapsules by laboratory binocular، scanning electron microscope photographs as well as particle size analysis illustrated that the optimum conditions namely ratio and microwave power for microencapsulation of citric acid by both casein and inulin were 1:10 and 1200 W with slightly different treating time where it was 150 and 50 seconds، respectively. In the next step، these two microcapsules along with uncoated citric acid powder as well as commercial microcapsules of citric acid were added to the ribbon type chewing gum and the sensory evaluation regarding texture، stability of sour taste and aftertaste was done by a semi-trained taste panel. The findings revealed that in terms of sour taste stability and aftertastes، the chewing gum containing citric acid microencapsulated with inulin had highest score whereas with regard to texture one treated with the commercial microcapsules gained the highest score. In addition، the lowest sensorial scores were belonged to samples which treated by citric acid microencapsulated with casein. Finally، for the first time on a real foodstuff the practical capability of this novel، simple، low cost، and rapid microencapsulation technique was confirmed.

In this study، changes in color index (CI)، refractive index (RI) and viscosity in a range of commonly frying oils during frying process were investigated، and their performance compared to the carbonyl value (CV) as a reference method in monitoring of the quality of frying oils was evaluated. It was observed that the CI of the frying oils linearly increased with frying time. The initial CI of frying oils was 0. 36±0. 15 on average، and it reached 1. 73±0. 24 after 48 h of the frying process. The CI had a linear relationship with the CV with a high determination coefficient، R2 = 0. 97، during the frying process. Assuming that the limit of acceptance for the CV is 43. 50 µmol/g، this roughly corresponded to 1. 12 for the CI. As the oxidation accelerated by heat proceeded، the value of RI linearly increased. On average، the RI of the frying oils changed from 1. 468313±0. 00051 (0 h) to 1. 469671±0. 00032 (48 h). The RI of the frying oils showed a high correlation with the CV (R2 = 0. 94). Assuming that the maximum level permitted for the CV is 43. 50 µmol/g، the RI of a frying oil should be ≤ 1. 469075. Viscosity of the frying oils at 30 °C increased with time and changed from 45. 11±13. 84 mPa s (0 h) to 75. 03±12. 47 mPa s (48 h) on average. There was a strong correlation (R2 = 0. 96) between the viscosity and CV of the frying oils. If 43. 50 µmol/g of CV is the maximum level permitted in frying oils، viscosity of a frying oil should be ≤ 74. 78 mPa s at 30 °C.

Considering the high importance and the stand of bread in the nutrition of Iranian people، a research on making bread with rye flour in order to have a variety of bread was carried out. In this research the possibility of baking two different types of bread with proportion of 60% rye flour and 40%wheat flour as rye bread and 40% rye flour and 60% wheat flour as wheat bread was studied. The foresaid types of bread were baked with yeast and sourdough، using both Berlin and Detmold methods. The baking was done three times and the produced types of bread Were evaluated from organoleptic point by panelist. The evaluation table was designed according to the views gathered from citizens and in accordance with the scientific and practical Criteria and or the basic of 7 characteristics of bread. The statistical method was based on the random selection and factorial experiments. The results show that although rye bread may find specific stand in the bread making، taste of people will remain in favor of wheat bread. Also using multi stage sourdough with long period of fermentation will promote the quality of bread from the aspect of the foresaid 7 characteristics. The lowest rank refers to rye bread using yeast in production which indicates not using sour dough will adversely affect the quality of rye bread.

Natural Waters are normally Considered as Healthy، and most of the sources of pollution such as heavy metals، get Through the water، during the passage to reach the consumption aera. Therefore to search the total pollution، sampling was performed from the tap water (7 stations in Tehran). Samples were analyzed to determine the concentration of the elements such as Pb، Cd، Ni، Zn and Cr. Comparison of the results with that of the EPA Standard values showed that the concentration of Pb were much higher in few stations. Considering the canceriogenic effects of Pb، this can be very hazardous. There were no problems due to the other elements، One of the sources of Pb uptake is the piping network system، sharing 29% which seems to be the main source. However reduction and removal of heavy metals were examined by the Reverse Osmiss method at the second step. The results showed high reduction and removal of Pb by this method، so the method looks to be very applicable. /s

Food protection has always captured the mans mind. In a way that، through many years he has used different ways and methods in protecting his needs such as preservation of agricultural products by cold storage، shrink wrapping and controlled or modified atmosphere packaging. In this investigation، effects of modified atmosphere packaging (MAP) with 3% O2 and 1% CO2 in polypropylene film with two thicknesses، 30 and 40 micron.، and temperature treatments، 1 and 4˚C in cold storage with 85-90% relative humidity، for 4 weeks on two types of lettuce (Cos and Crisphead) were considered. The experiments as well as percentage of weight loss، humidity، chlorophyll، total soluble solids، Vitamin C، sodium and potassium content and rate of ethylene production were performed. In the end of fourth week and after exit the cases from cold storage، apparent quality and marketable tests were done too. Experiments were done weekly، in five times، from beginning to end of storaging. The results showed that the potential of storaging for type Cos was better than type Crisp. Furthermore three weeks storage in 1˚C had the better effects on lettuce varieties. The result of analysis effect of MAP and polypropylene film showed that in Type Cos passive MAP in 40 micron polypropylene and active MAP in 30 micron polypropylene and in Type Crisp passive MAP in 40 and 30 micron polypropylene were the best treatments for preservation of quality and quantity characteristics of lettuce types.

Important role of milk in human، especially infacy nutrition is well known. On the other hand، contamination of milk with aflatoxins is considered as a potential risk for human health. In this study the presence of aflatoxin M1 in 86 samples of raw milk obtained from 86 dairy frams in Chahar Mahal & Bakhtiary by ELISA were analysed. In 41 out of 86 samples (%47. 70)، the presence of aflatoxin M1 was detected in concentration ranging between. 2/868-176. 192 ng/l. AFM1 level in 16 samples (18. 6%) of positive samples were higher than the standard limit (0. 05 mg/l) accepted by EU. In addition، the results showed that there were significant difference between AFM1 levels in milk with number of cow''s in herds and milk yield per kg a day (P<0. 05).

Shallot (Allium hirtifolium Boiss.) is a perennial plant from Alliaceae family. It is native to Iran and grows as a wild plant. This research was carried out to determine the fatty acid profiles and mineral elements (K، Na، Mg، Fe، Cu، Zn، Mn) of seventeen Iranian shallot landraces (Kangavar، Siakhdarengoon، Sahneh، Ashtian، Dashtearzhan، Koohrang، Sepidan، Divandareh، Boroujerd، Khomein، Yasuj، Nahavand، Khansar، Harsin، Arak، Doshmanziare and Koohmaresorkhi). Results showed that the highest and lowest dry matter (36. 71 and 29. 15%) were belonged to Harsin and Doshmanziare landraces، respectively. Kangavar landrace had the highest amount of Fe and Cu and Koohrang landrace had the highest amount of Mg. The highest amount of Na was determined in Harsin landrace. The highest amount of K and Mn were determined in Sahneh and Zn in Khomein landraces. Determination of fatty acids with gas chromatography showed that the highest lonolenic acid (ω3) and linoleic acid (ω6) were observed in Ashtian and Sepidan landraces، respectively. This research showed that Iranian shallot landraces are important in mineral elements and essential fatty acids content and are recommended for human nutrition. Key words:

Studies were conducted on properties of oil extracted from seeds of three date palm (phoenix dactylifera) cultivars، Khadrawi، Dayri and saamaran، grown in Khuzestan. Date seeds consistuent approximately 10% of the fruit. Amounts of seeds can be made available after the progress in date industrialization. Seeds contained 8. 5-10. 8% fat. The following values were obtained for samples: iodine value 44. 1-48. 2، saponification number 214-226، peroxide value 17-22، acid value 0. 98-1. 28، refractive index 1. 450-1. 459، specific gravity 0. 91656-0. 91793، viscosity 18. 1-20. 8 mPa. s. Gas-Liquid Chromatography revealed that major unsaturated fatty acid was oleic acid (38. 76-41. 15%)، while the main saturated fatty acid was lauric acid (22. 49-25. 44). Capric، myristic، palmitic، stearic and linoleic acid were also found 0. 19-1. 8%، 12. 47-18. 73%، 9. 91-11. 5%، 1. 92-2. 36%، 6. 18-7. 25%، respectively. Linolenic، arachidic and behenic acid were also found only in Dayri and saamaran very low. Results showed that date seed oil could be used in cosmetic، pharmaceutical and food products.

The EPA production of a marine bacterium، Shewanella putrefaciens MAC1 in four selected culture media and at incubation temperatures of 4°C for 72h and 10°C for 24h was studied. Eicosapentaenoic acid was found to be the sole polyunsaturated fatty acid produced by this bacterium. The major saturated fatty acids produced were palmitic and myristic acids. The highest yield of EPA production was 34. 7 mg/g dry cell weight which was obtained in a basic culture medium containing 1% peptone and 0. 5% yeast extract in ½ strength artificial sea water (ASW) at 10°C. The least EPA was produced when 2% glucose was added to the basic ingredients، indicating that EPA production is enhanced by culture media having limited source of carbon. Addition of 2 mg/l desaturase cofactors NADPH (Nicotinamide Adenine Dinucleotide Phosphate) and FAD (Flavin Adenine Dinucleotide) to the basic ingredients had a significant effect on the EPA production (21mg/g dry cell weight) at 4°C.