JOURNAL OF NUTRITION SCIENCES & FOOD TECHNOLOGY
Year:2011 | Volume:6 | Issue:3 (22)|Papers Count:12

Background and Objective: Type-2 diabetes is a major metabolic disease with many signs and symptoms, such as hyperglycemia, disorders in protein, carbohydrate and lipid metabolism, and partial or total insulin deficiency. It is accompanied with pancreatic beta-cell malfunction, reduced insulin sensitivity, and systemic inflammation. There is some evidence indicating a role of vitamin D in maintaining glucose tolerance and normal secretion of insulin. The objective of the present study was to assess the effects of calcitriol on the plasma insulin and glucose levels in non-insulin dependent diabetes mellitus patients.Materials and Methods: Seventy subjects (35 males and 35 female) with type-2 diabetes, aged 30-75 years old, were divided into 2 groups-an intervention and a control group. The intervention and control groups received, daily for 12 weeks, two 0.25-mcg calcitrio-capsules (0.5 mcg calcitriol) and 2 placebo capsules, respectively. Fasting blood samples were taken at the beginning and at weeks 6 and 12 for measuring glucose, insulin, and glycosylated hemoglobin (HbA1C).Results: The fasting plasma glucose level did not change noticeably at weeks 0, 6 or 12 in the intervention group, while it increased significantly (p=0.03) in the control group. The insulin level increased significantly in both the experimental (p=0.002) and control (p=0.0002) groups. Similarly, there were increases in the HbA1C concentration in the experimental (p=0.013) and control (p=0.0004) groups at week 12, as compared to baseline values. Also there was an increase in insulin resistance in both groups (p=0.023 and 0.0001 for experimental and control groups, respectively). Finally, HOMA-%b, which is an indicator of the activity of the pancreatic beta-cells, remained unchanged in the controls, while it increased significantly in the experimental group (p=0.009).Conclusion: Calcitriol at a daily dose of 0.5 mcg has no lowering effect on blood glucose in type-2 diabetic patients, although it may prevent its elevation. The findings further show that calcitriol dose not bring about a reduction in insulin resistance, however, it improves pancreatic beta-cell functioning, thereby increasing insulin secretion.

Background and objectives: Fish and fish products are highly perishable foods because of their high unsaturated fatty acids and high-quality protein contents. For this reason, preservatives are used in order to prevent or delay their spoilage. Sodium alginate is a natural antioxidant, and to increase its antibacterial properties one can add essential oils with antibacterial properties. The object of this study was to determine the antioxidant and antibacterial effects of sodium alginate enriched with thyme oil on rainbow trout fillets.Materials and methods: Solutions of sodium alginate (3%) and sodium alginate plus thyme oil (sodium alginate 3%+0.5%, 1% and 1.5% thyme oil) were applied for coating the fish fillet samples. The control (with no coating) and the coated fish fillet samples were analyzed periodically (at 5-day intervals) to determine microbiological [(total viable (TVC) and psychrotrophic (PTC)) counts] and oxidation characteristics [(peroxide value (PV) and thiobarbituric. acid (TBA)] and free fatty acids (FFA) content.Results: As compared with the control samples, smaller changes were observed in the bacterial and oxidative indices in the samples treated with sodium alginate and sodium alginate plus thyme oil during storage. In the samples treated with sodium alginate enriched with 1% and 1.5% thyme essential oil, the magnitudes of change in PV, FFA, TVC, and PTC were less than in the other treated samples (p=0.05), and there were no statistically significant differences between the 2 treatments (i.e., 1% and 1.5% thyme oil, p>0.05). The smallest change in TBA was seen in the sodium alginate sample enriched with 1.5% thyme oil (p<0.05).Conclusion: The results indicate that the sodium alginate coating enriched with thyme oil has the potential to reduce bacterial growth and oxidation in rainbow trout fillets during refrigerated storage (4±1oC).

Background and Objective: Poor vitamin D status has been associated with impaired glucose tolerance and diabetes. The purpose of this study was to compare the effects of daily intakes of Iranian yogurt drink dooghfortified with vitamin D or vitamin D+calcium on anthropometric and glycemic status in type-2 diabetes patients.Materials and Methods: Ninety patients with type-2 diabetes were randomly allocated to one of three groups as follows: group1: plaindoogh, group 2: vitamin D-fortified doogh (fortified with 500 IU vitamin D3 and 150 mg Ca/250 mL), group 3: vitamin D+calcium-fortifieddoogh (fortified with 500 IU vitamin D3 and 250 mg Ca/250 mL). The subjects took their respectivedoughs twice per day for 12 weeks.Anthropometric markers (weight, body mass index, and waist circumference), fasting serum glucose (FSG), glycated hemoglobin (HbA1c), and homeostasis model of insulin resistance (HOMA-IR) were measured before and after the intervention.Results: In both groups 2 and group 3, the mean serum 25 (OH) D3 level increased significantly (P<0.001). As compared to group 1, in groups 2 and 3 the decreases in FSG [-12.9±33.7 mg/dL (P=0.015) and -9.6±46.9 mg/dL (P=0.035), respectively], Hb A1c [-0.4±1.2% (P<0.001) and -0.4±1.9% (P, 0.001), respectively], HOMA-IR [-0.6±1.4 (P=0.001) and -0.6±3.2 (P, 0.001), respectively], and waist circumference (WC, -3.6±2.7 and -2.9±3.3, respectively, P<0.001 for both) were significantly higher. An inverse correlation was observed between changes in serum 25 (OH) D3 and FSG (r=20.208, P=0.049) and HOMA-IR (r=20.219, P=0.005).Conclusion: Daily consumption of vitamin D-fortified doogh with or without added calcium, improves anthropometric and glycemic status in diabetic patients.

Background and Objectives: Because of the high perishability of fish, keeping the quality of fresh fish is one of the most important problems in the fish-processing industry and for the consumers. The aim of this study was to determine the antibacterial and antioxidant effects of bacteriocine Z on silver carp fillets during refrigerated storage.Materials and Methods: After being weighed, fish fillets were sprayed with nisin Z (0.2 g/kg) packaged in vacuum and refrigerated (4oC). Microbial (TVC, PTC, LAB) and chemical (PV, TBA, TVB-N) parameters were measured at days 0, 3, 6 and 9.Results: As compared with the nisin Z-treated fish samples, the psycrotrophic, lactic-acid, and aerobicmesophilic bacterial counts were higher in the control samples. The microbial parameters decreased significantly in the nisin Z-treated samples at the beginning of the period, followed by a slower rate of increase than the control, the chemical parameters showed a slower rate of decrease.Conclusion: Using metabolites as natural preservatives in fish fillets may increase shelf-life of silver carp fillets during refrigerated storage. Bacteriocine Z may extend their shelf-life at 4oC by 3 days.

Background and Objective: There is evidence on reciprocal effects of insulin and desacylghrelin (DAG), but associations between secretions of hormones (insulin and DAG) and saturated and unsaturated proportions of edible oils in high-fat diets have not been studied. The aim of this study was to investigate the impact of different sources of dietary fat and the extent of fatty acid saturation on plasma insulin and DAG levels and determine the association between DAG and insulin action in rats.Materials and Methods: Weaning male Wistar rats were randomly divided into four groups to be fed on one of 4 high-fat diets containing, as the source of fat, butter (HF-b), soybean oil (HB-S), olive oil (HFO), or fish oil (HF-F). A fifth group was put on a standard diet (SD). Blood samples were collected after 8 weeks at non-fasting state and after a 24h fast. Body weight, food intake, and plasma parameters-glucose, insulin, DAG, and HOMA-IR, as an insulin resistance index – were measured.Results: Body weight and food intake in the HF-S and HF-B groups were higher than in the other groups (p<0.05). In the HF-B group the fasting insulin level and HOMA-IR were both higher as compared to the ST, HF-O or HF-F group (p<0.05). In addition, the fasting DAG level in the HF-B group was lower than in HF-F, HF-O or ST group (p<0.05). Finally, the HF-F group had a significantly higher DAG level than the HF-S group (P<0.05).Conclusion: Diets containing polyunsaturated w-3 and monounsaturated fatty acids cause lower weight gains and energy intakes. It is likely that these dietary fats could bring about a decrease in appetite through increasing the DAG level, thereby causing weight reduction. It is concluded, then, that they may have a role in lowering HOMA-IR or insulin level.

Background and Objective: In the last few years there has been a growing trend to use chickpea as a good protein source. Chickpea protein products, such as chickpea flour, concentrate and isolate, are considered as functional food supplements, alternatives to soy protein. The objective of this study was to determine and compare the functional and thermal properties of chickpea and soy-protein concentrates and isolates.Materials and Methods: Chickpea protein concentrate and isolate were prepared from defatted chickpea flour by applying alkaline extraction and isoelectric precipitation. Chemical composition (protein, fat, ash, crude fiber, and water contents), functional properties (water and fat absorptions, gelation, foaming capacity, and foam stability), and thermal properties (glass transition and denaturation temperatures) of chickpea protein concentrate and isolate were determined and compared with those of the soy protein products.Results: The protein contents of the concentrate and isolate obtained from defatted chickpea flour were 80% and 88.6%, respectively, the corresponding proportions for soy concentrate and isolate were 83.1% and 90.2%. There were no statistically significant differences as regards water and oil absorptions between soy and chickpea proteins. The gelation properties and foaming capacity of all the samples increased with an increase in protein concentration. However, soy protein had a higher foaming capacity and foam stability as compared to chickpea protein (P£0.01). Both the chickpea and soy-protein isolates had a semicrystalline structure, while soy protein showed a higher thermal stability than chickpea protein.Conclusion: The results reveal that some functional properties of chickpea protein are similar to those of soy protein. Its high nutritional value, the high indispensible amino acid content and good functional properties of chickpea, makes it ideal substitutes for other dietary proteins.

Background and Objective: No information is available on the consumption of creatine supplements in Iran. Creatine supplements are very popular among athletes. The annual sales only in USA in 2001 were reported to exceed $400 million. Considering the claims of creatine ethyl ester (CEE) manufacturers and distributers about its effects on muscle tissue and strength compared to other creatine forms (specially creatine monohydrate), this investigation was initiated to determine the effects of dietary supplementation of CEE on muscle strength and body composition in underweight non-athlete males.Materials and Methods: This was a double-blind placebo-controlled study. Sixteen underweight nonathlete volunteers were randomly assigned to either a CEE group (CEE, n=8) or a placebo group (PL, n=8). In the CEE group, the supplements were orally ingested at a dose of approximately 20 g/day for the first 5 days (the loading phase), followed by ingestion of approximately 5 g/day for 37 days (the maintenance phase). Subjects in the PL group took rice-flour capsules instead of CEE. Body weight, fatfree mass, and fat mass, as well as muscular strength (bench press and leg press) of the subjects, were measured at the beginning and at the end of a training period of 6 weeks, 3 sessions per week. The independent t-test was used for statistical analysis.Results: Results showed that the CEE group demonstrated greater improvements in 1 Repetition Maximum (1RM) of bench press (12.5 vs.7.5 kg) and leg press (8.12 vs.5 kg) than the PL group, although the differences were not statistically significant. Also, body weight (1.69 vs.0.5 kg) and aft-free mass increased to a greater extent, and fat mass decreased, in the CEE compared to the PL group, but in this case the differences did not reach statistical significance either. Finally, no significant changes were observed in thigh (1 vs 0.63 cm) or upper arm (0.63 vs.0.48 cm) circumference or body mass index in either group.Conclusion: It is concluded that CEE supplementation is not necessarily effective as regards increasing muscle mass and strength or improving body composition in underweight non-athlete males.

Background and Objective: Date-palm fruit is an important horticultural fruit in Iran with a high nutritive value due to its contents of minerals, sugars, vitamins and antioxidant compounds. In this research the effects of drying process on phenolic-compounds content and antioxidant properties of two common date varieties in Kerman Province, Iran, namely, Mazafati and Kaluteh, were investigated.Materials and Methods: Two common date varieties in Kerman province, Iran, namely, Mazafati and Kaluteh, were chosen. They were dried by 2 methods-sun-drying and oven-drying at 50o, 60o, 70o and 80oC. The phenolic content was measured by the Folin-Ciocalteau method and the antioxidant activity by reducing-power assay, total antioxidant capacity, and DPPH methods.Results: The drying process causes a decrease in phenolic compounds in comparison with fresh dates. The reductions in both total phenolic-compounds content and total antioxidant activity increased by increasing the drying temperature. The highest and lowest contents of phenolic compounds and antioxidant activity were found in the sun-dried and oven-dried (at 80oC) samples, respectively. The Mazafati variety had a higher content of phenolic compounds (780 mg galic acid/100 g dry weight) and a higher antioxidant activity (35% radical scavenging DPPH) than the Kaluteh variety (720 mg galic acid/100 g dry weight and 28% radical scavenging DPPH, respectively). Keeping date fruits at a constant temperature for a long period also led to decreases in the phenolic-compounds content.Conclusion: Drying process results in decreases in phenolic compounds and antioxidant activity of dates, the higher the drying temperature, the higher in losses in phenolic compounds and antioxidant activity.

Background and Objective: The increasing trend in recent years of overweight and obesity in children, known to be associated with adult obesity and other physical and mental diseases, makes them one of the most important health and social problems today. Lifestyle is an effective factor in the etiology of child overweight and obesity. The purpose of this study was to examine the relationship of overweight and obesity in primary schoolgirls in the 3rd-5th grades in the 6th district of Tehran with some lifestyle variables.Materials and Methods: This was a case-control study including 314 primary schoolgirls in the 3rd-5th grades, selected by simple cluster-sampling in the 6th district of Tehran. Data were collected on the following variables: body weight, height and body mass index (BMI), pocket money, types of snacks usually consumed and the amount of money spent on them, duration of daily sedentary activities and snack consumption during these activities, sleeping hours, skipping main meals, type of snack taken in case of skipping breakfast, physical activity, and how the girls went to school (i.e., on foot, by bus, etc.).The statistical tests used were Chi-square (or Fisher), Mann Whitney, one-way ANOVA, Turkey’s HSD, and backward stepwise regression.Results: The following variables were positively associated with overweight and obesity in the schoolgirls: media use (such as TV watching, electronic games, computer using) during weekdays and weekends, pocket money and the proportion of it spent on snacks, frequency and kinds of snacks during sedentary activities, meal skipping frequency and the kind of snack substituted for breakfast. Sleep duration, frequency of snacking, daily physical activity, and walking duration (between school and home) were inversely related to overweight and obesity. No associations were found between overweight and obesity on the one hand and after-dinner snack or homework duration on the other hand.Conclusion: Overweight and obesity among the 3rd-5th grade are related to schoolgirls’ lifestyle variables, the most important of which are sleep duration, eating snacks when watching television or working with the computer, skipping breakfast or dinner, and pocket money and the proportion of it spent on snacks. Not all these associations are statistically significant.

Background and Objectives: Fish is an excellent protein source due to its valuable essential amino acid composition. Physical, chemical and thermal treatments applied during processing of food will influence both the nutritional value and functional properties of proteins. The purpose of this study was to determine the effects of grilling on the nutritional value of Persian sturgeon fish fillet.Materials and Methods: Fresh Persian sturgeon fillets were grilled using an automatic griller (Bq100, Delongi, Germany) for 20 min at 50-60 Hz frequency. The nutritional value of fresh fillets was determined on the basis of moisture, protein, fat, ash, and amino acid contents, while the nutritive value of cooked fillets was estimated usingin vitro protein digestibility (IVPD) and various computed indices, including chemical score (CS), essential amino acid index (EAAI), biological value (BV), and protein digestibilitycorrected amino acid score (PDCAAS).Results: There were significant increases in protein, lipid, and ash contents (p<0.05) after grilling.In vitrodigestibility of raw fillets was 81.50%, which increased to 93.46% after cooking. Glutamic and aspartic acids were amino acids with the highest contents, while cysteine and methionine were the limiting ones in both cooked and uncooked fillets. Grilling brought about improvements in the protein efficiency ratio, essential amino acid index, nutritional index, biological value, and chemical score.Finally, the protein digestibility- corrected amino acid score of both the cooked and uncooked samples and for both the 10-12 year-old and adult age groups was 100.Conclusion: The results indicate that grilling improves the nutritional value of Persian sturgeon fish fillets.