فصلنامه علوم تغذیه و صنایع غذایی ایران
سال چهارم شماره 1 (پیاپی 12، بهار 1388)

Information of the effects of different types of fat on liver pathology are limited. The present study was designed to compare the effects of a fish-oil containing diet, a diet with a fat composition based on the Iranian fat consumption pattern, and a standard diet on pathologic changes in the Wistar rat liver. Thirty female Wistar rats were randomly allocated to one of three diets: a standard diet (containing soy bean-oil), a diet containing fish oil, and one containing mixed oil based on the Iranian population fatty acid intake. Dams in each group were fed one of the diets during pregnancy and lactation, and the pups were weaned onto the same diet. Hepato-cellular pathology in pups was assessed on days 21 and 70 postnatal. Data were analyzed using the SPSS software and Kruskal-Wallis test. Fish oil-fed and Iranian mixed oil-fed pups showed more ductular cell hyperplasia on day 70 postnatal, as compared to the soy bean oil-fed pups (p=0.005). The pathologic changes increased from day 21 to day 70 in all the 3 groups (p=0.002). The magnitude of the increase was significant in the fish oil-fed rats (p=0.007). A diet containing fish oil as the only fat source and a diet with the Iranian population fatty acid intake pattern may lead to pathologic changes in the rat liver. It seems this adverse effect increases by age of the animal.

Doogh is a kind of Iranian fermented dairy-based drink produced by adding water and salt to yoghurt. The major problem of this product is serum separation during storage, because of its low pH and aggregation of caseins. In the present study, the efficiency of some hydrocolloids in preventing serum separation as well as the stabilization mechanism of gum tragacanth–a local gum–were investigated. The effects of high-methoxyl pectin, tragacanth, and locust bean gum at different concentrations, individually and in combined forms, tragacanthin, and soybean soluble polysaccharides type M, on the stability of sour Doogh were investigated. In addition, the influence of gum tragacanth and locust bean gum on the stability of prebiotic Doogh (containing inulin) was also studied. In each case the duration of the study was 30 days. In order to elucidate the stabilization mechanism of gum tragacanth, the rheological properties, zeta potential, and microstructural characteristics of the stabilized Doogh samples were measured. According to our findings, tragacanthin, tragacanth and locust bean gum could inhibit serum separation for 30 days at a concentration of 0.1, 0.2 and 0.3%, respectively, while type M soybean soluble polysaccharides caused the stabilization at a concentration of 0.6% only for 6 days. Furthermore, combinations of gum tragacanth and locust bean gum were also effective in fully stabilizing Doogh (at a concentration of 0.15% and ratios of 80:20 and 50:50). Inulin was not effective in stabilizing the sour Doogh samples. However, tragacanth and locust bean gums inhibited serum separation in prebiotic Doogh. Based on our findings, the most suitable rheological model for the control samples and the samples containing hydrocolloids were the Newtonian and Power law, respectively. Based on the results of this study, tragacanthin (the water-soluble part of gum tragacanth) seems to have a major role in stabilizing Doogh, probably by being adsorbed onto caseins (via electrostatic and steric repulsion). On the other hand, bassorin (the water-insoluble part of gum tragacanth) may help stabilization by increasing viscosity. Therefore, gum tragacanth could be strongly recommended to be used as an adsorbing hydrocolloid in sour Doogh to inhibit serum separation.

Bioelectrical impedance analysis (BIA) is a simple and noninvasive body composition analysis technique. The aim of this study was to assess the body composition and its trend of changes in adult cancer patients referred to Tehran Rasol-e-Akram and Firoozgar Hospitals for chemotherapy. In this cross-sectional study, 71 patients (41 men and 30 women, 51.9±15.4 years old) with different types of malignancies were selected from the 2 hospitals by stratified sampling. Body composition was determined by the BIA technique at the beginning, in the middle, and at the end of the chemotherapy treatment period. Data were analyzed by repeated measure ANOVA and Wilcoxon tests, using the SPSS12 software. Nonsignificant changes were observed in the mean weight, fat-free mass, fat mass, dry fat-free mass and total body water of the 50 patients who successfully completed the treatment (average of 5 months). Twenty-one patients died during the treatment cycles (average of 2.5 months). They had a significant decreasing trend for weight, fat mass and dry fat-free mass (P= 0.01, P= 0.02, and P= 0.01, respectively); they had a higher reduction of fat mass than fat-free mass (2 ± 3.8 kg and 0.7±1.9 kg respectively). Weight reduction of the cancer patients who died during the study was due to both fat mass and dry fat-free mass reductions, while in the patients who successfully completed the treatment no significant changes in body weight or body compositions were observed. It can be concluded that weight loss due to reductions in fat mass and dry fat-free mass in cancer patients during chemotherapy may result in their decreased survival.

Biosurfactants are a heterogenous group of surface active molecules produced on microbial cell surfaces or excreted extracellulary. They are powerful natural emulsifiers, solubilizing and wetting agents. Rhamnolipids belong to the glycolipid class of biosurfactants and were first isolated from Pseudomonas aeruginosa. Rhamnolipids are an attractive alternative to synthetic surfactants because of low toxicity, better environmental compatibility, and high selectivity. The aim of this work was to optimize biosurfactants production by Pseudomonas aeruginosa ATCC 9027 and two hyper producing mutant strains (M6 and M34) using different culture conditions. The rhamnolipid-producing medium (Lindhardt) containing different carbon sources were inoculated with 5% (v/v) of a 24-h preculture. The cultures were then incubated on a rotary shaker at different temperatures and rates, with different durations. The rhamnolipids were precipitated by acidification of the culture below pH 2.0 and the precipitate was extracted by organic solvents. The results showed that the carbon source used in a culture medium, bacterial strain, and temperature are the most important factors in the production of biosurfactants. The maximum rhamnolipid concentration, 2.21g/l, was reached when the M34 strain was incubated at 30oC and 150 rpm for 7 days using Canola oil as the carbon source The mutant strain M34 can be used to produce large amounts of rhamnolipid for food, chemical, pharmaceutical and hygienic applications.

Malnutrition is an important health problem in hospitals and its association with increased morbidity and mortality has been well-documented. Since the condition can be readily treated, often at low cost, it is logical that efforts should be made to identify malnutrition for timely nutritional interventions. A nutrition screening tool (a questionnaire) was designed on the basis of recommendations of the British Association for Parenteral and Enteral Nutrition and used to identify individuals who are malnourished, at-risk of malnutrition, or may need nutritional support. The aim of this study was to evaluate the validity and reliability of this tool in a hospital in Tehran, Iran. A total of 446 patients, aged over 18 years, admitted consecutively to different wards of Taleghani Hospital in Tehran, Iran during six months were studied in the first 24 hours of admission. For testing validity of the questionnaire used, first a nutritionist made a full nutritional assessment of all the patients. The assessment included the following items: a. measurements of weight, height, body mass index (BMI), triceps skinfold (TSF), and mid-arm circumference (MAC); b. weight history and percentage of involuntary weight loss over the previous 3-6 months; a 24-hour dietary recall; c. gastro-intestinal symptoms. The results of the assessment were, then, compared with the results obtained from the screening questionnaire. The inter-rater reliability of the screening tool was assessed by two nurses who completed the screening questionnaire separately during 72 hours following admission of the patients. The agreement between results was calculated. There was 66% agreement between the nutritionist’s assessment results and the nurses’s assessment results using the nutritional screening tool. The sensitivity and specificity of the screeing tool were 83.7% (95%CI: 80.0-87.4 %) and 84.7% (95%CI: 81.1-88.1 %), respectively. Further analysis of the data showed the positive predictive value to be 92.3% (95%CI: 89.6-95./0 %) and the negative predictive value to be 70.2% (95%CI: 65.8-74.8%). The mean inter-rater reliability (K=0.51) was moderate. The screening tool, completed separately for each patient by the two nurses, is reliable and, in comparison with the more objective nutritional assessment, has an acceptable validity. The questionnaire is useful for identifying malnourished patients in a hospital setting.

Xanthan gum is an important natural biopolymer with numerous applications in various technologies, specially food industry. In this research, microbial production of xanthan by Xanthomonas campestris PTCC1473 from sugarcane molasses and date sugar in submerged fermentation (SmF) and also dried date waste (cake produced after pressing) in solid state fermentation (SSF) were compared. The Plackett-Burmann design (PBD) was used in this study. Chemical composition and characteristics (dried cell weight, nitrogen, moisture, ash and pH) of the substrates were determined. Yeast malt broth (YMB) and yeast malt agar (YMA) were used as maintenance and inoculum preparation media, and incubation was performed in a shaker incubator (at 28 °C, 72 h and 200 rpm). The fermentation medium was centrifuged at 5°C and 21055  g for 50 minutes and the supernatant separated from the pellet for further xanthan extraction. After precipitation of xanthan by isopropanol, resuspension and further purification by centrifuge (at 2056  g), the xanthan dry weight was determined. The effects of several variables, including the kind and concentration of carbon (date sugar and sugarcane molasses), nitrogen (ammonium nitrate and diammonium phosphate) and phosphorus (KH2PO4), temperature, shaking, and size and age of inoculum, on the yield were determined. The most effective variables were found to be the type of carbon and nitrogen sources in the medium. It can be concluded that both the yield (% w/w of xanthan/consumed sugar) and productivity (g/g.day xanthan/consumed sugar) are higher in SmF (22.4 and 7.46) than in SSF (13.3 and 4.43). In addition, date extract results in a higher productivity than date waste and sugarcane molasses. The xanthan yield could be increased by changing the composition and physical conditions of the culture medium.

Urolithiasis is the third urinary disease and evidence shows that its incidence has increased continually during the past decades. The relationship between urinary stones and diet is known to some extent, but there are controversies about it. The aim of this study was to determine the relationship between dietary habits, food intake patterns and urinary stone disease. This was a case-control study with 161 adult patients with urinary stone disease referred to Hasheminejad Urology Center, Tehran, Iran, and 254 healthy subjects matched for age and gender. All the subjects were interviewed using a questionnaire to obtain data on demographic characteristics, dietary habits, and food consumption frequency. Data were analyzed using SPSS version 14. The independent T-test, chi square and regression were used to examine the differences. Findings showed that male-to-female ratio was 1.98:1. The prevalence of renal stone was highest in men aged between 30 and 50 years and in women aged between 40 and 60 years. There were no differences in height and weight between the two groups, but BMI was significantly higher in the case group (p=0.007). A family history of renal stones was observed more frequently in the patients (59% compared to 31.9%; p<0.001). The mean intakes of food sources of several nutrients were lower in the patients than in the healthy subjects: calcium (p=0.048), phosphorus (p=0.001), potassium (p<0.0001), vitamin A (p<0.0001), vitamin D (p<0.0001), and vitamin C (p=0.004). Regression analysis confirmed the differences between the two groups as regards sources of vitamins A and D. The intakes of sources of magnesium and vitamin B6, as well as of foods rich in oxalate, were not significantly different between the 2 groups. Results suggest that there are associations between urinary stone formation and the dietary intakes of nutrients such as calcium, phosphorus, potassium, vitamin A, vitamin D, and vitamin C. Considering the challenges of treatment and the costs of this relatively common disease, dietary recommendations may be an easy and cost-effective way to reduce its burden.

Lactic acid bacteria are microorganisms with ability to produce a wide range of chemical compounds that affect the shelf-life of foods. The objective of this study was to determine the potential ability of probiotics isolated from Iranian local yogurts to produce lactacins and assess their antimicrobial activity. Samples were prepared from 20 kinds of local yogurts (Arak, Sarein, Shahandasht, and Damavand) to isolate and purify lactic acid bacteria in an MRS agar medium and compare them with 3 isolated probiotics strains, i.e., L. casei (PTCC 1608), L. reuteri (PTCC 1655) and L. rhamnosus (PTCC 1637). The inhibition of growth zone was tested, by the well diffusion agar method, on 5 gram-positive and gram-negative bacterial strains. The maximum amount of antimicrobial substance produced was determined by comparing the growth curves, and extraction purification of the lactacins was done by dialysis. In each stage the amount of protein extracted was determined by the Lowry method, and the recovery percent, total protein, unit activity, specific activity, purification fold, and bacteriocin field were calculated. The molecular weight of the extracted protein was determined by the SDS-PAGE method. A total of 21 lactic acid bacterial strains were isolated. The maximum antimicrobial components were found to be produced by Ln11 and Ld17 during the logarithmic phase of growth curve. The results of SDS-PAGE showed lactacins with molecular weights ranging from 48 to 57 KD. Considering the antimicrobial properties of the bacterial strains isolated from the local yogurts, they can be used as local probiotic strains in production of fermented foods in preference to the 3 standard strains.