[Studies on the electrostatic interactions between beta -lactoglobulin and tragacanthin: the first step towards fabrication of biopolymeric micro- and nanoparticles]

Investigation of the colloidal behaviour of protein-polysaccharide systems is becoming increasingly important to provide a foundation for their applications in areas such as production of biopolymer micro-and nano-particles, designing food analogues, and microencapsulation technology. The aim of the present study was to investigate the pH-induced critical transitions during associative phase separation between beta -lactoglobulin [BLG] and tragacanthin [T]. The formation of electrostatic complexes in BLG/T dispersions [0.3wt.% total concentration; BLG:T ratio 2:1] was investigated as a function of pH [2.00-6.00] by spectrophotometry and particle size analysis. In addition, coupling of slow in situ acidification of the blend, with gluconodelta-lacton, and rheometry were used to monitor the structural transitions during the associative phase separation. The influence of salt type and concentration on the formation of micro-particles were also determined. The formation of soluble complexes started at pH -5.20, and at pH -4.85 the aggregation of intrapolymeric complexes occurred, followed by a bulk phase separation at pH -4.30. The data indicated that coacervation occurred at pH 4.15. Finally, the mixture returned to a mono-phasic system at pH 2.5. Particle size analysis showed that the assembled structures experienced a contraction process upon complexation. Rheometry provided deeper insights into the colloidal behaviour of the system and the results were in good agreement with quiescent pH-induced transitions established by HCl titration. The formation of the micro-particles was strongly salt-dependent. Under controlled pH conditions, electrostatic interactions between beta -lactoglobulin and tragacanthin can be used to form a variety of biopolymer particles. These biopolymeric micro- and nanoparticles may be used in the food industry as natural delivery systems or fat-replacers

[Production of selenium-enriched yeast using a Plackett-Burman design]

Today dietary deficiency of selenium [Se], an important mineral in human nutrition, is common in many regions and communities. Se-enriched yeast, obtainable by growing Saccharomyces cerevisiae in Se-rich media, is considered as a source of organic Se suitable for alleviating its deficiency due to its high bioavailability, stability, digestability, and absorbability. Using a Plackett-Burman design, the effects of various culture medium conditions, including temperature [28 and 30°C], initial pH [4.5 and 5.8], shaking speed [130 and 160 rpm], fermentation duration [24 and 48 h], size of inoculum [30 and 60 g/l], Se concentration [15 and 25 micro g/ml] and time of Se addition [0 and 9 h], on the bioaccumulation of Se in the yeast were investigated.. The Se content in the yeast was determined by graphite-furnace atomic-absorption spectroscopy. The results showed that Se concentration, size of inoculums, temperature, time of Se addition and fermentation duration were, in ascending order, the most significant factors on the yield of total Se accumulation and organic Se formation in the yeast. Manipulating these conditions/variables could markedly affect the magnitudes of incorporation of Se and formation of organic Se in the yeast, the ranges being 107.9 to 287.6 mg/kg and 93.27 to 269.05 mg/kg, respectively. The most suitable culture medium conditions to attain the highest level of total and organic selenium Se biotransformation in yeast are a concentration of 25 micro g/ml sodium selenite, an inoculum size of 30 g/l, a temperature of 28°C, an initial pH of 5.8, a shaking speed of 130 rpm, an incubation time of 48 h, and adding the selenium source to the culture medium 9 hours after the start of fermentation

Effect of phytase supplementation on zinc, iron and calcium status in rats fed with diet containing Iranian high phytate bread [Sangak]

Restricted mineral bioavailability of minerals in Iranian breads due to high levels of phytic acid has been reported for more than 50 years. Bread intakes still provide over one-third of the food energy through out the country. Hence improving bread mineral bioavailability can play an important role in decreasing the prevalence of many mineral deficiencies. The aim of this study was to assess the effect of phytase supplementation on blood, liver and bone zinc, blood and liver iron and femur bone calcium in growing Wistar male rats, fed a diet containing high phytate Iranian bread [Sangak]. Thirty weaning Wistar rats were assigned to the phytase [Aspergillus niger] or the control group for 6 weeks. The diet was designed based on Iranian food patterns and 34.2% of energy was supplied from Sangak bread with high amount of phytic acid. Feed intakes, weight gain, liver and femur bone weight did not differ between the groups. Blood zinc was higher in the phytase group [p=0.03], indicating the positive effect of phytase supplementation on blood zinc levels, independent of the growth process. Other variables did not show any differences between groups. We conclude that the addition of high phytate Iranian bread phytase to the diet can improve blood zinc status in growing rats

Diagnostic value of NT-BroBNP in HF patients admitted with dyspnea in Emergency Department

Considering the increasing prevalence of patients with dyspnea and the possibility of heart disease, as well as unavailability of echocardiography specially in primary care situations and unreliability of echocardiography findings in some diseases and finding NTProBNP as a diagnostic factor in heart failure in these patients, this study was done to determine the accuracy of NTProBNP in comparison to echocardiography in the diagnosis of heart failure in Modarress Hospital, in Tehran, between 2006 and 2007. This study, with a clinical trial diagnostic design, was performed on patients with chief complaint of dyspnea. The NTProBNP marker of serum was determined by Elecsys and patients were categorized according to age adjusted reference book values into two groups of with and without heart failure. Then, the patients underwent Simpson Echocardiography and Tissue Doppler; and the positive and negative predictive value for NTProBNP in relation to the echocardiography was determined and analyzed by statistical tests. One hundred patients were analyzed. Mean age was 59 +/- 11.8 years and 70% were male. PPV was 84%, NPV was 70.4%, false positive was 16%, while false negative was 29.5%. Sensitivity was 78%, specificity 77%, and accuracy was equal to 78%. It seems that NTProBNP marker is a good test for screening patients with dyspnea and besides clinical criteria it has an acceptable diagnostic value. It would be good to perform other studies, using more precise laboratory methods and reevaluation of cut point especially for Iranian patients considering factors other than age to obtain a rapid, easy, and costeffective test in primary care

[Comparison of bench-scale production of xanthan by xanthomonas campestris in solid state and submerged fermentation]

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 28degreeC, 72 h and 200 rpm]. The fermentation medium was centrifuged at 5degreeC and 21055 multiplied by 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 x 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

Comparison of the effects of vacuum oven-, freeze-, solar-, and microwave- drying with traditional drying methods on the qualitative characteristics of ghaen saffron

Saffron, the world's most expensive condiment, is one of Iran's most important non-petroleum exports. Its annual production in the country is about 220-228 tons and its export value over 59-70 million USD [the price is 454-482 USD/kilogram]. The aim of this study was to compare the effects of different dehydration methods, including vacuum oven-, freeze-, microwave- and solar0drying methods with the traditional drying method on the characteristics of saffron and determine the most suitable method. The study was conducted in the National Nutrition and Food Technology Research Institute, Tehran, Iran between 2001 and 2002. The methodology was experimental. A farm in the safflower-growing region of Ghaen was selected randomly, and the flowers were picked and mixed thoroughly. The percentage yield of the stigmas, and the morphological and chemical [moisture, ash, total nitrogen and acid-insoluble ash] characteristics were determined. Stigmas were dried, followed by determinations of the moisture content, total ash, acid-insoluble ash, cold water-soluble extract, total nitrogen, crude fiber, crocin, picrocrocin, and saffranal. The total microbial, choliform, yeast, mold, and Esherishia coli counts were also measured in the dried samples. The results indicated that from the color [crocin] point of view the solar-, vacuum oven-, and microwave-dried samples were the best [p<0.05]. As regards the contents of saffranal and picrocrocin, responsible for aroma and taste, respectively, there were no significant differences among the dried samples. The results of the microbial tests on the dried samples indicated that all the samples except those dried using the traditional or the freeze-drying method, the counts conformed with the Iranian standards. Although all of the four non-traditional methods of drying were better than the traditional method, we recommend sun-drying as a suitable method in the rural areas where saffron is produced