فصلنامه علوم تغذیه و صنایع غذایی ایران
سال هفتم شماره 1 (پیاپی 24، بهار 1391)

Phenylketonuria is a hereditary disease caused by a lack or deficiency of the enzyme phenylalanine hydroxylase, its most severe clinical manifestation being irreversible mental retardation. Presently, the only therapy available is the dietary restriction of phenylalanine. The objective of this study was to produce laboratory-scale low-phenylalanine milk to be used as a dietary supplement by phenylketonurics. Low-phenylalanine milk can be used to make a variety of palatable, low-phenylalanine foods and beverages. Three milk hydrolysates were prepared enzymatically (1g of enzyme/100 g of substrate), using a protease from Aspergillus oryzae and papain, separately and in combination (0.5 g of either enzyme/100 g of substrate), followed by adding different amounts of activated carbon (0.3, 0.9, and 1.5 g) to them to remove phenylalanine. The combination of Aspergillus oryzae protease and papain, along with the use of 0.9 g activated carbon in the post-hydrolysis process, resulted in the lowest final phenylalanine content. The best condition for removing phenylalanine from milk was use of a combination of Aspergillus oryzae enzyme(0.5g of enzyme/100g of substrate) and papain (0.5 g of enzyme/100 g of substrate) with 0.9 g activated carbon in the post-hydrolysis process, resulting in removal of 99% of the phenylalanine.

Although diabetic patients are recommended to increase their intake of fiber, there is evidence showing that these patients have a low fiber intake in Iran. The purpose of this qualitative research project was to investigate the benefits and barriers regarding consumption of high-fiber foods as perceived by type-2 diabetes patients. In this qualitative study, conducted in 2010, six focus group discussions (FGDs) were held with 55 type-2 diabetes patients 34 –70 years old. Data analysis was done using the Strauss and Corbin' s analytical method for qualitative studies. Perceived benefits of high-fiber food consumption included better blood sugar control, improved gastro-intestinal function, and prevention and control of some diseases. The main perceived barriers could be classified into 3 groups: personal (lack of awareness, lack of interest, lack of sufficient time, cost, dental problems, false beliefs, fear of hyperglycemia, fatigue, and gastrointestinal problems); social (lack of awareness, lack of family support, and family pressure); and educational (insufficient education and insufficient service accessibilty). The results reveal the benefits of, and the barriers to, high-fiber food consumption as seen by type-2 diabetes patients. These findings can be used in designing educational intervention programmes based on the transtheoretical model, aiming at changing nutritional behavior of these patients leading to increased consumption of high-fiber foods.

Developing minced-based products is a good opportunity for production of value-added products. Fish burgers are an example of an acceptable value-added fast food. In the present study, fish burgers were produced from deep flounder fish with no coating and their chemical, microbial, and sensory characteristics during storage at 18C for 5 months were determined periodically after thawing at 4 °C. Fish burgers were produced and packaged in PVC/PE polymer bags. Microbial load (including total plate count, total coliform count, Escherichia coli, Staphylococcus aureus, and psychrotrophic bacteria), chemical characteristics (moisture, pH, total volatile base nitrogen (TVB-N), and TBA), and sensory characteristicswere were determined monthly. Data were analyzed using the SPSS for Windows program. The TVB-N and TBA values increased significantly by the end of the first and second month, respectively. After that no further statistically significalt changes occured in the former, while the latter decreased until the end of storage period, presumably due to reaction of the MDA produced with protein breakdown products and formation of new peoducts. The data also showed that pH increased significantly by the end of the first month; no changes were observed afterwards. All of the microbial counts and sensory parameters had decreased significantly (p<0.05) at the end of storage period. The best expiry time for lizardfish burgers (if stored at C˚18-) is 3 months after production, and sensory evaluation is the most reliable way for predicting their shelf life.

There is evidence suggesting an association between insomnia and obesity and probable beneficial effects of magnesium supplementation on insomnia. The objective of this study was to determine the effects of dietary magnesium supplementation on the energy intake and weight reduction of insomniac overweight or obese elderly subjects. A double-blind randomized clinical trial was conducted on 46 overweight or obese subjects randomly allocated into the magnesium or the placebo group, receiving, daily for 8 weeks, either 500 mg magnesium or a placebo, respectively. Using appropriate questionnaires, data were collected on insomnia (insomnia severity index = ISI), physical activity, and sleep-log at baseline and at the end of the intervention period. In addition, information was obtained on anthropometric confounding factors and daily intakes of magnesium, calcium, potassium, caffeine, energy form carbohydrates, fat and protein, and total daily energy intake using the 24-hr dietary recall questionnaire for 3 days. The N4 and SPSS software version 16 were used for data analysis, the level of significance being a p-value < 0.05. No significant differences were observed in the assessed variables between the two groups at baseline. As compared to the placebo group, in the experimental group diatery magnesium supplementation brought about statistically significantl increases in sleep duration and sleep efficiency, as well as significant decreases in the total energy intake and energy from carbohydrate and fat. The total length of time in bed, morning awakening time, energy from protein, serum magnesium concentration, or body weight were not different between the experimental and the placebo groups. In this study diatery magnesium supplementation resulted in improvements in sleep indices and a decrease in energy intake in elderly subjects. However, it had no beneficial effect on their body weight.

Increasing trends of overweight and obesity prevalence have prompted food producers to develop products that can enhance satiety signals. The role of short-chain fatty acids as satiety-inducing triggers seems to be of interest in this regard. The objective of this research was to investigate the impact of two process variables, namely, incubation temperature and inoculation ratio of starter bacteria, on propionic acid production in the fermented dairy beverages containing Propionibacterium immediately after fermentation and during cold storage. Fermented dairy beverage (FDB) samples were prepared using mixed cultures of Lactobacillus acidophilus and Propionibacterium freudenreichii ssp. shermanii at a ratio of 1:2, 1:4 and 1:8, repectively, at incubation temperatures of 30, 35 and 40°C, until the pH reached 4.0 ± 0.1. Propionic, lactic and acetic acid contents of the samples were measured immediately after fermentation using HPLC. The FBD samples were refrigerated for 28 days and the concentrations of the acids in the samples with the highest propionic acid content were measured. Sensory evaluation of the samples produced was made by 11 trained panelists using the hedonic scale. The maximum propionic acid content (w/w%) was observed in a mixed culture of L. acidophilus and P. freudenreichii ssp. shermanii at a ratio of 1:4 and an incubation temperature of 30 °C. It increased from 0.75 at day 0 to 1.2 at day 28 during storage at 4 °C. The incubation temperature had a statistically significant inverse effect (P<0.05) on the propionic acid production in the fermented dairy beverages.

Few studies have examined the association between dietary patterns and bone mineral density (BMD). The aim of the present study was to determine the association between dietary patterns and BMD in a sample of postmenopausal women living in Tehran. A group of 160 postmenauposal women participated in this cross-sectional study. Data were collected on their general characteristics, physical activity, and food consumption frequency using questionnaires, and their lumbar spine and femoral neck BMD were measured by dual-energy X-ray absorptiometry. Dietary patterns were identified using factor analysis, and multivariate logistic regression was used to estimate odds ratio (OR) for having lower BMD (values less than the median) as related to dietary patterns. Six dietary patterns were identified. The first (high consumption of high-fat dairy products, organ meats, red and processed meats, and whole grains) and the second (high consumption of French fries, mayonnaise, sweets and desserts, and liquid oils) patterns were associated with a lower BMD. Analysis of the data, after adjustment for potential confounders, showed that women in the second median of the first or the second dietary pattern scores were more likely to have a lower BMD at lumbar spine (OR=2.29, 95% CI: 1.05-4.96, P=0.04) and femoral neck (OR=2.83, 95% CI: 1.31-6.09, P<0.01), respectively. Dietary patterns rich in foods with a high content of saturated fats (similar to the first pattern) or those with a low density of essential nutrients for bone health (similar to the second pattern) may be negatively associated with BMD in postmenopausal women living in Tehran.

Starch-based biopolymer films have disadvantages such as poor mechanical and barrier properties against water vapour that restrict their application in packaging. To improve the properties of starch-based films, different methods such as blending with other polymers and adding nanofillers have been suggested. Cellulose nanocrystals (NCC) are a suitable candidate for reinforcing starch biopolymers due to their biodegradability, nontoxicity, abundance in nature, low price, and renewability. The objectives of the current research were to investigate the effects of NCC and polyvinyl alcohol (PVA) on the properties of starch-based films to improve their mechanical and barrier properties.

NCC was produced from cotton linter and added to the starch-PVA film-forming blend. Tests used to determine the properties of the films thus produced included mechanical, water- vapour permeability, thermal property, X-ray diffraction (XRD), and transmittance electron microscopy (TEM) tests.

Addition of PVA and NCC to film-forming solutions caused an increase in the maximum tensile stress (UTS) and a decrease in water-vapour permeability and solubility of the nanobiocomposit films. In addition, the XRD test showed that the 2 components − polymer matrix and nanofiller – were well dispersed in the blend. The optimum structure was observed at a concentration of 10% NCC.

Polyvinyl alcohol has OH groups and, hence, it can form hydrogen bonds with the starch OH groups, resulting in enhanced mechanical strength of polymer and improved mechanical and barrier properties of the biocomposite produced. Due to their high crystalline structure (as a result, high rigidity and elastic modulus) and their ability to form strong hydrogen bonds with starch and PVA, cellulose nanocrystals can potentially improve the mechanical and barrier properties of starch-based bionanicomposite films. The starch-based nanocomposites showed the highest UTS at a concentration of 10% NCC. At higher concentrations the UTS decreased, which could be attributed to aggregation of NCC in the polymer matrix. Aggregation of NCC at a level of 15% or 20% was observed as shown by XRD pattern peaks.

Presently 20-40% of Iranians suffer from food insecurity. Since factors associated with food insecurity vary in different communities, this study was initiated to determine the factors influencing food insecurity in mothers having primary school children living in Ray (a District of Tehran), Iran. A cross-sectional survey was conducted, in spring 2010, on 430 mothers having primary school children, selected by two-stage cluster sampling. A general information questionnaire was used to collect data on economic status and socio-cultural characteristics, and data on food intake and food security were collected using the 24-hour food recall and the USDA food security questionnaire, respectively. The statistical tests used for data analysis included the chi-square test, one-way analysis of variance, and simple regression. The prevalence of food insecurity among the mothers was 50.2%. The education level of the mothers and of the heads of households, ownership of residential unit, and having better home facilities were inversely associated with food insecurity. On the other hand, food insecurity increased with an increase in family size. The intakes of all the macronutrients except fat was statistically singnificantly lower in the food-insecure group. Based on the findings of this study the following recommendations can be made to improve household food security: increasing education level of family members, promoting family economic status, and adopting and implementing better population control policies.

One of the most common problems in modern communities is long-term high energy intakes due to consumption of high-energy foods, resulting in overweight and obesity. The objective of this study was to investigate the possibility of producing a low-energy sponge cake by complete or partial substitution of sucrose with erythritol and oligo-fructose.

Cake batter properties, including specific gravity and viscosity, as well as cake characteristics, including volume, apparent density, solid density, porosity, moisture and water activity, crust and crumb color, textural firmness, and flavour were determined.

Cake batter prepared using a mixture of erythritol-sucrose-oligofructose had a specific gravity and viscosity similar to the control batter. Furthermore, the volume, apparent density, solid density, porosity, moisture and crumb color of cakes prepared with such a mixture were not statistically different (p>0.05) from those of the control cake. The data also showed that, even while in storage, the cakes containing erythritol-sucrose-oligofructose were less firm than the control sample. The crust color of the experimental cakes was not singnificantly different from that of the control cakes (p>0/05), while their crumb color was less. Samples prepared with complete or partial replacement of sucrose with erythritol had a higher water activity as compared with the control value (P<0.05). Finally, cake samples prepared with a mixture of erythritol-sucrose-oligofructose had the closest taste score to that of the control cake.

It is possible to produce a low-energy and high-quality sponge cake with characterstics similar to those of the control cake by using an erythritol-sucrose-oligofructose mixture. Keywords:

Exam stress is an unpleasant emotional reaction to the process of assessment. It is considered as a serious and common educational problem. Exam stress causes eating disorders, including binge eating, which can lead to obesity and complications that usually accompany it. This study investigated the correlation between food intake and exam stress in 3rd-grade high school female students in Educational district 3 of Tehran, 2010. A cross-sectional study was conducted, in which 140 high school female students in the third grade of Educational District 3 of Tehran participated. Data was collected through interviews, one dietary recall and 3 food record questionnaires durig a week. Exam stress was assessed by the Test Anxiety Inventory. Data on 10 students were excluded because of unriable/inappropriate responses. Therefore, data analysis was done on the data collected on 130 subjects, using the SPSS 16 program. There were no relationships between food intake and the 4 exam stress groups or stress scores. The food subgroups which were found to have a significant association with exam stress were bread (p=0.003), rice (p=0.035), processed meats (p=0.031), dairy products (p=0.029) and industrially produced fruit juices (p=0.049). However, after adjustment for body mass index (BMI) and changes in food intake at stress time, the only food subgroup which had a significant positive relationship with stress scores was industrially produced fruit juices. The average intakes of energy, carbohydrate, and protein in the 4 stress groups differed significantly, but here again, after adjustment for BMI and changes in food intake at the time of stress, the differtences disappeard. Consumption of industrially produced fruit juices increases with increases in exam anxiety. Since such juices have a high content of sugar, this observation can be said to confirm the hypothesis of existence of apositive association between anxiety and carbohydrate consumption.

Biscuits are the most common bakery product after bread in Iran and have a long shelf-life. The technological properties of Iranian wheats used to produce biscuits have not been investigated so far. The objective of this study was to investigate the physico-chemical properties of 20 Iranian wheat flours and the sensory properties of biscuits produced from them. Twenty Iranian wheat cultivars released by the Seed and Plant Improvement Institute (SPII), Karaj, Iran were studied. The wheat grains were milled using the Quadrumate Senior Mill. The physicochemical characteristics of the resulting flours were determined according to AACC (2000) methods. Biscuits were then baked from each flour and their organoleptic characteristics determined by trained panelists. The physical and chemical characteristics of the wheat flours differed significantly due to differences in genetic make-up and environmental factors. Sensory evaluation showed no significant differences between the colors and tastes of the biscuits. However, significant differences were found among them with regard to texture, shape and surface and overall acceptability. Further analysis of the data showed that the sensory characteristics of the biscuits were statistically negatively correlated with their protein and gluten contents, gluten index, and SDS sedimentation. Biscuits produced from Golestan, Moghan, Prishtaz, and Omid wheat cultivars had the highest quality and acceptability. The Moghan cultivar was found to give the highest yield of flour, so it is the most suitable cultivar for biscuit production.

Germinated pinto bean flour (GPBF) has a high nutritional value. The objective of this study was to investigate the possibility of using it instead of wheat flour in producing sausages. Pinto beans were purchased from the local market, soaked in tap water for12 hours, and allowed to germinate at room temperature for 48 hours. The germinated beans were dried at 50°C for 16 hours, followed by milling to prepare flour, which was stored at –18 °C. Sausages (an experimental sample) were produced according to a commercial formulation, only replacing wheat flour with germinated pinto bean flour (GPBF) at levels of 4, 8, and 12% W/W. A sample produced with wheat flour served as the control. Moisture, fat and protein contents, and color, texture, flavour, and microbiological properties of the experimental samples were determined and compared with those of the control sample. There were no statistically significant differences (p<0.05) between the experimental and the control samples with regard to fat content, color, or texture. Samples produced with 12% GPBF had the highest contents of moisture (57%) and protein (12.32%) and the highest total bacterial counts (2800 cfu). The flavour of the control and the 4%-GPBF samples did not differ significantly (p<0.05), but their flavour was better than that of the 8%- and 12%-GPBF samples (p<0.01). Using germinated pinto bean flour in preference to wheat flour in producing sausages, it would be possible to develop a product with a higher nutritional value and acceptable physical, chemical and sensory properties.