فصلنامه علوم تغذیه و صنایع غذایی ایران
سال پنجم شماره 2 (پیاپی 17، تابستان 1389)

In the preparation of soft and hard frozen yogurt, it is desirous to have a final product that is not only stable but also attractive in appearance, as well as smooth and free from graininess. The effects of some stabilizers on physicochemical and sensory properties of frozen yogurt was investigated in this study, so that we could identify the most suitable stabilizers to be used in future studies. All samples contained 10% fat, 13% sucrose, 13% non-fat milk solids, and 0.1% vanilla, and the stabilizers used were Panisol ex, carboxymethyl cellulose, and a mix of stabilizers and emulsifiers (sodium alginate (0.23%), guar (0.13%), carageenan (0.05%), propyleneglycole (0.48%), and polysorbate 80 (0.097%)) at 3 concentrations, namely, 0.144, 0.198, 0.254%. Statistical analysis of data was performed using a two-factor completely randomized design in three replications, using the MSTAT-C software. Analysis of variance was done with Duncan’s multiple range test (p<0.05). No significant changes were observed in the acidity and pH of the products, but viscosity, over-run capacity, and melting resistance were influenced significantly by type and concentration of stabilizers (p<0.05). The highest values for over-run and melting resistance were observed in samples containing Panisol ex and the lowest in samples containing carboxymethyl cellulose. The findings on the sensory scores showed that frozen yogurt produced using mix of stabilizers/emulsifiers at a concentration of 0.254% had the highest score in texture (p<0.05). Type and concentration of stabilizers had no significant effects on mouth feel and flavour of the samples. The use of Panisol ex and mix of stabilizers/emulsifiers at a concentration of 0.254% is recommended for producing frozen yogurt.

Severe and intense exercises by athletes will increase the risks of infectious diseases of the upper respiratory system and digestive system disturbances, resulting in chronic exhaustion and reduced efficiency. Very few studies have been made on the effects of probiotics on athletes’ immunity system and work efficiency during training and in tournaments. This study was carried out to determine the effects of consuming probiotic yogurt on performance, respiratory infections, and digestive disorders of Tehrani juvenile athlete girls involved in intensive swimming during 2009. This was a randomized controlled trial. It included 46 endurance girl swimmers with a mean age, weight, and height of 13.8±1.8 years, 48.6±7.5 kg, and 159 ±5.6 cm, respectively, participating in 400 and 800-m crawl swimming tournaments in 2009. They were randomly assigned to two groups, receiving daily for 8 weeks, either 400 ml probiotic yogurt (intervention group) or ordinary yogurt (control group). All the subjects were asked to record daily, on a questionnaire, digestive symptoms; respiratory infections, exercise performed (in meters), intake of medicines, and the exact quantity of yogurt consumed. At the beginning and at the end of the eighth week the 400-m free swimming record was recorded and the Harvard Step test was employed to measure VO2max. The data were analyzed using the SPSS17 software. The average changes in the records of the intervention and control group were 3.9 and 0.5 seconds, respectively (P = 0.22). On the other hand, the change in VO2max in the intervened group was 0.56, and in the control group 0.01, ml/kg-1.min-1, in both cases statistically significant (p=0.02). Analysis of the data also showed that, on the average, the intervention group complained of dyspnea, a symptom of respiratory infection, for 2.4 days, the control value being 4.3 days (p=0.024); the corresponding figures for ear pain, another symptom of respiratory infection, were 0.52 and 1.6 days (p=0.008). The average number of episodes of respiratory infection in the intervention group was one day, which was statistically fewer than that in the control group (1.4), the difference being statistically significant (p=0.009). In addition, the average number of episodes of digestive disorders was 0.9 in the intervention group and 0.6 in the controls (p=0.05). After 8 weeks of intervention, no significant difference was found between the 2 groups with regard to the average duration of respiratory infection or digestive disorders. Consumption of probiotic yogurt results in a reduction in the number of episodes of respiratory infections and in duration of some of its symptoms as dyspnea and ear pain; the reduction in digestive symptoms did not reach statistical significance. It also brought about a significant improvement in VO2max and a non-significant decline in the record of 400m crawl swimming. Further studies on the effects of probiotics on athletes’ nutritional health and performance in other sports are recommended.

Citrus peel, a by-product of fruit juice industry, is a source of natural antioxidants. The search for natural antioxidants for use in food technology, cosmetics, and pharmaceutical science has become a major industrial and scientific research challenge in recent decades. The objective of this study was to determine the antioxidant activity of the inner sour orange peel (mesocarp) extract, the antioxidant stability of the extract by the ferric reducing antioxidant power (FRAP) method, and its protective effect on lipid oxidation in raw and cooked fish by the thiobarbituric acid reactant substances test (TBARS) technique.

An ethanol extract of the inner sour orange peel (mesocarp) was prepared. Samples of the aqueous solution of the extract were then stored for 1 month under different conditions (light, room temperature,, dark room temperature, refrigerator, and freezer). The antioxidant activity and stability of the samples were measured by the FRAP assay and their short- (90 minutes) and long-term (14 days) protection effect on lipid oxidation was evaluated using the TBARS test.

The initial FRAP value of the 0.1% aqueous solution of the extract at room temperature (570 µM) decreased by 14% after one month (p=0.007). The change in the FRAP value of a 0.005% aqueous solution of vitamin C under the same conditions was a 77% decrease (p=0.000) from an initial value of 541 µM. The data also showed that the TBARS value of the raw fish samples containing no extract increased from 1.32µM to 3.173 µM after 14 days, while in presence of a 5% aqueous solution of the extract the increase was from 0.92 µM to 1.09 µM (p<0.05). Under the same conditions, the increases in the TBARS value of the cooked fish samples were also significant─from an initial value of 2.28 µM to 5.85 µM (p=0.000) and from 1.77µM to 3.11 µM (p=0.000) in the absence and in the presence of a 5% aqueous solution of extract, respectively.

The results show that sour orange mesocarp extract has antioxidant activity with high stability during storage and a protective effect on lipid oxidation.

Dietary diversity score (DDS) is a general index for assessing the whole dietary intake. This study was conducted to determine the relationship between dietary diversity score (DDS) on the one hand and obesity and central adiposity on the other hand in female students in Isfahan University of Medical Sciences. Subject and A random sample of 289 healthy female university students aged 18-28 years, representative of Isfahan University of Medical Sciences female students, participated in this cross-sectional study. A validated semi-quantitative food frequency questionnaire was used to evaluate the usual dietary pattern. DDS was calculated based on scoring 5 food groups. Weight, height, and waist circumference were measured according to the standard protocols. The subjects were categorized based on quartile cut-points of dietary diversity score. Means (±SD) of body mass index, waist circumference, and DDS were 25.9±5.1 kg/m2 and 85.5±14 cm, and 6.78±1.12, respectively. The probability of both obesity and central obesity decreased with quartiles of DDS (odds ratios among quartiles for obesity were 1.00, 0.39, 0.30, and 0.20 (P<0.04) and for central adiposity 1.00, 0.53, 0.35, and 0.20 (P<0.03). Subjects in the lowest DDS quartile had the highest risk for being overweight. There are inverse associations between DDS and obesity or central adiposity in Isfahani female university students. Further prospective investigations will be needed to confirm these findings.

Mustard is a plant belonging to the Crucifera family and brassica genus. There exist more than 40 cultivated and 200 wild species of this plant in the U.S. and Canada. Yellow mustard has antimicrobial and flavouring properties and is used in the food industry as an additive. The purpose of this study was to investigate the effects of different concentrations of yellow mustard powder on pH, microbial population, shelf-life, and organoleptic properties of mayonnaise. Samples of mayonnaise were prepared with different contents of yellow mustard powder (0.0%, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5%) and with and without 2 chemical preservatives, namely, potassium sorbate (0.065% and 0.008%) and sodium benzoate (0.035% and 0.004%). The microbial population was counted in the samples at 0 hour and after 24 hours, 1, 2, and, finally, 3 months, when the pH, colour, and organoleptic properties were also determined. The results showed that the mayonnaise sample containing 0.5% yellow mustard powder was desirable due to its microbial population-reducing effect and longer shelf-life, while the sample containing 0.3% yellow mustard powder was the most suitable with regard to its good organoleptic properties. Mustard powder contents above 0.3%, although they decreased the microbial population and increased the shelf life of mayonnaise, produced undesirable sensory changes, such as increased bitterness and dark color, confirmed by the Hunter Lab spectrophotometer test and taste panel results. The findings of this study confirm the anti-microbial effect of yellow mustard powder, resulting in longer shelf-life of mayonnaise. More research should be conducted with a view to producing a mayonnaise with no chemical preservatives by adding yellow mustard powder at concentrations which will bring about less undesirable changes in flavor and color.

Overweight and obese individuals usually are not satisfied with the current weight-losing programs; such programs fail too often. Therefore, finding approaches such as motivational interviewing, which may potentially increase the effectiveness of the treatments, seems essential. The aim of this study was to determine the effect of motivational interviewing on weight loss in overweight and obese individuals. This was a quasi-experimental study. The subjects were 40 overweight or obese persons (body mass index (BMI) above 25) working in Isfahan Poly Akril Company in 2009. They were selected by random sampling and randomly assigned to an experimental (No.=20) or a control (No.=20) group. The experimental group was given a weight control program and attended 5 sessions of group motivational interviewing. Weights and heights were measured before, during, and after the intervention. The data were analyzed using the covariance analysis and the independent t-test. Both groups lost weight, but the extent of weight loss and BMI reduction was more in the experimental than in the control group (P-value 0.001 and 0.0001, respectively). Although the statistical significance of the effect of motivational interviewing decreased a little over time, the amount of weight lost was still more in the experimental group. Including motivational interviews in the current weight control programs can lead to higher reductions in body weight and body mass index in overweight and obese people.