فصلنامه علوم تغذیه و صنایع غذایی ایران
سال دوم شماره 1 (پیاپی 4، بهار 1386)

Ultrasound has found wide application as an advanced technology in processing technologies, including food technology. It is used both in measurements and diagnostic tests, and, as a processing aid, with the other technologies in food processing. The objective of this study was to determine the effects of combined caustic soda and ultrasound on reducing the drying time of grapes in raisin production and the possibility of substituting the ultrasound technology for conventional methods. Two samples of Thompson seedless grapes, one intact and one pre-treated with caustic soda (0.5% W/V, at 80oC for 30 sec.), were sonicated in an ultrasonic bath (28 KHz frequency and 150 W intensity) for 0, 10, 20, 40 and 60 minutes and immediately dried by conventional sun-drying for 7 days. The moisture content, weight, and water activity of the samples were determined daily. The ultrasound treatment of short durations alone had no affect. The treatment was statistically significantly effective only when the exposure time was 40 or 60 minutes or longer. Further analysis of the data showed that the combined treatment of ultrasound with caustic soda significantly reduced the length of time required for dehydration of grapes and raisin production. The findings indicate that the ultrasonication technology can be used economically, reducing the length of time for drying grapes and, thus, increasing productivity in the process of raisin production. However, more studies are needed to determine whether ultrasound alone can be substituted for caustic soda technology in raisin production

Spreads are products with the property of spreadability on bread, usually containing 40-80% fat. The morbidity and mortality of cardiovascular diseases, which have a strong association with the type and amount of fats consumed, are on the increase. The objective of this study was to formulate and produce at the laboratory scale low-fat (40%) and low-trans fatty acid (<5%) spreads by blending, using two types of stabilizers, sodium alginate and modified waxy maize starch (MWMS). The characteristics of the oils to be used (peroxide value=PV, iodine value= IV, and slip melting point-mp) and suitable amounts of stabilizers (1% sodium alginate and 3% MWMS) were first determined. Then six samples of low-fat (40%) spreads were formulated (2 Kg) by combining three oil phases and two stabilizers as follows: F1 and F2 formulas with palm stearin and canola oils (40:60), the stabilizers being sodium alginate (F1) and MWMS (F2); F3 and F4 with fully hydrogenated soybean oil (flakes) and soybean oil (25:75), the stabilizers being sodium alginate (F3) and MWMS (F4); F5 and F6 with palm, cottonseed and canola oils (40:40:20), the stabilizers being sodium alginate (F5) and MWMS (F6). A high-fat spread (F7, 80% fat) containing palm stearin and canola oils (40:60), with no stabilizer, served as control. The physical and chemical characteristics of the samples, including fat and moisture contents, PV, IV, mp, fatty acid composition, solid fat content (SFC), and consistency, were determined. The trans-fatty acid content of the oil phases in the formulas and their nutritional value (P/S+T) were <1 % and ≥1 respectively which is considered desirable. The solid fat contents (SFC) of F1 and F2 at 0, 10, 20, 30 and 35 °C were similar to the respective control (F7) values, with desirable spreadability (p<0.05). Penetration of the low-fat spreads was higher than that of control. Ranking of the samples, performed on the basis of the nutritional value and the physical and chemical characteristics, gave the following F7>F2 & F1>F5& F6>F4 & F3. Considering the cost of oil hydrogenation and the effects of the amounts and types of fat on health of the individuals and communities, and on the basis of the results of this research, F1 and F2 are recommended to be used as spreads, for further research in larger scale.

One of the methods for preserving foods is decontamination by using food preservatives. Food preservatives exert antagonistic effects on microorganisms through interference with the structure and function of their cell membrane, enzyme action, or genetic structure. The effects of different preservatives on the growth of Bacillus cereus isolated from cheese were determined. First the growth curve of the bacteria was studied without addition of the preservatives. Then the curve was re-drawn after adding acetic acid and nisin as a chemical and a natural preservative, respectively, at sub-minimum inhibitory concentrations (sub-MIC). Finally growth curves were drawn in the presence of both citric acid and potassium sorbate at different concentrations, the pH changes being determined. Bacillus cereus did not grow well in acetic acid at a concentration of half-MIC, and the pH was 5 and did not change. However, it caused changes in the pH at ¼-MIC and ⅛-MIC of acetic acid and grew. Furthermore, it could increase the pH in the presence of nisin and grow after a lag phase of 12 hours. The simultaneous use of citric acid and potassium sorbate showed a synergistic preservative effect. Bacillus cereus isolated from cheese is resistant to sub-MIC concentrations of different preservatives. Therefore, it is recommended not to use preservatives at such concentrations.

Results of epidemiologic studies on the relationship between fruit and vegetable consumption and the renal cell carcinoma (RCC) risk have been inconsistent and inconclusive so far. This study was conducted to further explore the issue and throw more light on the subject. In a population-based prospective cohort study of Swedish women (Swedish Mammography Cohort) dietary information from 61,000 women 40–76 years old was collected using a food-frequency questionnaire. A 13-year follow-up showed that 122 of the women developed RCC. Cox proportional hazards models were used to estimate relative risks (RR) with 95% confidence interval (CI). Women consuming 5 or more combined servings of fruit and vegetables daily had a relative risk of 0.59 (95% CI=0.26–1.34) in comparison with those consuming less than once serving. When fruits and vegetables were examined separately, those women who had consumed more than 75 servings of either fruits or vegetables per month had a multivariate relative risk of 0.59 (95% CI=0.27–1.25) and 0.60 (95% CI=0.31–1.17), respectively, compared with those consuming 11 or less servings per month. Within the fruit group, bananas showed the strongest inverse association (p=0.07 by Wald test), while of all the vegetables studied root vegetables proved to have the strongest inverse association (p = 0.03 by Wald test), with RCC. The risk of RCC decreased with an increase in the consumption frequency of white cabbage (p for trend=0.07). The data also revealed that the consumption by women of salad vegetables (at least once per day) could reduce the RCC risk by 40% (RR= 0.60; 95% CI =0.30 –1.22), in comparison to those not consuming this type of vegetables. Our results suggest that a high consumption of fruits and vegetables may reduce the risk of RCC in women.

Although there are reports in the literature on the antimicrobial effects of green tea, the effect of black tea, the most common beverage in Iran, on growth of bacteria, such as Streptococcus pyogenes, has not been studied extensively. This study was undertaken to determine the inhibitory effect of black tea on the growth of Streptococcus pyogenes in vitro and compare it with green tea.

Extracts from both green and black teas were prepared using the percolation method and dried. This was followed by assessment of the total anti-oxidant capacity (TAOC) of solutions of the dried extracts with different concentrations. The assessment was done by determining percentage inhibition of oxidation of ABTS and reduction of its radical by 1 mg/ml extracts of black and green teas at 37°C. Viability of the bacteria was determined by exposing them to different concentrations of the tea extracts in an aqueous medium and then transferring the cultures to a solid medium, followed by colony counting at certain intervals. In the next step, the growth inhibitory effects of black and green tea extracts were determined on the basis of interactions between the extracts with some of the antibiotics routinely used against Gram-positive by the disc diffusion method (11 times on different days).The data were analyzed using the Wilcoxon sign and Kruskal Walis tests.

The data showed that the antioxidant capacity of green tea extract is significantly higher than that of black tea extract (p<0.001). Conjugation of the standard antibiotics disk with 1.25 mg green tea extract had a synergistic effect on ampicilin in a dose-dependent manner, it had no effect on amoxicillin, but an inhibitory effect on cephalexin. Increasing the green tea extract dose to 2.5 mg caused the zone of inhibitory growth of cephalexin to return to the basal limit and that of amoxicillin even beyond that. In the case of black tea, the increased doses resulted in increases in the antibacterial effect of ampicilin in vitro, reaching statistical significance (P<0.001) at the 2.5mg dose. Although a 1.25 mg-dose of black tea extract inhibited the antibacterial effect of amoxicilin and cephalexin, the inhibitory effect decreased significantly (p<0.001) when the dose was increased to 2.5 mg; however, the zone of inhibition was still less than the basal limit.

It seems that the inhibitory effects of tea on bacterial growth is directly related to its TAOC. The mechanism involved is probably through production of hydrogen peroxide by the tea polyphenols acting as pro-oxidants. Our findings indicate the possibility of using proper amounts of tea or polyphenols as nutritional supplements as an adjunct nutritiona therapy in certain infections.

The objective of this study was to examine the content of food advertising in the children’s and adolescents’ program on the Iranian television. The study, a content analysis of advertisements, monitored 3 hours of children’s and adolescents’ TV programs broadcast on Channel 1 for one week (4-10 November 2000). A detailed record of advertisement style and content was used for analysis. Advertisements for food products comprised 25% in number (second rank) and 21% in duration (third rank) of the total TV commercials during the monitoring period. Puffed cereals comprised the largest category (36%) of advertised foods. The messages most frequently used to promote the sale of a product were “quality” (59%) and “taste” (46%). The most frequent appeals of food advertisements were “stimulation of hunger/thirst” (67%) and “attributed quality” (64%). “A” puffed corn was the most frequent brand (23%) among the food brands advertised. In 37% of the food advertisements half of the nutritional properties attributed to products were scientifically untrue or misleading. Food advertisements aimed at children on TV were dominated by those for foods of questionable nutritional value, designed in a manner mainly to attract children.

Obesity is an independent risk factor for cardiovascular diseases and diabetes. The abnormalities involved may be mediated by increased secretions of inflammatory proteins called adipocytokines by the adipose tissue. Thus, monitoring adipocytokines during weight loss could be helpful in progress evaluation of weight reduction programs. Since high-protein diets are considered diets of choice for weight reduction in some communities, their effectiveness should be re-evaluated. The objective of this study was to compare the effects of a standard-protein diet with a high-protein diet on weight loss and biochemical health indices, e.g., the blood lipid profile and plasma inflammatory proteins, in obese women. Twenty-eight 20-48 year-old obese women (BMI= 30-41 kg/m²) were divided into 2 groups. One group was assigned to a high-protein diet (HP, protein supplying 30% of energy) and one to a standard-protein diet (SP, protein supplying 15% of energy). Anthropometric and biochemical variables were measured at the beginning and after 10 weeks. The magnitude of weight loss (6.0 ± 2.3 kg on HP and 4.9 ± 2.4 kg on SP; P = 0.43) and fat loss (4.6 ± 2.1kg on HP and 3.9 ± 2.0 kg on SP; P = 0.63) did not differ significantly between the 2 groups. Insulin sensitivity index improved more on the HP diet (P = 0.01). The reduction in the serum triacylglycerol concentration was significant in both groups (HP, P= 0.005; SP, P = 0.03) without any diet effect. Total cholesterol, HDL-C and LDL-C did not change significantly in either group. On the other hand, plasma leptin decreased more on the HP than on the SP diet (diet effect; P<0.05). No significant changes in adiponectin, TNF-a, IL-6 or log CRP were observed after weight loss, although there was an desirable trend in all these inflammatory proteins. The high-protein diet was more effective in lowering plasma leptin concentration and improving insulin sensitivity than the standard-protein diet. However, the magnitude of weight loss and changes in the serum lipid or plasma inflammatory protein levels did not differ significantly between the energy-restricted high-protein and standard-protein groups.

Saffron, the world’s most expensive condiment, is one of Iran’s most important non-petroleum exports. Its annual production in the country is about 220-228 tons and its export value over 59–70 million USD (the price is 454–482 USD/kilogram). The aim of this study was to compare the effects of different dehydration methods, including vacuum oven-, freeze-, microwave- and solar0drying methods with the traditional drying method on the characteristics of saffron and determine the most suitable method. The study was conducted in the National Nutrition and Food Technology Research Institute, Tehran, Iran between 2001 and 2002. The methodology was experimental. A farm in the safflower-growing region of Ghaen was selected randomly, and the flowers were picked and mixed thoroughly. The percentage yield of the stigmas, and the morphological and chemical (moisture, ash, total nitrogen and acid-insoluble ash) characteristics were determined. Stigmas were dried, followed by determinations of the moisture content, total ash, acid-insoluble ash, cold water-soluble extract, total nitrogen, crude fiber, crocin, picrocrocin, and saffranal. The total microbial, choliform, yeast, mold, and Esherishia coli counts were also measured in the dried samples. The results indicated that from the color (crocin) point of view the solar-, vacuum oven-, and microwave-dried samples were the best (p<0.05). As regards the contents of saffranal and picrocrocin, responsible for aroma and taste, respectively, there were no significant differences among the dried samples. The results of the microbial tests on the dried samples indicated that all the samples except those dried using the traditional or the freeze-drying method, the counts conformed with the Iranian standards. Although all of the four non-traditional methods of drying were better than the traditional method, we recommend sun-drying as a suitable method in the rural areas where saffron is produced.