فصلنامه علوم تغذیه و صنایع غذایی ایران
سال پنجم شماره 3 (پیاپی 18، پاییز 1389)

Reactive oxygen species (ROS) are produced due to prolong and intensive exercises, such as intense swimming training, leading to cell injury. Antioxidant supplementation seems to reduce exercise-induced oxidative stress. This study aimed to investigate the effects of antioxidant ─ vitamin-mineral ─ supplementation on oxidative stress and muscle injury indices after a strenuous training period in elite female swimmers. Subject and Twenty-four elite female swimmers (aged 12.931.22 years, weight 45.8010.39 Kg, height 153.112.9 cm), members of Tehran and Karaj Swimmimg Clubs, volunteered to participate in this study. They were randomly divided into two groups: a vitamin-mineral-supplemented (n=12) and a control (n=12) group. Both groups participated in streneous swimming sessions for a period of 4 weeks (3 times a week, each time swimming 3.5 to 4 km). Blood samples were taken before and after the period to determine muscle injury indices, such as aspartat aminotransferase (AST), creatine kinase (CK), lactate dehydrogenase, and myoglobin, as well as malon dialdehyde (MDA). In addition, 100m crawl records were determined at the beginning and at the end of the period. Paired sample and independent t- tests were used for data analysis. Results showed that some of the muscle injury indices, namely, CK and AST, decreased significantly in the vitamin-mineral-supplemented group (p=0.011 and 0.04, respectively). The decrease in MDA was not statistically significant. Inter-group comparisons showed a difference only with regard to CK (p=0.021). No significant differences (intra- and inter-group comparisons) were observed in swimming performance. ROS affects exercise-induced muscle injury indices. Vitamin-mineral supplementation can have a beneficial role in such injury. Keywords: Cell injury, Oxidative stress, Swimmers, Antioxidant supplementation

Edible films are generally defined as stand-alone thin layers of materials. They can form pouches, wraps, capsules, bags, or casings in many processes. Coatings are a particular form of films directly applied to the surface of foods. Films are generally prepared using biological polymers such as proteins, polysaccharides and lipids. Edible films have weak mechanical properties and water-vapor permeability (VWP), which can be improved by physicochemical modifications, e.g., ultrasound (US) treatment. Also, edible films, due to their biodegradable nature, can substitute (after appropriate physiochemical modifications) synthetic packaging for foods such as bread. Edible films of methylcellulose (MC) were prepared and the effects of US treatment (5-, 15-, 30- and 45-min durations) on their WVP, tensile strength (TS), and percentage elongation at break (E%) were determined. The effect of relative humidity (52, 57 and 75%) on WVP of the films was also determined. In addition, we also investigated the ability of applied wrappings to retard baguette bread staling by assessing the mechanical and organoleptic properties of breads. 15µm films containing 45% glycerol, treated with ultrasound waves for 5min (the best conditions), were selected and their effect on retarding bread baguette staling determined. Results showed a significant effect of ultrasound treatment on the MC films’ WVP and mechanical properties. Moreover, relative humidity influenced WVP of the films. The MC films retarded staling of the bread samples only for one day. Ultrasound treatment can affect physical and mechanical properties of MC films to a large extent. Mechanical and organoleptic tests of bread indicate that the wrapping can retard staling of baguette bread only for one day. Thus, more research in needed to elucidate more light on the applicability of edible MC films in food packaging.

The overweight and obesity epidemic in Iran started in about 2001. Obesity in the early decades of life is a strong predictor of adult obesity. Some of the most important risk factors of overweight and obesity in childhood are related to infant feeding pattern, parents obesity, family socioeconomic status, birth weight, physical activity, and diet. Breastfeeding is a good strategy for reducing childhood overweight and obesity. In this study the association between overweight and obesity with birth weight and breastfeeding pattern in 7 year-old children in Shiraz was investigated. Subject and This case-control study included a total of 400 Shirazin first-year primary school children (200 obese children as case and 200 normal-weight ones as control) selected by multistage sampling. The schools were selected by stratified random sampling and then all of the overweight and obese children (case group) were selected by cluster sampling. Overweight and obesity were defined as 85  BMI  95 and BMI ≥ 95 percentile of CDC 2000, respectively. For each case subject a control child was chosen matched for age, sex, school and grade. Data were collected by a nutritionist on demographic and socioeconomic characteristics, breastfeeding pattern, birth weight, physical activity, and food consumption (24-hour diet recall) by interviewing mothers, using appropriate questionnaires. Weights and heights of the mothers were also measured. The SPSS software was used for data analysis. The length of breastfeeding, mothers’ BMI, and obesity in first-degree family members were statistically significantly different between the case and control groups (P = 0.005). On the other hand, there was no significant difference between the 2 groups with regard to the family socio-economic status. Further analysis of the data showed no association between birth weight and overweight and obesity in the case group. The results of this study show that overweight and obesity in 7- year old children in Shiraz city are related to breastfeeding pattern, although the relationship may not be an independent one.

Chocolate is very popular among consumers of all ages. However, its consumption is limited for the obese and diabetic people due to its high energy and sucrose contents. Replacing sucrose by low digestible carbohydrates (LDCS) will result in lowering its energy content and glycemic index, as well as in preventing tooth decay. The objective of the present study was to investigate the effects of replacing sucrose with 2 sugar substitutes, namely, D-tagatose and inulin, on the physical, chemical, rheological and sensory properties of dark chocolate Inulin, a dietary fiber, and D-tagatose, a natural keto-hexose with a degree of sweetness similar to that of sucrose, were used as sucrose substitutes in dark chocolate formulas. The inulin:tagatose ratios in the mixtures were 100:0, 75:25, 50:50, 25:75, and 0:100. The physical, chemical, rheological, and sensory properties of chocolate samples prepared with the mixtures were determined. With a reduction in the inulin content and an increase in the tagatose content, the moisture contents of the chocolate samples decreased, while their aw increased. Increased D-tagatose resulted in increased hardness of the samples, the sample with 100% being the hardest, comparable to the control (sucrose) value. With regard to color indices, the least amounts of L*,a*,b*,c* and hue° were observed in chocolate samples with 100% inulin. Increasing D-tagatose led to increases in the color indices. The data also showed that reductions in inulin resulted in decreases in apparent and plastic viscosity and increases in τ0 and τ1. Thus, the lowest real and linear yield stresses were found to be in the sample with 100% inulin. The least apparent viscosity and the lowest plastic viscosity were observed in samples with 25% inulin-75% tagatose and 100% tagatose, respectively, with no significant difference with the control value. Overall acceptability of the chocolate samples increased with increasing the D-tagatose level. It can be concluded that in chocolate formula samples an inulin-tagatose ratio of 25%-75% and 100% tagatose are the best sucrose substitutes. As inulin is a dietetic fiber and tagatose and inulin have prebiotic properties, chocolate samples prepared using them are also desirable from a nutritional point of view and can be considered as functional foods. Keywords: Dark chocolate, Inulin, Tagatose, Stevia, Rheology

Creatine is a dietary supplement that is used by athletes to increase muscle mass and strength and especially to improve sports performance. The purpose of this study was to determine the influence of creatine-monohydrate supplementation on hormonal responses in resistance exercise. Subjects and Twenty-seven trained men took, daily, either creatine- monohydrate (CR, n=15) or a placebo (PL, n=12) for 7 days, followed by performing exercise testing (6 sets of no more than 10 repetitions of the squat exercise at 80% of their 1RM). Blood samples were taken at baseline and on the exercise testing day [pre-exercise (Pre), immediately post-exercise (1P), and 15 (2P) and 30 (3P) minutes post-exercise] to measure of serum growth hormone (GH) and testosterone concentrations. Significant increases in the number of repetitions (7.2±1.2) and volume of exercise (1569±1.8)were observed in the CR, as compared to PL group in set 5 of the exercise protocol. GH was significantly higher at minutes 15 (6.1±1.8 ng/ml) and 30)3.6±1.9ng/ml) post-exercise, as compared to the pre-exercise values in the CR group. In addition, in the CR group the testosterone concentration was also significantly higher (69.1±19.2 pmol/L) at minute 15 post-exercise as compared to the pre-exercise and PL values. These results suggest that creatine supplementation can enhance acute exercise performance by increasing the number of repetitions performed and the total volume of exercise. The enhanced performance results in an increase in both GH and testosterone concentrations, indicating an augmented anabolic hormone response to creatine supplementation.

Sourdough starter contains lactic acid bacteria which can improve quality and taste of bread. The lactic acid bacteria in sourdough have antifungal and antibacterial activities. As some lactobacilus-fermented traditional foods contain salt as a preservative, this study was initiated to investigate the effect of different concentrations of sodium chloride on the kinetics of growth and antimicrobial potential of autochthonous isolates of lactobacilli isolated from Iranian traditional sourdough. MRS broth media containing sodium chloride concentrations up to 7% were inoculated with two sourdough isolates of lactobacilli, namely, Lactobacillus casei and Lactobacillus fermentum. The kinetics of growth of individual lactic acid bacteria at different concentrations of sodium chloride was investigated using the conventional plate-count method. Also the antibacterial effects of supernatants of the lacto bacterial strains grown in media with different salt concentrations on several pathogenic bacteria were assessed. The pathogenic strains included methicillin-resistant Staphylococcus aureus, Kelebciella pneumonia, and Pseudomonas aeruginosa. The highest growth of both lactobacilli isolates was 109 cfu/ml, which occurred at a salt concentration of 2-4%; at a concentrtation of 5% salt the total bacterial counts dropped to 7.5x108. There were further decreases in the lactic acid bacterial counts at a 7% salt concentration to 3.7x106 and 2.5x105 for L. casei and L. fermentum, respectively. Both lactobacilli isolates tolerated salt concentrations up to 5%, but L. casei was found to be more salt-tolerant than L. fermentum. Salt concentrations did not affect the antimicrobial effects of supernatants of individual lactobacilli isolates. However, low bacterial biomass achieved at high salt concentrations negatively affected antipathogenic effect of these isolates, presumably due to less metabolite production.

Hyperlipedemia is a health problem in type-2 diabetes patients. This study was designed to investigate the effects of carrot juice fortified with ß-carotene on the blood lipids in these patients. Subject and This controlled randomized double-blind clinical trial was performed on 44 patients with type 2 diabetes. They were randomly divided into two groups receiving, daily for 8 weeks, either 200 ml carrot juice fortified with 10 mg ß-carotene (group A) or 200 ml ordinary carrot juice (group B). All the subjects would drink the juice (exchanged for one serving of bread) at lunch. Twenty-four hour dietary recalls were done on 3 consecutive days and 6 alternate days by a nutritionist at the beginning and the end of the period. Initial and final fasting blood glucose, ß-carotene, and lipids were also measured. The dietary data were analyzed using Nutritionist IV and statistical analysis was done using SPSS 11.5. The serum level of ß-carotene increased and that of total cholesterol and triglyceride, as well as the LDL-C/HDL-C and TC/HDL-C ratios, decreased significantly in group A as compared to group B. The treatments did not affect HDL-C or glucose concentrations in either group. Daily consumption of both 200 ml carrot juice fortified with 10 mg ß-carotene and ordinary carrot juice for 8 weeks brings about desirable changes in some of the blood lipids in type-2 diabetic subjects without any change in the serum glucose level, although fortified carrot juice is more effective. Such an intervention may prevent hyperlipedemia in these patients.

Iranian white cheese is a type of cheese ripened in brine with high concentrations of Sodium Chloride (NaCl). The brine influences curd development in the process of making cheese and its shelf-life. However, considering that NaCl increases the risk of cardiovascular and renal diseases, cheese producers try to replace it with substitutes, such as potassium chloride. Iranian white cheese samples prepared using pasteurized cow’s milk were ripened in different brines containing either 10% NaCl (control) or a mixture of NaCl/KCl with ratios of 1:1 and 3:1 (case). The effect of partial substitution of NaCl by KCl was investigated on the chemical composition, proteolysis, and lipolysis, as well as on the physical properties (textural hardness) of the cheese samples during ripening for up to 56 days. Lipolysis was assessed by measuring acid degree value (ADV). The physical and chemical properties (dry solids, salt, pH, and acidity) of the experimental and control cheese samples were not significantly different. Neither were there any significant differences with regard to proteolysis (measured by Kjeldhal method and electrophoresis). Finally, substituting NaCl with KCl had no effect on ADV or textural hardness of the experimental samples either. It can be concluded that a reduction of NaCl up to 50% in brine has no effect on the quality of the cheese produced. Furthermore, substituting NaCl with KCl will not cause noticeable changes in ADV and textural properties of the cheese.