JOURNAL OF NUTRITION SCIENCES & FOOD TECHNOLOGY
Year:2011 | Volume:5 | Issue:4 (19)|Papers Count:9

Background and Objectives: One of the major defects in acidified milk–fruit juice mixtures is their physical instability due to low pH, low viscosity, and sedimentation of caseins. In the present study, the influence of some commercial and local gums on the stability, rheological, and sensory properties of milk–orange juice mixture was investigated.Materials and Methods: The effects of pectin, locust bean gum, guar gum, gum tragacanth, Persian gum, water-soluble fractions of gum tragacanth (tragacanthin) and Persian gum over a wide range of concentrations on the physical stability of milk–orange juice mixtures during storage at low temperature (4oC, 30 days) were determined. Moreover, the stabilization mechanisms were studied using rheological (rotational and oscillatory tests), zeta potential measurements, and microstructural observations. Finally, sensory evaluation was made on the physically stabilized samples.Results: Pectin, locust bean gum, guar gum, gum tragacanth, Persian gum, and water-soluble fractions of tragacanth and Persian gum effectively prevented phase separation for 30 days at concentrations of 0.5%, 0.5%, 0.4%, 0.3%, 2.2%, 0.175% and 1.0%, respectively. Furthermore, combinations of water-soluble fractions of gum tragacanth and Persian gum (ratios of 4:96 and 19:81) at a concentration of 0.37% or 0.53% caused stabilization. The best fitted rheological models for the control (milk–orange juice mixture without hydrocolloids), the pectin-containing one, and rest of the samples were Bingham, Herschel-Bulkley, and Power law, respectively. In terms of sensory properties, the mixture stabilized with a combination of water-soluble fractions of gum tragacanth and Persian gum (0.53% w/w) achieved the highest scores by the taste panels (p<0.01).Conclusions: Based on the findings of the present study, water-soluble fractions of gum tragacanth and Persian gum can be categorized as anionic hydrocolloids which are adsorbed on the surface of caseins which can prevent aggregation via steric and electrostatic repulsions by simulating a hairy layer. In addition, their insoluble fractions could promote physical stability of the mixtures due to making a gel-like network and increasing viscosity.

Background and Objectives: Protein-energy malnutrition (PEM) is prevalent among hemodialysis patients. So far, no study has compared various methods for determination of PEM, including subjective global assessment (SGA), dialysis malnutrition score (DMS), malnutrition inflammation score (MIS), and body mass index (BMI), in hemodialysis patients. The present study was designed to determine sensitivity, specificity, accuracy, positive and negative predictive values, as well as positive and negative likelihood ratios of DMS, MIS and BMI in comparison with SGA as the most common method for determination of PEM inhemodialysis patients. Subject and Methods: A total of 291 hemodialysis patients were randomly selected by systematic sampling from among 2302 eligible adult hemodialysis patients in Tehran hospitals. The nutritional status of the patients was assessed by completing SGA, DMS and MIS forms and determining BMI. In addition, after a 12- to 14-hour fast, 4-mL blood samples were obtained from each patient before dialysis for measurement of serum urea, creatinine, albumin and total iron binding capacity. Results: Based on SGA, DMS, MIS, and BMI, the prevalence of mild-to-moderate PEM in Tehrani hemodialysis patients was, respectively, 60.5%, 61.5%, 54%, and 16.5%, and that of severe PEM 1%, 1.5%, 1%, and 1%. In comparison with SGA, the sensitivity, specificity, accuracy, area under the receiver operating characteristic (ROC) curve, positive and negative predictive values, and positive and negative likelihood ratios were, respectively,  94%, 88%, 92%, 97%, 93%, 92%, 7.8, and 0.07 for DMS; 87%, 96%, 91%, 97%, 97%, 83%, 22.0, and 0.13 for MIS; and  23%, 91%, 50%, 64%, 80%, 43%, 2.5, and 0.85 for BMI. Conclusion: The results of the present study indicate that the DMS and MIS are almost similar to SGA, in identifying malnutrition in hemodialysis patients, while BMI is not an appropriate index in this regard. In addition, it appears that the DMS is a more appropriate alternative method for SGA in routine hospital assessments. 

Background and Objectives: Chemical production of vitamin B12 is a complicated process. The purpose of this study, done for the first time in Iran, was to produce vitamin B12 by Propionibacterium freudenreichii and investigate the effect of adding betaine on its yield.Materials and Methods: Propionibacterium freudenreichii was added to a fermention culture medium containing filtrated soaked corn. This was followed by incubation at 30oC and, then, adding betaine at six concentrations (0, 5, 10, 15, 20 and 30 g/l). Separation and purification were done and the presence and the amount of vitamin B12 produced were determined by HPLC.Results: The most effective concentration of betaine for vitamin B12 production (318.33 Pg/ml) was 10 g/l, which had a negative effect on dry weight of the cells (22.37 g/l). The results demonstrated that betaine could greatly stimulate vitamin B12 biosynthesis by Propionibacterium  freudenreichii and inhibit cell growth. Conclusion: Based on the findings of this study, betaine added to the culture medium of Propionibacterium  freudenreichii at a suitable concentration could increase the yield of vitamin B12, paving the way to a commercial, more economic method for its production.

Background and Objectives: A deficiency of folate or vitamin B12, particularly in tissues with a high cell replication rate, could inhibit RNA and DNA synthesis, DNA methylation, as well as cell maturation. Therefore, a sufficient intake of these vitamins in childhood is of vital importance. Since there are no published reports on the status of folic acid and vitamin B12 in Iranian children, the present study was conducted to assess serum and red blood cells concentrations and some related factors in healthy 3-6 year-old children in Tehran, Iran, 2010.Subject and Methods: This was a cross-sectional, descriptive-analytical study, in which 228 children, 3-6 year old (105 girls and 123 boys), were selected by random systematic cluster sampling from 20 (out of 270) day-care centers in Tehran. A 2-ml non-fasting blood sample was drawn from each child and analyzed for serum and red blood cell folate and vitamin B12 by the RIA method. SPSS.16 was used for data analysis, the statistical tests being t-test, Chi-square and ANOVA. Results: There were no significant differences between the 2 sexes with regard to age, weight, height, BMI, RBC folate, or serum folate and vitamin B12 levels. Based on the serum folate level, 9.6% and 37.8% of the children suffered from severe and mild deficiency, respectively; 52.6% had normal folate serum levels. The data also showed that 97.4% of the children had a normal serum vitamin B12 level, only 2.6% being mildly deficient. As judged by the RBC folate level, of 105 children (60 boys and 45 girls), 1% and 37% had severe and mild deficiency, respectively, an absolute majority (62%) having normal levels. The distributions of serum folate, serum vitamin B12, and RBC folate levels were not statistically different between boys and girls. Similarly, no associations were observed between the RBC folate level, serum folate level, or serum vitamin B12 level and age, weight, height, family size, birth order, or head of the family. There were positive significant correlations between serum folate on the one hand and RBC folate (r=0.4, p<0.001) and serum vitamin B B12 (r=0.8, p<0.001) on the other hand. Furthermore, folate, RBC folate, and serum vitamin B12 were all positively related to father’s education (p=0.01), mother's education (p=0.008) and father’s job status (p<0.027). In addition, the vitamin levels were higher in children of the working mothers, as compared to those of non-working mothers (p<0.036). There were no differences between the 2 groups with regard to other variables. Conclusion: Folate deficiency is highly prevalent, while the deficiency of vitamin B12 is low, among Tehrani preschoolers. It is recommended to design and implement suitable intervention programs. Major components of such programs should be mothers’ nutrition education and improving family food consumption patterns with particular emphasis on optimum utilization of folate sources, particularly vegetables.

Background and Objectives: Nowadays, acid-induced milk protein gels are used extensively in the dairy industry and are the base of many food products. Therefore, a deeper fundamental understanding of the effects of process parameters and system components on the mechanisms of gel formation and final gel properties in real and model systems is important for researchers and industries. The present study was designed to investigate the effects of casein-to-whey protein ratio, incubation temperature, and heating temperature on viscoelasic properties of the final gel in a model system.Materials and Methods: Samples of solutions with different casein-to-whey protein ratios (2.1:0.9, 2.4:0.6 and 2.7:0.3) were prepared and refrigerated overnight. This was followed by heating the samples at different temperatures (70, 80, or 90oC) for 15 minutes using a water bath and cooling to incubation temperatures (25, 35 or 45oC). In the next step lucono-d-lactone was added and the samples were transferred to a rheometer. The gelation process was monitored by the time sweep oscillatory test. A second-order polynomial model was fitted to the experimental data and the optimum response was determined using the Minitab15 software. Results: Incubation and heating temperatures influenced significantly (P<0.001 and P<0.01, respectively) the G'200 value (storage modulus value of the final gel measured 200 minutes after addition of GDL). The casein-to-whey protein ratio had no significant influence on the G'200 value. Increasing the incubation temperature led to a decrease, whereas increasing the heating temperature led to an increase, in the G'200 value. The maximum value of G'200, 268/93 Pa, was obtained at the presence of 2.6152% (w/w) casein and at incubation and heating temperatures of 25oC and 90oC, respectively. Smaller quantities of casein and higher incubation and heating temperatures shortened the length of time required for gel formation. Finally, increased incubation temperatures and decreased heating temperatures led to increased the damping factor (tan d).Conclusion: The effects of different process parameters on the viscoelastic properties of dairy gels can be determined and characterized by oscillatory rheometry. The findings of this study show that incubation temperature is the most effective factor, whereas casein-to-whey protein ratio has no significant effect on the final gel strength.

Background and Objectives: This study was carried out with the aim of comparing the effect of diet therapy and narrative intervention on the extent of body mass index (BMI) reduction in overweight and obese women.Subject and Methods: This was a quasi experimental-interventional study, in which 30 overweight women were selected by random sampling from among those consulting the Diet Clinic and randomly assigned to one of 2 intervention (group 1, diet therapy alone; group 2, diet therapy plus narrative therapy) and a control group (receiving no intervention). The period of intervention was 5 weeks. Weight of all the subjects with light clothing was measured by a Seca scale to the nearest 0.5 kg and their height by a stadio-meter to the nearest 0.5 cm. The BMI was calculated by dividing weight (in kg) by squared height (m2). The data were analyzed using the SPSS 16 software, the statistical test being covariance analysis and paired t- test.Results: Data analysis showed that diet therapy alone (group 1) had no significant effect on the BMI (P>0.05), while in group 2 (diet therapy plus narrative therapy) BMI decreased significantly (P<0.001). Inter-group comparison (among the 3 groups) showed that there were no significant difference between diet therapy and narrative therapy with regard to BMI.Conclusion: The findings show that in the first phase of intervention life narratives about overweight help obese women correct their nutritional habits. This is followed by BMI reduction in the second phase. Since diet therapy is not consistent with the women’s life narratives, it plays no role in correcting life narratives for more successful dieting. Considering the efficacy of narrative therapy in body mass index reduction and no effect by diet therapy alone, further studies on the life narratives of overweight women and their correction are recommended.

Background and Objectives: Studies show that huge amounts of bread are wasted in our country. One reason for this is the dough preparation process. The objective of this study was to explore the possibility of making bread from frozen dough to reduce bread wastage.Materials and Methods: Dough was prepared by the all-in method and frozen at -30oC to -35oC (fast freezing) or -18oC to -20oC (home freezer, slow freezing). The frozen doughs were packed in two-layer polyethylene bags and stored at -18oC, defrosted after 24h, 48h, 72 h, and one week storage, and tested for extensographic characteristics. Barbari bread (a type of Iranian flat bread) was then made from the thawed dough samples and, after sensory evaluation, was stored for 1-4 d in two-layer polyethylene bags at ambient temperature, in order to do staling tests.Results: Storage time significantly affected extensibility, resistance and the coefficient D (p<0.05). The type of flour had no significant effect on extensibility, resistance, or energy changes. Sensory evaluation showed that shape and upper crust surface of the Barbari bread was significantly affected by the freezing method and flour type (p<0.05). The data also showed that the lower crust surface, chewiness, aroma, and taste of the bread were statistically significantly associated with the flour type. The flour type, freezing method, and storage time had no significant effects on porosity, firmness, or staling. Conclusion: Fast-frozen dough prepared from strong flour can be an appropriate alternative for fresh dough for making Barbari bread.

Background and Objectives:  Early child nutrition plays a vital role in the growth and development not only in infancy but also later in life. This study was carried out to determine the views, beliefs and experience of mothers, caregivers and health professionals about the role of socio-economic and cultural factors in child feeding practices in Damavand, a district located in the north of Tehran, in 2008.Subject and Methods: In a qualitative study 23 focus group discussions (FGDs) were held with the presence of a facilitator, 2 rapporteurs, and a supervisor. Mothers of under-2-year-old children attended 11 FGDs, and 8 FGDs were arranged for home caregivers (grandmothers), out-of-home care-givers (community child health nurses), and rural and urban health workers. At the end of the field work all the notes taken in the FGDs were coded based on objectives of the study. Then the subgroups for each objective and emerging themes were derived and reported. The data were analyzed using content analysis.Results: Most participants were aware of breast feeding and complementary feeding benefits. However, exclusive breast feeding was not followed precisely and the quality and diversity of the diet of children were ignored. The participants thought that social and economic factors, such as literacy, income, erroneous beliefs, family restrictions, and interference of elderly females, had a role in failure of breast and complementary feeding. Cultural factors appeared to have an important influence on mothers’ infant feeding practices and feeding patterns of their children.Conclusion: To overcome the problems related to breast feeding and complementary feeding practices, revision of the current nutritional protocols and educational programs is essential. In addition, involvement of mothers, caregivers, elderly women, and all those involved in child care, in nutrition education activities is recommended.