فصلنامه علوم تغذیه و صنایع غذایی ایران
سال پنجم شماره 1 (پیاپی 16، بهار 1389)

In recent years sport-drinks industry has developed extensively and ergogenic beverages are used for increasing performance or reduction of dehydration. The objective of this study was to investigate the effects of an energy drink upon running time, blood glucose level, heart rate (HR) and rate of persceived excertion (RPE) in in elite male endurance runners.

Nine elite male endurance runners participated in 2 treadmill sessions. In session 1 they took an energy drink 15 minutes before (6 ml/kg body weight), and 15, 30, 45 and 60 minutes after (2 ml/kg body weight), start of the activity. In session 2, with the same design, the runners took a placebo. The HR was 70% of the maximum value (HRmax) for the first 60 minutes, followed by 85% until exhaustion.

The distance run when the subjects had taken the energy drink was significantly longer than when they had taken the placebo (p<0.05). In addition, there was a significant difference between the experimental and placebo sessions with regard to the plasma glucose level before and 60 minutes after start of the activity. The data also showed a significant difference in HR (p<0.05) as a function of time: the longer the activity, the higher the HR. The differences between the heartbeat and RPE of the subjects in the 2 sessions were also significant (p<0.05).

It can be concluded that taking an energy drink may be effective only towards the final minutes of a severe activity, increasing performance and decreasing rate of persceived excertion in male elite endurance runners.

Two main methods for obtaining natural vanillin are direct extraction from botanic sources and microbial bioconversion. Considering the widespread use of vanillin and increasing consumer-led demand for natural vanillin, and also due to the fact that extraction from botanic sources is very time-consuming and expensive, alternative ways for its production are being constantly explored. In this study, conducted for the first time in Iran, the possibility of preparing natural vanillin from isoeugenol by microbial bioconversion was investigated

The tolerance of bacterial strains to isoeugenol and vanillin was measured by the agar dilution method. Primary screening of strains for converting isoeugenol to vanillin was done by thin layer chromatography (TLC). Vanillin formation was measured by the AOAC method. The vanillin prepared from isoeugenol was identified by TLC analysis and compared with standard vanillin using UV spectra.

The highest vanillin concentration (880 mg/L) was obtained by the KOA1 strain, at 30°C and 150 rpm, after 96 hours. The molar yield of vanillin produced from isoeugenol was 9.5 %.

Isolation and initial characterization of strains capable of producing vanillin from natural sources is the first step in selecting suitable strains for biotechnological production of vanillin from isoeugenol.

Protein-energy malnutrition (PEM) is common in hemodialysis patients. So far, no comprehensive study has been performed on prevalence of PEM in various areas of Iran, including Tehran with the largest number of hemodialysis patients in the country. Furthermore, according to the available literature, there is no report on prevalence of various types of PEM in hemodialysis patients. Therefore, the present study was designed to investigate prevalence of PEM and its various types in Tehran hemodialysis patients in 2008.

In this cross-sectional study, using systematic sampling, 291 hemodialysis patients were randomly selected from among 2302 eligible adult hemodialysis patients in Tehran hospitals. The nutritional status of the patients was determined by subjective global assessment (SGA) and their dietary intakes were assessed using a 4-day dietary recall (2 dialysis and 2 non-dialysis days). At the end of the first dialysis session, patient's heights and weights were recorded. Finally, after a 12- to 14- hour fast, 4 mL of blood were obtained from each patient before dialysis and analyzed for the serum urea, creatinine, albumin and CRP.

The prevalence of mild-to-moderate and severe PEM based on SGA was 60.5% and 1% in Tehran hemodialysis patients, respectively. The distribution of the malnourished hemodialysis patients according to type of PEM was as follows: 20.5%, type I (inadequate energy or protein intake, without inflammation); 65.5%, type IIa (inadequate energy or protein intake, with inflammation); and 14% type IIb (adequate energy and protein intake, with inflammation). The distribution of those hemodialysis patients who did not suffer from PEM was as follows: 3.5%, type Ia normal nutritional status (adequate energy and protein intake, without inflammation); 34% type Ib normal nutritional status (inadequate energy or protein intake, without inflammation); 55.5% type IIa normal nutritional status (inadequate energy or protein intake, with inflammation); and 7% type IIb normal nutritional status (adequate energy and protein intake, with inflammation).

The results of the present study indicate that PEM in Tehran hemodialysis patients is considerably prevalent and type IIa is the most common type. In addition, hemodialysis patients with no PEM based on SGA should also be paid attention to because they may have inadequate intake‎ of energy and/or protein and inflammation.

No studies have been done in Iran so far on the fatty acid composition of meat products and the effect of various factors on it. This study investigated and compared the effects of length of storage period (45 days) and initial cooking (at 72C) on the fatty acid composition of two types of heated 40%-beef products prepared with soya and canola oils.

Samples of the products were analyzed at 5 stages, namely, before cooking and on days 1, 15, 30 and 45 after cooking. Fatty acid composition of the products was determined using gas chromatography and flame ionization detector (FID). Chemical analysis (determination of peroxide value, free fatty content, and the thiobarbituric acid value) was carried out to assess the spoilage progression and fat content changes. Also, in order to investigate the role of microbial growth in spoilage, microbial tests including total psychrotrophic bacteria and Lactobacillus counts were done on the samples. Furthermore, for comparison of sensory properties of the two products, paired-preference test was used at the middle of storage period.

Significant differences were observed in the soya batch at the beginning of storage (day 1) with regard to linoleic acid, on day 15 with regard to palmitic acid, and on day 30 with regard to linolenic acid. On the other hand, in the canola batch on day 45 the contents of the following four fatty acids were statistically different: palmitic, stearic, linoleic and linolenic acids. Furthermore, in the canola batch, the linolenic acid content also increased significantly on day 30. Microbiological examinations showed lower counts in products containing soya oil, but the results of chemical experiments showed different trends in the 2 products. Finally, the canola batch had a higher sensory acceptance than the soya batch.

Based on the findings, the product containing canola oil is the more desirable product as regards quality and resistance to spoilage. Thus, considering the higher sensory acceptance of the canola batch, soya oil, which is currently used widely in the cooking oil industry in Iran, can be substituted with canola oil.

The metabolic syndrome (MetS) is associated with overweight and obesity. It is also considered a risk factor for cardiovascular disease and type II diabetes. Almost one-third of Iranian adults are afflicted with MetS, with a higher prevalence among women. In this study the relationship of dietary pattern with the metabolic syndrome among non-menopausal women (18-50 yr) in District 13 of Tehran was determined.

This was a nested case-control study using the Tehran Lipid Glucose Study (TLGS) data on 920 non-menopausal women (18-50 yrs) as the case group. The control group was an equal number of subjects matched for age. Dietary intakes were assessed with a 168-iteme semi-quantitative food frequency questionnaire (26 food groups). Using factor analysis, the predominant food patterns were identified. The odds ratio of MetS (defined according to the International Diabetes Federation guidelines) and its components was calculated using logistic regression, after adjusting for confounding variables.

Two predominant dietary patterns were identified. The desirable food pattern was characterized by the consumption of raw vegetables, fruits, starchy vegetables, olives, fried vegetables, low-fat d high-fat dairy products, legumes, nuts, eggs, oil, whole grains, fish, and chicken. In the undesirable food pattern the widely consumed food items included soft drinks, commercial fruit juices, cookies and high-sugar sweets, ready-to-eat foods, mayonnaise, snacks (potato chips and puffed corn), oil, pickles, organ meats, refined grains, meat, and salt. After adjustment for various confounding variables (energy intakes, energy expenditure, education level, job, family history of diabetes or stroke, smoking, and BMI), the desirable food pattern was found to be inversely associated with MetS (odds ratio=0.87; 95% confidence interval: 0.16-0.73, P-value <0.001) and hyperglycemia (odds ratio=0.34; 95% confidence interval: 0.13-0.87, P-value <0.05). No associations were observed between MetS and the undesirable food pattern, and of the components of MetS only triglyceride level was associated with this food pattern (odds ratio=2.17; 95% confidence interval: 1.09- 4.32, P-value <0.001).

The desirable food pattern is significantly inversely associated with the metabolic syndrome, whereas the undesirable food pattern has no association.

Flat bread the main source of Iranian diet and the important carbohydrate supplier at food basket of our country. With regard to important of extension of shelf life and decrease of their wastage the objective of this study was to produce Iranian barbary bread with soymilk powder in an attempt to enhance its nutritional value and retard its staling.

Soymilk powder was substituted at 4 levels, namely, 3%, 5%, 7%, and 10%, for wheat flour to produce barbary bread a type of traditional, flat thick bread. The samples of soymilk powder, treated and control flours were analyzed for moisture, ash, protein, fat, fibre, pH, particle size, wet and dry gluten, falling number, and Zeleny value). Staling of bread samples was assessed by six trained panelists 1, 3, and 5 days after production.

Soymilk powder brought about statistically significant (p<0.05) increases in the ash, fiber, total fat, and protein contents, while it decreased wet and dry gluten, Zeleny value and falling number. pH of the treated samples was not significantly affected. Results of the sensory evaluation showed that a 10% substitution of wheat flour by soymilk powder created an unpleasant odor in the bread sample, though the least value was reported for the staling of this bread sample. However, addition of 7% soymilk powder had no undesirable effect on the sensory characteristics of bread; in addition, the rate of staling was also acceptable for this sample.

Substitution of soymilk powder (at 3%, 5%, and 7% levels) for wheat flour in making Iranian barbary bread not only will enhance the nutritional value of the bread, but it will also improve its shelf-life, without any undesirable effect on its sensory characteristics.

More than 80% of human dietary intake of nitrate comes from vegetables. Nitrate is converted to nitrite and nitrosacids, which can combine with primary and secondary amines, producing nitrosamines. Nitrosamines have hazardous effects on human health. Based on the results of the last National Food Consumption Survey in Iran (2002), lettuce, tomatoes and potatoes are the most widely consumed green leafy, fruit-bearing and tuberous vegetables. This study was carried out to determine the nitrate contents of these 3 vegetables on sale in the Tehran Central Fruit and Vegetable Market.

Three-Kg samples of lettuce, tomatoes, and potatoes, distributed in Tehran (Tehran Central Market, the Main Fruit, Vegetable and Agricultural Products Market) were taken during summer and winter 2007, at least 25 samples of each vegetable (a total of 157 samples). After separating inedible portions, the samples were washed, rinsed, minced, mixed thoroughly, freeze-dried and stored at -18◦C until analyzed. Nitrate was determined in the samples using HPLC based on the EC 12014-2 method, and Mann-Whitney nonparametric test, Kruskal-Wallis ANOVA and Bon-Ferroni multiple comparison were used for statistical analysis of the data.

The mean concentration of nitrate in lettuce, tomatoes, and potatoes was 1123.46, 155.65, and 188.41 ppm, respectively. It is seen that the nitrate content of leafy vegetables was the highest, followed by fruit-bearing and tuberous vegetables. Nitrate accumulation in summer lettuce (1223.57 ppm) was higher than in the winter sample (1046.82 ppm), but in the case of tomatoes and potatoes it was the other way round: 210.25 and 264.64 ppm in winter and 101.11 and 104.45 ppm in summer, respectively. The average nitrate contents of lettuce in both seasons were within the internationally permitted range, while in the case of winter potatoes and tomatoes the averages exceeded the respective permitted ranges.

Nitrate accumulation in vegetables can vary according to the harvesting season. Further research is recommended to determine the effects of such factors as variety, age, agricultural practices and storage conditions.