فصلنامه علوم تغذیه و صنایع غذایی ایران
سال ششم شماره 1 (پیاپی 20، بهار 1390)

The objective of this study was to compare the effects of 8 weeks of aerobic exercise with low and intermediate intensity on appetite, body weight, exercise energy expenditure, and plasma ghrelin level in women. Sixteen relatively obese (BMI>28) and 14 relatively thin (BMI<22) volunteer female-subjects were divided randomly into four groups, including obese with low intensity exercise (age=45.75±6.75 years, BMI=29.21±0.50 kg/m2); obese with moderate intensity exercise (age=47.12±4.12 years, BMI= 29.59±0.127 kg/m2); thin with low intensity exercise (age = 8±4.65 years, BMI = 21.21±0.53 kg/m2); and thin with moderate intensity (age = 38.125±2.53 years, BMI= 21.49±0.377 kg/m2) exercise. Both the thin and obese groups with low intensity exercise ran 30 minutes per session (3 sessions/wk) for 8 weeks by 50% of the Maximum Heart Rate (MHR). The intermediate exercise counterparts did the same exercise by 60% of MHR. Body weight at the beginning of each session and the distance run were recorded in each session. The Visual Analog Scale-based appetite questionnaires were filled in the morning of the 1st session of the first and fifth weeks and also in the morning of the day after the final session of the 8th week of the training; in all cases blood samples were taken to measure plasma acylated ghrelin level. The statistical tests used for data analysis included one-way ANOVA, ANOVA for repeated measurements, pair t-test, and partial Pearson correlation at 0.05 significance level. In all groups, feeling of hunger and plasma acylated ghrelin level increased, while body weight and satiety decreased (P<0.05). There were significant differences in the magnitude of changes in hunger and satiety among the groups between the 4th and 8th weeks of exercise (P<0.05). The distances run in each group between the 4th to 8th weeks were longer than those run in first 4-week of exercise (P<0.05). The distances run by the thin groups in both the 1st and 2nd 4-week periods were longer than those run by the obese groups (P<0.05). The data also showed that both the thin groups’ exercise energy expenditures were higher than those of the obese groups between the 4th and 8th weeks of the training (P<0.05). A statistically significant correlation was observed only in the thin group with low-intensity exercise between the body weight changes and hunger changes by the end of the 8-week period and between the aerobic exercise energy expenditure and the acylated ghrelin level changes between the 4th and 8th weeks (P< 0.05). Moreover, there was a significant correlation between the distance run and changes in the plasma acylated ghrelin level between the 4th and 8th week of the training only in the thin group with moderate-intensity excercise (P<0.05). It is unlikely that the aerobic exercise intensity or obesity/thinness would be the only effective factors on appetite in women. It seems moderate-intensity exercise would be preferential in weigh loss programs because of its higher energy expenditure. Additionally, it is expected that moderate-intensity exercise would give better results also in body weigh gain programs due to smaller increases in a feeling of hunger in thin individuals with low-intensity exercise. However, since true energy intake was not measured in this study (and considering lack of evidence in this area), longitudinal studies are needed to throw more light on the subject.

An effective way to prevent oxidation of oils and fats is addition of antioxidants. However, the use of synthetic antioxidants for this purpose is gradually being discontinued due to their undesirable side effects. Therefore, extraction and production of natural antioxidants is a necessity. The objective of this study was to isolate cinnamon extract by the Soxhlet and cold solvent methods, employing acetone and methanol as solvents, and to investigate its effects on the stability of sunflower oil. Acetone and methanolic extracts of cinnamon were obtained by the Soxhlet and cold solvent methods. Extraction efficiency was determined and the total content of phenolic compounds in the extracts measured by the Folin Ciocalteau method. The extracts were added to refined sunflower oil samples at concentrations of 0.02%, 0.04%, 0.06%, 0.08% and 0.1%, followed by determination of stability of the samples (as assessed by delayed oxidation). Peroxide value and induction period measurements were used to evaluate the antioxidant activity, the control being synthetic antioxidant TBHQ at a concentration of 0.01%. The extraction efficiency by the Soxhlet method was higher than that of the cold solvent method; however the phenolic compounds content of the extracts isolated by the cold solvent method was higher. In both the Soxhlet and cold solvent methods, the efficiency of exrtarction by methanol was higher than by acetone solvent, while the phenolic compounds content was higher when acetone solvent was used. The data also showed that the antioxidant activity of the extracts was concentration-dependent. The extract isolated with acetone acted better than that isolated with methanol, such that at a concentration of 0.1% it showed the highest activity, second only to synthetic antioxidant TBHQ at the same concentration. Cinnamon extract has antioxidant activity, which is related to its content of phenolic compounds and other antioxidants. Further research is required to get more information before it can be used routinely as a source of natural antioxidants.

Reports in the literature on the menstruation cycle and its effect on exercise performance are contradictory, while consumption of nutrient supplements by women aiming at enhancing performance is invreasing. The purpose of this study was to investigate the effect of L-carnitine supplementation in the follicular and luteal phases of the menstrual cycle on the aerobic capacity and metabolic responses and performance after exhausted exercise in active women. The study design was a double-blind cross-sectional trial. Twenty-six active volunteer college girl-students, 22.8 ± 3.0 years old, with a regular menstrual cycle with the folowing anthropometric measurements were selected: weight, 56.6±6.0 Kg; height, 163.3±4.0 cm; BMI, 20.8 ± 1.2 kg/m2. They were invited to come to our laboratory 3-9 days (i.e., in the follicular phase) and 18-25 days (i.e., in the luteal phase) after bleeding, at 2 consecutive months. They took either L-carnitine or placebo (40 mg/Kg body weight) capsules 2 hours before the Brunce test. The statistical tests used for data analysis were the one-way ANOVA with repeated measurement for parametric, and the Freidman test for non-parametric, data. The maximal oxygen consumption and time to exhaustion in both follicular and luteal phases increased significantly with L-carnitine supplementation by 5.5% and 6.7% (as compared to placebo), respectively. Also, L-carnitine supplementation in both phases led to a statistically significant decrease in blood lactate accumulation (F3,66 = 5.235, P =0.003); the magnitude of reduction in the follicular phase was 28.2% higher than in the luteal phase. On the other hand, the respiratory ventilation in the luteal phase increased significantly with L-carnitine supplementation (15% higher compared to the follicular phase). L-carnitine supplementation in the follicular phase, when estrogen is at its minimal level, can help decrease a reduction in VO2max and excrcise performance. The increased serum L-carnitine level may cause an increase in ß-oxidation and, thereby, increase VO2max and enhance performance.

Raw milk is a source of new strains of bacteriocin-producing lactic acid bacteria (LAB) with the potential to inhibit undesirable microorganisms. The aim of this work was to detect the bacteriocin-producing LAB from raw ewe's and goat's milks and characterize the isolated bacteriocins. A total of 100 samples of ewe's and goat's milks were screened for bacteriocin-producing lactic acid bacteria. Two strains were selected and identified phenotypically to genus level. The serums of cultures of the selected strains were treated with various enzymes to detrmine the nature of their antimicrobial substances. The inhibition potential of the substances was investigated by agar well diffusion assay and their stability at different temperatures and pH's were determined. The antimicrobial substances were partially purified by ammonium sulphate and poly-ethylene gltcol (PEG) and the titer determined. In addition, their molcular weights were determined by SDS-PAGE analysis and their resistance estimated during storage at 4 °C. The two strains of Enterococcus, Le40 and Le50, exhibited a broad antimicrobial activity in several replicates. The sensivity of the inhibitory substances to proteolytic enzymes confirmed the production of enterocin-like substances (ELS) by these strains. Listeria monocytogenes and Staphylococcus aureus were inhibited by the ELSs. The ELSs were both stable at a wide pH range (pH 3-10) and the one isolated from Le50 was resistant to heat. Partial purification of both the ELSs increased their activity and titer. Their molcular weights were between 24 and 29 KD. Finally, the ELS's activity was maintained during storage at 4 °C for 28 days. Considering the desirable antimicrobial characteristics and biochemical properties of the isolated ELSs, further studies to explore the possibility of using them as biopreservatives in food processing is recommended.

This study was conducted to determine the shares of energy and nutrients intakes from subsidized food items in meeting nutritional requirements of Iranian urban and rural households in different socio-economic (SES) groups.

The data collected in the Comprehensive Study on Household Food Consumption Patterns and Nutritional Status of I.R. Iran during 2001-2003 were used in this study. Households were selected by systematic cluster sampling in urban and rural areas and their SES was assessed through in-depth interviews. Assessment of food consumption patterns was done using three consecutive 24-hour diet recalls by trained nutritionists. To determine subsidized food items consumption in the households direct weighing and purchasing tables of major food items (rice, oil, and sugar) and 2-day records were used. In the data file, subsidized and non-subsidized food item subgroups were separated from each other and the shares of each subgroup in supplying energy and nutrients intake in the households were determined. From among the socio-economic variables, some were extracted by factor analysis as indicators of SES based on factor loading. Factor analysis detected 3 significant components for SES. These factors could explain 70% of the variance in SES. The population was divided into three categories (tertiles) according to the factors extracted. The first, second and third tertiles were considered as low, medium and high socio-economic groups, respectively. Finally, the shares of subsidized food items in supplying energy and macronutriets in the 3 categories were estimated.

Of the 7158 households studied, 2496 (34.9%) were rural and 4662 (65.1%) urban. The highest consumption of bread was seen in the low SES groups, while the energy, carbohydrate, and protein supplied by bread was low in the high SES groups. The daily per capita consumption of hydrogenated and liquid oils was 82 and 3.6 grams in urban and rural areas, respectively. In spite of increasing non- subsidized liquid oil proportion in urban areas (2.6, 3.0, and 4.1 gram/person/day in the low, medium and high SES tertiles, respectively), consumption of hydrogenated and total oils decreased with increasing SES in both urban and rural areas. The data also showed that in cities, with increasing the SES level the proportions of non-subsidized rice and sugar increased and that of hydrogenated (subsidized) fat decreased. Shares of dietary energy obtained from bread (42.3±0.5, 37.4±0.5, and 33.0±0.5 grams in rural, and 36.4±0.4, 30.0±0.3, and 26.4±0.3 grams in urban, areas in low, moderate and high SES groups, respectively) and hydrogenated subsidized oil were higher, and that from sugar was lower, in low SES groups, as compared to moderate and high SES groups in both rural and urban areas. Finally, in the high SES groups the shares of energy from non-subsidized and total rice, as well as from non-subsidized liquid oil, were higher.

In IR Iran, higher SES groups receive lower proportions of their dietary fat, rice and sugar from subsidized food items. In contrast, in the lower SES it is the subsidized food items that supply most of the energy, carbohydrates and proteins.

The demand for natural orange juice with a high quality in terms of nutritional value, physicochemical properties and sensory characteristics, and processed with a minimum of heat treatment, is presently increasing. The shelf-life of orange juices now marketed is short due to rapid microbial growth in them, even when refrigerated. The objective of this study was to determine the potential of ZnO- and Ag-filled LDPE (low-density polyethylene) nanoparticle packaging, as a new packaging method, for preserving the maximum nutritional value, freshness and shelf-life of orange juice. Nanocomposite LDPE films containing Ag and ZnO nanoparticles were prepared by melt-mixing in a twin-screw extruder. Packages prepared from these films were then filled with fresh orange juice and stored at 4oC. Microbial stability, ascorbic acid (AA) content, browning index, color value, and sensory characteristics of the juices were determined immediately after packaging and after 7, 28, and 56 days of storage. Microbial growth rate significantly decreased as a result of using the nanocomposite packaging up to 28 days of storage (p<0.05). Reduced degradation of AA and development of brown pigments were also observed (p<0.05) in the orange juice packaged in nanocomposite packages containing 0.25% of nano-ZnO. Moreover, odor, taste and overall sensory attributes ranked highest for the orange juice packed after 28 days of storage (p<0.05). Packages containing nanosilver increased the shelf-life of fresh orange juice to 28 days, although parts of its sensory attributes weres lost. Nanocomposite packaging containing 0.25% nano-ZnO can extend the shelf-life of natural orange juice for up to 28 days at 4oC, without any undesirable effects on its sensory characteristics.

Most of the information on the adverse health effects of trans fats has been mainly obtained from studies done in western populations; very little information is available in this area from the Middle-East. The objective of this study was to determine the association between consumption of partially hydrogenated vegetable oils (PHVOs) and non-HVOs and circulating levels of inflammatory markers among Tehrani female-teachers 40-60 years old. Usual dietary intakes of 486 apparently healthy women were assessed using a semi-quantitative food frequency questionnaire. The vegetable oils consumed were catagorized into PHVOs (commonly used for cooking in Iran) and non-HVOs (sunflower, corn, canola, soybeanm., and olive oils) Anthropometric measurements were made and fasting blood samples were taken for measuring inflammatory markers. The energy-adjusted daily intakes of PHVOs and non-HVOs were 23±11 and 22±10 g/d, respectively. After controlling for potential confounders, the plasma levels of CRP, TNF-α, IL-6, and soluble intercellular adhesion molecules (sICAM-1) of the women in the top quintile of PHVOs intake (as compared to the lowest quintile) were 45% (Ptrend< 0.01), 66% (Ptrend< 0.1), 72% (Ptrend< 0.05), and 22%(Ptrend<0.01), respectively. In contrast, a higher consumption of non-HVOs was associated with lower circulating levels of CRP (-23%, Ptrend=0.05), TNF-α (-29%, Ptrend<0.01), SAA (-24%, Ptrend<0.01), and soluble intercellular adhesion molecule ICAM-1 (-19%, Ptrend<0.05) when the top intake quantile was compared with the lowest. Adjustment for body mass index, fasting plasma glucose, and lipid profile slightly attenuated the associations in some cases. Higher intakes of PHVOs are associated with elevated levels of inflammatory biomarkers, while higher intakes of non-HVOs are associated with lower plasma levels of these biomarkers in female-teachers.

Tofu (soybean curd) is one of the most important soya protein products. It has a low-energy content and is a very suitable replacer for cheese and meat for persons who are sensitive to lactose, cholesterol and saturated fatty acids contained in these animal products. In this research, the effects of a hydrocolloid, namely, carrageenan, at a concentration of 0.1% and 0.2% (w/w of soya milk) and two coagulants, namely, glucono-Delta-lactone (GDL) and calcium chloride (CaCl2), on the quality characteristics of Tofu were investigated.

Soya milk, carageenan and the 2 coagulants, GDL and CaCl2, were used in the formulation of Tofu. Soya milk samples were heated at 100C and then carageenan and coagulants were added and mixed to obtain soya curd. This was followed by removing the serum phase of the soya curd specimens and measuring the quality parameters (yield, color, texture and sensory properties) of the final product..

Addition of carageenan brought about increases in the yield, lightness (L*- hunter parameter), softness and flexibility of the Tofu produced by using GDL and CaCl2. The CaCl2-Tofu specimens showed more hardness (fracture force) than the GDL-Tofu samples. The results of sensory evaluation showed that addition of carageenan caused decreases in hardness and elasticity and increases in freshness and moisture of the samples, the effects being more pronounced in the GDL-Tofu specimens.

The types and amounts of hydrocolloids and coagulants, as well as interaction between them, in making Tofu can have important effects on its yield and quality parameters. In this study, carageenan (at a level of 0.1%) and GDL showed the best results.