Iranian Journal of Nutrition Sciences and Food Technology
Year:2008 | Volume:3 | Issue:3 (10)|Papers Count:9

Background and Objectives: High fat consumption has been shown to be associated with an increased risk of diseases, such as obesity, atherosclerosis, coronary heart disease, high blood pressure, and tissue injury diseases associated with lipid oxidation. Increased public awareness of this subject had led to a dramatic increase in the demand for low-fat foods. Dairy products are becoming one of the most widely consumed low-fat food group. Recently, a significant increase has been observed in the consumption of low–fat cheese. Iranian white-brined cheese has 18-20% fat content. In this study, we have evaluated the effects of two hydrocolloid–Guar gum and Arabic gum –as fat-replacers, on the physicochemical and rheological properties of low-fat white-brined cheese. Materials and Methods: Using an industrial method, samples of Iranian white-brined cheese in 3 levels of milk fat (0.4%, 0.9%, and 1.4%) were prepared from cow's milk at a small scale. The effects of 4 levels of Guar gum (0, 75, 150, and 300 ppm) and 3 levels of Arabic Gum (0, 150, and 300 ppm) in samples on chemical (dry matter, fat content, ferry fatty acid, salt, and acidity) and rheological (storage modulus) properties of the cheeses were evaluated using the Response Surface Methodology. Results: The effects of reducing the fat content of cheese and the use of the two hydrocolloids on the chemical and rheological attributes were evaluated by response surface and contour plots, and the full-term second-order polynomial response surface models were fitted to each of response variables. Then, based on the rheological properties of Iranian white-brined cheese, optimum points of low-fat Iranian white-cheese production were obtained. Conclusion: Arabic Gum at concentrations higher than 150 ppm, caused an increase in the storage modulus, therefore an undesirable hardness in texture of low-fat cheeses was obtained. By increasing the concentration of guar gum, the storage modulus and stress at the fracture point were decreased. It is concluded, that by using guar gum as a fat replacer in the manufacturing of low-fat cheese, an improvement in the texture of product can be obtained.

Background and objectives: The application of factor analysis methodology to dietary patterns has recently become of considerable interest in nutritional epidemiology. Rather than considering nutrients or foods individually, pattern analysis provides an alternative approach to study highly correlated food groups commonly consumed. In this study we tried to identify major dietary patterns in our study population in the Kurdistan Province, Iran, and determine their associations with the risk of esophageal squamous-cell carcinoma in a hospital-based case-control study. Materials and methods: In this case-control study, 47 patients with esophageal squamous-cell carcinoma and 96 controls were interviewed to obtain information on general characteristics, physical activity, and food consumption frequency (125 food items). Following classification of food items in groups, factor analysis was used to identify possible dietary patterns, and then the odds ratio for esophageal squamous-cell carcinoma was estimated. The software used was SSPS-14. Results: Two major dietary patterns were identified: Pattern1: the healthy dietary pattern (including nuts, fruits, green leafy vegetables, yellow vegetables, other vegetables, tomatoes, olives, low-fat dairy products, fish, Doogh (a traditional buttermilk), and cabbages), and Pattern 2: the western dietary pattern (including hydrogenated fats, sugar, sweets and desserts, salt, pickles, eggs, soft drinks, tea, and small amounts of liquid oil). After adjustment for confounding factors such as age, sex, years of education, body mass index, physical activity, symptomatic gastroesophageal reflux, and smoking, a high score of Pattern 1 was associated with a reduced risk esophageal squamous-cell carcinoma by 67% (high second median vs. low 1st median, OR=0.33, 95%CI=0.12-0.86), whereas the Pattern 2 diet significantly increased the risk of the disease (high second median vs. low 1st median, OR=9.8, 95%,CI=3.2-29.7; p<0.001). Conclusion: Our results suggest that a healthy diet tends to reduce the risk of esophageal squamous-cell carcinoma, whereas a western-type diet increases the risk of this kind of cancer.

Background and objectives: Phenolic compounds, commonly found in plants, retard oxidative degradation of lipids and thereby improve the quality and nutritional value of foods. Using synthetic antioxidants has begun to be restricted because of their health risks and toxicity. In the present study extraction of phenolics from Raja potato peel was determined and the effects of Raja potato peel extract as a natural antioxidant in refined soybean oil were investigated. Materials and methods: Phenolic compounds of potato peels were extracted by two different solvent extraction methods–perculation with methanol, and an ultrasound-assisted method using different solvents, including methanol, ethanol, hexane, acetone and water. The total phenolic compound contents of the extracts were determined by the Folin–Ciocalteu method. Two methods were used to determine the oxidative activity the potato peel extracts in refined soybean oil–the oven test and the Rancimat method. Oxidation was periodically assessed by measuring the peroxide and thiobarbituric acid values. Results: The maximum amount of extract was obtained with water (15.5%), followed by methanol (6.9%), while the maximum amount of phenolics was obtained with methanol (680.68 mgGAE/gdw) using the ultrasound method. After 16 days storage at 63oC, the soybean oil samples containing the methanolic extract of potato peels showed lower peroxide and thiobarbituric acid values than the control sample, indicating strong antioxidant activity. Also, the Rancimat method revealed that the Raja peel extract, at concentrations of 1600 and 2400 ppm, exhibited strong antioxidant activity. Conclusion: Sonication increased the total phenolic compounds of the potato peel extract and shortened the extraction times. In addition, the Raja potato peel extract proved to have a strong antioxidant activity, comparable to that of the synthetic antioxidants BHA and BHT.

Background and objectives: Cardiovascular diseases are the most important cause of death in patients with chronic renal failure, including hemodialysis patients. Systemic inflammatory factors, including serum amyloid A and vascular inflammatory factors, are two major risk factors for atherosclerosis in these patients. The present study was designed to investigate the effects of L-carnitine supplement on serum amyloid A and vascular inflammatory factors in hemodialysis patients. Materials and methods: The study was a double-blind randomized clinical trial. Fourty-two hemodialysis patients (25 females and 17 males) were randomly assigned to either carnitine or a placebo group. The patients in the carnitine group received a vial containing 1000 mg oral L-carnitine daily for 12 weeks, while the placebo group received a corresponding placebo vial. At the baseline and the end of the 12th week of the study, 5 ml blood was collected from each patient and each control individual after a 12- to 14-hour fast before dialysis and serum amyloid A, free carnitine, sICAM-1, sICAM-2, sVCAM-1, sE-selectin, sP-selectin and ox-LDL levels were measured. Results: The mean serum free carnitine concentration increased by 150% in the carnitine group at the end of the 12th week as compared to the baseline value (P<0.001), while the serum amyloid A level decreased by 32% (P<0.001). No significant changes were observed in the serum concentrations of free carnitine or serum amyloid A in the control group. In addition, no significant differences were observed between the two groups in the mean changes of serum sICAM-1, sICAM-2, sVCAM-1, sE-selectin, sP-selectin or ox-LDL concentrations. Conclusion: The results of the present study indicate that L-carnitine supplement can reduce serum amyloid A concentration, as a systemic inflammatory indicator, in hemodialysis patients and may play an effective role in preventing cardiovascular diseases in these patients, while it has no effect on the serum vascular inflammatory factors.

Background and objectives: Salmonella is one of the important food poisoning agents. The common method for its identification in foodstuffs is by using media cultures. This method is timeconsuming and does not have good precision. In the present study we compared PCR as an alternative, rapid and more precise method in identification of Salmonella Typhimurium serovar in milk purchased from the local supermarkets. Materials and methods: Six pasteurized milk sample bags were purchased and divided in 2 parts; 3 were contaminated manually with different numbers of Salmonella typhimurium (10-1 –103), the other, non-contaminated, 3 being used as control. All were enriched in BPW (buffer peptone water) media and analyzed by both the PCR and common bacterial culture methods. Results: The PCR method could identify 10, 5, and 1 Salmonella typhimurium in the contaminated samples after 8, 12, and 16 hours of enrichment with BPW, respectively. Identification by the common culture media required a longer time (4-6 days) and was less precise. All the purchased milk samples were found to be free of any contamination with Salmonella typhimurium, using either both methods. Conclusion: These findings show that by using the PCR method it is possible to isolate and identify Salmonella typhimurium in milk in less than 24 hours with at least one bacterium in the sample, while with the culture media methods the time required is 4-6 days. Furthermore, in spite of good agreement between results obtained by the 2 methods, the PCR method has a higher precision and sensitivity.

Background and objectives: Increasing evidence suggests that a high dietary intake of n-3 fatty acids attenuates inflammation in chemically induced colitis, but there is no report the effect of different dietary oils on Citrobacter rodentium-induced colitis. The aim of this study was to determine the effect of fish oil, canola oil, and safflower oil on Citrobacter rodentium-induced colitis in mice. Materials and methods: Groups of 9 mice were fed isoenergetic diets varying only in fat composition for three weeks, before and 10 days after Citrobacter rodentium inoculation. The distal colon was assessed for the histopathology score, bacterial count, and host immune response factors. Results: While the bacterial count was similar in all groups, the histopathology score was at minimum level in the fish oil group, followed (in an increasing order) by canola oil, safflower oil, and chow-diet groups. Conclusion: Our results indicate that in the Citrobacter rodentium-induced colitis model, fish oil, the richest source of omega-3 fatty acids, is most effective in attenuating inflammation. Fish oil has no effect on the number of the bacteria.

Background and objectives: High sugar content is one of the major concerns in chocolate formulations. Although much research has been conducted aiming at replacing sugar with suitable replacres in milk chocolate, the results have not been very conclusive due to inducing undesirable texture and laxative effects. Therefore, in the present study we investigated the production of a low-energy milk chocolate with prebiotic properties using a Simplex Lattice Mixture Design. Materials and methods: Inulin as a prebiotic compound, with polydextrose, maltodextrin and a synthetic sweetener (sucralose), were used as sugar replacers in chocolate-making. Fifteen formulations were prepared using various ratios of these ingredients, and their effects on physicochemical, mechanical, rheological and sensory properties were determined. Results: In general, chocolates with high a level of sugar substitutes had a higher moisture content, viscosity and yield stress and a lower hardness than other samples and the controls. The lowest moisture content, viscosity and yield stress, as well as the highest hardness, were observed at the moderate levels of the ingredients. From among the 4 mathematical models used, Casson model showed the best fitting with our data and was employed for predicting rheological properties of the low-energy chocolates. The overall acceptance of the chocolate samples showed a direct relation with inulin and polydextrose and an inverse relation with maltodextrin. Based on the results of superimposed contour plots, the optimal values of inulin, polydextrose, and maltodextrin were 6.48–32.41% and 67.2–86.2%, 0–28.3% and 58.8–78.3%, and 0–30.6%, respectively. In addition, our data on fat reduction showed the possibility of fat reduction up to 5% and, consequently, a considerable energy cut (29%), in milk chocolates. Conclusions: Based on our findings, the Simlex Lattice Mixture Design is an appropriate method for finding optimal levels of inulin, polydextrose and maltodextrin in formulation of milk chocolate and producing a low energy–prebiotic milk chocolate very similar to ordinary chocolates.

Background and objectives: Plastics have been used in the food industry as packaging materials for over 50 years. However, their use causes environmental and economic problems. To solve these problems, edible films and coatings based on polysaccharide, proteins, lipids and/or their blends have found use in the food packaging industry. Edible films and coatings offer a variety of advantages in the meat-processing industry, such as reducing moisture loss; preserving color, odor and nutrients; and reducing microbial loads. The objectives of this study were to determine the physical properties of a whey protein-monoglyceride edible film and its effect on the moisture loss and sensory properties of fresh mutton. Materials and methods: Two types of edible films–a whey protein-monoglyceride one and a whey protein one–were prepared and their physical properties (permeability to water-vapor and oxygen) were determined. Samples of thigh muscles of mutton were then coated with a solution of the whey protein-monoglyceride edible film and refrigerated. At days 0, 1, 3, and 5 days the moisture content, moisture loss, and sensory properties (juiciness, color and odor) of the coated samples were determined and compared with those of uncoated samples. Results: The permeability to water vapor and to oxygen of the whey protein-monoglyceride edible film was significantly lower than of the whey protein edible film (P<0.05). The moisture content, percentage of moisture loss, juiciness, and color were significantly different between the coated and uncoated meat samples (P<0.05), but their odor was not different (P>0.05). Conclusions: Permeability to water vapor and to oxygen of a whey protein edible film could be reduced by adding monoglyceride. Thus, using a whey protein-monoglyceride as a coating on the fresh mutton can lead to a good-quality product with regard to moisture loss, juiciness and color.