مجله علوم غذایی و تغذیه
سال یازدهم شماره 4 (پاییز 1393)

Lipolysis during cheese ripening is one of the main biochemical reactions. In pasteurization natural lipase present in milk becomes inactive. Therefore lipolysis occurs in Iranian cheeses at low level. The aim of this study is to accelerate the ripening of traditional and ultra-filtered Feta cheeses by lipolysis and evaluate the effect on the microbiological characteristics of the cheeses. Aspergillus niger encapsulated lipase was prepared according to Sol-Gel method. For producing cheeses after milk fat standardization where the pasteurization was carried out at 75 °C for 15 s, the milk was cooled and the starter, rennet and lipase were added in three forms of encapsulated, encapsulated with arabic gum and non- encapsulated to the traditional and UF-Feta cheeses. The amount of added lipase to curd or retentate was 4 g/100kg. The lipolysis development and evaluations of chemical, microbial and sensory characteristics were performed during the 60 days of ripening. On the 15th day of ripening period the lipolysis development and chemical compounds observed had significant differences at the P< 0.05 between the traditional and UF- Feta cheeses. The microbial counts were negative after 15 th day.Encapsulated lipase treatment of UF-Feta cheeses had the highest sensory score. Accelerated lipolysis in cheese might be regarded as a ripening indicator. Production of free fatty acid and hygroscopic additive like arabic gum had prevention effect on microbial counts in the final product and improved the sensory properties.

The hazards of antibiotics and synthetic preservatives have been identified, therefore researchers are looking for natural and safe alternatives. Annatto dye is used in the food industry, widely. Annatto dye has antimicrobial and antioxidant properties. The subject of this study was to evaluate the antimicrobial effect of annatto dye on Salmonella Enteritidis in mayonnaise. Annatto dye was extracted by maceration methods and after concentration, the powder was produced using vacuum oven. Samples containing 0.1, 0.2 and 0.4 percent annatto dye and 1 ml of 1.5 mac farlan microbial suspension (include 1.5 × 108 CFU) were prepared and stored at 4 and 25 ˚C. 1 ml from each dilution was cultured as pour plate to evaluate the bacterial survival of the sauce. The colonies were counted as log cfu/g for the duration of twenty days in triplicate orders. The survival of S.enteritidis was decreased by increasing the annatto dye in both temperatures and has a significant difference with the control sample (P < 0.05). The population of S.enteritidis has shown more reduction at 25 ˚C as compared to 4 ˚C. Therefore the population of S.enteritidis would reach the minimum concentration under 25 ˚C after 17 days. Annatto dye decreased the survival of S.enteritidis in mayonnaise sauce. Temperature of 25 ˚C imposed more fatality effect on S.enteritidis in mayonnaise sauce. Therefore, annatto dye might be employed as an inhibitor in such products.

Sugar is highly consumed and is used as an ingredient for other foods. This product is produced by a long and expensive process. Some parts of this process might be eliminated to prevent the loss of nutrients with high value. In this study phenolic compounds have been considered as a valuable indicator among the nutrients to be studied regarding the changes during one year storage that is the mean shelf life for sugar. In this study the effect of storage time on sugar samples is investigated by measuring the changes in phenolic compounds by singleton method and changes of chemical and microbial attributes by the international standards of ICUMSA. Chemical tests indicated that the storage time reduced the color, invert sugar and sucrose while the phenolic compounds were increased considerably. According to the results, with controlled conditions one might produce sugars of high quality and on the other hand through the production one might prevent the loss of nutrients.

Appropriate nutrition is an essential prerequisite for effective improvement of athletic performance, conditioning and recovery from fatigue after exercise, and avoidance of injury. Nutritional supplements containing carbohydrates, proteins, vitamins, and minerals have been widely used in various sporting fields to provide a boost to the recommended daily allowance. Coenzyme Q10 (CoQ10) is a naturally occurring, lipid-soluble compound that has been marketed for use by endurance athletes as an ergogenic aid. The aim of this study was to examine the effect of coQ10 dietary supplementation on athletics’ physiological factors such as: aerobic power, peak power, min power, average power and fatigue index. In this semi-experimental study, we studied 20men football players (age30±2.22, weight 72.85±8.64kg, height175.75±6.04cm, BMI23.50±1.90). Double-blind, placebo controlled method was employed. Players were divided randomly into two groups, oral CoQ10 group (DG) and placebo group (PG). Players in both groups performed RAST and Cooper test both before and after giving 100mg per day CoQ10 or placebo for 6 weeks to determine physiological factors such as aerobic power, peak power, min power, average power and fatigue index. We used paired t test and independent t test to analyze the data. Independent t test were performed and p < 0.05 were considered statistically significant. DG group demonstrated improvements in aerobic endurance over the course of the study and there was significant difference (P=0.016) between the two groups. Supplementation with CoQ10 has no measurable effect on peak power (P=0.933), min power (P=0.258), average power (P=0.625) and fatigue index (P=0.569). Oral CoQ10 has measurable effect on aerobic endurance. The result of this study showed that at the end of the six week there was no difference between the two groups concerning peak power, min power, average power, and fatigue index.

Raspberry has been considered a good source of some micro and macro nutrients namly (anthocyanins, polyphenol, ascorbic acid, fiber, proteins and minerals). Due to high metabolic activity and susceptibility to fungal decay and especially gray mold, it is one of the most perishable fruits and has a short shelf life. The use of modified atmospheric packaging increases the shelf life of the fruits like raspberries and therefore the commercial value of the fruit is increased. In this study the RSM design is used to assess the effects of three variables; CO2/O2 (three levels; zero, one and two v/v), time (0, 5 and 10 days) and perchlorine concentration (0, 250, 500ppm) on raspberry weight loss, acidity, texture and microbial load. Rasberry fruits were packed in the two layer plastic packaging made of polyamide with thickness of 50 microns and stored at 4˚C The results showed that the time, perchlorine concentration and CO2/O2 ratio had significant effects on the qualitative properties of raspberry fruit and its shelf life. Increases in perchlorine concentration and CO2/O2 ratio had positive effects on keeping quality of the fruit. The application of modified atmospheric packaging can improve the qualitative characteristic of raspberry fruit.

In recent years chemical preservatives have been commonly used in foods to increase the shelf life. Due to these preservatives their continuous use in food might not be recommended therefore the application of natural preservatives, substances that have been employed for a long period is preferred. In this research, the antimicrobial effects of garlic extract, a natural preservative has been investigated in ready to cook chicken. The minimum inhibitory concentrations of the garlic extract were determined by using agar dilution method for Staphylococousaureus and Escherichia coli O157:H7in vitro. Furthermore for testing the antimicrobial effect of garlic extract in food system, different concentrations of garlic extract (0, 6, 7, 8, 10 mg/ml) were added to ready to cook chicken and the activities were evaluated after 24, 48, 72 hours and one week. The effects of adding different concentrations of extract on sensory behaviour were also evaluated. The results have shown that Garlic extract has significant anti-microbial effects on the tested bacteria and the MIC was 7 mg/ml for both bacteria. By increasing the concentration of the garlic extract, the counts were reduced (p<0.05). It is also proved that the optimum concentrations (7, 8 mg/ml) of garlic extract had a significant effect on the sensory characteristics of cooked chicken. The optimum concentration of garlic extract, apart from decreasing the bacterial counts and increasing the shelf life, had a positive effect on organoleptic properties of cooked chicken. Therefore this compound might be employed as replacement for the chemical preservatives used in food industry.

Cherry is one of the most popular and important horticultural products for the food processing industry. Since polyamines compounds in postharvest processing have a special role, this study was conducted to examine the effect of polyamines on the firmness and the shelf life of cherries after harvesting. In this study, 16 trees of 19 years old with the same growth condition were randomly selected. After selecting the healthy branches the external parts were treated with two types of polyamines, spermidine and putrescine in triplicate orders. The former was applied at the concentrations of 0.1, 0.5 and 1 mM and the latter at 0.5 and 1 mM. External applications of polyamines were carried out in three phenological stages, 5 to 10 days before the full bloom, 5 to 10 days after the full bloom and the staining. After treatment, characteristics such as fruit size, fruit weight, acidity (TA), soluble solids, percent carbohydrate, and ratio of soluble solids to acidity were measured. Spermidine 1 mM treatment increased size and weight, and also increased the amount of carbohydrates and fruit firmness. Treatment of polyamines, especially spermidine in 1 mM increased the firmness and durability and the effect strongly depends on the time of spraying and the concentration of these compounds.

Hydrocolloids or gums are defined as macromolecules that could dissolve or disperse in water and give viscous solutions or gels. In this study, the effect of salts at different concentrations on the rheological properties of Basil seed gum solution was studied. The effects of sodium and calcium chloride at concentrations of 0.1, 0.25, 0.5 and 1% on the rheological properties of Basil seed gum solution (0.2%) were investigated. Rheological properties of solutions were measured by a Brookfield rotational viscometer. In all solutions, with increasing shear rate, the apparent viscosity decreased, indicating the pseudoplastic behavior of Basil seed gum. Interactions between gum and salts decreased the viscosity of solutions and the amount of viscosity change depends on the type of salt. Apparent viscosity is clearly decreased from 8.1 to 1.9 mPa.s with increasing sodium chloride concentration from 0.1 to 1 % (shear rate=61.2 s-1). Power law model well described the non-Newtonian behavior of Basil seed gum in the presence of salts. Fitting with this model showed that the consistency coefficient (k) and flow behavior index (n) were influenced by the type and the concentration of salts content. Addition of sodium and calcium chloride led to increases in flow behavior index and decreases in pseudoplastic properties of the solutions.

Tempeh is a traditional soy product originally from Asia. Because of its nutritional value, tempeh is used worldwide in vegetarian cuisine, where it is used as a meat analogue Oat tempeh is produced with Rhizopus oligosporus PTCC 5287 with approximately 104 CFU/g. Biological acidification is carried out with inoculation of three starters containing streptococcus,Lactobacillus, lactococcus and chemical acidification is provided by the addition of 5ml/100g vinegar. Bacillus cereus is inoculated with approximately 105 CFU/g. The Results showed that co- fermentation of lactic acid bacteria and Rhizopus oligosporus caused a decrease in mold growth (p<1%). The highest effect is from the tempeh that was produced with lactococcus lactis sub sp lactis, lactococcus lactis subsp cremoris and the one that was acidified with vinegar. The highest ergostrol and hyphal length is related to the non- acidified tempeh. Biological and chemical acidification caused decreases in Bacillus cereus growth. The highest decrease was observed in tempeh that was made with lactococcus lactis sub sp lactis, lactococcus lactis subsp cremoris. In all the cases tempeh with good quality was produced.

The role and beneficial effects of antioxidants against various human diseases and food deterioration induced by oxidative stress have received much attention. The free radical scavenging antioxidants are one of the important classes of antioxidants and the assessment of their capacity has been the subject of extensive studies and argument. Various methods have been developed and applied in different systems, but many available methods result in inconsistent results. In this review article, the some available methods are critically reviewed on the basis of the mechanisms and procedure and pros and cons of the methods are proposed to assess the capacity of radical scavenging and inhibition of lipid peroxidation in vitro. The ABTS, DPPH, FRAP, ORAC, TRAO, CBA Fast BB, Folin-Ciocalteu and DSC assays were used to evaluate the comparability of the most common radical scavenging assays and achieve a wide range of technical principles of them. Chemical-based methods are useful for assessment of antioxidant capacity, they are low cost, simple and yield an index value (expressed as equivalents of Trolox) that allows to compare the results. However, the antioxidant capacity indexes obtained by chemical assays cannot extrapolate the performance of the sample in vivo. Because some of the assays are done in non-physiological pH values, it is necessary to move to cellular assays in order to evaluate the potential antioxidant activity of a compound or extract. Animal models and human studies are more appropriate but also more expensive and time-consuming. At present, in spite of the diversity of methods, there is a great need to standardize the measurements of antioxidant activity. The consensus of opinion is that a mix of these tools should be used in assessing the antioxidant activities in vitro.