فصلنامه علوم تغذیه و صنایع غذایی ایران
سال سوم شماره 1 (پیاپی 8، بهار 1387)

Recently, especial therapeutic effects and nutritional values of probiotic dairy products have made them as one of the most interesting research topics in the field of production and maitenance methods and the nutritional and therapeutic aspects of these products. The technological problems encountered in the production of these products can be overcome by using methods to improve the growth of probiotic bacteria in fermented milk. In this paper the effect of milk composition (skim milk and whey powder), percent of inoculum (Lactobacillus acidophilus La-5 and starter culture) and incubation temperature on the growth of the probiotic bacteria in yogurt was investigated, and suitable conditions to reach maximum growth were determined using the Taguchi design. The effect of five independent variables (at three levels) on the growth of Lactobacillus acidophilus La-5 (6 hr incubation) in probiotic yogurt production was investigated by Taguchi approach. The variables included: skim milk powder (10, 12, 14% w/w), whey powder (0, 0.75, 1.5% w/w), size of yogurt culture inoculum (0.2, 0.4, 0.8% v/v), L. acidophilus inoculum (0.1, 0.3, 0.5% w/v), and incubation temperature (37, 40, and 43°C). Among the variables evaluated, yogurt culture inoculum had the maximum effect on the growth of probiotic bacterium, while the incorporation of L. acidophilus inoculum and the incubation temperature had no significant effect on the bacterial growth stimulation. Anyway the most suitable conditions for enhancing the probiotic bacterial growth include: skim milk powder, 10 % w/w; without adding whey powder and size of yogurt culture and L. acidophilus inoculum, 0.1%w/v and 0.4% v/v, respectively incubation temperature at 37°C. By exact determination of milk composition, inoculum size and incubation temperature, the maximum number of the probiotic bacterium can be achived in the product. Data of this research work, that are very useful for the industrial production lines, show that by using the minimum level of milk total solid, without the enrichment and by adding the standard yogurt inoculum size and minimum probiotic inoculum size and by low incubation temperature, the growth rate increased and the production of probiotic yogurt with high number of Lactobacillus acidophilus become possible.

Soybean soluble polysaccharides (SSPS) are a food additive with various applications, including the stabilization of emulsions and dairy-based acid beverages. They are normally extracted from okara, a waste product in the production of soy products. In this study the feasibility of the extraction of SSPS from dried okara with and without demethoxylation and from wet okara (obtained in the process of soy milk extraction) with demethoxylation was investigated. In order to optimize the demethoxylation conditions, the response surface methodology (RSM) was used and demethoxylation was carried out at different temperatures (60, 75 and 90oC) and okara:water ratios (1:6, 1:8 and 1:10). Different types of SSPS were extracted at various temperatures (120 and 130 oC), pHs (3 and 4.5) and heating times (2 and 3 h). Then, the extracted juices were purified (using ethanol for precipitation of high-molecular weight SSPS), dehydrated, and analyzed. Each one of the independent variables (demethoxylation temperature and okara:water ratio) was linearly related to the response (total soluble solids extracted), the effects being statistically significant (P<0.01 and P<0.0001, respectively). In addition, the total soluble solids increased at high extraction temperature and low pH conditions. The findings also showed that pH was an important factor in the extraction of high-molecular weight SSPS (HM-SSPS). Furthermore, when the demethoxylation process was used, the maximum yield of HM-SSPS (22.4%±1.04%) was achieved at the following conditions: 130 oC, 3h, and pH=4.5; on the other hand, without demethoxylation the highest yield (30.8%±1.6%) was obtained at these conditions: 120oC, 2 h, and pH=4.5. The soymilk okara was found to be a feasible natural source for the extraction of various types of SSPS. Our findings also revealed that the dehydration of wet okara could prevent its spoilage and improve the yield of SSPS.

Introduction and Iron deficiency and iron-deficiency anemia are one the most important health problems in the world. Iron supplementation can reduce both Zn absorption and plasma vitamin C concentration. In this study, effects of iron supplementation with and without ascorbic acid on Zn and vitamin C status in iron-deficient university female students have been studied. This study was a double-blind randomized clinical trial. Sixty non-anemic iron-deficient (NAID) girls were selected from 289 female students at Fatemeh Zahra (PBUH) dormitory, Shahid Beheshti University of Medical Sciences, Tehran. They were divided randomly into 2 groups, receiving either 50 mg/d elemental iron supplement (group I, intervention) or the supplement plus 500 mg/d ascorbic acid (group II, control) for 12 weeks. Blood analysis was made at the beginning and the end of the 6th and 12th weeks in the two groups. Hemoglobin and serum ferritin concentrations were measured using cell-counter and ELISA, respectively. Serum zinc and iron concentrations were analyzed by atomic absorption spectrophotometry and plasma vitamin C was analyzed by the 2, 4-DNPH method. The Student's t and repeated-measures tests were employed to analyze the data using the SPSS software. The serum zinc level was not initially significantly different between the two groups. It decreased from 80.94.2 to 68.92.7 and from 81.24.5 to 66.12.9 µg/dl by the 6th week in groups I and II, respectively (p<0.001), but by the 12th week it increased significantly to the pre-intervention value of 792.9 µg/dl (p<0.01) in group I and, non-significantly, to 70.53.1 in group II. On the other hand, plasma vitamin C increased from 3.00.1 to 3.30.2 mg/l (NS) in group 1 and from 2.7.0.1 to 4.20.2 mg/l (p<0.01) in group II by the 6th week. The incremental trend in group II continued between the 6th and 12th weeks (3.30.2 to 4.70.3 mg/l in group I, and 4.20.2 to 7.10.2 mg/l in group II; in both cases p<0.001). Serum ferritin and iron levels increased significantly in both groups (p<0.01). Iron supplementation with and without vitamin C in iron-deficient female students causes serum Zn reduction after 6 weeks. However, the decreasing trend stops after repletion of iron stores, the Zn level returning to the baseline value. Twelve weeks of iron supplementation does not seem to cause reductions in the serum zinc and plasma vitamin C levels in this age group.

In April 2002, a research group at Stockholm University and the Swedish Food Administration announced that significant amounts of acrylamide might be formed during common heat processing of foods. Since acrylamide is classified as “probably carcinogenic to humans” by the International Agency for Research on Cancer (IARC), these findings were considered as alarming. The most important food sources of dietary acrylamide are fried potato products like chips and French fries, which are popular snacks in Iran. The aim of this study was to investigate the effects of reducing sugars and amino acids in three potato cultivars on acrylamide formation in potato chips produced on a laboratory scale. Potato chips samples were produced on lab-scale from three potato cultivars namely Sante, Agria and Omidbakhsh by frying at 180 ºC for 4.15 min. Reducing sugars (glucose and fructose) and asparagine concentration in raw potato samples were determined using HPLC. A suitable and valid method was set up for determination of acrylamide in the chips samples by gas chromatography/mass spectrometry, GC/MS. The reducing sugars and acrylamide contents were significantly different among potato chips samples produced from different cultivars (p<0.05). The highest amount of reducing sugars was found in cultivar Sante (3513 mg/kg) followed by Agria (2111 mg/kg) and Omidbakhsh (1622 mg/kg), respectively. On the other hand, cultivar Omidbakhsh had the highest amount of asparagine (1871 mg/kg). The highest amount of acrylamide (8825µg/kg) was formed in the chips from cultivar Sante and the lowest amount was formed in the chips from cultivar Omidbakhsh (5112 µg/kg). A high content of asparagine in raw potatos was not necessarily an indication of high content of acrylamide in the produced chips. The two cultivars with higher content of reducing sugars, showed the higher potential for acrylamide formation in the chips. This indicates that the concentration of reducing sugars is a more important parameter than asparagine content in the formation of acrylamide in potato chips. The selection of proper potato cultivars with naturally lower contents of precursors of acrylamide specially reducing sugars is important factor to reduce the acrylamide formation during production of potato chips. With respect to the results obtained from this study, it is suggested that cultivar Omidbakhsh is the most suitable cultivar in Iran for the industrial production of potato chips with low levels of acrylamide.

An understanding of resting energy expenditure (REE) in hospitalized patients is essential for determining their daily energy needs, which can be measured or estimated by equations. Estimation is by far the more common method. This cross-sectional study investigated the degree of agreement between the resting energy expenditure as measured by indirect calorimetry and that predicted by the Harris Benedict and Mifflin-St Jeor equations. Methods and Materials: In 60 randomly selected patients, aged 18 and 83 years, REE was measured by fitmate indirect calorimetry (Cosmed company, Rome, Italy) and compared with values predicted using Harris Benedict and Mifflin-St Jeor equations. Statistical analysis was done using the method of Bland-Altman, one-sample t-test and Pearson’s correlation. There were no significant differences between mean REEs measured by indirect calorimetry (1311/66 ± 373/98 kcal/day) and mean REE values predicted by Mifflin-St Jeor (1303/11 ± 230/94 kcal/day) or Harris Benedict (1339/36 ± 223/48 kcal/day) equations. However, at an individual level the limits of agreements between the measured values and those predicted by both equations were quite wide (Mifflin-St Jeor: 792/83 to 775/73 kilocalorie/day, Harris Benedict: 714/58 to 769/98 kilocalorie/day). At a group level, Harris-Benedict and Mifflin-St Jeor equations are suitable for predicting REE of hospitalized patients. However, the results suggest that for an individual the limits of agreement are very wide in both equations and clinically important differences in REE would be obtained.

Diversity of sources and information services in the field of food science and technology in Iran, and problems and difficulties of having access to them, are inhibiting factors in their use. Preparation and publication of the Iranian Food Science and Technology Data Bank (IFSTDB) and its regular updating have facilitated complete and quick access to the existing information sources in Persian. In this article the methodology of the preparation of IFSTDB is explained, followed by analysis of its contents during the period 1978-2001. Research Information was collected by a trained team. The team members consulted directly the educational, research and executive institutes and canters active in the field of food science and technology and completed bibliographic worksheets containing items/questions on seven types of documents,, including articles in scientific journals, abstracts/full papers presented in conferences, M.Sc. and doctoral dissertations, research project reports, books, food standards, and patents, during the period 1978-2001. The documents were classified into main groups and subgroups, using the Food Science and Technology Abstracts (FSTA) as a model, followed by coding and selecting proper keywords. Data entry and processing were carried out using a software designed for the purpose, and a compact disk (CD) of IFSTDB was prepared. Relative frequency distributions of the documents were determined according to the type of document, time period (3-year intervals), and subject, and an analysis of the shares of journals and conferences and the contribution of specialists and researchers in publishing the documents was made. The findings are presented in the form of tables and histograms. The total number of documents collected was 5071, consisting of 443 (8.7%) journal articles, 1725 (34.0%) conference abstracts/full papers, 405 (8.0%) research projects, 956 (18.9%) dissertations, 344 (6.8%) books, 1046 (20.6%) food standards, and 152 (3.0%) patents, classified into 18 groups and 118 subgroups, and 4750 keywords were chosen. This Data Bank contains published information from 780 organizations, 46 scientific journals, 111 conferences, and 3739 authors. The highest proportions of the documents were on fruits, vegetables and nuts (18.0%), milk and milk products (10.9%), and food additives, spices, and condiments (10.5%) groups, while the lowest proportions belonged equally (0.6%) to cocoa, chocolate and confectionary products, eggs and egg products, and food economics. The largest number of documents belonged to the 1999-2001 period and the lowest number to the 1981-83 period. The average number of documents added annually to the Data Bank was 211. Publication of IFSTDB aims at facilitating selection of scientific documents, information collecting, avoiding unnecessary repeats, and improving and promoting educational and research activities, by accurate and precise planning for the future, taking into account the needs and gaps. It is recommended that IFSTDB be updated and presented in different forms and a survey on its documents is carried out regularly.

Most of our food habits and preferences originate during childhood. Following an adequate and balanced diet from childhood is one of the most important factors in preventing degenerative diseases in adulthood. Thus, determining children’s food consumption patterns is a high health priorities. The present study was initiated to determine meal and snacking patterns of primary school children during 2003-2005 in Tehran. Methods and Materials: A total of 761 male and female primary school children (378 grade 1, 383 grades 2 to 5) from all the 19 Educational Areas in Tehran, selected by multistage cluster sampling, were included in the study. General information was collected in 2 parts, by interviewing (1). the students, and (2). the students’ mothers or caregivers. For collecting information on food consumption during the previous month the 24-h-recall technique and a snack-frequency questionnaire were used. Results are reported as means ± standard deviations and frequency distributions. The mean daily intakes of energy among the first and other grade students were 1910±551 and 2014±539 kcal, respectively. As compared to RDA, energy intake (95% RDA for grade 1 and 91% for other grades) and iron intake (86% for other grades) were inadequate, while the intakes of other nutrients were adequate. The mean intakes of energy, protein and some of the B vitamins among girls were higher than among boys (P<0/05). The largest proportions of daily energy were supplied by lunch (%28) and the afternoon snack (%22). Snacks provided about 40% of the daily total energy intake. Densities of protein and fat (per 1000 Kcal) were higher in the main meals, while those of carbohydrate, calcium and vitamin C were higher in snacks in both boys and girls. The iron density was almost the same in the main meals and snacks. Fruits and confectionary products were consumed as snacks by almost all of the students during the week. Snacks have a significant role in meeting daily energy and nutrients needs of primary school children. In some cases the role of snacks was even more significant in fulfilling energy needs than that of main meals (e.g. breakfast). It is very important to implement appropriate educational programs aiming at improvement of children's food choices.